James S.A. Corey's answer to There Aint No Stealth In Space.

[morr...@gmail.com]

I'm a long-time voracious consumer of science fiction of all sorts, but only recently came across the wonderful resource that is Atomic Rocket. I was particularly interested in his thoughts on stealth because I, apparently like many others, had envisioned space combat as far more like submarine combat, and nothing at all like Carrier Air Warfare as it is so frequently and romantically portrayed. I thought there were a few things missing in his analysis though, let me know if you agree.

http://www.projectrho.com/public_html/rocket/spacewardetect.php#nostealth

Item the first: All the math seems to assume a very conventional Fission Reactor with a very modern and conventional 20% thermal efficiency. That's all well and good, but there are even today designs and prototypes for Fusion reactors of various types with thermal efficiencies significantly higher than that, with projections as high as 90% which would dramatically reduce the Waste Heat Problem.

https://en.wikipedia.org/wiki/Direct_energy_conversion

While obviously there are a lot of challenges to be overcome here, I would think that an author could with some justification use numbers in this range without being accused of handwavium.

The other missing item is the idea that while you must, at SOME point radiate, you can choose when and where to do so. The stealth warships that appear in James S A Corey's 'Leviathan Wakes' series are what I'm thinking of primarily, but I'm pretty sure I recall David Brin using a similar technique.

Essentially, you 'run cold' and use a heat sink to keep all your emissions trapped within the hull until it's time to fight. Then you unfold your radiators and let your heat sink dump. The primary limitation would be twofold: How long can your heat sink accumulate before you HAVE to dump heat, and 2: how do you move around without generating an easily detectable drive plume.

Again, the answer here seems to be improved efficiency in electromagnetic reaction drives like an Ion drive. Not in terms of thrust/power, but rather in precision focus of the drive stream. Any kind of 'rocket' generates a cloud of hot reaction mass behind the vessel that's radiating in all directions, so nothing to be done there. If, however, you can ensure your reaction mass only travels in ONE direction, very precisely, a theoretical sensor would have to be not only within range (likely) but also within your line of thrust to a very high degree of precision (unlikely). This, again, is just an efficiency improvement on existing technologies surrounding VASMIR and Ion drives.

So, what am I missing here, because I feel like Corey sort of nailed how this could work in a practical way.

[eripe]

I mostly agree with you but there is a couple of issues.

Even if you are as dark and cold as an asteroid, can you keep that up for days as you cruise through space?

A very directed exhaust might not hit a sensor, but there are still enough atoms in space that a sensitive enough sensor will detect them lighting up under the massive plasma beam.
I was thinking to use a water jet at 10000 bar for a cold drive gas, but it has some weight issues…

To go anywhere you will need to turn your drive on, and then people will know your trajectory, and they will be able to calculate it very precisely, so even if they can’t see you, they will still know where you are.

You would have to separate your craft from a booster section during boost, so you would have a different trajectory than the booster part, but the mission would then have to include a legal objective for the booster.

[Mikkel Haaheim]

While Atomic Rockets is an excellent reference site, I agree they have made a few mistakes in their analysis of stealth in pace. Most important is a major conceptual error.

Stealth has NEVER been about invisibility, or about not being detectable. Nothing conceived has EVER been undetectable. Rather, it is more about not being NOTICED before it is too late to respond appropriately. There is an important distinction here: "detection" is about registering on some sort of senser, while "noticing" is about recognising something as being significant.

AR points out that the energy generated can be easily detected. But it is also rather easy to detect an F-117 or B-2 flying overhead from the noise (although the person or equipment hearing that noise might not be able to identify it as anything other than a simple jet). The two planes are even, less easily, detectable by radar... but since the radar returns have about the same energy as a return for a duck or goose, they are often simply ignored, assuming that they haven't been cmpletely screened out by software.

This leads to a second error on the part of AR: they do not consider the factors of the "environment". If you have warships, you have property that you want to protect. To merit the cost of a torchship, you are talking about a booming economical infrastructure. You are not looking at a single torchship. You are looking at an environment of dozens of colonies with their own high output reactors. You are looking at fleets of thousands of vessels serving those colonies, dozens or hundreds probably torchships in their own right. You are looking at tens of thousands (at least) of small craft used for local transport, both of freight and personnel. You are probably looking at both business and private traffic, in addition to routine military traffic. That is another issue: you KNOW there is going to be military traffic... one of the major funtions of stealth is simply not to project that UNUSUAL manoeuvres are taking place. The purpose of stealth is not to go undetected, but not to appear as something out of the ordinary. You might be able to detect a stealth torchship, but being able to pick out a torchship on attack manoeuvres is something different entirely.

Ken Burnside makes additional errors in his evaluation of stealth for AR. Not technical errors, as such, but errors of omission. From what I have read, he fails to consider resolution, economic realities, and strategy/tactics. First, his 350 megapixel resultion of 100°^2 wideangle scans comes down to a resolution of approximately 1225 km^2/pixel at 1 AU. At this resolution, it will be impossible to extract the size of a plume, let alone the exhaust speed and direction. He also fails to consider resolution of intensity. There are very high power telescopes that could probably provide a much better resolution, but these have much narrower fields of vision. You will be sifting through 1225 km^2 of space trying to find the single km^2 that contains the torchship, and this will have to be broken down to a more precise scale to be able to use the euipment that could possibly give you the data you need. It becomes much more of a challenge because imaging reveals a 2D plan... you need 3D information to obtain data that is tactically useful (such as the thrust vector).

Next, there is the issue of the 4 hour scan. This might not seem like a lot of time. However, a vessel or craft travelling at normal interplanetary speeds of about 10 km/s will travel 144 000 km during that 4 hours. With a pixel length (not area, this time) of 35 km, the ship could be over 4000 pixels away (if travelling laterally to your location). It doesn't even need to make a burn to achieve this.

This brings us to Strategic/tactical factors. Detection à la Burnside depends upon continuous emissions. If you dump your acquired waste heat during a periodic burn lasting twenty minutes or so, you have only 1 chance in 12 of being detected during the burn. If you stagger the burn times, this leaves very little chance of being detected. Even if you are detected, there will be no time to bring in the high res optics for a detailed analysis. This means virtually no chance to determine where you are heading, so virtually no chance for a second detection. Even if you are detected multiple times, there will be no means for the detectors to determine if it is even the same ship. Mix this all in with regular traffic, and there is virtually no means to detect a meaningul manoeuvre.

Taking a step back to economic issues, contributers to AR have assumed that there will be detectors everywhere. First, this is unlikely, given that there are litterally millions of other things that also require investment. Second, you need to deploy those detectors. The stealth argument applies as much toward those craft deploying detectors as it does to attack vessels. Either there is stealth or there isn't. if there is no stealth, your detectors are going to be smoldering ruins within the first ten minutes of the declared war (actually, the formal declaration is likely to come ten minutes AFTER all your detectors have gone dark). Strategic planners will realise this, and they will therefore refrain from building targets. The detectors that they DO deploy will be primarily assigned to civil tasks. Of course, some military detectors will be deployed with the civilian ones, just to provide ongoing intelligence to best plan for an eventual hostle action based on projected capabilities. By the way, this stealth argument also applies to any nukes sent to attack the torchships.

One final matter, for the moment. AR talks about using planets to hide behind. This is not necessary. A vessel could deploy a very large, very thin whipple shield with low visibility. Since there is no need for streamlining in space, this could be several hundred meters on diameter... quite effective for hiding the bulk of the exhaust gases from known detectors... and even many unknown detectors.

[Mikkel Haaheim]

Le mardi 7 juin 2016 02:43:53 UTC+2, eripe a écrit :

>
> Even if you are as dark and cold as an asteroid, can you keep that up for days as you cruise through space?

You really don't have to. All you have to do is make short term, intermittent burns, during which you dump all the waste heat in the exhaust... yes, this will likely decrease Isp, but it is a tactical trad off.

>
> A very directed exhaust might not hit a sensor, but there are still enough atoms in space that a sensitive enough sensor will detect them lighting up under the massive plasma beam.

There are, on average, approximately 5 atoms or particles per cm^3. Most of these are the high energy product of the solar winds. It is extremely unlikely that anyone would be able to retrieve any useful information from such secondary bombardment.

> I was thinking to use a water jet at 10000 bar for a cold drive gas, but it has some weight issues…

Not necessary. Even if the secondary collisions were to provide some useful information, this can be effectively nullified through the use of intermittent burns.

>
> To go anywhere you will need to turn your drive on, and then people will know your trajectory, and they will be able to calculate it very precisely, so even if they can’t see you, they will still know where you are.

This is not so easy as the AR crew would have us believe. All observation is essentially 2D. In order to determine the trajectory, you need 3D information. For example, is that 2km gas cloud travelling laterally to your location? is it at an angle (which means it is considerably longer than 2km)? Is it the entire cloud, or is part of it being obscurred?
Next, the detectors that can extract such precision data are extremely narrow field. You need to now exactly where the target is in order to use it. Burnsides 4 hour scan can only provide resolution of 1225 km^2/pixel at 1 AU... and that is assuming you actually know the distance. At such low resolution, at such intervals of detection, it will not be possible to maintain a position lock long enough to bring the precision equipment into play.

>
> You would have to separate your craft from a booster section during boost, so you would have a different trajectory than the booster part, but the mission would then have to include a legal objective for the booster.

Nonsense. You just need to make sure you are not projecting signs of a military manoeuvre.

[Patrick Janecke]

The idea that there is no stealth in space is true at some level, and yet falls apart at others.

Ken Burnside has created a tactical game with very specific situations in mind. In light of those tactical environments, there is practically no application of stealth available.

Consider range. As Mikkel Haaheim points out, distance and resolution cancel one another out. Burnside was considering combat in ranges well short of a light-second, by ships that were easily recognizable by their national origin.

Now consider the stage of combat. There is much less stealth when fighting the "War for Lunar Independence" than "Hacking Piracy in the Kuiper Belt". Whether one handwaves a form of FTL in would drastically alter combat between two fully populated systems a parsec away from each other.

[Morris The Cat]

On Monday, June 6, 2016 at 8:43:53 PM UTC-4, eripe wrote:
> I mostly agree with you but there is a couple of issues.
>
> Even if you are as dark and cold as an asteroid, can you keep that up for days as you cruise through space?
>

Well, that's exactly the tradeoff. No, you couldn't Even without being under thrust, the crew generates heat, the life support that keeps them alive generates heat, the power systems that run everything generate heat, and that all has to be dissipated somehow. The best you can do is control WHEN you're releasing heat, and potentially limit how visible it is.

[Alie...@gmail.com]

You're forgetting the mythical "heat storage" and "dump stored heat into your exhaust" tricks.

I call them mythical for good, solid engineering reasons, but some authors don't let them get in their way.


Mark L. Fergerson

[eripe]

> >
> > To go anywhere you will need to turn your drive on, and then people will know your trajectory, and they will be able to calculate it very precisely, so even if they can’t see you, they will still know where you are.
>
> This is not so easy as the AR crew would have us believe. All observation is essentially 2D. In order to determine the trajectory, you need 3D information. For example, is that 2km gas cloud travelling laterally to your location? is it at an angle (which means it is considerably longer than 2km)? Is it the entire cloud, or is part of it being obscurred?
> Next, the detectors that can extract such precision data are extremely narrow field. You need to now exactly where the target is in order to use it. Burnsides 4 hour scan can only provide resolution of 1225 km^2/pixel at 1 AU... and that is assuming you actually know the distance. At such low resolution, at such intervals of detection, it will not be possible to maintain a position lock long enough to bring the precision equipment into play.
>
>

For this one, a few other detectors in say, Earth-Sun Lagrange points, would let you triangulate.
Considdering how important it would be to have the intel of where all dangerous vessels are, im sure we can do better than a 4 hour scan time. Just spend 100 times the money, and your down to 144 seconds. (Im assuming the is still small compared to the cost of any spacecraft, and peanuts compared to a surprise visit from an angry torchship)

For nuclear vessels with cold narrow exhausts, one might imagine enormous neutrino detectors on Earth, Mars and a few asteroids.

But it depends on the scenario. Will Earth ever be surprised?. Dont think so. Will a roid hopper without an updated subscription to the intel? Oh yes.

[Mikkel Haaheim]

Le mercredi 15 juin 2016 15:31:28 UTC+2, eripe a écrit :
> > >
> > > To go anywhere you will need to turn your drive on, and then people will know your trajectory, and they will be able to calculate it very precisely, so even if they can’t see you, they will still know where you are.
> >
> > This is not so easy as the AR crew would have us believe. All observation is essentially 2D. In order to determine the trajectory, you need 3D information. For example, is that 2km gas cloud travelling laterally to your location? is it at an angle (which means it is considerably longer than 2km)? Is it the entire cloud, or is part of it being obscurred?
> > Next, the detectors that can extract such precision data are extremely narrow field. You need to now exactly where the target is in order to use it. Burnsides 4 hour scan can only provide resolution of 1225 km^2/pixel at 1 AU... and that is assuming you actually know the distance. At such low resolution, at such intervals of detection, it will not be possible to maintain a position lock long enough to bring the precision equipment into play.
> >
> >
>
> For this one, a few other detectors in say, Earth-Sun Lagrange points, would let you triangulate.
> Considdering how important it would be to have the intel of where all dangerous vessels are, im sure we can do better than a 4 hour scan time. Just spend 100 times the money, and your down to 144 seconds. (Im assuming the is still small compared to the cost of any spacecraft, and peanuts compared to a surprise visit from an angry torchship)

The triangulation will only work if two different observation posts happen to be scanning the same zone at the same time, and happen to detect a simultaneous reading. Even then, resolution is a big problem, because the four hour scan, even if you reduce the scan time through redundant observation posts, will not permit accurate size measurements. You only know that there is something within about a 40 000 km^3 swath... assuming that the distance from each observation post is less than 1 AU.
So, two problems here: low res, and very small likelihood that two observation posts will actually be scanning the same patch of space at the right time. This latter becomes even more difficult because in a future with high volume space traffic, scans from any single detector are going to identify potentially hundreds of targets, which means you have to try to match the targets from the two observation posts. This is even more difficult if you have dense traffic patterns.
Another consideration is the amount of money you are talking about, and the strategic/political environment. For the former, you might think that 100 time the cost of a small observation satellite is negligible... until you consider that you have to deploy that platform in space. In order to reduce the scan time by a factor of 100, you need to increase the volume (and mass) of equipment by a factor of 100. Interplanetary probe space flights cost tens of MILLIONS of dollars (or much more... the current count for the two voyager probes is reported at over $800 million, in 1970s currency). Multiply this by a hundred times, then multiply that by a few thousand times to get reasonable 3D coverage, then multiply THAT by at least a several thousand times to get useful resolution. Then factor in the strategic/political environment. In a time of war, you can either use the money to buld observation platforms, or you can use it to build warships. As useful as observation is, wartime is too late. The military is going to want to maximise offensive and defensive capability. In a time of peace, you have to convince the population that there is a credible threat that will warrant such costs, and lots of the public are going to be rather nervous about having all those spies deployed. The public simply won't condone such an expense to spy on forces that are not even a threat (yet), especially if they consider that the enemy might some day be themselves.
In our age, nuclear power is reserved for warships. But in days of interplanetary travel, nuclear power will be a requirement for virtually all commerce and enterprise. ALL interplanetary vessels will have at least fission power. Many colonies will have civil fusion reactors, if anyone actually gets them to work. Some level of fusion drive will be available to anyone who has the resources.

[eripe]

On Thursday, June 16, 2016 at 1:43:14 AM UTC+7, Mikkel Haaheim wrote:
> Le mercredi 15 juin 2016 15:31:28 UTC+2, eripe a écrit :
> > > >
> > > > To go anywhere you will need to turn your drive on, and then people will know your trajectory, and they will be able to calculate it very precisely, so even if they can’t see you, they will still know where you are.
> > >
> > > This is not so easy as the AR crew would have us believe. All observation is essentially 2D. In order to determine the trajectory, you need 3D information. For example, is that 2km gas cloud travelling laterally to your location? is it at an angle (which means it is considerably longer than 2km)? Is it the entire cloud, or is part of it being obscurred?
> > > Next, the detectors that can extract such precision data are extremely narrow field. You need to now exactly where the target is in order to use it. Burnsides 4 hour scan can only provide resolution of 1225 km^2/pixel at 1 AU... and that is assuming you actually know the distance. At such low resolution, at such intervals of detection, it will not be possible to maintain a position lock long enough to bring the precision equipment into play.
> > >
> > >
> >
> > For this one, a few other detectors in say, Earth-Sun Lagrange points, would let you triangulate.
> > Considdering how important it would be to have the intel of where all dangerous vessels are, im sure we can do better than a 4 hour scan time. Just spend 100 times the money, and your down to 144 seconds. (Im assuming the is still small compared to the cost of any spacecraft, and peanuts compared to a surprise visit from an angry torchship)
>
> The triangulation will only work if two different observation posts happen to be scanning the same zone at the same time, and happen to detect a simultaneous reading. Even then, resolution is a big problem, because the four hour scan, even if you reduce the scan time through redundant observation posts, will not permit accurate size measurements. You only know that there is something within about a 40 000 km^3 swath... assuming that the distance from each observation post is less than 1 AU.

For 99% of the sky, thats fine. If you get a blib, you can dedicate more sensor resourses to that area.

> So, two problems here: low res, and very small likelihood that two observation posts will actually be scanning the same patch of space at the right time. This latter becomes even more difficult because in a future with high volume space traffic, scans from any single detector are going to identify potentially hundreds of targets, which means you have to try to match the targets from the two observation posts. This is even more difficult if you have dense traffic patterns.

But not impossible. All legal vessels will be carrying transponders allowing you to match them up with the blibs. If you get a blib without a transponder you can put a kee

> Another consideration is the amount of money you are talking about, and the strategic/political environment. For the former, you might think that 100 time the cost of a small observation satellite is negligible... until you consider that you have to deploy that platform in space. In order to reduce the scan time by a factor of 100, you need to increase the volume (and mass) of equipment by a factor of 100. Interplanetary probe space flights cost tens of MILLIONS of dollars (or much more... the current count for the two voyager probes is reported at over $800 million, in 1970s currency). Multiply this by a hundred times,

Each ship in your own fleet will cary such a sensor package.

then multiply that by a few thousand times to get reasonable 3D coverage,

I think 3-4 would do.

then multiply THAT by at least a several thousand times to get useful resolution.

No, we dont need full resolution for the whole sky.

Then factor in the strategic/political environment. In a time of war, you can either use the money to buld observation platforms, or you can use it to build warships. As useful as observation is, wartime is too late. The military is going to want to maximise offensive and defensive capability. In a time of peace, you have to convince the population that there is a credible threat that will warrant such costs, and lots of the public are going to be rather nervous about having all those spies deployed. The public simply won't condone such an expense to spy on forces that are not even a threat (yet), especially if they consider that the enemy might some day be themselves.

Today, to public accepts the NSA, spying on every email. The US army is developing system for total battlefield awareness, along with cruise missiles and GPS guided bombs, specifically to hit the target. They know that you cant hit what you cant see.

[elie....@gmail.com]

I'll point out the Stealth in Space series on the ToughSF blog:
http://toughsf.blogspot.fr/2016/03/stealth-in-space-is-possible.html
http://toughsf.blogspot.fr/2016/03/stealth-in-space-is-possible-ii.html
http://toughsf.blogspot.fr/2016/03/stealth-in-space-is-possible-iii.html
http://toughsf.blogspot.fr/2016/04/stealth-in-space-is-possible-iv.html

One type of possible stealth (proposed by Isaac Kuo) design is a jet-black (for example Vantablack) solar-thermal craft: most of the craft is in the shadow of the solar-thermal mirror, which flash-heat liquid hydrogen to use as propulsion.
The craft's surface is cooled down at 3K (or maybe slightly higher for the zodiacal light, or depending on where you are), and the excess heat from the ship's surface, ship operations and possibly crew are dumped into the liquid hydrogen before flash-heating it.

It can still be detected, but depending on your tech/industrial assumption it can be very hard:
- no nuclear power, so no neutrino
- relatively cool, fast dissipating hydrogen exhaust in an universe full of hydrogen, that's going to be hard to detect
- Nearly impossible to visually detect, even occulting only works at knife range

It is low-thrust and meh-Isp, but can still go places and has an autonomy in months (bigger gets better autonomy due to the square-cube law)

One proposed usage is to smuggle extremely high-value payloads (for example VIPs) around.

[Mikkel Haaheim]

Le samedi 18 juin 2016 03:48:51 UTC+2, eripe a écrit :

>
> For 99% of the sky, thats fine. If you get a blib, you can dedicate more sensor resourses to that area.

Two problems with this: First, you need qualitatively different sensor packages for the task; second, the dedicated resources either mean less coverage or greater costs.
There is a limit to how much resultion can be achieved. The formula for telescopic resolution is R=wavelength/baseline. At 1AU, a capital ship of 362m in length would cover 0.001 arcseconds. This is the resolution limit for visible light, using a 200m telescope. This means that the Arecibo Observatory (305 m) would detect the visible light from this capital ship as a single dot (you might be able to see two capital ships, if they are at least a a hundred meters apart from one another). If you want to acquire an IR signature of the same vessel, again as a single dot, you will need an 800 KILOmeter telescope array. If you want 1m resolution, which is still not good enough for the kind of analysis that AR was suggesting, you will need a single telescope array baseline AT LEAST 100 000 km long. This would, again, not be good enough to analyse the exhaust plume. But, yes, this will at least give you a fairly good position, for as long as you have a signal.
Next, you have to consider the cost of this array. You still need a second array in order to get the 3D info... but again, this is not good enough for the kind of analyses AR was suggesting.
In any case, your suggestion ignores the simple bulk of military traffic, involving vessels of all sizes. You put an array to the task of tracking one blip, you leave open quite a lot of space for all the others to pass through.

>
> > So, two problems here: low res, and very small likelihood that two observation posts will actually be scanning the same patch of space at the right time. This latter becomes even more difficult because in a future with high volume space traffic, scans from any single detector are going to identify potentially hundreds of targets, which means you have to try to match the targets from the two observation posts. This is even more difficult if you have dense traffic patterns.
>
> But not impossible. All legal vessels will be carrying transponders allowing you to match them up with the blibs. If you get a blib without a transponder you can put a kee

In peace time, sure. In war time, all transponder traffic will go dark. For that matter, you are making some assumptions about the laws that will be in place, and about how many people will actually be following those laws. Then you have to consider the volume of legitimate military traffic that is not always going to want to advertise its presence.

>
> > Another consideration is the amount of money you are talking about, and the strategic/political environment. For the former, you might think that 100 time the cost of a small observation satellite is negligible... until you consider that you have to deploy that platform in space. In order to reduce the scan time by a factor of 100, you need to increase the volume (and mass) of equipment by a factor of 100. Interplanetary probe space flights cost tens of MILLIONS of dollars (or much more... the current count for the two voyager probes is reported at over $800 million, in 1970s currency). Multiply this by a hundred times,
>
> Each ship in your own fleet will cary such a sensor package.

Sure. All ships will be equipped with sensor packages. But the resolution of those sensor packages will be quite limited. At best, they will carry sensors with a 10m baseline (this is being generous: most of those sensors will be hard pressed to put in a 1 m baseline). This will give you a resolution of 13 000 km^2 per pixel.
Of course, future tech will allow you to link all your vessels together so that your fleet can provide you with a collective array baseline on the order of perhaps 1 000 000 km. However, it will take a long time for the sensor data from all these vessels and craft to be processed... and you need to maintain active communication.
Also, the sensor arrays will take away from the other capabilities of the vessel. Every g of sensor array is a g that has to be subtracted from somewhere else. There is absolutely zero possibility that ANY ship will be able to provide full field of view coverage with any kind of resolution, let alone every ship.

I made a small miscalculation earlier. I assumed that small observation platforms would be suffiient to provide the resolution if there were a sufficient number of platforms. Sorry, no. I followed up with the research, and that is when I found that there is a physical limit (not a tech limit) on the relationship between resolution and baseline. Even your 100 °^2 scanning array s going to be huge if you want both the sensitivity and the resolution to even sort out one capital ship from another.

>
> then multiply that by a few thousand times to get reasonable 3D coverage,
>
> I think 3-4 would do.

Perhaps. This depends a bit. If you have arrays of large (sensative) telescopes with a baseline of 1 000 000 km, and full field of view; then, yes, 3 or 4 such arrays will give you reasonable 3D coverage... except, for some blind spots very near obstructions (the more sensor arrays you have, the fewer and smaller those blindspots). However, each base telescope is going to have to be at least 35 m in order to have the necessary sensativity. Four such telescopes 1 000 000 km apart can give you the baseline, for all axes. Assuming a 100 °^2 window for each telescope, 480 telescopes (not 100, because that would mean you still have to scan) arranged in a sphere at each point in the tetrahedon should give you the full field of view without need for scanning. Stand each of these arrays a billion km or so from one another, then yes, 3 or 4 arrays should be sufficient.
The problem with this is that we're assuming that the arrays can be placed in stable tetrahedron formations. Not likely given gravitational dynamics. You will want more platforms in order tomake up for irregularities in positioning. However, you would be correct that you don't need 1000 x the number of platforms. Rather, it is the cost of all the supporting equipment that will bring that number up to 1000 x.

>
> then multiply THAT by at least a several thousand times to get useful resolution.
>
> No, we dont need full resolution for the whole sky.
>

True. OTOH, it is a trade off. If you don't have full coverage, there is the possibility of an enemy saturating the coverage you DO have, and let something else slip by unseen. The greater the online coverage, the less likely this is to happen, but the more expensive the network is going to be.
A made another error, though, as I said. I assumed that more equipment would allow for ore concentrated scans that would allow for better resolution. That is not the case. More equipment will allow you to look for smaller objects (they will be more sensative), but there is the physical limit that will prevent better resolution without a much greater baseline. either you have the resolution or you don't.

>
> Today, to public accepts the NSA, spying on every email. The US army is developing system for total battlefield awareness, along with cruise missiles and GPS guided bombs, specifically to hit the target. They know that you cant hit what you cant see.
>

Well, the public doesn't exactly accept the spying, but they know there is nothing they can do to prevent it.
Technology for systems awareness IS increasing. So is the cost. They can not pay for everything they want, so they have to make some hard choices. Many of these systems are designed to allow them to do more with what they have. Such as linking the sensor arrays of all ships in a fleet together. It's not perfect, but it IS useful.
GPS allows for better guidance. It is not particularly useful, however, against anything but fixed installations. It is great for bunker busting. Not so useful against aircraft or vehicles.


I thought of something else relevant to the argument: we are talking about the equivalent of capital ships, or at least large destroyer type vessels. But this is seldom where militaries use stealth, except for submarine warfare. Most stealth is designed more for small and medium attack craft, although larger vessels incoporate stealth technologies to make it a little harder to spot the elephant wandering onto the playground. Stealth craft and vessels (the ones that are actually built for stealth missions) are not going to be running with active nuclear reactors or nuclear engines. They probably won't have nuclear reactors at all. They are going to be very careful about not shining a penlight in any direction where there are likely to be detectors, let alone a refridgerator light. Nor is there likely to be any crew. They will be small, and passively powered. Any thrust will be strictly intermittent, random, and short duration (less than a few seconds). More likely than not, they will be launched using electromagnetic catapults, with very small ion thrust for course corrections (or possibly passive solar sails).

[Ian Mallett]

I wrote a short story about this:
https://nanoficscifi.wordpress.com/2016/01/29/brave-new-world/
The basic premise is that you can radiate heat into an internal Lithium reservoir during a planet-to-planet orbit, and hide/radiate safely in the background noise at destinations. Even so, it only works with decoys/shields/burning-on-wrong-side-of-planet to disguise engine signatures.

It turns out the math works out, but only just barely. You need most of your ship to be cold, and anything longer than a few years in transit is asking for engineering trouble. But it's possible.

You can't have any engine burns or exterior lights or stabilization or communication, though. Essentially, you're pretending to be an undiscovered asteroid, and you have to act the part. It's much harder to justify a battleship boosting around willy-nilly whenever it wants, leaping out to ambush or running away to hide.

[Patrick Janecke]

Excellent point. My biggest concern with even that form of stealth is that there are bound to be far more sensor installations for prospecting for metal (or possibly salvage) than military. How does a cold running battleship fend off a swarm of hull-cutting salvage drones and remain cold?

[Alie...@gmail.com]

On Sunday, June 26, 2016 at 9:54:03 AM UTC-7, Patrick Janecke wrote:
> Excellent point.

About what, by whom?

By having the outermost layer being made of something the drones are programmed not to mine. Worst you have to cope with then is the occasional sampling laser.


Mark L. Fergerson

[emmett...@gmail.com]

I strongly agree with Mikkel's point that these observation posts are going to be the first targets in a military engagement. It's standard procedure to take out the enemy's intelligence gathering methods as fast as you possibly can. Since these observation posts are not spaceships moving around the star system (orbiting various bodies, yes, they're not under power) all I have to do is fire kinetic kill vehicles at them. They can even be cold for the vast majority of the time. Poof! No more sensor net!

The other thing that the whole "NO stealth" argument misses is that we have a real life analog of the proposed situation right now. The Juno space craft is around 60ft (10m ish) wide. Most of the time it's not under thrust. Could NASA tell where Juno is if the probe didn't report it's position? Usually when a craft fails, it takes about a week to analyze the data from telescopes that are pointed at where the craft was supposed to be to give a post mortem. Thats with knowing where the craft was supposed to be. Granted, yes, that's with ground based telescopes that have resolution issues because of the atmo.

Are you telling me though, that if an outsider (not from earth) launched a Juno space probe into our star system, we would detect it? I'd be impressed if we detected it even when firing it's engines. Although we have thousands of telescopes pointing in all directions, we're not looking for it. Even if we received a message from our outsiders saying "Hey, we're launching a probe into your star system." I can't imagine NASA or ESA finding it for weeks or months.

The point is that it's not a optics issue, it's an information processing issue. Yes you might be able to reduce the amount of information that you have to sift through, but automated detection systems are really dumb. They give false positives frequently and miss things they're no supposed to. If the kind of information processing being discussed is really as trivial as is assumed by the no stealth group, then there would be no need to have a security guard watching CCTVs. There are automated systems that can monitor the feeds, but they give false positives all the time. In the end, you need a human as the last filter. Suppose that we have human level AI at the point these space battles are going on and yes, you may have a better filter, but that's about as speculative as saying we'll have FTL. We don't know what form that AI will take or what it's real capabilities would be. Can it be predictably fooled? Will it ignore certain events that an enemy could exploit? What if I get access to the AI network and hack it? Give it a nasty bug? Then the whole network of satellites go down.

The other issue I have with the whole "NO stealth" argument is that it should, more accurately be "Stealth is unlikely in a heavily industrialized star system under peacetime situations." But it's proclaimed as an absolute. Many times, authors of science fiction are interested in FTL scenarios and a meeting between single crafts operating alone. It doesn't matter that such a situation is purely speculative, the message of "NO stealth" makes it appear like it's impossible under any circumstances. I know I started to think that way just from reading AR. Now that I've read through the arguments in this group on the matter, I see that the argument is under very specific conditions you would not be able to use stealth in a industrialized system, until you've destroyed the sensor net.

[Patrick Janecke]

I am of two minds on the situation. First, I am glad that Ken Burnside threw down the gauntlet as it requires us to be very careful about some preposterously silly ideas of stealth. Second, yes, there are indeed gaping holes in Burnside's assessment, holes that may be exploited in the next great hard science-fiction story.

In the end, there are lots of variables for the author to consider:

- Does FTL exist? If not, an inter-stellar aggressor would need massive resources in the way of Δv, redundant systems, fabrication, and material storage just to complete a journey of, say, one parsec. Such a ship would be massive, and therefore its propellant stores would have to be yet even more massive. How fast is the enemy willing to travel? Even running cold, an invasion fleet moving at a decent fraction of light-speed would light up every particle it hits as if it were made of anti-matter. Unless the mission is that of a suicide kinetic strike or a drive-by, the invader would need to initiate quite a substantial retro-burn before arriving at the target.

- FTL through gates or predictable coordinates? Good luck, as the other side is bound to be the most heavily defended position in the system. Also, while the no-stealth rule is hard to swallow at 1 AU or more, a firing squad 10 km away, trained at the gate is going to see everything that comes through.

- FTL with a flash? Does the energy put into ripping the space-time continuum make you flare up like a nova? If so, you had better have some pretty neat methods of dumping your heat and changing your position and bearing quickly.

- Intra-Stellar combat? The Jovians may rule the Belt, but that's a whole lot of space to control. On the flip side, every kind of stealth that can be employed offensively is generally better employed defensively.

[Rick Pikul/Chakat Firepaw]

On Sun, 10 Jul 2016 05:16:48 -0700, emmett.obrian wrote:

> I strongly agree with Mikkel's point that these observation posts are
> going to be the first targets in a military engagement. It's standard
> procedure to take out the enemy's intelligence gathering methods as fast
> as you possibly can. Since these observation posts are not spaceships
> moving around the star system (orbiting various bodies, yes, they're not
> under power) all I have to do is fire kinetic kill vehicles at them.
> They can even be cold for the vast majority of the time. Poof! No more
> sensor net!

Assuming you can hit them. Even if the locations and orbits of the
platforms are 100% known, all they have to do is have a solar sail and
tweak their orbit every couple months and you don't know where it's going
to be in a year when your KKV arrives.

It's not like they're all going to be sitting right next to you to plink
at. Many are going to be in things like highly inclined 2 AU solar
orbits.


It also wouldn't be that strange for such platforms to have one or more
"oh shit" rockets that allow them to make a rapid manoeuvre once or twice
during their service life. (To react to things like, say, something that
appears to be a KKV adjusting course to counter a solar sail 'jink'.)


Another problem with a 'kill the sensor net' plan is that making it
useful for hiding your fleet movements means giving up any pretence of
strategic surprise. The first reaction to large parts of the sensor net
going down is going to be shifting to a state of high alert.

--
Chakat Firepaw - Inventor and Scientist (mad)

[Mikkel Haaheim]

Le dimanche 26 juin 2016 18:54:03 UTC+2, Patrick Janecke a écrit :
> Excellent point. My biggest concern with even that form of stealth is that there are bound to be far more sensor installations for prospecting for metal (or possibly salvage) than military. How does a cold running battleship fend off a swarm of hull-cutting salvage drones and remain cold?

FUN!! ... But unlikely. For efficiency, the prospectors will be independent of the miners (etc). Salvage is not particularly profitable, so the prospectors will be targetting larger asteroids and other astronomical bodies first. Most of these will probably be rovers, dedicated to a single body until that body has been completely surveyed. Also, you don't want to build so many surveyors (prospectors) that the cost starts cutting into profits, so you will only build as many as required to keep the miners busy... and you will only build as many miners as necessary to keep up with demand (plus a modest reserve for growth).

[Mikkel Haaheim]

Le dimanche 10 juillet 2016 14:16:49 UTC+2, emmett...@gmail.com a écrit :

>
> In the end, you need a human as the last filter. Suppose that we have human level AI at the point these space battles are going on and yes, you may have a better filter,
>
>

Humans are also susceptable to error... in fact, existing filters generally fail because humans programme them based on false assumptions. If the filter misses something, it is either because the detection tech is not good enough, or it is because humans have programmed it to ignore responses that sometimes ought not to be ignored. Alternatively, they might be programmed to respond to situations that are irrelevant... just as bad because it ties up resources on pink elephant hunts.

I like to say that stealth is less about not being seen than it is about not being noticed. It is meant to deceive the humans that control the tech.

[Mikkel Haaheim]

Le mercredi 13 juillet 2016 03:13:18 UTC+2, Rick Pikul/Chakat Firepaw a écrit :

> Assuming you can hit them. Even if the locations and orbits of the
> platforms are 100% known, all they have to do is have a solar sail and
> tweak their orbit every couple months and you don't know where it's going
> to be in a year when your KKV arrives.

Not quite so easy as that. Useful platforms with considerable range and/or field of view are going to be rather large and heavy. Solar sails have to be incredibly large just to accelerate small masses on the order of a few kg, let alone a few tonnes. Keep in mind that the sails are essentially giant mirrors... they won't reflect a quality optical image, but they WILL reflect a bright one. Your solar sail will make it more likely to track the platform because it will be shining brilliantly sun-side, and occluding a nice patch of sun on its "dark" side (that is, you will see a big dot where sunlight is supposed to be.

>
> It also wouldn't be that strange for such platforms to have one or more
> "oh shit" rockets that allow them to make a rapid manoeuvre once or twice
> during their service life. (To react to things like, say, something that
> appears to be a KKV adjusting course to counter a solar sail 'jink'

it might... but it is not going to be able to make accurate observations if it is jinking all the time, so sending in a drone to keep it occupied serves the same purpose... until it DOES manage a track and kill. OTOH, the platform is likely to have some of those OTHER "oh shit" rockets... the kind that go boom when attackers get too close.
You are right that killing the platforms will not always be easy, and you might not get all of them... but you are going to take out as many as you can.

>
>
> Another problem with a 'kill the sensor net' plan is that making it
> useful for hiding your fleet movements means giving up any pretence of
> strategic surprise. The first reaction to large parts of the sensor net
> going down is going to be shifting to a state of high alert.

There is strategic stealth, but there is also tactical stealth. Even when you are at full out war, and very non-stealthy engagements are raging, stealth can be applied at lesser scales to allow a critical mission to succeed. Sometimes, the best stealth method is simply to overwhelm all the counter-stealth tech, until the enemy no longer has the resources to detect one last stealth manoeuvre.


>
> --

[Rick Pikul/Chakat Firepaw]

On Wed, 20 Jul 2016 11:03:31 -0700, Mikkel Haaheim wrote:

> Le mercredi 13 juillet 2016 03:13:18 UTC+2, Rick Pikul/Chakat Firepaw a
> écrit :
>
>> Assuming you can hit them. Even if the locations and orbits of the
>> platforms are 100% known, all they have to do is have a solar sail and
>> tweak their orbit every couple months and you don't know where it's
>> going to be in a year when your KKV arrives.
>
> Not quite so easy as that. Useful platforms with considerable range
> and/or field of view are going to be rather large and heavy. Solar sails
> have to be incredibly large just to accelerate small masses on the order
> of a few kg, let alone a few tonnes. Keep in mind that the sails are
> essentially giant mirrors... they won't reflect a quality optical image,
> but they WILL reflect a bright one. Your solar sail will make it more
> likely to track the platform because it will be shining brilliantly
> sun-side, and occluding a nice patch of sun on its "dark" side (that is,
> you will see a big dot where sunlight is supposed to be.

Remember that this is granting that all the observation platforms are
known. Saying "that would make them easy to spot" isn't exactly a
counterargument.

Given the ranges involved, your KKVs are going to have to go for a high
speed pass if you want to take out a platform in a relevant amount of
time. This makes the manoeuvres far more costly in deltaV for the KKV.

>> It also wouldn't be that strange for such platforms to have one or more
>> "oh shit" rockets that allow them to make a rapid manoeuvre once or
>> twice during their service life. (To react to things like, say,
>> something that appears to be a KKV adjusting course to counter a solar
>> sail 'jink'
>
> it might... but it is not going to be able to make accurate observations
> if it is jinking all the time, so sending in a drone to keep it occupied
> serves the same purpose...

A constant low-g acceleration isn't going to be much of a problem to
compensate for with the sensors. The "oh shit" rockets are going to
blind the platform for a few minutes/an hour but they only fire the once
to maximize the deltaV to intercept for the KKV.

> until it DOES manage a track and kill. OTOH,
> the platform is likely to have some of those OTHER "oh shit" rockets...
> the kind that go boom when attackers get too close.
> You are right that killing the platforms will not always be easy, and
> you might not get all of them... but you are going to take out as many
> as you can.

And if you miss more than a couple it will all have been for naught.

>> Another problem with a 'kill the sensor net' plan is that making it
>> useful for hiding your fleet movements means giving up any pretence of
>> strategic surprise. The first reaction to large parts of the sensor
>> net going down is going to be shifting to a state of high alert.
>
> There is strategic stealth, but there is also tactical stealth. Even
> when you are at full out war, and very non-stealthy engagements are
> raging, stealth can be applied at lesser scales to allow a critical
> mission to succeed. Sometimes, the best stealth method is simply to
> overwhelm all the counter-stealth tech, until the enemy no longer has
> the resources to detect one last stealth manoeuvre.

One part of going to high alert is going to be launching backup sensor
platforms. Sure, the coverage won't be as good but you also have the
same year+ lag time before they can be attacked, (especially if you have
managed to conceal the fact that your intelligence agency owns a
particular half-dozen asteroid refining ships[1]).

Remember that interplanetary combat is s l o w .

And, TBH, you are almost certainly going to have your KKVs noticed long
before they hit. That will result in a war footing, (and extra sensors),
even before the existing ones die.


[1] The one thing you can conceal is the exact contents of a cargo hold.
Sure, I know there is about 100 tonnes of stuff in there but not exactly
what it is.

[Mikkel Haaheim]

Le mercredi 20 juillet 2016 23:04:00 UTC+2, Rick Pikul/Chakat Firepaw a écrit :

>
> Remember that this is granting that all the observation platforms are
> known. Saying "that would make them easy to spot" isn't exactly a
> counterargument.

Yes. the initial assumption was that the locations of the platforms were known. This was followed by the suggestion that a slow repositioning will prevent them from being destroyed. This assumes that the target is not going to be where the attack hits, which means either the target "dodged the bullet" by moving out of the way faster than the attack could respond, or that the attack would be unaware of the change in position. The slowness of light sails means that the array would not be able to simply "dodge the bullet"... not when the "bullet" is capable of course correction. Using a light sail means that "not being there" is not going to work either, because you are hanging up a sign saying "please track me".

>
> Given the ranges involved, your KKVs are going to have to go for a high
> speed pass if you want to take out a platform in a relevant amount of
> time. This makes the manoeuvres far more costly in deltaV for the KKV.

Invalid assumption. Careful planning is much more useful.

>
>
> A constant low-g acceleration isn't going to be much of a problem to
> compensate for with the sensors. The "oh shit" rockets are going to
> blind the platform for a few minutes/an hour but they only fire the once
> to maximize the deltaV to intercept for the KKV.

The constant g? No, not at all. Constant manoeuvering using the "oh shit" rockets to try to evade the TRACKING kill squad, however, will. Do not assume that there will be a single warhead, and do not assume that someone is going to just use a sniper rifle... this is going to be a fleet of kill drones.

>
> And if you miss more than a couple it will all have been for naught.

Wrong. Military operations NEVER assume that all detectors have been dispatched from service. Military engagements don't require an enemy to be blind... but they WILL blind the enemy as much as possible to make responding more difficult.

>
> One part of going to high alert is going to be launching backup sensor
> platforms. Sure, the coverage won't be as good but you also have the
> same year+ lag time before they can be attacked, (especially if you have
> managed to conceal the fact that your intelligence agency owns a
> particular half-dozen asteroid refining ships[1]).

Yes. Which is why strategic planners allow for contingencies. Sensor targeting is NOT a one-time-only operation.
And, yes, I myself have pointed out subterfuge as stealth. Honestly, the attacker will probably never have to launch most of those kill drones, because they will already have used subterfuge to arrange premature deaths for those platforms... or methods for disinformation (why destroy a useful asset if you can hack it instead?).

>
> Remember that interplanetary combat is s l o w .

Yes it is... until you have everything htting at once. You have very long pause intervals where nothing happens, and then a few minutes or hours of pure adrenaline rush.

>
> And, TBH, you are almost certainly going to have your KKVs noticed long
> before they hit. That will result in a war footing, (and extra sensors),
> even before the existing ones die.

Depends upon what you are hitting with... and what it looks like. Yes, they will probably be seen, but there is always the question of if they will be recognised for what they are. The Japanese fleet was spotted long before hitting Pearl Harbor. Just imagine if those zeros weren't mistaken for a training flight.
Yes, there will be an ongoing attempt to field new sensors throughout the war. There will also be ongoing drives to knock them out of service. As I said, it is not a one-time-only deal.

>
>
> [1] The one thing you can conceal is the exact contents of a cargo hold.
> Sure, I know there is about 100 tonnes of stuff in there but not exactly
> what it is.
>

There is actually quite a lot that can be concealed... if you know how.

[emmett...@gmail.com]

On Wednesday, July 20, 2016 at 5:04:00 PM UTC-4, Rick Pikul/Chakat Firepaw wrote:
> On Wed, 20 Jul 2016 11:03:31 -0700, Mikkel Haaheim wrote:
>

A KKV doesn't have to be powered, and can be quite fast. Yes it's going to take months for them to arrive but they also could be far cheaper than your sensors, as in slugs of iron or asteroid regolith.

The problem with your "you can't find my sensors" argument is that it contravenes the existence of the "no stealth" argument. If the principle is true then I know where all your sensors are.

The other loophole to your argument is you've ignored a technical attack. A sensor net requires communication, which requires co-ordination. By necessity then there is a system that collects and processes the inputs of these sensors. A computer virus could leave the network working until I don't want it to, or could ignore targets I specify and leave the impression that it's still up and running. Viola! instant stealth and I don't even have to worry about heat.

You might argue this can't happen because militaries would already be using it. The fact is that this is exactly what the US is scared to death of and leaves many systems as "dumb" as possible with manpower handling the information collection causes you can't hack a human (hopefully this stays true for the foreseeable future). But humans are inefficient on this scale.

But to prove that this no stealth argument is total and utter rubbish, I give you this article. http://www.gizmag.com/nasa-asteroid-hunting-algorithm/36601/

If the idea of finding objects in space is as easy as stated, there would be no need for NASA to release it's asteroid hunting software and offer a $55,000 reward for improvements. We would already have total knowledge of every near earth asteroid in existence.

The really interesting part in the article is the section "However, there are significant limitations to the current generation of asteroid hunting algorithms. Often they are either not sensitive enough to pick up the objects, or instead, provide false positive readings due to imperfections in the data." which debunks the "total awareness" concept that "no stealth" hinges on.

[Rick Pikul/Chakat Firepaw]

On Thu, 21 Jul 2016 08:11:37 -0700, Mikkel Haaheim wrote:

> Le mercredi 20 juillet 2016 23:04:00 UTC+2, Rick Pikul/Chakat Firepaw a
> écrit :
>
>> Remember that this is granting that all the observation platforms are
>> known. Saying "that would make them easy to spot" isn't exactly a
>> counterargument.
>
> Yes. the initial assumption was that the locations of the platforms were
> known. This was followed by the suggestion that a slow repositioning
> will prevent them from being destroyed. This assumes that the target is
> not going to be where the attack hits, which means either the target
> "dodged the bullet" by moving out of the way faster than the attack
> could respond, or that the attack would be unaware of the change in
> position. The slowness of light sails means that the array would not be
> able to simply "dodge the bullet"... not when the "bullet" is capable of
> course correction. Using a light sail means that "not being there" is
> not going to work either, because you are hanging up a sign saying
> "please track me".

The instant your shot corrects to maintain an intercept you have just
fired the opening shot of the war and everyone knows it.

Also remember that the initial suggestion I was responding to was the use
of KKVs that would run cold. That means even a small manoeuvre by the
target and they miss.

>> Given the ranges involved, your KKVs are going to have to go for a high
>> speed pass if you want to take out a platform in a relevant amount of
>> time. This makes the manoeuvres far more costly in deltaV for the KKV.
>
> Invalid assumption. Careful planning is much more useful.

Slower, easier, intercepts means much much longer times in flight. As in
multiple years.

At that point, your attack fails simply because of the new launches that
have occurred while you were waiting for your shots to hit. (Two dozen
stations with a service life of 20 years means a launch about every 10
months.)

>> A constant low-g acceleration isn't going to be much of a problem to
>> compensate for with the sensors. The "oh shit" rockets are going to
>> blind the platform for a few minutes/an hour but they only fire the
>> once to maximize the deltaV to intercept for the KKV.
>
> The constant g? No, not at all. Constant manoeuvering using the "oh
> shit" rockets to try to evade the TRACKING kill squad, however, will.

So if you assume something completely different from what I suggested....

> Do not assume that there will be a single warhead, and do not assume
> that someone is going to just use a sniper rifle... this is going to be
> a fleet of kill drones.

Well, there goes any thought of "surprise, your sensor net is down."

>> And if you miss more than a couple it will all have been for naught.
>
> Wrong. Military operations NEVER assume that all detectors have been
> dispatched from service. Military engagements don't require an enemy to
> be blind... but they WILL blind the enemy as much as possible to make
> responding more difficult.

You have given up strategic surprise and your fleets can still be tracked.

The moving goalposts are also noted.

>> One part of going to high alert is going to be launching backup sensor
>> platforms. Sure, the coverage won't be as good but you also have the
>> same year+ lag time before they can be attacked, (especially if you
>> have managed to conceal the fact that your intelligence agency owns a
>> particular half-dozen asteroid refining ships[1]).
>
> Yes. Which is why strategic planners allow for contingencies. Sensor
> targeting is NOT a one-time-only operation.

You can't take out new sensors fast enough, your shots simply can't hit
them for months, if not years.

> And, yes, I myself have pointed out subterfuge as stealth. Honestly, the
> attacker will probably never have to launch most of those kill drones,
> because they will already have used subterfuge to arrange premature
> deaths for those platforms... or methods for disinformation (why destroy
> a useful asset if you can hack it instead?).

Hmmm, two people assuming espionage successes on a scale that the
Bircher's would expect.

>> Remember that interplanetary combat is s l o w .
>
> Yes it is... until you have everything htting at once. You have very
> long pause intervals where nothing happens, and then a few minutes or
> hours of pure adrenaline rush.

And in the time period between taking out a sensor net and being able to
actually do anything with that fact you are faced with a new net forming.

A new net that is going to start by focusing on all the places your fleet
could have gone in the brief period of sensor blindness you got. That's
assuming you even got any.

>> And, TBH, you are almost certainly going to have your KKVs noticed long
>> before they hit. That will result in a war footing, (and extra
>> sensors),
>> even before the existing ones die.
>
> Depends upon what you are hitting with... and what it looks like. Yes,
> they will probably be seen, but there is always the question of if they
> will be recognised for what they are. The Japanese fleet was spotted
> long before hitting Pearl Harbor. Just imagine if those zeros weren't
> mistaken for a training flight.

There is something on an intercept course for a sensor platform that's in
a polar orbit of the sun, we didn't send it and it's adjusting course to
maintain the intercept. I wonder what it could possibly be?

Remember that these platforms are going to be way out in the middle of
nowhere, (orbitally speaking). Things aren't going to 'just happen' to
be passing by them.

[Rick Pikul/Chakat Firepaw]

On Thu, 21 Jul 2016 08:26:57 -0700, emmett.obrian wrote:

> On Wednesday, July 20, 2016 at 5:04:00 PM UTC-4, Rick Pikul/Chakat
> Firepaw wrote:
>> On Wed, 20 Jul 2016 11:03:31 -0700, Mikkel Haaheim wrote:
>>
> A KKV doesn't have to be powered, and can be quite fast. Yes it's going
> to take months for them to arrive but they also could be far cheaper
> than your sensors, as in slugs of iron or asteroid regolith.

Which means one tiny orbital jink and you miss.

> The problem with your "you can't find my sensors" argument is that it
> contravenes the existence of the "no stealth" argument. If the principle
> is true then I know where all your sensors are.

You're attacking the wrong counterargument to finding a way to make
stealth work.

I wasn't using the "any stealth technique you can use to try and hide
your ships will work better for the sensor platforms," counter. I was
using "taking out the sensor platforms isn't as easy or effective as is
being assumed."

Remember, knowing the location and orbit of something now only places
constraints on where it will be in a year.

> The other loophole to your argument is you've ignored a technical
> attack. A sensor net requires communication, which requires
> co-ordination. By necessity then there is a system that collects and
> processes the inputs of these sensors. A computer virus could leave the
> network working until I don't want it to, or could ignore targets I
> specify and leave the impression that it's still up and running. Viola!
> instant stealth and I don't even have to worry about heat.

And all you have to do is assume that you can undetectably compromise
multiple high-security computer systems that are going to be operated in
a way that reflects that such intrusion must be avoided at all costs.

> But to prove that this no stealth argument is total and utter rubbish, I
> give you this article.
> http://www.gizmag.com/nasa-asteroid-hunting-algorithm/36601/
>
> If the idea of finding objects in space is as easy as stated, there
> would be no need for NASA to release it's asteroid hunting software and
> offer a $55,000 reward for improvements. We would already have total
> knowledge of every near earth asteroid in existence.

Congratulations, you have noticed that looking for unpowered objects that
aren't thrusting using effectively no resources is hard.

[Sea Wasp (Ryk E. Spoor)]

On 7/21/16 6:38 PM, Rick Pikul/Chakat Firepaw wrote:
> On Thu, 21 Jul 2016 08:26:57 -0700, emmett.obrian wrote:
>
>> On Wednesday, July 20, 2016 at 5:04:00 PM UTC-4, Rick Pikul/Chakat
>> Firepaw wrote:
>>> On Wed, 20 Jul 2016 11:03:31 -0700, Mikkel Haaheim wrote:
>>>
>> A KKV doesn't have to be powered, and can be quite fast. Yes it's going
>> to take months for them to arrive but they also could be far cheaper
>> than your sensors, as in slugs of iron or asteroid regolith.
>
> Which means one tiny orbital jink and you miss.
>

REALLY tiny. Do the calculations, dude, please. If I've got two months
before you hit me, and I do a jink, and let's say your KKV is an
asteroid 50 kilometers wide, my jink has to be an average of about ONE
cm/sec AVERAGE VELOCITY to ensure you miss -- even if my jink is in the
*exactly* wrong direction so I have to move a full 50 kilometers. That's
either a pretty damn tiny rocket burn for any station that's got any
stationkeeping ability at all, or 0.0000004 centimeters/sec^2
acceleration. That's 1/2,592,000,000 of a gravity.

A solar sail the size of a *bedsheet* could manage that.

--
Sea Wasp
/^\
;;;
Website: http://www.grandcentralarena.com Blog:
http://seawasp.livejournal.com

[elie....@gmail.com]

While it is keeping a very conservative of future available technologies, the developer of the upcoming Children of a Dead Earth (the only realistic space combat simulation I've ever heard about so far) actually tested stealth in space:
https://childrenofadeadearth.wordpress.com/2016/07/12/stealth-in-space/

His conclusions so far are that, in fact, the one thing that can be effectively stealthed is sensor platforms. So major players will have big sensor platform nets, which will in turn prevent enemies to effectively use stealth for anything but their own sensor platform nets - and shooting sensor platforms down to blind the enemy won't be efficient enough.
(Of course, we aren't talking about Q-ships or Pearl Harbour-like surprise here.)

Hopefully, once released the game will be moddable enough to try for more outlandish tech assumptions.

[Mikkel Haaheim]

The solar flux allows a maximum pressure of 3 MICRO-Newtons/m^2. This means a 1 m^2 sail will be able to push 3 mg at 1 m/s^2. Useful Observation platfroms are not small. The hubble, which has a capability of about 1 arcsecond resolution (max), and a rather limited field of view, masses out at just over 10 tonnes. Working through the numbers, you will actually need a little over 10 m^2 of sail to get your 0.0000004 centimeters/sec^2. However, this is the MAXIMUM performance, and assumes that the sail is exactly perpendicular to the solar flux. You will have to multiply the sail area by the sin^2 of the angular degree of manoeuverability you desire. Don't forget that the sail mass has to come out of your mass budget for the sensor platform.
Oh, yes, this is all oversimplified, because orbital manoeuvres really don't work this simply.

What makes you think there would be a single, large KKV? Instead of 1 asteroid at 50 km, You could easily send a spread of KKV "buckshot"... each pellet 1 cm^3, average areal density of about 3 or 4 pellets / m^2, and coverage spread of tens of thousand of km (with much less mass). Alternatively, use remotely detonated explosive pellets, 125 cm^3, with an aerial density of about 40 000 pellets / km^2.
Clouds of such pellets are unlikely to be detected, and even if detected they would be indistinguishable from small granular asteroid material. Even if detected and analysed with a 2 month warning, it will be impossible to avoid the spread (and the size of the platform guarantees that several pellets, or the debris of explosive pellets, are going to hit).

[Mikkel Haaheim]

First, the author is relying a little too much on the AR arguments, which are not based upon entirely valid assumption. second, the author does not realise that sensor platforms are BIG (at least, useful ones are). These are on the order of at least several m^2, and several tommes mass.

[Mikkel Haaheim]

Le vendredi 22 juillet 2016 00:38:17 UTC+2, Rick Pikul/Chakat Firepaw a écrit :

>
> The instant your shot corrects to maintain an intercept you have just
> fired the opening shot of the war and everyone knows it.

Quite correct. That is not going to save the platforms, and once the first couple platforms are lost, everyone is going to know it anyway.

>
> Also remember that the initial suggestion I was responding to was the use
> of KKVs that would run cold. That means even a small manoeuvre by the
> target and they miss.

I just doublechecked: running cold was an option, and even that was qualified to "a vast majority of the time", not an absolute. However, even if we limit it to purely cold running, you are assuming single KKVs. Not a wise assumption.

>
>
> Slower, easier, intercepts means much much longer times in flight. As in
> multiple years.

Perhaps, but not necessarily. You don't know where the KKVs are going to be launched from.

>
> At that point, your attack fails simply because of the new launches that
> have occurred while you were waiting for your shots to hit. (Two dozen
> stations with a service life of 20 years means a launch about every 10
> months.)

No... the attack doesn't fail. Remember that strategists are always keeping track of current activities. 2 or 3 platform launches is not going to hamper overall strategy that much, and planners tend to have contingencies in place for just such events.

> So if you assume something completely different from what I suggested....

Not completely different. I am just stating that evasive manoeuvres, as opposed to the slow changes from the sails (which will be largely ineffective), will keep the platforms occupied, and unable to perform.
If they don't do MAJOR evasive course corrections, they are dead.

>
> > Do not assume that there will be a single warhead, and do not assume
> > that someone is going to just use a sniper rifle... this is going to be
> > a fleet of kill drones.
>
> Well, there goes any thought of "surprise, your sensor net is down."

No. Drones do not have to be big. In fact, they cn be extremely small. However, if you prefer, there is also the "buckshot" approach. Sniper rifles will not be used... those will be for targets that actually CAN'T manoeuvre. Shot is always still an option. If you REALLY want, these can be the size of small pebbles or even grains of sand, if you want the high relative speed approach. They will be virtually undetectable, and even if you DO detect them, they can be scattered across thousands, or even hundreds of thousands, of km. There is going to be no question of avoiding them.

> >
>
> You have given up strategic surprise and your fleets can still be tracked.

Strategic surprise is always relative... at the strategic level, it is just to limit the amount of advance warning, and the inforamtion that advanced warning can offer, thereby limiting possible response options. Tactical surprise is much more important.
When you reduce the number of sensor platforms, you are reducing the amount of information that can be collected. From here, it is a matter of either working your way through the ensor holes, or everwhelming the sensor input. You might be able to track fleets, but you will not be able to track all the elements within that fleet if your intelligence resources are overwhelmed.

>
> The moving goalposts are also noted.

A consequence of ALL strategic planning. There is no such thing as a fixed goal poast.

>
>
> You can't take out new sensors fast enough, your shots simply can't hit
> them for months, if not years.

It is not how long the shots take to hit. It is how quickly they hit and how many hit, in succession. Remember: planning. Careful planning. Planning based on long periods of observation.

> Hmmm, two people assuming espionage successes on a scale that the
> Bircher's would expect.

Espionage happens. So do hackers. OTOH, you can't prevent both by preventing access, in which case it is up to other means... like the buckshot, the drones, coordinated battle forces, long range missiles, etc.

>
> And in the time period between taking out a sensor net and being able to
> actually do anything with that fact you are faced with a new net forming.

Planning. You do not wait for the net to go down. You move in coordination with the forces taking down the net.

>
> A new net that is going to start by focusing on all the places your fleet
> could have gone in the brief period of sensor blindness you got. That's
> assuming you even got any.

It is not so easy to simply put up a new net. Platforms are expensive. The means to deploy them are expensive. It takes as much tim getting them into position as it takes shooting them down... the SLOW way. That, and launch facilities are often the easiest to track. BTW: planetary launch facilities will be the sniper targets.

> There is something on an intercept course for a sensor platform that's in
> a polar orbit of the sun, we didn't send it and it's adjusting course to
> maintain the intercept. I wonder what it could possibly be?
>
> Remember that these platforms are going to be way out in the middle of
> nowhere, (orbitally speaking). Things aren't going to 'just happen' to
> be passing by them.

Depends on how obvious you want your platforms. If you want EVERYONE to know where your platform is, sure, it is going to be difficult to hide your intent to kill these. OTOH, polar orbits intersect regular orbits, so a couple of these might be in the wrong place at the wrong time. The rest will be easily dispatched by shot. Most likely scenario: the shot will be so small and so thinned out that they are never detected. If they are detected? Well... it was a boring conversation anyway.

[Mikkel Haaheim]

Le vendredi 22 juillet 2016 00:38:19 UTC+2, Rick Pikul/Chakat Firepaw a écrit :

> Which means one tiny orbital jink and you miss.

Depends upon how many KKVs you have. "Buckshot" scattered KKVs covering tens of thousands of km can take very little mass and energy to deploy, but they will do the job, and there is no way of evading all of them.

>
> I wasn't using the "any stealth technique you can use to try and hide
> your ships will work better for the sensor platforms," counter. I was
> using "taking out the sensor platforms isn't as easy or effective as is
> being assumed."

No one is assuming that it is easy.

>
> Remember, knowing the location and orbit of something now only places
> constraints on where it will be in a year.

And tracking how much it has deviated in course over a couple years gives a fairly reliable stadnard of deviation of how much allowance has to be taken into account.

>
> And all you have to do is assume that you can undetectably compromise
> multiple high-security computer systems that are going to be operated in
> a way that reflects that such intrusion must be avoided at all costs.

As I said, no one said it would be easy. OTOH, having a few well place agents...

>
>
> Congratulations, you have noticed that looking for unpowered objects that
> aren't thrusting using effectively no resources is hard.

Time and patience. Take a big ball of rock. Dig a deep hole, with many smaller holes branching out. Fill those holes with attack resources. Give that big rock a slight nudge. A few years later, start activating your systems, and get ready to let fly.
>

[Mikkel Haaheim]

Something that always seems to be missed in these discussions. Precedent.
We ALREADY LIVE in the world where "stealth is impossible". Forget about tracking rockets in space. We are talking about existing tech, why don't we just track targets on land and in the air? There is no such thing as an undetectable aircraft.We have the tech to track every aircraft in existence. So why do we have aircraft that we can't find for months after going missing? These aren't even the "stealth" aircraft. We have the tech to put up satellites that cover every inch of the Earth's surface. We have cameras everywhere.
Every agrument we consider for why "there ain't no stealth in space" already applies for anything on land or in the air. And yet...


The F-117 is not invisible to radar, nor is it invisible to sight. It just produces ery small radar returns, and is very hard to see (when flying at night). Even though the engine exhaust is treated to reduce the exhaust temperature, that exhaust is still hotter than normal air, and so still detectable by IR. That, and NOTHING hides the sound of a jet.
The reality is that the people arguing that "there ain't no stealth in space" have no real understanding of what stealth actually is or how it is used. It is not about not being detected. It is about not being NOTICED. Even then, it is not an absolute. The purpose of stealth is to offer time. Delaying detection limits the options of response TO detection. Sometimes, it means having the situation misanalysed, leading to an inappropriate response.

The other thing is, the arguments assume that tech is the only consideration. You also have to consider available resources, the demand for those resources, and how those resources are being used. You have to consider social and political climate: there is nothing preventing governments from putting cameras everywhere, and collecting data from cameras everywhere; so where are all those cameras that could prevent crime from going unpunished? Answer, not everyone wants those cameras, and there is enough opposition to stop governments from deploying them. Also consider context: if you are not already expecting war or conflict, why put up sensor platforms to track vessels?

If you REALLY want to know why the "there ain't no stealth in space" arument fails, consider why it doesn't work NOW, on Earth. Every argument already applies.

[Rick Pikul/Chakat Firepaw]

On Fri, 22 Jul 2016 07:43:19 -0700, Mikkel Haaheim wrote:

> Le vendredi 22 juillet 2016 00:38:17 UTC+2, Rick Pikul/Chakat Firepaw a
> écrit :
>
>
>> The instant your shot corrects to maintain an intercept you have just
>> fired the opening shot of the war and everyone knows it.
>
> Quite correct. That is not going to save the platforms, and once the
> first couple platforms are lost, everyone is going to know it anyway.

Your fleets can't move until the sensor platforms are down or the whole
point of shooting them down is lost. Any fleets that happen to be under
way when your KKVs are spotted get KKVs of their own launched at them.

>> Also remember that the initial suggestion I was responding to was the
>> use of KKVs that would run cold. That means even a small manoeuvre by
>> the target and they miss.
>
> I just doublechecked: running cold was an option, and even that was
> qualified to "a vast majority of the time", not an absolute. However,
> even if we limit it to purely cold running, you are assuming single
> KKVs. Not a wise assumption.

He clarified to to be stuff like "chunks of regolith".

>> Slower, easier, intercepts means much much longer times in flight. As
>> in multiple years.
>
> Perhaps, but not necessarily. You don't know where the KKVs are going to
> be launched from.

There are a limited number of places you can launch from, most of the
sensor platforms are going to require that kind of time in flight from
any of them.

>> At that point, your attack fails simply because of the new launches
>> that have occurred while you were waiting for your shots to hit. (Two
>> dozen stations with a service life of 20 years means a launch about
>> every 10 months.)
>
> No... the attack doesn't fail. Remember that strategists are always
> keeping track of current activities. 2 or 3 platform launches is not
> going to hamper overall strategy that much, and planners tend to have
> contingencies in place for just such events.

New platforms means that you haven't gotten stealth by killing the
sensors.

>> So if you assume something completely different from what I
>> suggested....
>
> Not completely different. I am just stating that evasive manoeuvres, as
> opposed to the slow changes from the sails (which will be largely
> ineffective), will keep the platforms occupied, and unable to perform.
> If they don't do MAJOR evasive course corrections, they are dead.

Yes completely different.

>> > Do not assume that there will be a single warhead, and do not assume
>> > that someone is going to just use a sniper rifle... this is going to
>> > be a fleet of kill drones.
>>
>> Well, there goes any thought of "surprise, your sensor net is down."
>
> No. Drones do not have to be big. In fact, they cn be extremely small.
> However, if you prefer, there is also the "buckshot" approach. Sniper
> rifles will not be used... those will be for targets that actually CAN'T
> manoeuvre. Shot is always still an option. If you REALLY want, these can
> be the size of small pebbles or even grains of sand, if you want the
> high relative speed approach. They will be virtually undetectable, and
> even if you DO detect them, they can be scattered across thousands, or
> even hundreds of thousands, of km. There is going to be no question of
> avoiding them.

So now we're up to _trillions_ of evenly distributed pellets, all to
probably _fail_ at getting any kind of mission kill. 100Mm radius at 1
pellet/ha equals 3 trillion pellets, one pellet per hectare means you
probably do no more than a few micrometeorite holes in the sail.

If you want to have a good chance at a mission kill, you are going to
need something like one pellet per 10 m^2 or 1000 per hectare.

>> You have given up strategic surprise and your fleets can still be
>> tracked.
>
> Strategic surprise is always relative... at the strategic level, it is
> just to limit the amount of advance warning, and the inforamtion that
> advanced warning can offer, thereby limiting possible response options.
> Tactical surprise is much more important.
> When you reduce the number of sensor platforms, you are reducing the
> amount of information that can be collected. From here, it is a matter
> of either working your way through the ensor holes, or everwhelming the
> sensor input. You might be able to track fleets, but you will not be
> able to track all the elements within that fleet if your intelligence
> resources are overwhelmed.

It doesn't take many platforms for there to be no holes. This is
especially true if the platforms are on highly inclined solar orbits.

>> The moving goalposts are also noted.
>
> A consequence of ALL strategic planning. There is no such thing as a
> fixed goal poast.

This discussion isn't about "how to fight a space war" in general, it's
about the standard Nicoll's law efforts to find a way to get stealth in
space.

>> You can't take out new sensors fast enough, your shots simply can't hit
>> them for months, if not years.
>
> It is not how long the shots take to hit. It is how quickly they hit and
> how many hit, in succession. Remember: planning. Careful planning.
> Planning based on long periods of observation.

You can't shoot at them until after they launch, unless you are going to
start obsessively shooting at every potential launch window.

>> Hmmm, two people assuming espionage successes on a scale that the
>> Bircher's would expect.
>
> Espionage happens. So do hackers.

Successes on this scale are incredibly rare, there's a reason I was
alluding to the idea of the President of the United States being a Soviet
agent.

> OTOH, you can't prevent both by
> preventing access, in which case it is up to other means... like the
> buckshot, the drones, coordinated battle forces, long range missiles,
> etc.

You still aren't getting stealth out of it.

>> And in the time period between taking out a sensor net and being able
>> to actually do anything with that fact you are faced with a new net
>> forming.
>
> Planning. You do not wait for the net to go down. You move in
> coordination with the forces taking down the net.

IOW: You don't have stealth.

>> A new net that is going to start by focusing on all the places your
>> fleet could have gone in the brief period of sensor blindness you got.
>> That's assuming you even got any.
>
> It is not so easy to simply put up a new net. Platforms are expensive.
> The means to deploy them are expensive. It takes as much tim getting
> them into position as it takes shooting them down...

They become useful very quickly, nearly instantly if you have more than
one launch point. Sure, you would rather the platforms be way out of
plane so that they can use the ecliptic as 'free' range data but they can
still spot things.

> the SLOW way. That,
> and launch facilities are often the easiest to track. BTW: planetary
> launch facilities will be the sniper targets.

And the operation gets bigger and bigger....

>> There is something on an intercept course for a sensor platform that's
>> in a polar orbit of the sun, we didn't send it and it's adjusting
>> course to maintain the intercept. I wonder what it could possibly be?
>>
>> Remember that these platforms are going to be way out in the middle of
>> nowhere, (orbitally speaking). Things aren't going to 'just happen' to
>> be passing by them.
>
> Depends on how obvious you want your platforms.

Again, I conceded known platform locations from the get-go. Someone
intercepting a concealed platform is an even bigger red flag.

> If you want EVERYONE to
> know where your platform is, sure, it is going to be difficult to hide
> your intent to kill these. OTOH, polar orbits intersect regular orbits,
> so a couple of these might be in the wrong place at the wrong time.

Any sensor net is going to be designed to absorb such losses. For this
kind of net you get some of it intrinsically, (since you always want
platforms well away from the ecliptic).

> The
> rest will be easily dispatched by shot. Most likely scenario: the shot
> will be so small and so thinned out that they are never detected.

Thinned out means ineffective.

[Rick Pikul/Chakat Firepaw]

On Fri, 22 Jul 2016 07:55:19 -0700, Mikkel Haaheim wrote:

> Le vendredi 22 juillet 2016 00:38:19 UTC+2, Rick Pikul/Chakat Firepaw a
> écrit :
>
>> Which means one tiny orbital jink and you miss.
>
> Depends upon how many KKVs you have. "Buckshot" scattered KKVs covering
> tens of thousands of km can take very little mass and energy to deploy,
> but they will do the job, and there is no way of evading all of them.

This operation just keeps getting bigger and bigger. You are now evenly
distributing billions, (covering a 10Mm radius at one KKV per hectare
takes ~30 billion KKVs), of KKV pellets and all you can guarantee is to
restrict it's ability to do long term avoidance.

>> I wasn't using the "any stealth technique you can use to try and hide
>> your ships will work better for the sensor platforms," counter. I was
>> using "taking out the sensor platforms isn't as easy or effective as is
>> being assumed."
>
> No one is assuming that it is easy.

The guy I initially responded to did. Furthermore, you did notice the
context of that remark, right? That was pointing out that someone was
arguing against the wrong thing in his response to me.

>> Remember, knowing the location and orbit of something now only places
>> constraints on where it will be in a year.
>
> And tracking how much it has deviated in course over a couple years
> gives a fairly reliable stadnard of deviation of how much allowance has
> to be taken into account.

That would be part of those constraints.

>> And all you have to do is assume that you can undetectably compromise
>> multiple high-security computer systems that are going to be operated
>> in a way that reflects that such intrusion must be avoided at all
>> costs.
>
> As I said, no one said it would be easy. OTOH, having a few well place
> agents...

Which both sides will have and you can thus assume that your shots are
known. Thus the war starts a couple years before your 'surprise' attack
on the sensor net.

>> Congratulations, you have noticed that looking for unpowered objects
>> that aren't thrusting using effectively no resources is hard.
>
> Time and patience. Take a big ball of rock. Dig a deep hole, with many
> smaller holes branching out. Fill those holes with attack resources.
> Give that big rock a slight nudge. A few years later, start activating
> your systems, and get ready to let fly.

So you are going to war with a ship a generation out of date.

The "little nudge and drift" plain fails because of the time scales
involved: It either takes forever to get there or you need a lot more
than a little nudge.

[Rick Pikul/Chakat Firepaw]

On Fri, 22 Jul 2016 08:20:54 -0700, Mikkel Haaheim wrote:

> Every agrument we consider for why "there ain't no stealth in space"
> already applies for anything on land or in the air. And yet...

Here's your problem, you don't actually understand the core problems with
stealth in space.

There is no horizon. On a planet you only have to be able to keep from
being detected by sensors that are really close to you.

Space gives a very uncluttered background. On a planet you have
everything from mountains to shifts in atmospheric conditions causing
sensor clutter.


Space really is a different sensor environment.

[Rick Pikul/Chakat Firepaw]

On Fri, 22 Jul 2016 03:40:15 -0700, Mikkel Haaheim wrote:

> These are on the order of at least several m^2, and several tommes
> mass.

Compared to a warship, that's tiny.

A laser armed warship is going to have radiators bigger than that.

[Sea Wasp (Ryk E. Spoor)]

On 7/22/16 11:20 AM, Mikkel Haaheim wrote:
> Something that always seems to be missed in these discussions. Precedent.
> We ALREADY LIVE in the world where "stealth is impossible".

No. No we don't.

Space doesn't have anything to HIDE you. Earth does. You can't see
through clouds like Superman's X-Ray vision and scan the bottom of the
sea like the Enterprise searching for that one life-form on all of Beta
Proxima XVI. There's Other Stuff There. WAAAAY too much Other Stuff. You
can't track every plane all the time -- we have devices that sorta give
us tracking but we don't and can't track them along their entire paths
accurately (or we'd never lose a plane).

This is actually one of the key points I make in the Arenaverse novels.
Fighting in Arenaspace is NOTHING like fighting in our home space,
because the Arenaverse is filled with atmosphere (and other stuff) that
makes it quite possible for you to pull off "stealth" tricks and end up
with engagement ranges back in the "humanly comprehensible" distance range.

Space is, for the most part, empty. It's got some number of dust
particles and molecules per cubic meter but it is effectively completely
empty for most purposes. It won't attenuate your signals or absorb them
or allow you to refract them.

Earth's lower atmosphere, land, and sea? They've got all SORTS of ways
to screw up your ability to detect, track, locate, and identify.

[Mikkel Haaheim]

Le vendredi 22 juillet 2016 19:30:23 UTC+2, Rick Pikul/Chakat Firepaw a écrit :

>
> Your fleets can't move until the sensor platforms are down or the whole
> point of shooting them down is lost. Any fleets that happen to be under
> way when your KKVs are spotted get KKVs of their own launched at them.

Depends. Sure the fleets can move. You just have to be careful that the movement does not look like hostile manoeuvres. It helps if your warships do not look or act like warships.

>
> He clarified to to be stuff like "chunks of regolith".

I did not see this, but yes, it is an option, especially for the buckshot.

>
> There are a limited number of places you can launch from, most of the
> sensor platforms are going to require that kind of time in flight from
> any of them.

nonsense. There are literally hundreds of thousands of different astronomical bodies to launch from. Plus, you could easily launch from any vessel in transit. Get a simple mass driver, and there will be no way to detect such launches.
I will grant that polar orbit will need time to get to, or they will need the high velocity flight. Buckshot time.

>
> New platforms means that you haven't gotten stealth by killing the
> sensors.

Wrong. You don't need to kill ALL the sensors. You only need to kill ENOUGH sensors.


>
> Yes completely different.

Well, this is a matter of interpretation, and it is not really important.

>
> So now we're up to _trillions_ of evenly distributed pellets, all to
> probably _fail_ at getting any kind of mission kill. 100Mm radius at 1
> pellet/ha equals 3 trillion pellets, one pellet per hectare means you
> probably do no more than a few micrometeorite holes in the sail.

400 trillion, to be exact (4 pellets/m^2, 10 000 km^2); which comes to (200m)^3 material (for 1 cm^3 pellets). However, considering the smallest cross section for a "useful" (I am being extremely generous) platform would be just over 16 m^2, this estimate is overkill. Forget high kinetic impact... if you shot the hubble with 64 9mm rounds, even underpowered, its optics would be ripped to shreds. Also, 10 000 km is probably unnecessary.
Let's try something more realistic: 1 pellet / 10 m^2, 1000 km^2 spread. This only requires (30 m)^3 of material. For that matter, with high kinetic energy, 5mm pellets would be sufficient, so you only need 1/8 of that material estimate.
If you went with the explosive route, you would have lateral saturation from the explosion, meaning that you don't need to have even 1 pellet / platform cross section area (let alone 2 to 64). If a single larger pellet (remote detonation grenade, actually) approaches within 10m, the platform will be shredded. This would mean an areal density of 1 unit / 400 m^2 (this time, being conservative... it would actually be closer to 1 / 900 m^2)...I don't remember my suggested spread.
There is no hope of escape for any useful platform. I used hubble as a basis, and its 1 arcsecond maximum resolution is not even useful for the purpose.

>
> If you want to have a good chance at a mission kill, you are going to
> need something like one pellet per 10 m^2 or 1000 per hectare.

Yes. I originally had 4 per m^2. For clarification, I was talking about a spread of 10 000 km, not a radius.

>

>
> It doesn't take many platforms for there to be no holes. This is
> especially true if the platforms are on highly inclined solar orbits.

Dead. Wrong.
Unless you are talking about super-platforms with thousands of telescopes, each. Thousands of 10m+ telescopes, each. I am being generous... 10m telescopes are next to useless in terms of resolution... but if you have several such platforms (at least 4), you can link them up to provide a vrtual telescope. Prcoessing power is going to be a horror, though.
Scanning takes time, and is easily defeated.
Honestly, given the field of view involved, it is questionable that you would be able to pack the number of required telescopes to provide real-time coverage in a volume smaller than a small moon.

> This discussion isn't about "how to fight a space war" in general, it's
> about the standard Nicoll's law efforts to find a way to get stealth in
> space.

Which is meaningless without context. You have to understand how stealth works, and how it is used, in the context of fighting battles... in space, or on Earth. There is not a single argument that does not apply to the current state of warfare. There is no such thing as an undetectable construct, even now. It is within our current technical abilities to put up observation platforms that could track every moving thing on the surface or in air, so long as it is outdoors. We don't even need satellites to do so, but they are much more efficient. yet we still have stealth aircraft.

> You can't shoot at them until after they launch, unless you are going to
> start obsessively shooting at every potential launch window.

Every launch installation, yes. Launch installations are also difficult to hide, especially after they have already been used. But, again, warfare is never easy. It is assumed that you will never get all of them. You get as many as you can, and take advantage of what you can.

>
> Successes on this scale are incredibly rare, there's a reason I was
> alluding to the idea of the President of the United States being a Soviet
> agent.

And yet... ...
There is nothing preventing a soviet spy from becoming president. We would never know. The only difficulty to overcome is that it is so difficult for ANYONE to become president, but a soviet spy would have as good a chance as anyone else. But that would likely stop the war from happening in the first place. Espionage is not so rare. It occurs in the corporate world all the time... and most militaries rely on corporations to produce their observation platforms. There are security measures, but these are never perfect... especially when you don't know if war is coming, or who the enemy is going to be.

>
> You still aren't getting stealth out of it.

You still aren't understanding what stealth actually is.

>
> IOW: You don't have stealth.

No... IOW, stealth is not an absolute.
Stealth is not about not being seen. It is about not being noticed.

>
> They become useful very quickly, nearly instantly if you have more than
> one launch point. Sure, you would rather the platforms be way out of
> plane so that they can use the ecliptic as 'free' range data but they can
> still spot things.

Wrong. For protection, optics are kept covered during acceleration, up to the moment of final deployment. Even then, it takes time to analyse the data, especially if you are using interferomtric methods to resolve distant objects.

>
> And the operation gets bigger and bigger....

You expect wartime operations to be small?!? If someone is going to plan a preemptive war, the start of that war is going to be planned to the most minute detail. The operation is going to be "global" in scale, based on decades of strategic analysis and planning.

>
> >> There is something on an intercept course for a sensor platform that's
>

> Again, I conceded known platform locations from the get-go. Someone
> intercepting a concealed platform is an even bigger red flag.

Depends upon the approach. Even if they come directly for you it is not necessarily a red flag. If you are concealed, you are by definition an unknown. You can' exactly hide. People are going to come to see what is there. If you are concealed, and if you are smart, you do nothing except watch... perhaps it is a survey crew looking to see if you are an asteroid with useful ores.
If you are in polar orbit, you are not concealed. Everyone is going to know you are there (mostly because you expended a tremendous amount of energy to get yourself there), and they are going to have a fairly good idea of WHY you are there (you can explain 1 or 2 by calling them "mapping arrays"... but you are not going to be able to explain 4 or 5, let alone dozens).

> Any sensor net is going to be designed to absorb such losses. For this
> kind of net you get some of it intrinsically, (since you always want
> platforms well away from the ecliptic).

Sensor nets are going to anticipate a very low percentage of losses, and may pad this by multiplying the expected losses. Doesn't matter. It just adds more targets.

>
>
>
> Thinned out means ineffective.

DEAD. WRONG.
You only need a single kinetic impact. So long as you have the areal density, the impact is going to happen. Spread the pellets linearly by a few thousand km (a couple seconds), the impact is STILL going to happen, but it is much more difficult to see the cloud.

[Mikkel Haaheim]

Le vendredi 22 juillet 2016 19:30:24 UTC+2, Rick Pikul/Chakat Firepaw a écrit :

> This operation just keeps getting bigger and bigger. You are now evenly
> distributing billions, (covering a 10Mm radius at one KKV per hectare
> takes ~30 billion KKVs), of KKV pellets and all you can guarantee is to
> restrict it's ability to do long term avoidance.

From my original proposal on this point: 400 trillion, exactly. (200m)^3 material. This was extreme overkill. I have since brought it down to (30m)^3 of material... or even less, using smaller pellets.

>
> > No one is assuming that it is easy.
>
> The guy I initially responded to did. Furthermore, you did notice the
> context of that remark, right? That was pointing out that someone was
> arguing against the wrong thing in his response to me.

Interpretation. I interpreted that the mechanism was not complicated, which is correct... essentially, you through stones. You interpreted that it was not difficult, which I agree is false... you need to make careful calculations based upon careful observations.
Yes, I noticed. The correction was irrelevant.

> >
> > And tracking how much it has deviated in course over a couple years
> > gives a fairly reliable stadnard of deviation of how much allowance has
> > to be taken into account.
>
> That would be part of those constraints.

Yes. We are in agreement here. My point being that constraints are relevant.

>
> > As I said, no one said it would be easy. OTOH, having a few well place
> > agents...
>
> Which both sides will have and you can thus assume that your shots are
> known. Thus the war starts a couple years before your 'surprise' attack
> on the sensor net.

Oh, absolutely, all sides will have agents. This is a large part of why wars drag out. It is also why many wars never get started. OTOH, you can never assume anything. Your spies miss the opportunity to sabotage the platforms, and you have to kill them instead. The other side misses the opportunity to gather key intelligence on the intents of a separatist movement (for example), and a wave of surprise attacks commences.
Espionage isn't easy, either. Nothing is going to be easy. You take the opportunities you can.

> So you are going to war with a ship a generation out of date.

Yes. Just like militaries always have. There is an adage, "armies always plan for the last war". Most of the forces used in WWII were built for WWI... some literally. The majority of forces used in Korea and Vietnam were built for WWII. Most of the vessels we have deployed now were built in the '80s. Our newest carriers and destroyers were put on the drawing board 20 years ago, based on 30 year old concepts.

>
> The "little nudge and drift" plain fails because of the time scales
> involved: It either takes forever to get there or you need a lot more
> than a little nudge.

Well, yes, the "little nudge" was actually a mass driver spitting out tonnes of excavated material at a few km/s. Such phrasesare relative.

[Mikkel Haaheim]

Le vendredi 22 juillet 2016 19:44:53 UTC+2, Rick Pikul/Chakat Firepaw a écrit :
>
> Here's your problem, you don't actually understand the core problems with
> stealth in space.

Actually, I do. You don't understand that we are already faced with the same problems.

>
> There is no horizon. On a planet you only have to be able to keep from
> being detected by sensors that are really close to you.

Have you noticed that there are camera EVERYWHERE? That does not even take into account where cameras COULD be. Ever hear of aerial drones? You can put a camera in the air for less then $100. For the cost of the Zimwalt programme, you can have cheap drones covering every square km of the Earth. If we REALLY wanted, there would be no place to hide.
Horizon is only an issue when there are places you can not, or do not, go. satellites made horizons irrelevant long ago.

>
> Space gives a very uncluttered background. On a planet you have
> everything from mountains to shifts in atmospheric conditions causing
> sensor clutter.
>

And all of this sensor clutter can be fairly easily "blue-screened" out. We only care about what moves, and we have had the software to clear such clutter for decades. The problem is it takes time to analyse.
Space, OTOH, is NOT uncluttered. Not at all. Especially when you bring in sensitive observation instruments. CBR is EVERYWHERE. Then you have all the stars you can't see with the naked eye... but sensitive instruments CAN. Then you have all the nebulae, galaxies, etc. Then there is all the particulate dust in space, and all the charged particles. Why don't care about these because we can't see them. Sensitive observation platforms CAN. There is also a HELL of a lot more space to sift through. On Earth, there is only about half a trillion square meters to sift through. You really don't have to be concerned about anything smaller, so resolution is not so much an issue.

>
> Space really is a different sensor environment.

Yes it is. On Earth, you are only limited by the technical capabilities of your sensors. In space, you are limited by hard absolutes. On Earth, there are people, with cameras, litterally everywhere. In space, there are great swathes where there is no one. On Earth, off the shelf, hand held optics, even the poorest quality, will give you usable information. In space, you need oversized optics, and the most minute deformations will destroy the image.

>

[Mikkel Haaheim]

Le vendredi 22 juillet 2016 19:50:17 UTC+2, Rick Pikul/Chakat Firepaw a écrit :
> On Fri, 22 Jul 2016 03:40:15 -0700, Mikkel Haaheim wrote:
>
> > These are on the order of at least several m^2, and several tommes
> > mass.
>
> Compared to a warship, that's tiny.
>
> A laser armed warship is going to have radiators bigger than that.
>

Compared to centimetric KKVs, they are gigantic. Compared to space-launched missiles or drones, they are merely big.

[Mikkel Haaheim]

Le vendredi 22 juillet 2016 20:19:09 UTC+2, Sea Wasp (Ryk E. Spoor) a écrit :

> Space doesn't have anything to HIDE you. Earth does.

Air doesn't have anything to hide you (if you are using IR, anyway).

>You can't see
> through clouds like Superman's X-Ray vision

You can with IR.

> and scan the bottom of the sea .

You have a point there. OTOH, stealth only works underwater because nations still WANT it to work underwater. Sonar is extremely effective in water... but it gives your position away. This is not a problem, however, if the sound generators are deployed throughout the oceans en mass... but EVERYONE will be able to hear the reflections. Nothing in the oceans would ever by stealthy again.

> You can't track every plane all the time --

Sure you can, if you deploy the kind of tracking network we are talking about for space use. We don't... but this is not because of tech limits, but other constraints that will also affect space-based sensor platforms. Also, keep in mind, the future where we will be placing military vessels in space toprotect space assets will also be the future where space traffic is common place... as common as air traffic.

> we have devices that sorta give
> us tracking but we don't and can't track them along their entire paths
> accurately (or we'd never lose a plane).

There is no tech limit preventing us from doing so. The reasons preventing us from tracking every plane are EXACTLY the reasons that cause the "there ain't no stealth in space" argument to fail. That is, it's expensive and we don't consider it a worthwhile investment.

>
> This is actually one of the key points I make in the Arenaverse novels.
> Fighting in Arenaspace is NOTHING like fighting in our home space,
> because the Arenaverse is filled with atmosphere (and other stuff) that
> makes it quite possible for you to pull off "stealth" tricks and end up
> with engagement ranges back in the "humanly comprehensible" distance range.

Atmosphere does not permit stealth. Actually, atmosphere makes stealth much harder, because now you have to deal with sound and airborne chemical diffusion.

>
> Space is, for the most part, empty. It's got some number of dust
> particles and molecules per cubic meter but it is effectively completely
> empty for most purposes. It won't attenuate your signals or absorb them
> or allow you to refract them.

Which is exactly why you have so much trouble with background sources (CBR, stars, galaxies, etc). Furthermore, the distances involved set absolute physical limitations on resolution. Most of the analyses suggested by Atomic Rockets are simply not possible unless you have an array with a baseline extending from the Earth to the moon, and this will only allow resolution on one plane, so you will need at least a third unit in a polar orbit greater than 100 000 km. Even this might not be sufficient to resolve 3D images.

>
> Earth's lower atmosphere, land, and sea? They've got all SORTS of ways
> to screw up your ability to detect, track, locate, and identify.

But none that can't be overcome. The tech exists. What doesn't exist is the quatnity of deployment of that tech necessary. And the reasons we don't have the quantity of tech are the same reasons we won't be able to defeat stealth in space.
We even have more options for terrestrial sensors. Space is limited largely to EM detection, and some high energy physics detectiobn that really does not apply. Earth has the EM detection. It also allows for good (air) to excellent (underwater or underground) sonar. It also allows for seismic... if you wanted to, seismic detectors would be able to trace every footstep taken. It also allows for chemical anamysis and tracking. Distances are not a problem. Getting blind ally views is not problem, because people go everywhere, and typically have very little problem getting there. There is no place in the biosphere where we can not place detectors... somewhat unlike in space, where current tech will not allow us to place large masses in solar polar orbits (there is too much gravity to overcome without the free boost we get from Earth's orbital velocity). Earth observation allows cameras that fit in the palm of the hand. If you want any sort of strategically useful info, the smallest a space platform can be is several meters in diameter. Earth observation does not require high quality. Space observation requires extremely high quality optics, with virtually zero tolerance over large areas.


>
>
>
>
> --
>

[Greg Goss]

Mikkel Haaheim <mikkel...@gmail.com> wrote:

>So why do we have aircraft that we can't find for months after going
>missing?

Months? There have been cases where search parties looking for a
downed plane found the WRONG crashed plane -- one that had been lost
and the search abandoned years earlier.
--
We are geeks. Resistance is voltage over current.

[Greg Goss]

Mikkel Haaheim <mikkel...@gmail.com> wrote:

>Have you noticed that there are camera EVERYWHERE? That does not even take into account where cameras COULD be.

More cameras than THAT. I was reading a conspiracy theory that the
Pokemon "augmented reality" is incidentally vacuuming up streetviews
of essentially entire countries, including places that are supposedly
secure.

[Alie...@gmail.com]

On Saturday, July 23, 2016 at 12:33:13 PM UTC-7, Mikkel Haaheim wrote:
> Le vendredi 22 juillet 2016 20:19:09 UTC+2, Sea Wasp (Ryk E. Spoor) a écrit :
>
> > Space doesn't have anything to HIDE you. Earth does.
>
> Air doesn't have anything to hide you (if you are using IR, anyway).

I've been lurking this thread, and have noticed lots of unstated assumptions by all participants.

It might help to state exactly what we're trying to stealth, what we're trying to stealth it *from*, and then we can start talking about the characteristics of the environment that might help or hinder our stealthing efforts *for that particular case*.

Emphases because hiding a battleship from a mosquito is not the same task as hiding a mosquito from a battleship, or hiding one mosquito from another or one battleship from another.

Both have different profiles *in the sensorium of the other* which is the critical point. Yes, the mosquito is limited to the sensorium it evolved with and the battleship can retrofit whatever humans can think up, but not generally while trying to hide *or* seek.

Environmental variable obviously affect chance of detection too but you have to start somewhere.

> >You can't see through clouds like Superman's X-Ray vision
>
> You can with IR.

Yes, if it's available, and if there isn't a chemical fog in the way that absorbs or diffuses IR beyond reliability or emits masking IR of its own. Producing such "smokescreens" in space is far more difficult than in atmosphere but certainly not necessarily impossible or infeasible on the inherently massive economic scale of interplanetary or interstellar warfare.

> > and scan the bottom of the sea .
>
> You have a point there. OTOH, stealth only works underwater because nations
> still WANT it to work underwater. Sonar is extremely effective in water...
> but it gives your position away.

Active sonar does, yes. Passive sonar doesn't which is a better analog of the typical systems suggested for space warfare detection.

> This is not a problem, however, if the sound generators are deployed
> throughout the oceans en mass... but EVERYONE will be able to hear the
> reflections. Nothing in the oceans would ever by stealthy again.

Until the easily-located "illuminators" are destroyed, which will be a priority for all sides.

Passive sonar imaging on small scales (arrays a few meters square, range a few dozen meters, resolution a few centimeters) has been demonstrated in the public domain. The "illumination" is ambient ocean noise.

I have absolutely no doubt that all major military maritime players have already deployed large networked passive arrays that can track pretty much any object that might be a threat anywhere in Earth's oceans, if all were linked together (eliminating hiding behind seamounts, thermal layers, etc.). The hoary old SF cliche of aliens having submarine bases is just flat-out impossible now, barring collusion from the humans in charge of the part monitoring the alien base's location.

Using that information is a different matter in submarine warfare- the collated, analyzed data has to be securely accessible by the subs. You can't use comms lasers as you can with spacecraft.

Notice that if we used submarines for shipping rather than surface ships, the commercial carriers would have had to develop this capacity if only for traffic control.

In space it's actually easier unless warships don't have to limit themselves to things like Hohmann trajectories, but that's way beyond the "current tech" goalpost that keeps being referred to.

If they do, the volume of space that must be kept under constant *detailed* surveillance for planetary defense becomes much smaller. The same applies to intership engagements within the Hill spheres of astronomical bodies.

> > You can't track every plane all the time --
>
> Sure you can, if you deploy the kind of tracking network we are talking about
> for space use. We don't... but this is not because of tech limits, but other
> constraints that will also affect space-based sensor platforms. Also, keep in
> mind, the future where we will be placing military vessels in space to
> protect space assets will also be the future where space traffic is common
> place... as common as air traffic.

Our current air-tracking network coverage is driven mostly by commercial limits; we install only the minimum required to keep the risks of losing track of a plane to an insurance-acceptable minimum. Military expenditures for similar tasks tend to be more lavish because more is at stake.

> > we have devices that sorta give us tracking but we don't and can't track
> > them along their entire paths accurately (or we'd never lose a plane).
>
> There is no tech limit preventing us from doing so. The reasons preventing us
> from tracking every plane are EXACTLY the reasons that cause the "there ain't
> no stealth in space" argument to fail. That is, it's expensive and we don't
> consider it a worthwhile investment.

Losing an airliner or two per year is a few-dozen-millions-of-dollars risk airline insurers accept.

Losing a *planet* even once is not an equally-acceptable risk, so space warfare sensor capabilities will necessarily be much more elaborate than anything so far discussed.

> > This is actually one of the key points I make in the Arenaverse novels.
> > Fighting in Arenaspace is NOTHING like fighting in our home space,
> > because the Arenaverse is filled with atmosphere (and other stuff) that
> > makes it quite possible for you to pull off "stealth" tricks and end up
> > with engagement ranges back in the "humanly comprehensible" distance range.
>
> Atmosphere does not permit stealth. Actually, atmosphere makes stealth much
> harder, because now you have to deal with sound and airborne chemical
> diffusion.

Do not assume perfect seeing at all times, even in IR. It can even work against you if you do have it; attacking out of the Sun is an old WWI trick still used by today's fighter/bombers.

> > Space is, for the most part, empty. It's got some number of dust
> > particles and molecules per cubic meter but it is effectively completely
> > empty for most purposes. It won't attenuate your signals or absorb them
> > or allow you to refract them.
>
> Which is exactly why you have so much trouble with background sources (CBR,
> stars, galaxies, etc).

Not the exact equivalent of "ground clutter" because those sources don't move (much) and are thus fairly easily subtracted out- same for planets and known large asteroids because their motions are known and stable. Asteroidal bodies in the size range of typical warships discussed here are, because they move, there are so damn many of them, and we haven't catalogued a tiny fraction of them. Yet. The fact that we keep getting "surprised" by meteor falls like the recent one in Argentina suggest to me that our current detection setup is roughly analogous to the major players' sonar capabilities at the beginning of WWII. We really need to scale that up, and soon. Remember that such a *commercial* system, and its database, will likely already be in place *before* military planners start taking bids for the systems they think they'll need for a looming interplanetary conflict.

> Furthermore, the distances involved set absolute physical limitations on
> resolution. Most of the analyses suggested by Atomic Rockets are simply not
> possible unless you have an array with a baseline extending from the Earth to
> the moon, and this will only allow resolution on one plane, so you will need
> at least a third unit in a polar orbit greater than 100 000 km. Even this
> might not be sufficient to resolve 3D images.

Granted. OTOH you also have to grant that whoever insures the Jeff Bezos-descendant-analogs who operate interplanetary shipping lines will require them to maintain exactly the sort of sensor/analysis system you described, or better, because it's the direct analog of today's commercial air-tracking capability.

> > Earth's lower atmosphere, land, and sea? They've got all SORTS of ways
> > to screw up your ability to detect, track, locate, and identify.
>
> But none that can't be overcome. The tech exists. What doesn't exist is the
> quatnity of deployment of that tech necessary.

Correct, because we don't think we need it. And mostly, we're right.

> And the reasons we don't have the quantity of tech are the same reasons we
> won't be able to defeat stealth in space.

Different cost/benefit ratios though. You appear to have convinced yourself that the sheer scale of size and number of stations and dedicated processing power required will forever be cost-prohibitive. I disagree.

> We even have more options for terrestrial sensors. Space is limited largely
> to EM detection, and some high energy physics detectiobn that really does not
> apply.

Why do you dismiss high-energy emissions?

> Earth has the EM detection.

Yes, except when it doesn't.

> It also allows for good (air) to excellent (underwater or underground) sonar.
> It also allows for seismic... if you wanted to, seismic detectors would be
> able to trace every footstep taken.

That might be a tad hyperbolic considering the sheer amount of other seismic noise, both natural and artificial.

> It also allows for chemical anamysis and tracking. Distances are not a
> problem. Getting blind ally views is not problem, because people go
> everywhere, and typically have very little problem getting there. There is no
> place in the biosphere where we can not place detectors... somewhat unlike in
> space, where current tech will not allow us to place large masses in solar
> polar orbits (there is too much gravity to overcome without the free boost we
> get from Earth's orbital velocity).

Even limiting to current tech, we surely could place large masses pretty much anywhere we wanted to *if we thought it was worth it*.

> Earth observation allows cameras that fit in the palm of the hand.

Not if you're looking for something flying at several thousand feet with no contrail.

> If you want any sort of strategically useful info, the smallest a space
> platform can be is several meters in diameter.

Not a problem.

> Earth observation does not require high quality.

Only if you're willing to tolerate lower-quality images.

> Space observation requires extremely high quality optics, with virtually
> zero tolerance over large areas.

"Tricks" like adaptive optics and long-baseline interferometry tend to cancel out most of the imperfections of individual detectors.


Mark L. Fergerson

[Mikkel Haaheim]

Yes. I was being generous.

[Sea Wasp (Ryk E. Spoor)]

On 7/23/16 3:33 PM, Mikkel Haaheim wrote:
> Le vendredi 22 juillet 2016 20:19:09 UTC+2, Sea Wasp (Ryk E. Spoor) a écrit :
>
>> Space doesn't have anything to HIDE you. Earth does.
>
> Air doesn't have anything to hide you (if you are using IR, anyway).
>
>
>> You can't see
>> through clouds like Superman's X-Ray vision
>
> You can with IR.

Not so simply, you can't. The amount of humidity alone will strongly
affect what range you can see to with what detail and sensitivity.
Temperature differential is crucial -- you'll easily detect a human
being two kilometers away on a winter snowpack, but it'll be a lot
harder to pick out that human being in a jungle where the ambient
temperature is in the 90s.

And of course Earth provides other living beings, and other operating
machines, to confound your attempts to find them, while in space it's
likely that your target is the ONLY think in that volume of space that
isn't vacuum.

>>
>> This is actually one of the key points I make in the Arenaverse novels.
>> Fighting in Arenaspace is NOTHING like fighting in our home space,
>> because the Arenaverse is filled with atmosphere (and other stuff) that
>> makes it quite possible for you to pull off "stealth" tricks and end up
>> with engagement ranges back in the "humanly comprehensible" distance range.
>
> Atmosphere does not permit stealth.

Oh, the hell it doesn't. On the Arenaverse scale, even more so, because
instead of the trick we can use today -- put up a satellite and look
down through what amounts to only a couple miles of sea-level density
air -- you'd have to look through effectively infinite amounts of such
air, with accompanying dust, humidity, clouds, etc.

>>
>> Earth's lower atmosphere, land, and sea? They've got all SORTS of ways
>> to screw up your ability to detect, track, locate, and identify.
>
> But none that can't be overcome.

For any particular case with unlimited monetary expenditure, perhaps,
but you're dismissing stuff that we KNOW is a problem as though it
isn't, which really makes me question how much you know about the
*practical* limitations and not the theoretical. I work, as I said, with
multispectral imaging and sensors, some for the military, and our
experience with such imaging is more a matter of seeing more of its
limitations than its awesomeness.

[Mikkel Haaheim]

Le dimanche 24 juillet 2016 00:51:19 UTC+2, nu...@bid.nes a écrit :

> I've been lurking this thread, and have noticed lots of unstated assumptions by all participants.

Agreed. OTOH, I think it is hard to avoid that. I generally try to be as precise as I can, but often I just don't have the time.

>
> It might help to state exactly what we're trying to stealth, what we're trying to stealth it *from*, and then we can start talking about the characteristics of the environment that might help or hinder our stealthing efforts *for that particular case*.

Part of the problem, here, is that stealth is a fluid concept. There are no absolutes. Strategists analyse the current situation, try to anticipate advances, and then look for whatever they can to leverage the environment to their favour.
My usual explanation is that stealth is less about not being seen than it is about not being noticed. You take advantage of what you can. When conditions change, stealth changes with it.

>
> > >You can't see through clouds like Superman's X-Ray vision
> >
> > You can with IR.
>
> Yes, if it's available, and if there isn't a chemical fog in the way that absorbs or diffuses IR beyond reliability or emits masking IR of its own. Producing such "smokescreens" in space is far more difficult than in atmosphere but certainly not necessarily impossible or infeasible on the inherently massive economic scale of interplanetary or interstellar warfare.

...and there are always means to defeat the condition.

>
> > > and scan the bottom of the sea .
> >
> > You have a point there. OTOH, stealth only works underwater because nations
> > still WANT it to work underwater. Sonar is extremely effective in water...
> > but it gives your position away.
>
> Active sonar does, yes. Passive sonar doesn't which is a better analog of the typical systems suggested for space warfare detection.

OTOH, there is often not enough signal for passive sonar. Scandinavian subs, for example, are currently virtually undetectable using passive sonar. Also, passive sonar tends to require a LOT of manoeuvering and time in order to get a firing solution (a 3D fix), which makes it somewhat easier to detect you, even if you are not going active.

>
> > This is not a problem, however, if the sound generators are deployed
> > throughout the oceans en mass... but EVERYONE will be able to hear the
> > reflections. Nothing in the oceans would ever by stealthy again.
>
> Until the easily-located "illuminators" are destroyed, which will be a priority for all sides.

Quite true... unless they are well defended. As I said, stealth works because navies WANT stealth to work. If navies did NOT want stealth to work, they would put up such a network, establish multiple levels of redundancy, and establish strong defenses for the transmitters. But this would be a significant investment, and... navies WANT stealth to work.

>
> Passive sonar imaging on small scales (arrays a few meters square, range a few dozen meters, resolution a few centimeters) has been demonstrated in the public domain. The "illumination" is ambient ocean noise.

I Don't doubt it. I have read a few Cog Sci papers about the blind subconsciously using ambiant echolocation to navigate through rooms and busy streetsides, and the naval applications of sch research are obvious. However, if you want better range, you will need reliable sources with fixed positions.

>
> I have absolutely no doubt that all major military maritime players have already deployed large networked passive arrays that can track pretty much any object that might be a threat anywhere in Earth's oceans, if all were linked together (eliminating hiding behind seamounts, thermal layers, etc.). The hoary old SF cliche of aliens having submarine bases is just flat-out impossible now, barring collusion from the humans in charge of the part monitoring the alien base's location.

I have no doubt that such arrays are much more extensive than anyone imagines; however, we know from joint military excercises that such arrays do not exist everywhere. The US is in the best position to establish such arrays, given its wealth of natural resources and its unequaled access to the oceans... and yet the US often is unable to detect the opposition subs (notably scandinavian deisel subs that can park themselves within yards from an aircraft carrier without being noticed... after THAT particular event, the US asked Sweden if we could borrow their sub to try to work out how to detect it --this was about 3 or 4 years ago).

>
> Using that information is a different matter in submarine warfare- the collated, analyzed data has to be securely accessible by the subs. You can't use comms lasers as you can with spacecraft.

Quite correct. ELF is the currently preferred option, but that takes a lot of time. Sonic tranmission is an option, but you have to deal with the big bull's eye you have painted.

>
> Notice that if we used submarines for shipping rather than surface ships, the commercial carriers would have had to develop this capacity if only for traffic control.

Or establish tightly regulated traffic lanes, which is far more likely.

>
> In space it's actually easier unless warships don't have to limit themselves to things like Hohmann trajectories, but that's way beyond the "current tech" goalpost that keeps being referred to.
>
> If they do, the volume of space that must be kept under constant *detailed* surveillance for planetary defense becomes much smaller. The same applies to intership engagements within the Hill spheres of astronomical bodies.
>

>

> Our current air-tracking network coverage is driven mostly by commercial limits; we install only the minimum required to keep the risks of losing track of a plane to an insurance-acceptable minimum. Military expenditures for similar tasks tend to be more lavish because more is at stake.

...and militaries don't think that such networks are worth the investment. Every commercial plane that can go missing is a potential missile.

> Losing an airliner or two per year is a few-dozen-millions-of-dollars risk airline insurers accept.
>
> Losing a *planet* even once is not an equally-acceptable risk, so space warfare sensor capabilities will necessarily be much more elaborate than anything so far discussed.

Not more so than the asteroid hunters. Planets are assets. No one is going to destroy a planet if they can avoid it. It is pretty much the same reason we don't nuke Iran. Well, same sets of reasons, because it definitely is NOT the only one.
Stray asteroids are MUCH more dangerous, because they have no reason NOT to hit something.

>
> Do not assume perfect seeing at all times, even in IR. It can even work against you if you do have it; attacking out of the Sun is an old WWI trick still used by today's fighter/bombers.

Which only works if you have superior altitude. But no, there are always tricks that one can take advantage of. Or try to. OTOH, there are always countermeasures, as well. In an atmosphere, you can use your ears, as well as your eyes.

>

>
> Not the exact equivalent of "ground clutter" because those sources don't move (much) and are thus fairly easily subtracted out- same for planets and known large asteroids because their motions are known and stable. Asteroidal bodies in the size range of typical warships discussed here are, because they move, there are so damn many of them, and we haven't catalogued a tiny fraction of them. Yet. The fact that we keep getting "surprised" by meteor falls like the recent one in Argentina suggest to me that our current detection setup is roughly analogous to the major players' sonar capabilities at the beginning of WWII. We really need to scale that up, and soon. Remember that such a *commercial* system, and its database, will likely already be in place *before* military planners start taking bids for the systems they think they'll need for a looming interplanetary conflict.
>

Not so easy to subtract out. Astronomers are still pooring through 30 year old data (and older) trying to map out such objects... which is one of the reasons it is so hard to catalogue all those asteroids. Also, most typical ground clutter doesn't move either: mountains, vegetation, buildings, etc don't move; rivers and most traffic move in very regular patterns.

>
>
> Granted. OTOH you also have to grant that whoever insures the Jeff Bezos-descendant-analogs who operate interplanetary shipping lines will require them to maintain exactly the sort of sensor/analysis system you described, or better, because it's the direct analog of today's commercial air-tracking capability.

To the degree practical and feasible, yes. Also to the degree it is enforcible. Flight plans will routinely be required, as well as transponders, navigational suites, etc.

>
> > But none that can't be overcome. The tech exists. What doesn't exist is the
> > quatnity of deployment of that tech necessary.
>
> Correct, because we don't think we need it. And mostly, we're right.

There are also economical, social, and political factors, which will equally exist in a space-based future.

>
> Different cost/benefit ratios though. You appear to have convinced yourself that the sheer scale of size and number of stations and dedicated processing power required will forever be cost-prohibitive. I disagree.

Cost/benefit ratios shift. However, processing has to keep up with the traffic, just to give a single example. There is always going to be a tug of war between available resources and how to use them. The more tech evolves, the easier fabrication gets (and deployment, etc), but also the more things there are to compete against. It is always a question of what we value more, and how we balance everything out.
Is it possible to have a future world where there is an all encompassing "big brother" in the solar system? Sure... but you will probably have it n Earth first, and you will have to explain the dynamics.

>
> Why do you dismiss high-energy emissions?

Okay... qualification: does not apply in a semi-near term future based on existing propulsion theory. The reason is that there is no known energy source within the solar system capable of producing the high energy particles I'm refering to in quantities that can be measured reliably, especially at large distances.

>
> > Earth has the EM detection.
>
> Yes, except when it doesn't.

I don't know of any known substance that can block all detectable EM frequencies, except for extremely thick solid blocks, or extremely deep oceans... but that just means you need to get your detectors closer, which really isn't necessary, because that is when accoustic and seismic detectors are at their best.
Yes, you can beat specific EM detectors, especially those most likely to be used; but you can't beat everything.

>
>
> That might be a tad hyperbolic considering the sheer amount of other seismic noise, both natural and artificial.

Not so hyperbolic. Current seismic tech is extremely sensitive... to the extent that footsteps and other noise are a menace to good data. We are already able to filter out the bulk of that noise. For tracking footsteps, you actually want LESS sensitive sensors, reducing the amount of noise. In other words, the filter tech is already good enough, we just don't have a good reason to use it for tracking people... and there are currently much easier means to do location tracking of individuals.

>
>
> Even limiting to current tech, we surely could place large masses pretty much anywhere we wanted to *if we thought it was worth it*.

Eventually, perhaps. Not with current tech, though.
let's say we wanted to launch a probe from Earth into solar orbit at 1 AU. The required orbital velocity would be 30 km/2... the same as the velocity of the Earth around the sun. However, since you are already starting with the velocity of the Earth, you have to negate that velocity in order to achieve anything better than 45° inclination. This means you need a delta-v of at least 42.5 km/s (much more if you are using slow but steady propulsion). Now, keep in mind that we have only ever been able to achieve 17 km/s using multiple gravity assists, which would not be avilable for solar orbit insertions.

>
> > Earth observation allows cameras that fit in the palm of the hand.
>
> Not if you're looking for something flying at several thousand feet with no contrail.

Or if you are also flying at several thousand feet. I did not say that the small cameras could see everything, only that they would provide useful information.
Actually, come to think of it, I am fairly certain our current handhold cameras are easily capable of capturing the image of a commercial jet at 35 000 ft, or a fighter at 10 000 ft. A fighter at 35 000 ft + would be little more than a speck, so I do see your point. But again, useful information. At 1 AU, Hubble would be able to provide very little useful information unless you had two objects more than 10 km apart. Rough estimate. I will have to run the numbers again for 1 arcsecond resolution.

>
> > If you want any sort of strategically useful info, the smallest a space
> > platform can be is several meters in diameter.
>
> Not a problem.

Not for one, no. For enough to cover 360° x 360° of space at 4+ AU, it becomes a bit of a problem, especially for deployment costs.

>
> > Earth observation does not require high quality.
>
> Only if you're willing to tolerate lower-quality images.

Which rovide a wealth of tacticaland strategic info, yes. The poorest quality of images (a pinhole camera) provides recognisable images at ranges of dozens of meters.

>
>
> "Tricks" like adaptive optics and long-baseline interferometry tend to cancel out most of the imperfections of individual detectors.

Yes and no. These can clarify the images you are able to process, but they do so by filtering out the bits that "fall through the cracks". Interferometry only works if each of the units is sensitive enough to individually receive the source data, and only if there are no distortions caused by the optics (or anything intervening). Adaptive optics smooth out distortions, but only do so roughly, depending upon the degree of motion/control... these won't be able to "smooth out" distortion caused by scratches, etc.
>

[Rick Pikul/Chakat Firepaw]

On Sat, 23 Jul 2016 02:34:28 -0700, Mikkel Haaheim wrote:

> Le vendredi 22 juillet 2016 19:30:23 UTC+2, Rick Pikul/Chakat Firepaw a
> écrit :
>
>
>> Your fleets can't move until the sensor platforms are down or the whole
>> point of shooting them down is lost. Any fleets that happen to be
>> under way when your KKVs are spotted get KKVs of their own launched at
>> them.
>
> Depends. Sure the fleets can move. You just have to be careful that the
> movement does not look like hostile manoeuvres. It helps if your
> warships do not look or act like warships.

It doesn't matter that your ships haven't looked like they've been
engaged in hostile manoeuvres: You just started a war and I know where
your fleet is and where it is going.

What's more, your fleet has to stay in the relatively easy to reach parts
of the system. They can't do things like slingshot themselves out of the
ecliptic.

>> He clarified to to be stuff like "chunks of regolith".
>
> I did not see this, but yes, it is an option, especially for the
> buckshot.

An options, not an effective option, but an option.

>> There are a limited number of places you can launch from, most of the
>> sensor platforms are going to require that kind of time in flight from
>> any of them.
>
> nonsense. There are literally hundreds of thousands of different
> astronomical bodies to launch from. Plus, you could easily launch from
> any vessel in transit. Get a simple mass driver, and there will be no
> way to detect such launches.

You get a long time in flight unless you are right next to the target.
Do you really think that these platforms are going to be in 'busy' parts
of the system?

>> New platforms means that you haven't gotten stealth by killing the
>> sensors.
>
> Wrong. You don't need to kill ALL the sensors. You only need to kill
> ENOUGH sensors.

Enough = all or almost all.

>> Yes completely different.
>
> Well, this is a matter of interpretation, and it is not really
> important.

Yes, "do this once or twice during the entire service life," and "do this
constantly," being different or the same is merely "a matter of
interpretation."

>> So now we're up to _trillions_ of evenly distributed pellets, all to
>> probably _fail_ at getting any kind of mission kill. 100Mm radius at 1
>> pellet/ha equals 3 trillion pellets, one pellet per hectare means you
>> probably do no more than a few micrometeorite holes in the sail.
>
> 400 trillion, to be exact (4 pellets/m^2, 10 000 km^2); which comes to
> (200m)^3 material (for 1 cm^3 pellets).

There goes your tens or hundreds of thousands of km.

And avoiding a 10,000 km^2 barrage is easy: That's only 112 km across

> Let's try something more realistic: 1 pellet / 10 m^2, 1000 km^2 spread.
> This only requires (30 m)^3 of material. For that matter, with high
> kinetic energy, 5mm pellets would be sufficient, so you only need 1/8 of
> that material estimate.

Now we're down to a spread only 35km across. There's a pretty good
chance you'll miss even without the target doing a course adjustment.

> If you went with the explosive route, you would have lateral saturation
> from the explosion, meaning that you don't need to have even 1 pellet /
> platform cross section area (let alone 2 to 64). If a single larger
> pellet (remote detonation grenade, actually) approaches within 10m, the
> platform will be shredded. This would mean an areal density of 1 unit /
> 400 m^2 (this time, being conservative... it would actually be closer to
> 1 / 900 m^2)...I don't remember my suggested spread.

That doesn't really change things, (fewer shots, but bigger with even
distribution being more important).

> There is no hope of escape for any useful platform. I used hubble as a
> basis, and its 1 arcsecond maximum resolution is not even useful for the
> purpose.

Assuming your little spread can actually hit it.

>> If you want to have a good chance at a mission kill, you are going to
>> need something like one pellet per 10 m^2 or 1000 per hectare.
>
> Yes. I originally had 4 per m^2. For clarification, I was talking about
> a spread of 10 000 km, not a radius.

Then perhaps you should be using a measurement of _area_. Furthermore,
that means your response to Sea Wasp was completely dishonest, given that
you dismissed his calculation of how far you would have to move to avoid
the shot, even though it was on the exact same scale as you are now
giving for your attack spread.

>> It doesn't take many platforms for there to be no holes. This is
>> especially true if the platforms are on highly inclined solar orbits.
>
> Dead. Wrong.

Nope, you simply don't understand the tech.

> Unless you are talking about super-platforms with thousands of
> telescopes, each. Thousands of 10m+ telescopes, each. I am being
> generous... 10m telescopes are next to useless in terms of resolution...
> but if you have several such platforms (at least 4), you can link them
> up to provide a vrtual telescope. Prcoessing power is going to be a
> horror, though.
> Scanning takes time, and is easily defeated.
> Honestly, given the field of view involved, it is questionable that you
> would be able to pack the number of required telescopes to provide
> real-time coverage in a volume smaller than a small moon.

Oh, here's your confusion: You think you need to do the whole thing with
a single kind of sensor.

You use a low-resolution, fast scan, wide angle system to find things to
look at.
You use a high-resolution, slow scan, narrow angle system to lock down
the exact locations and get things like heat and drive signatures.
You use things like a high-power optical telescope once you already know
you have something you want to look at and exactly where it is.

>> This discussion isn't about "how to fight a space war" in general, it's
>> about the standard Nicoll's law efforts to find a way to get stealth in
>> space.
>
> Which is meaningless without context.

No, it isn't. It's simply about "how not to be seen", (before you go off
on some random tear, that's a reference).

> You have to understand how stealth
> works, and how it is used, in the context of fighting battles... in
> space, or on Earth. There is not a single argument that does not apply
> to the current state of warfare.

With interplanetary warfare everyone gets to put sensors of all kinds
just about anywhere they want. On Earth, you are limited to your own
territory, where you can send vehicles, (for sensors that fit in said
vehicles), and what can fit in a satellite and use from orbit to look at
the lower troposphere and surface.

> There is no such thing as an
> undetectable construct, even now. It is within our current technical
> abilities to put up observation platforms that could track every moving
> thing on the surface or in air, so long as it is outdoors. We don't even
> need satellites to do so, but they are much more efficient. yet we still
> have stealth aircraft.

And in space, spotting things is really easy. Meanwhile, any technology
to help one get stealth applies equally or more to the things doing the
spotting, (and generally require that you know where those things are).

>> You can't shoot at them until after they launch, unless you are going
>> to start obsessively shooting at every potential launch window.
>
> Every launch installation, yes.

No, launch window, (i.e. they could launch a platform on Sept.10th with
an ejection angle of...). If you are attacking the launch installations,
you are already making your main attack and have rendered the whole
operation to go after the sensor platforms moot.

> Launch installations are also difficult
> to hide, especially after they have already been used. But, again,
> warfare is never easy. It is assumed that you will never get all of
> them. You get as many as you can, and take advantage of what you can.

Launch instillations are often also known as planets and moons.

>> Successes on this scale are incredibly rare, there's a reason I was
>> alluding to the idea of the President of the United States being a
>> Soviet agent.
>
> And yet... ...
> There is nothing preventing a soviet spy from becoming president. We
> would never know. The only difficulty to overcome is that it is so
> difficult for ANYONE to become president, but a soviet spy would have as
> good a chance as anyone else.

Go look up a group called the John Birch Society, this is a group that
really did believe that the US President was a Russian spy, (which would
have been nutty enough, even if it hadn't been Eisenhower).

(N.B. It was to illustrate the scale of intelligence coup you were
talking about, not that the problems in pulling it off would be the same.)

> But that would likely stop the war from
> happening in the first place. Espionage is not so rare. It occurs in the
> corporate world all the time... and most militaries rely on corporations
> to produce their observation platforms. There are security measures, but
> these are never perfect... especially when you don't know if war is
> coming, or who the enemy is going to be.

The number of powers in an interplanetary conflict are going to be
limited. Besides, unexpected enemies at the great power level are pretty
much non-existent.

>> You still aren't getting stealth out of it.
>
> You still aren't understanding what stealth actually is.

No, you don't get how easy spaceships are to spot if you are looking for
them.

>> IOW: You don't have stealth.
>
> No... IOW, stealth is not an absolute.
> Stealth is not about not being seen. It is about not being noticed.

No, you yourself said, in the very bit that was a response to, that your
fleets would be under way _before_ the attacks on the sensors arrive.
That means that they are making their moves with all of the sensors still
functional.

(You have this bad habit of deleting context then making a response that
doesn't really fit with that context. It would be a good idea to stop
doing that before someone accuses you of doing it intentionally.)

>> They become useful very quickly, nearly instantly if you have more than
>> one launch point. Sure, you would rather the platforms be way out of
>> plane so that they can use the ecliptic as 'free' range data but they
>> can still spot things.
>
> Wrong. For protection, optics are kept covered during acceleration, up
> to the moment of final deployment.

Um, you do know that most of that trip is _not_ under acceleration,
right? After the ejection burn, (if launching from a planet), there will
be months of only limited, occasional, adjustments.

>> And the operation gets bigger and bigger....
>
> You expect wartime operations to be small?!? If someone is going to plan
> a preemptive war, the start of that war is going to be planned to the
> most minute detail. The operation is going to be "global" in scale,
> based on decades of strategic analysis and planning.

You are now doing the equivalent of adding San Francisco and Norfolk to
the list of Japanese targets in Dec.'41. It is quite correct to describe
your anti-sensor operation as getting overly large.

>> >> There is something on an intercept course for a sensor platform
>> >> that's
>>
>> Again, I conceded known platform locations from the get-go. Someone
>> intercepting a concealed platform is an even bigger red flag.
>
> Depends upon the approach. Even if they come directly for you it is not
> necessarily a red flag.

Yes, it is. The odds of a random intercept occurring is incredibly low
even if the platform is orbiting in the plane of the ecliptic. If it's
not in the plane then it pretty much won't ever happen.

> If you are concealed, you are by definition an
> unknown. You can' exactly hide. People are going to come to see what is
> there. If you are concealed, and if you are smart, you do nothing except
> watch... perhaps it is a survey crew looking to see if you are an
> asteroid with useful ores.

Asteroid prospectors, (crew? those things won't have a crew), aren't
going to be spending a lot of time chasing after oddballs. If you really
want to hide a platform, you send your own 'asteroid miners' out to claim
and 'mine out' some lump of rock and metal.

> If you are in polar orbit, you are not concealed. Everyone is going to
> know you are there (mostly because you expended a tremendous amount of
> energy to get yourself there), and they are going to have a fairly good
> idea of WHY you are there (you can explain 1 or 2 by calling them
> "mapping arrays"... but you are not going to be able to explain 4 or 5,
> let alone dozens).

And we are back to me needing to point out that I conceded the locations
of the platforms as known.

>> Any sensor net is going to be designed to absorb such losses. For this
>> kind of net you get some of it intrinsically, (since you always want
>> platforms well away from the ecliptic).
>
> Sensor nets are going to anticipate a very low percentage of losses, and
> may pad this by multiplying the expected losses. Doesn't matter. It just
> adds more targets.

You can have a universe where everyone is going to be knocking down the
sensor platforms left and right or one in which the systems aren't
designed to continue working as this happens, not both.

>> Thinned out means ineffective.
>
> DEAD. WRONG.
> You only need a single kinetic impact. So long as you have the areal
> density, the impact is going to happen. Spread the pellets linearly by a
> few thousand km (a couple seconds), the impact is STILL going to happen,
> but it is much more difficult to see the cloud.

Time spread like that effectively either shrinks the target or clumps the
pellets.

[Rick Pikul/Chakat Firepaw]

On Sat, 23 Jul 2016 09:02:54 -0700, Mikkel Haaheim wrote:

> Le vendredi 22 juillet 2016 19:30:24 UTC+2, Rick Pikul/Chakat Firepaw a
> écrit :
>
>> This operation just keeps getting bigger and bigger. You are now
>> evenly distributing billions, (covering a 10Mm radius at one KKV per
>> hectare takes ~30 billion KKVs), of KKV pellets and all you can
>> guarantee is to restrict it's ability to do long term avoidance.
>
> From my original proposal on this point: 400 trillion, exactly. (200m)^3
> material. This was extreme overkill. I have since brought it down to
> (30m)^3 of material... or even less, using smaller pellets.

Which gets you either a diffuse shot that probably won't do anything or a
narrow one that will probably miss.

(Not that getting this kind of even distribution is exactly easy.)

>> > No one is assuming that it is easy.
>>
>> The guy I initially responded to did. Furthermore, you did notice the
>> context of that remark, right? That was pointing out that someone was
>> arguing against the wrong thing in his response to me.
>
> Interpretation. I interpreted that the mechanism was not complicated,
> which is correct... essentially, you through stones. You interpreted
> that it was not difficult, which I agree is false... you need to make
> careful calculations based upon careful observations.

And it's still really hard to hit because of the long time in flight and
the need for information which is impossible to have because it doesn't
exist yet.

> Yes, I noticed. The correction was irrelevant.

He flat out made the argument "you can't hide the sensor platforms
either." It is 100% relevant to respond to that by pointing out that I
was not making an argument based on hiding the sensor platforms.

>> > And tracking how much it has deviated in course over a couple years
>> > gives a fairly reliable stadnard of deviation of how much allowance
>> > has to be taken into account.
>>
>> That would be part of those constraints.
>
> Yes. We are in agreement here. My point being that constraints are
> relevant.

They aren't anywhere near as tight as you seem to think, (given that you
have now revealed that you think a 100km wide attack is almost certain to
hit).

>> > As I said, no one said it would be easy. OTOH, having a few well
>> > place agents...
>>
>> Which both sides will have and you can thus assume that your shots are
>> known. Thus the war starts a couple years before your 'surprise'
>> attack on the sensor net.
>
> Oh, absolutely, all sides will have agents. This is a large part of why
> wars drag out. It is also why many wars never get started. OTOH, you can
> never assume anything. Your spies miss the opportunity to sabotage the
> platforms, and you have to kill them instead. The other side misses the
> opportunity to gather key intelligence on the intents of a separatist
> movement (for example), and a wave of surprise attacks commences.
> Espionage isn't easy, either. Nothing is going to be easy. You take the
> opportunities you can.

Spotting the launching of a large, coordinated, attack is a lot easier
than compromising a important and highly redundant system. To use an
analogy: I'm trying to spot when your ship leaves harbour while you are
trying to get a saboteur into each of my coastal forts.

>> So you are going to war with a ship a generation out of date.
>
> Yes. Just like militaries always have. There is an adage, "armies always
> plan for the last war".

You are misunderstanding the adage.

> Most of the forces used in WWII were built for WWI... some literally.

False. Even most of the small arms had been replaced by new designs.

> The majority of forces used in Korea and Vietnam
> were built for WWII. Most of the vessels we have deployed now were built
> in the '80s. Our newest carriers and destroyers were put on the drawing
> board 20 years ago, based on 30 year old concepts.

Those ships haven't gone a generation without systems upgrades.

They also don't have a crew that's a generation out of date, (although
you can get around that in space war).

>> The "little nudge and drift" plain fails because of the time scales
>> involved: It either takes forever to get there or you need a lot more
>> than a little nudge.
>
> Well, yes, the "little nudge" was actually a mass driver spitting out
> tonnes of excavated material at a few km/s. Such phrasesare relative.

IOW: You'll have nice bright radiators.

[Rick Pikul/Chakat Firepaw]

On Sat, 23 Jul 2016 10:19:56 -0700, Mikkel Haaheim wrote:

> Le vendredi 22 juillet 2016 19:44:53 UTC+2, Rick Pikul/Chakat Firepaw a
> écrit :
>>
>> Here's your problem, you don't actually understand the core problems
>> with stealth in space.
>
> Actually, I do. You don't understand that we are already faced with the
> same problems.
>
>> There is no horizon. On a planet you only have to be able to keep from
>> being detected by sensors that are really close to you.
>
> Have you noticed that there are camera EVERYWHERE?

No, there aren't.

Sure, cities are covered well. Go to Algonquin Park and get 100m from a
road and there aren't going to be any cameras you didn't bring with you.

> That does not even
> take into account where cameras COULD be. Ever hear of aerial drones?
> You can put a camera in the air for less then $100. For the cost of the
> Zimwalt programme, you can have cheap drones covering every square km of
> the Earth.

That gets you better coverage, but you are still going to need one of
those drones about every 20km, (terrain in some places will require
greater density). That includes the places where they are going to be
spending 90% of their time getting out to their station and returning to
refuel/recharge.

> If we REALLY wanted, there would be no place to hide.
> Horizon is only an issue when there are places you can not, or do not,
> go. satellites made horizons irrelevant long ago.

Satellites have other problems, (and horizons are still a problem for
them, they just do better than the 15km or so you get). The biggest one
being the need to look through a nice thick atmosphere.

>> Space gives a very uncluttered background. On a planet you have
>> everything from mountains to shifts in atmospheric conditions causing
>> sensor clutter.
>>
> And all of this sensor clutter can be fairly easily "blue-screened" out.

Not that easily, plus sometimes that clutter completely blocks any actual
signal.

> We only care about what moves, and we have had the software to clear
> such clutter for decades.

A lot of that noise isn't stationary. Worse, a lot of that noise
involves the very signals you are trying to detect taking multiple paths
to reach you.

> The problem is it takes time to analyse.
> Space, OTOH, is NOT uncluttered. Not at all. Especially when you bring
> in sensitive observation instruments. CBR is EVERYWHERE. Then you have
> all the stars you can't see with the naked eye... but sensitive
> instruments CAN. Then you have all the nebulae, galaxies, etc. Then
> there is all the particulate dust in space, and all the charged
> particles. Why don't care about these because we can't see them.
> Sensitive observation platforms CAN. There is also a HELL of a lot more
> space to sift through. On Earth, there is only about half a trillion
> square meters to sift through. You really don't have to be concerned
> about anything smaller, so resolution is not so much an issue.

And a functional spacecraft is incredibly bright compared to the 'noise'
of space.

>> Space really is a different sensor environment.
>
> Yes it is. On Earth, you are only limited by the technical capabilities
> of your sensors.

And an environment that both adds all kinds of noise and also absorbs and
distorts the very signals you are tying to detect.

> In space, you are limited by hard absolutes. On Earth,
> there are people, with cameras, litterally everywhere.

No, not everywhere.

> In space, there are great swathes where there is no one.

And sensor ranges such that you can 'stand' on the edge of those swathes
and see the whole thing.

> On Earth, off the shelf, hand held optics, even the poorest quality,
> will give you usable information.

Provided you happen to be right next to what you want to see. More than
20-30km or so and you can't see a thing.

> In space, you need oversized optics, and the most minute deformations
> will destroy the image.

Yes, a military-grade sensor net will involve larger and more capable
systems than hobbyist gear. Just like how a DEW station is better at
spotting aircraft than a couple guys with cameras.

[elie....@gmail.com]

Le lundi 25 juillet 2016 12:32:12 UTC+2, Mikkel Haaheim a écrit :

> > > This is not a problem, however, if the sound generators are deployed
> > > throughout the oceans en mass... but EVERYONE will be able to hear the
> > > reflections. Nothing in the oceans would ever by stealthy again.
> >
> > Until the easily-located "illuminators" are destroyed, which will be a priority for all sides.
>
> Quite true... unless they are well defended. As I said, stealth works because navies WANT stealth to work. If navies did NOT want stealth to work, they would put up such a network, establish multiple levels of redundancy, and establish strong defenses for the transmitters. But this would be a significant investment, and... navies WANT stealth to work.

Oh no, they really don't. To be specific, "they" means the US Navy here. They lost enough fully escorted aircraft carriers to sub (both diesel-electric and nuclear) during naval exercises to not want it.
Which is why they are deploying drone ships to criscross the seas and search for subs.
The reason no navy has full sonar coverage of the oceans is because there is simply too much of it. It's not that they don't want to pay for it, it is that they can't afford it.

It would also have devastating environmental effect on species using sonar for guidance, like dolphins and whales, but since when did we let zoocide get in the way of a strategic edge?

Note that navies use active (and passive) deployable sonar buoys, so the target is painted on the buoy instead of the ship/helicopter - in addition to provide better coverage.

So, once again, seas are not a good parallel to space here.

[Alie...@gmail.com]

On Tuesday, July 26, 2016 at 1:56:05 AM UTC-7, elie....@gmail.com wrote:

(snip to the crash)

> So, once again, seas are not a good parallel to space here.

It has to be said again:

This is another point some folks seem to keep forgetting while blue-skying (black-skying?) how space warfare will work. There are *no* fully applicable parallels in past forms of warfare, despite the fact that *some* elements of *all* past forms will apply. In space you can't just drop anchor to loiter at a constant distance from something or do a lot of other things tactically that are dead simple in an ocean.

That's why I said that passive sonar is a better analog for space warfare detection techniques. Better, not perfect.

The logistical considerations of strategic planning in particular are to me the greatest difference.

In really Olden Days it was feasible for a land army to leave home butt-naked and expect to be able to feed *and* arm itself on the way to a battle by foraging.

Later, it was feasible to build frighteningly flimsy seagoing craft and sail great distances, surviving on fish and rainwater (supplemented by the odd bit of starch and fruit from islands).

In space foraging is much more limited- you have to bring your frigging AIR with you as the most basic example. Even the assumption that the first few asteroids you encounter will make good mass-driver ammunition is risky.

(Loitering is simply impossible except for rare cases like Lagrange points and those will surely be closely monitored and defended if not continuously occupied *because* they're the rough equivalent of high ground. Orbiting doesn't quite count because your weapons' required delta-vee/time-to-target keeps changing.)

In the face of that, to me stealth becomes a relatively minor tactical consideration. That's not to say that it won't be *a* consideration, just that it won't be paramount in strategic planning.

I find that to be somewhat depressing because I favor the military philosophy of Sun Tzu over that of von Clausewitz. Campbellian battles between huge fleets of ships each trying to out-endure the other guy seems like the depressingly most likely scenario, over clever positioning of fast, minimalist forces that can "win" without actually fighting. I'd love to be proven wrong...


Mark L. Fergerson

[Mikkel Haaheim]

Le dimanche 24 juillet 2016 19:57:11 UTC+2, Sea Wasp (Ryk E. Spoor) a écrit :

>
> Not so simply, you can't. The amount of humidity alone will strongly
> affect what range you can see to with what detail and sensitivity.
> Temperature differential is crucial -- you'll easily detect a human
> being two kilometers away on a winter snowpack, but it'll be a lot
> harder to pick out that human being in a jungle where the ambient
> temperature is in the 90s.

Not simply, no.
True, I had not considered jungles and forests. OTOH, with rather limited exceptions, I had not been talking about individual troops (which you won't be able to track so easily even in wide open space); and when I was talking about air doing the hiding, I was actually refering to somewhat higher altitudes than mid-tree and surface height. Nor is it particularly necessary to track troops and equipment going into jungle, unless: you are looking for poachers, loggers, or drug smugglers, or are engaged in rather stupid (low strategic value) operations to try to support "friendly" regimes. As difficult as jungles make tracking, they make OTHER operations MUCH more difficult. Still, with significant investment, even jungles can be scoured effectively.

>
> And of course Earth provides other living beings, and other operating
> machines, to confound your attempts to find them, while in space it's
> likely that your target is the ONLY think in that volume of space that
> isn't vacuum.
>

Not so valid an argument when you consider that a future in space where there are assets worth protecting with expensive capaital ships, you are also going to have overly developed civilian and business infrastructures. There are going to be colonies everywhere, numbering in the millions, if not billions. With the high populations, you are going to have extensive local traffic, extensive traffic within each of the planetary systems, there is going to be considerable traffic between planetary systems. There will be the high delta-v transport fleets, "for when you absolutely HAVE to have it there next week". There will be daily mail, shipping, and vacation traffic from everywhere to everywhere. There will be all the people with their pleasure yachts, drifting out where they are trying to get away from as much of everything else as they can. There will be scientific excursions, there will be prospective business excursions... ... ...

>
>
>
>
> Oh, the hell it doesn't. On the Arenaverse scale, even more so, because
> instead of the trick we can use today -- put up a satellite and look
> down through what amounts to only a couple miles of sea-level density
> air -- you'd have to look through effectively infinite amounts of such
> air, with accompanying dust, humidity, clouds, etc.
>

Which limits EM range a little (depending on frequency, but vastly improves sonar.

>
>
>
>

>
> For any particular case with unlimited monetary expenditure, perhaps,
> but you're dismissing stuff that we KNOW is a problem as though it
> isn't, which really makes me question how much you know about the
> *practical* limitations and not the theoretical. I work, as I said, with
> multispectral imaging and sensors, some for the military, and our
> experience with such imaging is more a matter of seeing more of its
> limitations than its awesomeness.

NOW you are beginning to see what I have been talking about. No, we are not talking about unlimited expenditure. However, you are beginning to understand that you can not just simply put up sensor nets wherever you want. There is always a cost in resources. There are always other intervening considerations.
All of the obstacles can be overcome... but is it worth the costs? We don't have hundreds of thousands of RC ATVs with the equivalent of cell phones strapped on scouring the jungles for illegal activity, NOT because we can't afford the few million dollars that it would cost (or few hundreds of millions going at public market value, and for associated depolyment costs), but because drug running, poaching, illegal lumbering, and a few guerrilla skirmishes are not considered worth the investment. We don't have four cameras on every street and alley corner because occassional assaults, robberies, and thefts are not considered worth the investment. We won't have big brother in space because it will not be considered worth the investment.

>
>
>
> --

[Sea Wasp (Ryk E. Spoor)]

On 7/27/16 3:19 AM, Mikkel Haaheim wrote:
> Le dimanche 24 juillet 2016 19:57:11 UTC+2, Sea Wasp (Ryk E. Spoor) a écrit :

>> Oh, the hell it doesn't. On the Arenaverse scale, even more so, because
>> instead of the trick we can use today -- put up a satellite and look
>> down through what amounts to only a couple miles of sea-level density
>> air -- you'd have to look through effectively infinite amounts of such
>> air, with accompanying dust, humidity, clouds, etc.
>>
>
> Which limits EM range a little (depending on frequency,

Not "a little". With a good telescope in space, I can pick up details
on planets millions of miles away.

Look through a hundred-plus miles of atmosphere, even pure
nitrogen/oxygen and trace gases without a bit of dust in it, you'll be
losing definition already noticeably. With humidity, worse. With dust,
worse.

Space is easy. Air is hard.


> but vastly improves sonar.


Welll... yes, compared to VACUUM where the range of sonar is zero, yes.
But in the air? No. There's a good reason we don't generally use sonar
in air; it dissipates at relatively short ranges. Underwater, that's a
different thing, but there you've got water, vastly more dense than air,
to transmit the signals.

In air? No, not even at a few kilometers.

And even underwater, sonar's severely limited by all sorts of effects
-- boundary layers, multipath, etc. -- which are much less an issue with
EM sensing in space.

>>
>> For any particular case with unlimited monetary expenditure, perhaps,
>> but you're dismissing stuff that we KNOW is a problem as though it
>> isn't, which really makes me question how much you know about the
>> *practical* limitations and not the theoretical. I work, as I said, with
>> multispectral imaging and sensors, some for the military, and our
>> experience with such imaging is more a matter of seeing more of its
>> limitations than its awesomeness.
>
> NOW you are beginning to see what I have been talking about.

Not really. Because in space, my cheapo IR camera can sense you so
easily that you'll have to spend many orders of magnitude more trying to
hide from it. The person trying to see you will ALWAYS have an advantage
in space, while on Earth often the person trying to HIDE has the advantage.

[emmett...@gmail.com]

On Monday, July 25, 2016 at 3:13:12 PM UTC-4, Rick Pikul/Chakat Firepaw wrote:
> On Sat, 23 Jul 2016 09:02:54 -0700, Mikkel Haaheim wrote:
>
> > Le vendredi 22 juillet 2016 19:30:24 UTC+2, Rick Pikul/Chakat Firepaw a
> > écrit :

I've been busy, sorry for not jumping in and leaving Mikkel on his own.

> >> The guy I initially responded to did. Furthermore, you did notice the
> >> context of that remark, right? That was pointing out that someone was
> >> arguing against the wrong thing in his response to me.
> >

> He flat out made the argument "you can't hide the sensor platforms
> either." It is 100% relevant to respond to that by pointing out that I
> was not making an argument based on hiding the sensor platforms.

I tend to make my comments in reply to the whole thread, there were arguments that "you won't know where my sensors are" so I was addressing that. I tend to try and comment as expediently as possible. Sorry about the confusion.

The point about regolith being used as a projectile is an economic one. If you have several thousand sensors constantly jinking with thrusters, they're going to run out of fuel eventually. This means you'd either have to have a resupply network constantly resupplying them or you'd have to replace them. If you want to talk about a huge effort, there you have it. That doesn't mean it can't be done, but it does make it resource intensive.

If the solar sail concept is indeed functional, the sensors still can't maneuver infinitely because they would fall out of position or out of their orbits. They also have to be autonomous at this point, because you're looking at a whole lot of motion. That means more computing power and more expense.

If I then have ten to a hundred asteroid stations out in the belt (which one? depends on the scale the war its on), tracking your sensor net, each with multiple mass drivers, I can launch cheap rocks at your net. I can do this ad nauseam because my stations are relatively cheap (maybe they even pay for themselves because I'm using the mined rock as a resource) and my projectiles are cheap. If the two sides economies are relatively balanced, defeating a sensor net is cheaper than building it.

Now, the question is, is this at the start of a war, as an opening salvo? Or is it a tactic of an ongoing war? Maybe it would be useful as both. I could see these asteroid stations being really useful as a diversion tactic for a real assault or it could be used during the real assault to severely degrade the sensor net and then launch a stealth attack (at?).

In a war, it doesn't matter that you know I'm shooting at your sensors. If we assume that you go after my astroids with your fleet, I can then maneuver wherever I want with mine. If you bombard my stations at a distance, I wait for you to expend a good amount of energy and resources doing so and then attack while your supplies are low. The sensor net is a tactical disadvantage in a hot war. The same could be said about my asteroid stations, but again, they're cheap to the point of disposable.

I say all this to debunk that this has to be a surprise attack. In a air war on earth, the regular aircraft attack radar stations. The enemy knows this. They have missiles and aircraft defending those radar stations. But one hit on that station makes it harder to see. Not impossible, just harder. Then a stealth aircraft is used to hit the target the radar station is being used to defend. This isn't the opening attack, it's standard tactics that are followed through the whole war.

When it comes to space warfare I'm not very knowledgeable. As for a technical attack (hacking/viruses/spies) being too difficult or detectable, in this I know something about. I've worked in the sector at a relatively high level. Honestly, it's very difficult to impossible to detect a new, well made virus that hasn't been activated yet. It's sometimes difficult to find a virus that is active especially if it's designed to be sneaky. In this sci-fi setting, there could be AIs smart enough to monitor every communication going in and out of a computer, but then there would be AIs smart enough to work around them. Stuxnet was one of the computer worms the public knows about that the US military developed and it got into a secure facility with no network connections in or out. A sensor net is going to be leaky since it must communicate with the outside word or it doesn't do it's job. I could honestly think of dozens of ways to compromise a sensor platform and use it to spread a virus and I never have to set foot in a datacenter.

Now, to backtrack a little, my point about NASA looking for asteroids and having a very hard time of it is largely in response to earlier threads on this topic. There have been many that assert that any ship will be warmer than the CMB and therefore easily detectable. Even a cold running ship because it will absorb solar radiation. If that were true, then asteroids would be as easy to detect. But in the real world, they're not. There is therefore a flaw in the idea that since there's no horizon in space and no air, all objects are easily detectable.

Since all this is speculative, anchoring the conversation in real life astrophysics is hugely helpful. The fact of the matter is, that even though the sensor platforms to catalog every near earth asteroid already exist, the data processing capability does not. It's not an issue of processing power precisely (although more helps) but one of the ability to distinguish signal from the noise. This will undoubtably get easier as software becomes more capable and processors more powerful, but it still won't be trivial and that's the point. There's the assumption that detection (which combines sensing and recognition of a signal) is not difficult. Real life says that it is.

This plays in with Mikkel's point about stealth being relative. It's not about blinding sensors so that they can never see you, it's about preventing detection (denying either the sensing or the recognition criteria). The recognition criteria being the easier of the two in this case.

This whole conversation about undersea nets of sonar platforms is illustrative in a few ways that haven't been explored. One, it could be done but it hasn't. An economic argument against building it was brought up and that is valid, but I suspect another reason. The effort of assembling and coordinating such a net would be difficult and expensive. The real difficulty though would be using it. Manning posts so that you were getting the return on investment would also be expensive and possibly not more efficient than other tasks you could have your manpower acting on. Most of the time those sonar nets are going to be pinging away and returning nothing. The whole time you're sitting there listening to that feed, you've effectively wasted your time. Yes, you may be reducing your enemies options, but they're just going to build in a different direction. Why invest huge sums into knocking down a wall when you can go under, around or over it? (Philosophically speaking of course. The sonar is a "wall" to submarines.)

The point being, yes, *maybe* you could build a sensor net that would invalidate space stealth. But what if I see you building that net and think "Mwahahah! I was never planning on using stealth in the first place!" Well then, you just wasted an enormous amount of resources on a useless defense. You've essentially weakened yourself to a different form of attack. I think THAT is why we don't have impenetrable undersea sensor nets. I think that's also why a huge space sensor net would also be unlikely.

Again, precedence in the real world.

This plays to Mikkel's last war argument. You'd be entirely validated to build an expensive sensor net if I won the last war because of stealth attacks. Until I do though, you'll be busy building defenses against my last attack. You build defenses against existing threats, not hypothetical ones.

[Sea Wasp (Ryk E. Spoor)]

On 7/27/16 7:13 PM, emmett...@gmail.com wrote:
> On Monday, July 25, 2016 at 3:13:12 PM UTC-4, Rick Pikul/Chakat Firepaw wrote:
>> On Sat, 23 Jul 2016 09:02:54 -0700, Mikkel Haaheim wrote:
>>
>>> Le vendredi 22 juillet 2016 19:30:24 UTC+2, Rick Pikul/Chakat Firepaw a
>>> écrit :
>
> I've been busy, sorry for not jumping in and leaving Mikkel on his own.
>
>>>> The guy I initially responded to did. Furthermore, you did notice the
>>>> context of that remark, right? That was pointing out that someone was
>>>> arguing against the wrong thing in his response to me.
>>>
>> He flat out made the argument "you can't hide the sensor platforms
>> either." It is 100% relevant to respond to that by pointing out that I
>> was not making an argument based on hiding the sensor platforms.
>
> I tend to make my comments in reply to the whole thread, there were arguments that "you won't know where my sensors are" so I was addressing that. I tend to try and comment as expediently as possible. Sorry about the confusion.
>
> The point about regolith being used as a projectile is an economic one. If you have several thousand sensors constantly jinking with thrusters, they're going to run out of fuel eventually. This means you'd either have to have a resupply network constantly resupplying them or you'd have to replace them. If you want to talk about a huge effort, there you have it. That doesn't mean it can't be done, but it does make it resource intensive.
>
> If the solar sail concept is indeed functional, the sensors still can't maneuver infinitely because they would fall out of position or out of their orbits.

No. Minor -- and enough distance to be missed by any reasonable-sized
hazard is minor -- deviations won't take them out of orbit, and they can
maneuver BACK to orbit. Sure, if you keep firing huge salvoes in a way
that they CAN'T, yes, you could drive them out of their original orbits
permanently, but jebus, you'll be spending so many orders of magnitude
more to shoot at them than they cost to put there that your opponent
will be winning on pure economics.

Firing shotgun-concentration loads of pellets to fill gargantuan
volumes of space? No. Really, no, what the hell are you thinking? Let's
leave aside the economic and practical problems of setting up your
asteroid-sized shotgun loads, and note that the end result is you're
going to be basically making the entire near-asset (with "asset" being
"Earth or other area worth going to) space be filled with debris. We
have enough trouble with low and medium-orbit debris as it is, if
someone's firing gargantuan amounts of material at us, that's gonna make
it a pain in the ass for everyone.

[emmett...@gmail.com]

On Thursday, July 28, 2016 at 1:02:23 PM UTC-4, Sea Wasp (Ryk E. Spoor) wrote:

> No. Minor -- and enough distance to be missed by any reasonable-sized
> hazard is minor -- deviations won't take them out of orbit, and they can
> maneuver BACK to orbit. Sure, if you keep firing huge salvoes in a way
> that they CAN'T, yes, you could drive them out of their original orbits
> permanently, but jebus, you'll be spending so many orders of magnitude
> more to shoot at them than they cost to put there that your opponent
> will be winning on pure economics.

If you're maneuvering with a solar sail, you have some limits to where you can go. I've heard of tacking with a solar sail, and correct me if I'm wrong, but you really can't get back to your original position with one. If you can, I'd really like to hear more on that.

Given that, you're eventually going to move out of orbit.

Let's say you can fully "tack into the wind" with a solar sail. Ok, what does that mean? It means that the sensor drone (it's not just a platform this point) is going to leave it's set point and then travel in a random direction for a random but limited amount of time and then turn back and start heading back. There's going to be constraints on it's movement and that makes it predictable almost to a fault. I might take two or three shots (individual shots, not necessarily buckshot) just to up my chances, but this is classic hunting at this point. When I go out and hunt an animal, I don't have any guarantee that my bullet will hit, but I often do. Add a targeting computer to that and I feel my chances are pretty good.

The inclusion of all that maneuvering equipment and the constant strain is going to lead to equipment failures and an ever increasing spiral of costs. Now you need a maintenance fleet and the sensor drones need to monitor all the other drones to make sure they aren't straying due to a mechanical failure. It also means the drone has to be autonomous and so carries even more processing hardware. The other issue is that this solar sail is going to limit the drone's field of view and therefore require more drones (but that point may have been made already).

As far as my costs, like I said, I'm probably mining the asteroids anyway, so setting up the mass drivers are my main cost. My projectiles are literally dirt cheap since they're made of undesirable mining waste left over from making money.

> Firing shotgun-concentration loads of pellets to fill gargantuan
> volumes of space? No. Really, no, what the hell are you thinking? Let's
> leave aside the economic and practical problems of setting up your
> asteroid-sized shotgun loads, and note that the end result is you're
> going to be basically making the entire near-asset (with "asset" being
> "Earth or other area worth going to) space be filled with debris. We
> have enough trouble with low and medium-orbit debris as it is, if
> someone's firing gargantuan amounts of material at us, that's gonna make
> it a pain in the ass for everyone.

Which sounds like a valid war tactic to me. If my attempts to take down your sensor net also makes navigation hell, well, I'm all for it.

[emmett...@gmail.com]

I'd like to throw in here that asteroid based mass drivers and hacking are not the only methods of attack at this point. With the need from maintenance craft, a fake maintenance vehicle (not super easy to accomplish since there would be protective measures but feasible) could slowly work it's way through the network and place small explosive charges on sensitive systems.

Since we're talking about solar sails, a laser could be used to push the sensors out of orbit or into each other or other humorous actions.

Another tactic could be small "suicide" drones. They'd be launched at the net from different directions and attack the platforms at close range, possibly with lasers or short ranged mini missiles. The simpler the sensor net elements, the less this type of attack makes sense. The more capabilities the net's elements have, the easier it is to make the suicide drones cheaper than the net. The important part is to make them disposable.

Another type of attack is spoofing the net's communications and creating a denial of service attack with powerful radio transmitters.

[Sea Wasp (Ryk E. Spoor)]

On 7/28/16 4:24 PM, emmett...@gmail.com wrote:
> On Thursday, July 28, 2016 at 1:02:23 PM UTC-4, Sea Wasp (Ryk E. Spoor) wrote:
>
>> No. Minor -- and enough distance to be missed by any reasonable-sized
>> hazard is minor -- deviations won't take them out of orbit, and they can
>> maneuver BACK to orbit. Sure, if you keep firing huge salvoes in a way
>> that they CAN'T, yes, you could drive them out of their original orbits
>> permanently, but jebus, you'll be spending so many orders of magnitude
>> more to shoot at them than they cost to put there that your opponent
>> will be winning on pure economics.
>
> If you're maneuvering with a solar sail, you have some limits to where you can go.

That turns out not to be the case.

> I've heard of tacking with a solar sail, and correct me if I'm wrong,

Indeed.

> but you really can't get back to your original position with one.

In essence, remember that an orbit goes in a particular direction. If
your solar sail is turned so that it vectors AGAINST that orbital
direction, you will fall inward to a lower orbit. If you vector WITH
that direction, you fall outward to a higher orbit. The combination
allows you to go anywhere you like. You're not "tacking" in the same
sense as water sailing, of course -- it's simply a matter of orbital
mechanics -- but the net effect is yes, I can move to any orbit I like,
which means I can dodge and come back.

>
> Let's say you can fully "tack into the wind" with a solar sail. Ok, what does that mean? It means that the sensor drone (it's not just a platform this point) is going to leave it's set point and then travel in a random direction for a random but limited amount of time and then turn back and start heading back. There's going to be constraints on it's movement and that makes it predictable almost to a fault. I might take two or three shots (individual shots, not necessarily buckshot) just to up my chances, but this is classic hunting at this point. When I go out and hunt an animal, I don't have any guarantee that my bullet will hit, but I often do. Add a targeting computer to that and I feel my chances are pretty good.
>
> The inclusion of all that maneuvering equipment and the constant strain

WHAT strain? We're not talking stresses you will notice here. The
forces are trivial. Remember, to dodge an attack that covers fifty or
even hundreds of kilometers in area requires an absolutely *minuscule*
acceleration, something akin to a mosquito towing my Subaru. Literally
you will not notice it. The only strain is on the motors to extend or
retract, and as this can be done on timescales of a week or more just to
start the maneuver without making a significant difference, those can
also move slowly and very low-strain.


And I assure you, your repeated volleying of 50+km salvoes will be
costing you vastly more than the slight increased wear-and-tear.

>
> Which sounds like a valid war tactic to me.

If you don't mind making the only habitable world in your solar system
unreachable, yeah. Not seeing that happening in any reasonable timeframe.

[Sea Wasp (Ryk E. Spoor)]

On 7/28/16 4:59 PM, emmett...@gmail.com wrote:
> I'd like to throw in here that asteroid based mass drivers and hacking are not the only methods
> of attack at this point. With the need from maintenance craft, a fake maintenance vehicle

At this point we are no longer talking in ANY way about "stealth". Here
you assume you not only know where the target is, but that you're going
to destroy it using espionage methods, not "somehow shoot it without it
knowing your shooting", said concept being, so to speak, "shot down"
long ago.

No one has contended, as far as I know, that you couldn't fight a war
over assets in space. Just that you're not going to do it by ghosting up
to them and blowing them away like a Romulan Warbird because they didn't
see you until you were too close to escape.

[emmett...@gmail.com]

On Thursday, July 28, 2016 at 7:23:50 PM UTC-4, Sea Wasp (Ryk E. Spoor) wrote:

You have a point, but this arm of the discussion is still a valid one because it mirrors modern day stealth in combat. It's important to degrade an opponent's detection ability and often that means taking out their sensor platform.

I've brought up arguments that discuss why "No stealth" also wouldn't be true due to the current recognition limits displayed in the astronomy world, but no one has brought up a valid counterargument. I can't discuss if no one is willing to debate the point.

I prefer to allow concessions in a debate such as "It doesn't appear that would work, but in case it is. . ." and follow that logically to it's conclusion. In this case, I don't think a huge sensor net would be as effective as proponents think, but that aside I also feel that it would be an economic and strategic disadvantage to even launch one.

Since the whole argument hinges on the construction, deployment and maintenance of such a structure, the economics and tactics of defeating it are intrinsically linked to the conversation.

BTW Thanks for the info on solar tacking, that does make sense, I just hadn't thought of it that way before.

[Sea Wasp (Ryk E. Spoor)]

On 7/29/16 6:21 AM, emmett...@gmail.com wrote:
> On Thursday, July 28, 2016 at 7:23:50 PM UTC-4, Sea Wasp (Ryk E. Spoor) wrote:
>> On 7/28/16 4:59 PM, @gmail.com wrote:
>>> I'd like to throw in here that asteroid based mass drivers and hacking are not the only methods
>>> of attack at this point. With the need from maintenance craft, a fake maintenance vehicle
>>
>> At this point we are no longer talking in ANY way about "stealth". Here
>> you assume you not only know where the target is, but that you're going
>> to destroy it using espionage methods, not "somehow shoot it without it
>> knowing your shooting", said concept being, so to speak, "shot down"
>> long ago.
>>
>> No one has contended, as far as I know, that you couldn't fight a war
>> over assets in space. Just that you're not going to do it by ghosting up
>> to them and blowing them away like a Romulan Warbird because they didn't
>> see you until you were too close to escape.
>>
>>
>> --
>> Sea Wasp
>> /^\
>> ;;;
>> Website: http://www.grandcentralarena.com Blog:
>> http://seawasp.livejournal.com
>
> You have a point, but this arm of the discussion is still a valid one because it mirrors modern day stealth in combat. It's important to degrade an opponent's detection ability and often that means taking out their sensor platform.
>

The point being that taking out the sensors isn't stealth, any more
than I'm invisible because I poked you in the eye. I have to poke
EVERYONE in the eye to do it, and I'm quite visible while I'm trying.

> I've brought up arguments that discuss why "No stealth" also wouldn't be true due to the current recognition limits displayed in the astronomy world, but no one has brought up a valid counterargument. I can't discuss if no one is willing to debate the point.
>

In what way? Astronomers look for particular phenomena. Military types
look for others. An astronomer isn't the person who's going to be trying
to recognize your ship, it's the security people. They may use the same
EQUIPMENT but what they do with it, and what they know how to recognize,
will be very different.

Note that smart video detection, tracking, classification, and
identification are things I've done a fair amount of work with, and I
know the military's doing a lot of it for space-based objects and
phenomena of interest.

> BTW Thanks for the info on solar tacking, that does make sense, I just hadn't thought of it that way before.
>

Had to research that stuff for _Threshold_, as I was going to have a
dusty-plasma sail vessel chasing a mass-beam drive vessel and I wanted
to know if the dusty-plasma vessel could get HOME once they ended up in
Jupiter system.

[Rick Pikul/Chakat Firepaw]

On Wed, 27 Jul 2016 16:13:43 -0700, emmett.obrian wrote:

> On Monday, July 25, 2016 at 3:13:12 PM UTC-4, Rick Pikul/Chakat Firepaw
> wrote:
>> On Sat, 23 Jul 2016 09:02:54 -0700, Mikkel Haaheim wrote:
>>
>> > Le vendredi 22 juillet 2016 19:30:24 UTC+2, Rick Pikul/Chakat Firepaw
>> > a écrit :
>
> I've been busy, sorry for not jumping in and leaving Mikkel on his own.
>
>> >> The guy I initially responded to did. Furthermore, you did notice
>> >> the context of that remark, right? That was pointing out that
>> >> someone was arguing against the wrong thing in his response to me.
>> >
>> He flat out made the argument "you can't hide the sensor platforms
>> either." It is 100% relevant to respond to that by pointing out that I
>> was not making an argument based on hiding the sensor platforms.
>
> I tend to make my comments in reply to the whole thread, there were
> arguments that "you won't know where my sensors are" so I was addressing
> that. I tend to try and comment as expediently as possible. Sorry about
> the confusion.

Sounds like you are used to the flat 'threading' of web forums.

> The point about regolith being used as a projectile is an economic one.
> If you have several thousand sensors constantly jinking with thrusters,
> they're going to run out of fuel eventually. This means you'd either
> have to have a resupply network constantly resupplying them or you'd
> have to replace them. If you want to talk about a huge effort, there you
> have it. That doesn't mean it can't be done, but it does make it
> resource intensive.
>
> If the solar sail concept is indeed functional, the sensors still can't
> maneuver infinitely because they would fall out of position or out of
> their orbits.

As Sea Wasp pointed out, orbital mechanics don't work that way. Nor do
solar sails, a common misunderstanding is that they can only be used to
push out from the star, (radial-out in a solar orbit).

Solar sails are only restricted in that they can't do radial-in burns,
they are just fine with pro/retrograde, (anti)normal and radial-out. As
it so happens, any radial-out burn can be reversed by another radial-out
burn at the other point the initial and final orbits intersect.

> They also have to be autonomous at this point, because
> you're looking at a whole lot of motion. That means more computing power
> and more expense.
>
> If I then have ten to a hundred asteroid stations out in the belt (which
> one? depends on the scale the war its on), tracking your sensor net,
> each with multiple mass drivers, I can launch cheap rocks at your net. I
> can do this ad nauseam because my stations are relatively cheap (maybe
> they even pay for themselves because I'm using the mined rock as a
> resource) and my projectiles are cheap. If the two sides economies are
> relatively balanced, defeating a sensor net is cheaper than building it.

Not really, hitting the platforms involves firing shots that saturate a
target area at least one hundred _million_ square kilometres in size.
Cheap, unguided, shot means a minimum of about one 'pellet' per square
metre. And remember, these shot clouds are going to be coming back
around to intersect with the orbit of whatever you fired it from.

> In a war, it doesn't matter that you know I'm shooting at your sensors.
> If we assume that you go after my astroids with your fleet, I can then
> maneuver wherever I want with mine. If you bombard my stations at a
> distance, I wait for you to expend a good amount of energy and resources
> doing so and then attack while your supplies are low. The sensor net is
> a tactical disadvantage in a hot war. The same could be said about my
> asteroid stations, but again, they're cheap to the point of disposable.

You think that the sensor net is only useful in spotting ships that are
tying to hide?

> I say all this to debunk that this has to be a surprise attack. In a air
> war on earth, the regular aircraft attack radar stations. The enemy
> knows this. They have missiles and aircraft defending those radar
> stations. But one hit on that station makes it harder to see. Not
> impossible, just harder. Then a stealth aircraft is used to hit the
> target the radar station is being used to defend. This isn't the opening
> attack, it's standard tactics that are followed through the whole war.

There is a critical difference: In a space war you have to kill pretty
much _all_ of the 'radar stations', not just the ones around where you
want to act. Imagine the difficulty involved if the sensor blinding for
an attack on Hawaii meant taking out radar stations in Alaska,
California, Massachusetts, Nunavut, Greenland, the UK and Diego Garcia.

> Now, to backtrack a little, my point about NASA looking for asteroids
> and having a very hard time of it is largely in response to earlier
> threads on this topic. There have been many that assert that any ship
> will be warmer than the CMB and therefore easily detectable. Even a cold
> running ship because it will absorb solar radiation.

Remember that 'cold-running' means turning everything off, including
things like life support and any computer systems. If you have anything
running you will have waste heat to get rid of.

> If that were true,
> then asteroids would be as easy to detect. But in the real world,
> they're not. There is therefore a flaw in the idea that since there's no
> horizon in space and no air, all objects are easily detectable.
>
> Since all this is speculative, anchoring the conversation in real life
> astrophysics is hugely helpful. The fact of the matter is, that even
> though the sensor platforms to catalog every near earth asteroid already
> exist, the data processing capability does not.

Actually, those sensor platforms don't really exist. At least not on the
scale we would be talking about in even a minimalist interplanetary war
scenario. Putting a single satellite at the Earth-Sun L1 point was a big
deal.

This line of argument is like saying "oceanographers have a hard time
tracking whales using a couple ships trailing hydrophones, therefore NATO
can't build something to detect any ships crossing from the Greenland or
Norwegian Sea to the North Atlantic." (FTR: The G-I-UK SOSUS line can
pick up aircraft, never mind ships.)

> Most of the time those sonar nets are going to be
> pinging away and returning nothing. The whole time you're sitting there
> listening to that feed, you've effectively wasted your time. Yes, you
> may be reducing your enemies options, but they're just going to build in
> a different direction. Why invest huge sums into knocking down a wall
> when you can go under, around or over it? (Philosophically speaking of
> course. The sonar is a "wall" to submarines.)

Things like SOSUS don't ping away, they are passive systems that listen.
As for going under/around/over, that kind of gets you into the wrong
ocean, (getting around the G-I-UK line means going around either Cape
Hope or Cape Horn).

> The point being, yes, *maybe* you could build a sensor net that would
> invalidate space stealth. But what if I see you building that net and
> think "Mwahahah! I was never planning on using stealth in the first
> place!" Well then, you just wasted an enormous amount of resources on a
> useless defense.

I'm still building the sensor net because I still want to see what you
are up to.

> You've essentially weakened yourself to a different
> form of attack. I think THAT is why we don't have impenetrable undersea
> sensor nets. I think that's also why a huge space sensor net would also
> be unlikely.

Putting sensor nets everywhere in the oceans has three problems:

First, covering the whole thing would take a _lot_ of sensors, (contrast
with space, where you only need a few dozen at most).

Second, most of the oceans are places where deploying those sensors is
hard, (contrast with space, where there are harder spots that you want to
use, but the limitation for those is really deployment time, (you have to
wait for the slingshot that kicks your inclination up), and the easy
spots are still usable).

Third, many of the places you really want sensors are places someone who
doesn't want them there owns, (contrast with space, where solar orbits
are open to anyone).

[Mikkel Haaheim]

Le mercredi 27 juillet 2016 19:48:05 UTC+2, Sea Wasp (Ryk E. Spoor) a écrit :
> On 7/27/16 3:19 AM, Mikkel Haaheim wrote:
> > Le dimanche 24 juillet 2016 19:57:11 UTC+2, Sea Wasp (Ryk E. Spoor) a écrit :
>
> >> Oh, the hell it doesn't. On the Arenaverse scale, even more so, because
> >> instead of the trick we can use today -- put up a satellite and look
> >> down through what amounts to only a couple miles of sea-level density
> >> air -- you'd have to look through effectively infinite amounts of such
> >> air, with accompanying dust, humidity, clouds, etc.
> >>
> >
> > Which limits EM range a little (depending on frequency,
>
> Not "a little". With a good telescope in space, I can pick up details
> on planets millions of miles away.

Depends upon the scales. In your fantasy scenario (NOT SciFi, because a "universe" filled with atmosphere will rather quickly collapse on itself), perhaps (it is fairly easy to quantify the actual range, as "rule of thumb" absorbtion of gamma radiation -photons- is 9/10ths absorbtion per arial density of 500g/cm^2... this varies a little depending upon actual photon wavelength and atomic structure, but not too much). OTOH, this just determines the interval of sensor platforms, and/or the area of the platforms required to collect enough of a signal. However, in the REAL universe, especially in the given context of planetary observation from orbit, atmosphere is going to provide very little hindrance. Any polutant capable of blocking out detection completely will also pretty much prevent any field operations in the first place.

>
> Look through a hundred-plus miles of atmosphere, even pure
> nitrogen/oxygen and trace gases without a bit of dust in it, you'll be
> losing definition already noticeably. With humidity, worse. With dust,
> worse.
>
> Space is easy. Air is hard.

Vacuum is easy. Space also means distance, and you are ignoring the effects of radiative dispersion over distance (every time you multiply distance, intensity is reduced exponentially), which makes space rather hard.

>
>
> > but vastly improves sonar.
>
>
> Welll... yes, compared to VACUUM where the range of sonar is zero, yes.
> But in the air? No. There's a good reason we don't generally use sonar
> in air; it dissipates at relatively short ranges. Underwater, that's a
> different thing, but there you've got water, vastly more dense than air,
> to transmit the signals.
>
> In air? No, not even at a few kilometers.

Depends upon intensity of the source and the sensitivity of the sensor. Construct parabolic microphones with 100 m collector dishes, and you will have a pretty good signal for any heavy equipment. Or, an array with a larger number of 1m dishes in scan mode. Jet engines produce enough noise to be heard fairly well over dozens of km, in good conditions. They can detected with parabolic microphones at hundreds of km or more (depending, again, on the size of the dish).

>
> And even underwater, sonar's severely limited by all sorts of effects
> -- boundary layers, multipath, etc. -- which are much less an issue with
> EM sensing in space.

The effects you mention are all processing issues, not detection issues. The processing issues are VERY MUCH a concern with detection and identification of objects in space.

>
> >>
> >> For any particular case with unlimited monetary expenditure, perhaps,
> >> but you're dismissing stuff that we KNOW is a problem as though it
> >> isn't, which really makes me question how much you know about the
> >> *practical* limitations and not the theoretical. I work, as I said, with
> >> multispectral imaging and sensors, some for the military, and our
> >> experience with such imaging is more a matter of seeing more of its
> >> limitations than its awesomeness.
> >
> > NOW you are beginning to see what I have been talking about.
>
>
> Not really. Because in space, my cheapo IR camera can sense you so
> easily that you'll have to spend many orders of magnitude more trying to
> hide from it. The person trying to see you will ALWAYS have an advantage
> in space, while on Earth often the person trying to HIDE has the advantage.
>
>

Be very careful with absolutes. If you happen to be near a hot planet, your IR camera is going to have some serious difficulties. Also, you are again ignoring the effects of distance on emission radiation.

[Mikkel Haaheim]

Le jeudi 28 juillet 2016 19:02:23 UTC+2, Sea Wasp (Ryk E. Spoor) a écrit :

>
>
> No. Minor -- and enough distance to be missed by any reasonable-sized
> hazard is minor -- deviations won't take them out of orbit, and they can
> maneuver BACK to orbit. Sure, if you keep firing huge salvoes in a way
> that they CAN'T, yes, you could drive them out of their original orbits
> permanently, but jebus, you'll be spending so many orders of magnitude
> more to shoot at them than they cost to put there that your opponent
> will be winning on pure economics.

Incorrect on two points (at least). The first is, it is incredibly expensive to put large sensor platforms into orbit. Even relatively small Hubble and Keppler sized telescopes are rare, because they are so expensive to launch, let alone to try to place in Earth polar orbits. Shooting from space is incredibly cheap, especially since you don't have to worry much about the shells remaining intact.

>
> Firing shotgun-concentration loads of pellets to fill gargantuan
> volumes of space? No. Really, no, what the hell are you thinking? Let's
> leave aside the economic and practical problems of setting up your
> asteroid-sized shotgun loads, and note that the end result is you're
> going to be basically making the entire near-asset (with "asset" being
> "Earth or other area worth going to) space be filled with debris. We
> have enough trouble with low and medium-orbit debris as it is, if
> someone's firing gargantuan amounts of material at us, that's gonna make
> it a pain in the ass for everyone.
>
>

Actually, not so much. Objects in distant orbits are already going very fast. The shells being discussed are small enough to easily achieve over 1000 km/s delta-v, but even 5 km/s delta-v (achievable with current railgun designs firing military shells... I think those tested were on the order of 5 kg) would be sufficient to achieve solar escape velocity. In other words, the shells will progress along parabolic to hyperbolic paths, proceding to exit the solar system. Optionally, the shells could be fired against the direction of orbit, in which case the vector and reduced velocity will likely result in the shells spiralling into the sun. For that matter, the shells will continue to disperse, and larger shells can be detonated, reducing the shells to dust.

[Mikkel Haaheim]

Le vendredi 29 juillet 2016 01:21:29 UTC+2, Sea Wasp (Ryk E. Spoor) a écrit :
>
> In essence, remember that an orbit goes in a particular direction. If
> your solar sail is turned so that it vectors AGAINST that orbital
> direction, you will fall inward to a lower orbit. If you vector WITH
> that direction, you fall outward to a higher orbit. The combination
> allows you to go anywhere you like. You're not "tacking" in the same
> sense as water sailing, of course -- it's simply a matter of orbital
> mechanics -- but the net effect is yes, I can move to any orbit I like,
> which means I can dodge and come back.
>

It is true that Emmett does not have a full understanding of light sail manoeuvres. OTOH, keep in mind that tacking manoeuvres will require significantly larger sail areas. Also remember that such sails are inherently vulnerable to impacts. Large sails are also rather easy to track.

>
> And I assure you, your repeated volleying of 50+km salvoes will be
> costing you vastly more than the slight increased wear-and-tear.

No. Because even small wear and tear will require expensive support.

>
> >
> > Which sounds like a valid war tactic to me.
>
> If you don't mind making the only habitable world in your solar system
> unreachable, yeah. Not seeing that happening in any reasonable timeframe.
>

In the context we are discussing, Earth is no longer the only habitable world. The fact of there being a space based navy, with assets worth defending, implies that sufficient infrastructure has been developed to make the outer planets and moons habitable by permanently established colonies.
In any case, the velocities of the shells will result in them being ejected from the solar system completely. The shells will also continue to disperse, meaning that they would provide no more navigational obstruction than current meteoroids.

[Mikkel Haaheim]

Le vendredi 29 juillet 2016 01:23:50 UTC+2, Sea Wasp (Ryk E. Spoor) a écrit :
> On 7/28/16 4:59 PM, emmett...@gmail.com wrote:
> > I'd like to throw in here that asteroid based mass drivers and hacking are not the only methods
> > of attack at this point. With the need from maintenance craft, a fake maintenance vehicle
>
> At this point we are no longer talking in ANY way about "stealth". Here
> you assume you not only know where the target is, but that you're going
> to destroy it using espionage methods, not "somehow shoot it without it
> knowing your shooting", said concept being, so to speak, "shot down"
> long ago.
>
> No one has contended, as far as I know, that you couldn't fight a war
> over assets in space. Just that you're not going to do it by ghosting up
> to them and blowing them away like a Romulan Warbird because they didn't
> see you until you were too close to escape.

Examples of stealth: low visibility "buck shot", or moderately sized NEAs that have been drilled out to make room for embedded boosters and RCS that will allow "last minute" course deflections toward a target, too late for defences to respond. Tactical manoeuvres that are not immediately evident to an opponent, either because they do not have the means to detect all the assets in play, or because they do not have the means or the time to analyse the manoeure. Low visibility ships that can no longer be detected by a smouldering network of sensory platforms. The specific strike may or may not be stealthy, but this does not prevent further use of stealth... so remember the global perspective of what is happening.
Again, stealth is not about not being detected. It is about not being noticed for what you are, at least until it is too late for a defender to do anything about it.
>

[Mikkel Haaheim]

Le vendredi 29 juillet 2016 15:18:19 UTC+2, Sea Wasp (Ryk E. Spoor) a écrit :

>
> The point being that taking out the sensors isn't stealth, any more
> than I'm invisible because I poked you in the eye. I have to poke
> EVERYONE in the eye to do it, and I'm quite visible while I'm trying.

No. Taking out the sensors isn't stealth. Poking out an eye is not stealth. Exploiting the reduced sensory capabilities with the assistence of low-observable techniques and materials IS. Tip towing behind a blinded opponent in order to deliver a killing IS (don't forget that the blind opponent can still hear).

>

>
> In what way? Astronomers look for particular phenomena. Military types
> look for others. An astronomer isn't the person who's going to be trying
> to recognize your ship, it's the security people. They may use the same
> EQUIPMENT but what they do with it, and what they know how to recognize,
> will be very different.

Astronomers are neverthelessattempting to locate threats. They know what they are looking for, and how to recognise it, but it is still difficult due to processing limitations. The military ALSO have such processing limitations.

>
> Note that smart video detection, tracking, classification, and
> identification are things I've done a fair amount of work with, and I
> know the military's doing a lot of it for space-based objects and
> phenomena of interest.
>

Yes. Advances are being made. The issue of processing limitations remains valid. You yourself have pointed this out with the hot jungle IR and obstructed sonar scenarios.

[Mikkel Haaheim]

Le dimanche 31 juillet 2016 00:17:35 UTC+2, Rick Pikul/Chakat Firepaw a écrit :
>
>
> Solar sails are only restricted in that they can't do radial-in burns,
> they are just fine with pro/retrograde, (anti)normal and radial-out. As
> it so happens, any radial-out burn can be reversed by another radial-out
> burn at the other point the initial and final orbits intersect.

If I understand correctly what you have written, this is not quite accurate. The radial out burn at the opposing orbital point does not reverse the previou radial out burn. Rather, it circularises the higher orbit.

> Not really, hitting the platforms involves firing shots that saturate a
> target area at least one hundred _million_ square kilometres in size.
> Cheap, unguided, shot means a minimum of about one 'pellet' per square
> metre.

This is not a problem. Yes, I have suggested 1 pellet/m^2, but you actually only need 1 pellet per sensor. The sensors will have to be large in order to obtain useful info. 1 pellet/10m^2 would likely be more than sufficient.
Furthermore, pellets can be small. The impact of even a single gram will likely sufficiently damage the sensors. You don't even need pellets... sensors are VERY sensitive to any kind of impact. Even high velocity dust will scour the collector dishes and optics, rendering them unusable. Given the size of the pellets or dust in question, the mass required to do sufficient damage, results in high arial coverage actually yielding fairly low actual masses or volumes.

> And remember, these shot clouds are going to be coming back
> around to intersect with the orbit of whatever you fired it from.

Unlkely. The delta-v from a mass driver or coil/rail gun will easily place the shells in a parabolic, or even hyerbolic, escape trajectory. Also, dust and pellets will continue to disperse, leaving them no more a hazard than currently existing meteoroids.

>
>
> There is a critical difference: In a space war you have to kill pretty
> much _all_ of the 'radar stations', not just the ones around where you
> want to act.

Actually, you don't. I will explain shortly.

>

>
> Remember that 'cold-running' means turning everything off, including
> things like life support and any computer systems. If you have anything
> running you will have waste heat to get rid of.

Incorrect. Cold running simply means that waste heat will have to be limited to what can be safely absorbed by the internal heat sink (cryogenic supply) or what can be emitted without allowing for detection.
Let's say you ere emitting 2.25 watts/s IR radiation. This produces 10^19 photons (at most). The photon flux at 1 AU is then 1 photon / 26 000 m^2 per second. A 35m telescope would require almost half a minute to collect a single photon. Even dozens to hundreds of photons/s is too low to be accepted as a reliable signal. It is highly unlikely that any waste heat emission less than 50 w/s will be significantly detectable by ANY existing radio telescope. Much higher emissions could be undetectable if directed away from earth based receivers.
Furthermore, although electronics can produce significant waste heat, as can human bodies, life support generally will not. Actually, much of the human and electronics generated waste heat will be absorbed in the processof bringing cryogenic oxygen supplies to usable temperatures. Properly handled, waste heat will actually be the sole source of environmental heating.

>
>
>
> Actually, those sensor platforms don't really exist. At least not on the
> scale we would be talking about in even a minimalist interplanetary war
> scenario. Putting a single satellite at the Earth-Sun L1 point was a big
> deal.

Platforms for searching for asteroids DO exist, but you are correct that there are very limited numbers of such platforms. The cost of putting such platforms into space is rather the issue.

>

> Putting sensor nets everywhere in the oceans has three problems:
>
> First, covering the whole thing would take a _lot_ of sensors, (contrast
> with space, where you only need a few dozen at most).

False assumption. Again, I will get to this later.

>
> Second, most of the oceans are places where deploying those sensors is
> hard, (contrast with space, where there are harder spots that you want to
> use, but the limitation for those is really deployment time, (you have to
> wait for the slingshot that kicks your inclination up), and the easy
> spots are still usable).

Slingshots are of very limited use in kicking up inclination. They are more useful for accelerating to higher planal velocities. Deploying sensors in the water is MUCH less difficult and costly than even LEO launches. All you need is a sufficient amount of weight to sink the platform, and a relay cable sufficiently long to reach the surface (in order to transmit data and receive instructions)... and a battery powered propulsion system for accurate placement.

>
> Third, many of the places you really want sensors are places someone who
> doesn't want them there owns, (contrast with space, where solar orbits
> are open to anyone).
>
> --

Until you have colonies claiming regions of space. The entire reason for a space navy is to protect assets. Current space law will no longer apply in such settings.



Now... what does it actually take to build a miltary array?
Objectives for such arrays are to detect, identify, localise, track, and observe potential targets. You have a few physically defined limits to capabilities, and additional technological limits.
To detect a target, you need that target to be emitting or reflecting a sufficient amount of energy, not just for sensors to record detection, but for sensors to accept that information as reliable data. Assume that you have a sensor capable of detecting a single photon. Forget about determining if the target is "legitimate" (a spacecraft), you would need to know that the "ping" is from a detected photon, rather than just an anomoly resulting from some source of electric, magnetic, or EM interference (stray static discharges, wiring faults, etc). Even if you can detect single photons, you will probably require a steady stream of photons reliably impacting a detector over a singificant amount of time. Receiving a reliable signal is dependent upon the signal strength, but also on the photon flux produced by that signal strength. For a given energy level, shorter wavelengths produce fewer photons than longer wavelengths. The overall flux, whether measured by energy density or by photon count, will be affected by distance. Intensity is inversely, exponentially proportional to the distance. Or, from another context, the area of the receiving sensor required to detect a source is exponentially proportional to the distance from that source.
Realisticly, you will probably need at least a 35m platform to detect an object that is actively attempting to reduce emissions. This is a physical limit. Actual sensitivity of detectors will further limit your abilities.
Once detected, you need processing power to identify a source as a "legitimate" target. You need to eliminate all background sources. To understand how many sources have to be eliminated: someone had calculated that a "torchship" (fusion powered rocket) at full thrust would have a magnitude of +12 (he did not specify if this were absolute magnitude, or apparent magnitude at 1 AU or so, so I will assume apparent, which would actually yield a brighter absolute). This roughly coincides with the detection limit of a 5" to 10" telescope. Now, consider the hundreds to thousands of stars visible to the naked eye on a clear, dark night (the milky way)... and consider the tens to hundreds of thousands of stars and galaxies that become visible with a 5" telescope. This is the background you have to elliminate before detecting an unsheilded fusion drive.
Let's say that you have the means to filter out all this background. Limitations are a function of processing power, after all. Let's also say that you can use processing to establish an identification, to some level of accuracy. What is left to locate, track, and observe?
This is actually fairly easy, given the technique of virtual apperature (interferometric) telescopy. Angular resolution is a function of distance, wavelength, and array baseline. If you place satellites just outside of geosynch orbit (say, 50 000 km), the resulting baseline between platforms at opposite sides of this orbit would be sufficient to resolve the image to the order of millimeters, for wavelengths shorter than far IR. To establish this resolution in 2D, you will need at least three, and preferably four, platforms spaced equidistantly in the prescribed orbit. That isn't much. But you will need to use a polar orbit if you want to look at objects in the solar plane. You will need an actual 35m apperature in order to detect the emissions at 1 AU, however; and you will need 2 of these for each platform in order to see in front and behind. Such platforms will mass at least in the order of multiple metric tonnes, but a Saturn V booster for each platform should be sufficient.
The problem is, you are going to have a very limited field of vision. Well... probably. A planar array radiotelescope would allow for a 120° field of vision, but you will not have anywhere near the same sensitivity, so the array will have to be several times larger and heavier also, you might need to assemble it in space, in order for a Saturn V booster to be able to handle the configuration of the load, assuming a single booster would still be able to support the mass. A lens or parabolic antenna would allow energy to be concentrated, giving the required sensitivity, but these produce the limited field of view I was talking about. Being extremely generous, let's say we have a 10° field of view. This would require an array of 54 to 72 platforms (perhaps as little as 9 to 12 for planar arrays). A single degree field of view is MUCH more likely (still probably somewhat generous), but that would require 540 to 720 platforms... well, assuming that you want full coverage. You could reduce the requirement through scanning.
So... doable. Theoretically. However, this is the theoretical limitation to the resolution. The actual resoultion will depend upon the number of detector elements. In order to achieve this theoretical limit, each sensor will require something on the order of 10^18 pixels (this will require independent elements for each pixel, or a lesser number of much more complicated elements capable of receiving and measuring multiple photons coming from diverse angles. This will likely reduce the effective sensitivity of each element significantly... it also reuires greater processing power, since you are using interferometric techniques to obtain the resolution into pixels.
Please keep in mind that these platforms make REALLY easy targets. Also, they are extremely sensitive to micrometeroid impact. Also, they need to communicate with one another. I have not included the processing requirement or support infrastructure required for maintenance, repair, data communications, shielding, etc.

[Mikkel Haaheim]

Le jeudi 15 septembre 2016 17:57:19 UTC+2, Mikkel Haaheim a écrit :


> Once detected, you need processing power to identify a source as a "legitimate" target. You need to eliminate all background sources. To understand how many sources have to be eliminated: someone had calculated that a "torchship" (fusion powered rocket) at full thrust would have a magnitude of +12 (he did not specify if this were absolute magnitude, or apparent magnitude at 1 AU or so, so I will assume apparent, which would actually yield a brighter absolute). This roughly coincides with the detection limit of a 5" to 10" telescope. Now, consider the hundreds to thousands of stars visible to the naked eye on a clear, dark night (the milky way)... and consider the tens to hundreds of thousands of stars and galaxies that become visible with a 5" telescope. This is the background you have to elliminate before detecting an unsheilded fusion drive.

Right. I actually have a little more precise information.
I found a source that reports 156 182 070 295 stars catalogued with apparent magnitudes of 12 or brighter. Remember, this is the magnitude calculated for an unshielded fusion rocket engine at full thrust. Multiple this value by 4 to find the number of stars including magnitude 13 (2/5 the brightness, so it is what you have to sort through if your sensor sensitivity is increased by 5/2). Double that value for the count of catalogued stars going to magnitude 14. Double again if you want to go to magnitude 15 (each magnitude requires 5/2 the sensitivity to observe than the magnitude before). All these stars are observable by Hubble sized telescopes. Remember that Hubble is not sensitive enough to observe IR emissions less than kW levels at over 1 AU. This does not include the planets, nor reflected light from asteroids or meteoroids.
Note that the count is taken from stars catalogued as of 1997. also note that astronomers are STILL going through photographic plates up to 50 or even 80 years old trying to catalogue these stars (there are actually many, MANY more).

[Rick Pikul/Chakat Firepaw]

On Thu, 15 Sep 2016 08:57:18 -0700, Mikkel Haaheim wrote:

You did notice that this discussion was a month and a half ago, right?

Or are you playing the "necro to get the last word" game?

> Le dimanche 31 juillet 2016 00:17:35 UTC+2, Rick Pikul/Chakat Firepaw a
> écrit :
>>
>>
>> Solar sails are only restricted in that they can't do radial-in burns,
>> they are just fine with pro/retrograde, (anti)normal and radial-out.
>> As it so happens, any radial-out burn can be reversed by another
>> radial-out burn at the other point the initial and final orbits
>> intersect.
>
> If I understand correctly what you have written, this is not quite
> accurate. The radial out burn at the opposing orbital point does not
> reverse the previou radial out burn. Rather, it circularises the higher
> orbit.

You do not understand because I never said anything about the opposing
orbital point: "...the other point the initial and final orbits
intersect."

>> Not really, hitting the platforms involves firing shots that saturate a
>> target area at least one hundred _million_ square kilometres in size.
>> Cheap, unguided, shot means a minimum of about one 'pellet' per square
>> metre.
>
> This is not a problem. Yes, I have suggested 1 pellet/m^2, but you
> actually only need 1 pellet per sensor. The sensors will have to be
> large in order to obtain useful info. 1 pellet/10m^2 would likely be
> more than sufficient.
> Furthermore, pellets can be small. The impact of even a single gram will
> likely sufficiently damage the sensors.

And what will be the total mass of those pellets?

10,000,000 km^2 = 1e14 m^2

For a 1g pellet every 10 m^2 that's:

1e14 m^2 * 0.1 g/m^2 = 1e13g

That's ten _million_ _TONNES_. For a shot that isn't even certain to
connect, (perfectly spaced they're 5.77m apart).

> You don't even need pellets...
> sensors are VERY sensitive to any kind of impact. Even high velocity
> dust will scour the collector dishes and optics, rendering them
> unusable. Given the size of the pellets or dust in question, the mass
> required to do sufficient damage, results in high arial coverage
> actually yielding fairly low actual masses or volumes.

You obviously either didn't do the math or made rather unrealistic
assumptions.

Or are you jumping around between units again: Using one figure as the
radius of your shot cloud when claiming it will hit, then using the same
number as the area when claiming you can connect using a sane amount of
material.

>> And remember, these shot clouds are going to be coming back around to
>> intersect with the orbit of whatever you fired it from.
>
> Unlkely. The delta-v from a mass driver or coil/rail gun will easily
> place the shells in a parabolic, or even hyerbolic, escape trajectory.

Um, no. You need on the order of 10km/s for escape trajectories, and
that's if you eject prograde from the body orbiting the sun. For these
kinds of shots think 15-20km/at least.

> Also, dust and pellets will continue to disperse, leaving them no more a
> hazard than currently existing meteoroids.

Actually, they don't. They just transform into a stream, meteor showers
are annual for a reason.

>> There is a critical difference: In a space war you have to kill pretty
>> much _all_ of the 'radar stations', not just the ones around where you
>> want to act.
>
> Actually, you don't. I will explain shortly.

Actually, yes you do: All of the stations can see almost everywhere, you
have no horizon to hide behind.

>> Remember that 'cold-running' means turning everything off, including
>> things like life support and any computer systems. If you have
>> anything running you will have waste heat to get rid of.
>
> Incorrect. Cold running simply means that waste heat will have to be
> limited to what can be safely absorbed by the internal heat sink
> (cryogenic supply)

Which isn't that much, expect no more than a few months under ideal
conditions.

> or what can be emitted without allowing for detection.

Which also isn't that much

> Let's say you ere emitting 2.25 watts/s IR radiation.

So you are a tiny ship cooled to under 150K.

Even at a chilly 200K your hull is emitting 9 W/m^2, not the waste heat
from your systems, the hull itself, (and that's assuming you optimize for
minimal blackbody radiation).

(Psst: W/s would be how fast your emissions are increasing, you simply
want W.)

> Much higher emissions could be
> undetectable if directed away from earth based receivers.

Multiple sensor platforms, remember? Not simply orbiting a single
planet, remember? Besides, controlling the direction your heat goes
takes energy and quickly becomes a Red Queen's race.

> Furthermore, although electronics can produce significant waste heat, as
> can human bodies, life support generally will not.

Life support means you have portions of your ship heated to 280K or more.

> Actually, much of the
> human and electronics generated waste heat will be absorbed in the
> processof bringing cryogenic oxygen supplies to usable temperatures.
> Properly handled, waste heat will actually be the sole source of
> environmental heating.

Think about why you need environmental heating.

>> Actually, those sensor platforms don't really exist. At least not on
>> the scale we would be talking about in even a minimalist interplanetary
>> war scenario. Putting a single satellite at the Earth-Sun L1 point was
>> a big deal.
>
> Platforms for searching for asteroids DO exist, but you are correct that
> there are very limited numbers of such platforms.

Congratulations, you managed to repeat the very caveat I made.

Describing that sensor platforms looking for interplanetary objects don't
really exist is as correct as saying that passenger aircraft didn't
really exist in 1914.

(FTR: Four had been built by that time, with a total passenger capacity
of 30.)

> The cost of putting
> such platforms into space is rather the issue.

Right now it is, right now we aren't looking at even setting up the
preconditions of an interplanetary war being possible in the first place.

>> Putting sensor nets everywhere in the oceans has three problems:
>>
>> First, covering the whole thing would take a _lot_ of sensors,
>> (contrast with space, where you only need a few dozen at most).
>
> False assumption. Again, I will get to this later.

Nope, not false. Your later simply shows that you still don't understand
how a sensor system like this would work.

(Hint: Think about why radar dishes move and why they can get away with
not constantly staring at things.)

>> Second, most of the oceans are places where deploying those sensors is
>> hard, (contrast with space, where there are harder spots that you want
>> to use, but the limitation for those is really deployment time, (you
>> have to wait for the slingshot that kicks your inclination up), and the
>> easy spots are still usable).
>
> Slingshots are of very limited use in kicking up inclination.

Nope, they can do quite a bit of it. You can get plenty of (anti)normal
in a slingshot and that's what you need for a plane change.

(Let me guess: You don't play KSP, do you?)

> They are
> more useful for accelerating to higher planal velocities. Deploying
> sensors in the water is MUCH less difficult and costly than even LEO
> launches.

To compare apples with apples, what we can do now with space is along the
lines of what was being done subsurface in the mid-late 19th century.

> All you need is a sufficient amount of weight to sink the
> platform, and a relay cable sufficiently long to reach the surface (in
> order to transmit data and receive instructions)... and a battery
> powered propulsion system for accurate placement.

So you think trailing a 4km long cable to the bottom that can survive for
years is the easy way to do it?

Not that you would actually want your sensor at the bottom in most
places. In the ocean you want your sensor to be close to the same depth
as what you are trying to detect. Thus, you want a sensor platform that
can maintain a depth and counteract any currents that are pushing it
around.

You could do this with an anchor, (and a lot of anchor cable), or you
could build a free-floating platform that has engines and a long-duration
power source. I think the latter is the better choice, although they
might be too expensive to cover everything at once.

>> Third, many of the places you really want sensors are places someone
>> who doesn't want them there owns, (contrast with space, where solar
>> orbits are open to anyone).
>

> Until you have colonies claiming regions of space. The entire reason for
> a space navy is to protect assets. Current space law will no longer
> apply in such settings.

Space does not work that way. The only thing you could meaningfully
claim is the orbital space around your own planets/moons, the oceanic
equivalent would be things like the White Sea or the Gulf of St.
Laurence. Claiming solar orbits would be like claiming the Pacific Ocean.

Sensor platforms for interplanetary conflict go out in places like the
Pacific because they can see everything from there. Subsurface sensors
are placed in choke points because you can't cover everywhere and that's
where you get the most bang for your buck.


(Gah, seriously: Either indent or separate your paragraphs, that wall of
text is physically hard to read.)

> Now... what does it actually take to build a miltary array?
> Objectives for such arrays are to detect, identify, localise, track, and
> observe potential targets. You have a few physically defined limits to
> capabilities, and additional technological limits.
> To detect a target, you need that target to be emitting or reflecting a
> sufficient amount of energy, not just for sensors to record detection,
> but for sensors to accept that information as reliable data. Assume that
> you have a sensor capable of detecting a single photon. Forget about
> determining if the target is "legitimate" (a spacecraft), you would need
> to know that the "ping" is from a detected photon, rather than just an
> anomoly resulting from some source of electric, magnetic, or EM
> interference (stray static discharges, wiring faults, etc). Even if you
> can detect single photons, you will probably require a steady stream of
> photons reliably impacting a detector over a singificant amount of time.
> Receiving a reliable signal is dependent upon the signal strength, but
> also on the photon flux produced by that signal strength. For a given
> energy level, shorter wavelengths produce fewer photons than longer
> wavelengths. The overall flux, whether measured by energy density or by
> photon count, will be affected by distance. Intensity is inversely,
> exponentially proportional to the distance. Or, from another context,
> the area of the receiving sensor required to detect a source is
> exponentially proportional to the distance from that source.

For simple detection of an IR source with limited directional
information, this is false. What matters is radiance, not radiant flux,
(this is why IR fire detectors freak out about candles).

Your assumptions about how much flux there will be is also, well, wrong.

> Realisticly, you will probably need at least a 35m platform to detect an
> object that is actively attempting to reduce emissions. This is a
> physical limit. Actual sensitivity of detectors will further limit your
> abilities.
> Once detected, you need processing power to identify a source as a
> "legitimate" target. You need to eliminate all background sources. To
> understand how many sources have to be eliminated: someone had
> calculated that a "torchship" (fusion powered rocket) at full thrust
> would have a magnitude of +12 (he did not specify if this were absolute
> magnitude, or apparent magnitude at 1 AU or so, so I will assume
> apparent, which would actually yield a brighter absolute). This roughly
> coincides with the detection limit of a 5" to 10" telescope. Now,
> consider the hundreds to thousands of stars visible to the naked eye on
> a clear, dark night (the milky way)... and consider the tens to hundreds
> of thousands of stars and galaxies that become visible with a 5"
> telescope. This is the background you have to elliminate before
> detecting an unsheilded fusion drive.

Um, picking out new signals against a known background is _easy_. Heck,
there is a good chance that your _car_ is doing the kind of filtering
needed.

> Let's say that you have the means to filter out all this background.

Yes, let's say we can do something that we could do before you were born.

> Limitations are a function of processing power, after all. Let's also
> say that you can use processing to establish an identification, to some
> level of accuracy. What is left to locate, track, and observe?
> This is actually fairly easy, given the technique of virtual apperature
> (interferometric) telescopy. Angular resolution is a function of
> distance, wavelength, and array baseline. If you place satellites just
> outside of geosynch orbit (say, 50 000 km),

Have you missed the whole bit about how you place these things in _solar_
orbits?

> The problem is, you are going to have a very limited field of vision.
> Well... probably. A planar array radiotelescope would allow for a 120°
> field of vision, but you will not have anywhere near the same
> sensitivity, so the array will have to be several times larger and
> heavier also, you might need to assemble it in space, in order for a
> Saturn V booster to be able to handle the configuration of the load,

Dude: Stop talking about how we might launch such things from the
surface of the Earth. In any scenario where this kind of thing matters
you will have to have cheap access to space as the very minimum and are
more likely going to be engaging in orbital manufacture. You won't be
launching them into orbit, you're going to be _building_ them there.

> assuming a single booster would still be able to support the mass. A
> lens or parabolic antenna would allow energy to be concentrated, giving
> the required sensitivity, but these produce the limited field of view I
> was talking about. Being extremely generous, let's say we have a 10°
> field of view. This would require an array of 54 to 72 platforms
> (perhaps as little as 9 to 12 for planar arrays).

Wrong, you don't need to look at everything at all times. This is one of
the two constant errors pro-stealth people make.

Instead you look at any given direction periodically, using a search
pattern that makes it impossible to manage to 'sneak though' by moving
from areas about to be scanned to ones that were just scanned.

> A single degree field
> of view is MUCH more likely (still probably somewhat generous),

Getting a 0.8 degree field of view with a single sensor that could do 1.5
FOV/s was possible _TWENTY YEARS AGO_. That gives you two whole sky
surveys, (not a band, the full 4pi steradians), per day using hardware
that isn't as good as the phone in your pocket.

Combine an array, (let's say a 3x3), with faster CCDs and processors,
(let's say 5 FOV/s), and an out of plane sensor platform that only looks
at half of the sky, (because everything interesting is either staying in
the plane of the ecliptic or coming from it), and you are down to one
full scan every 12 minutes.

> but that
> would require 540 to 720 platforms... well, assuming that you want full
> coverage. You could reduce the requirement through scanning.

Oh man can you ever reduce it.

> So... doable. Theoretically.

Doable, easily.

> However, this is the theoretical limitation
> to the resolution. The actual resoultion will depend upon the number of
> detector elements. In order to achieve this theoretical limit, each
> sensor will require something on the order of 10^18 pixels (this will
> require independent elements for each pixel, or a lesser number of much
> more complicated elements capable of receiving and measuring multiple
> photons coming from diverse angles. This will likely reduce the
> effective sensitivity of each element significantly... it also reuires
> greater processing power, since you are using interferometric techniques
> to obtain the resolution into pixels.

You are continuing to make another error I pointed out to you earlier:

That you use one type of sensor to do the whole thing.

You start with one that scans fast, gives limited angular detail and
generates false positives left, right and centre.

You pass off its potential detections to a narrow FOV, higher resolution
system that confirms the detection.

That then hands off to other platforms to confirm with their narrow FOV
systems and lock in the location.

At this point you know where it is and where it's heading and can also
start looking at it with the really high resolution stuff.

> Please keep in mind that these platforms make REALLY easy targets.

This claim of yours has been repeatedly shown to be false. You have to
either engage in a massive effort, telegraph your attack months in
advance or accept a probable failure.

> Also,
> they are extremely sensitive to micrometeroid impact. Also, they need to
> communicate with one another. I have not included the processing
> requirement or support infrastructure required for maintenance, repair,
> data communications, shielding, etc.

Um, you don't go out and fix these kinds of platforms unless you are past
what would be plausible midfuture technologies, (IOW, you have reached
the point where the entire discussion is as moot as would be one Pliny
the Elder might have about WWII naval tactics). You assume they will
last about 50% of their MTBF and use that for their replacement schedule.

[Sea Wasp (Ryk E. Spoor)]

On 9/15/16 2:27 PM, Mikkel Haaheim wrote:
> Le jeudi 15 septembre 2016 17:57:19 UTC+2, Mikkel Haaheim a écrit :
>
>
>> Once detected, you need processing power to identify a source as a "legitimate" target. You need to eliminate all background sources. To understand how many sources have to be eliminated: someone had calculated that a "torchship" (fusion powered rocket) at full thrust would have a magnitude of +12 (he did not specify if this were absolute magnitude, or apparent magnitude at 1 AU or so, so I will assume apparent, which would actually yield a brighter absolute). This roughly coincides with the detection limit of a 5" to 10" telescope. Now, consider the hundreds to thousands of stars visible to the naked eye on a clear, dark night (the milky way)... and consider the tens to hundreds of thousands of stars and galaxies that become visible with a 5" telescope. This is the background you have to elliminate before detecting an unsheilded fusion drive.
>
>
> Right. I actually have a little more precise information.
> I found a source that reports 156 182 070 295 stars catalogued with apparent magnitudes of 12 or brighter.

And if you have them catalogued, a modern computer will be able to
notice "hey, that sucker just appeared out of nowhere and isn't in the
catalogue" in less time than a human can notice.

This is a trivial job. You include the catalogue as part of your scan,
and look for *change*, not analyzing everything from scratch.

[Greg Goss]

"Sea Wasp (Ryk E. Spoor)" <sea...@sgeinc.invalid.com> wrote:

> This is a trivial job. You include the catalogue as part of your scan,
>and look for *change*, not analyzing everything from scratch.

Even the mark 1 eyeball was used that way looking for planets and
comets in "blink comparators".
--
We are geeks. Resistance is voltage over current.

[Greg Goss]

Mikkel Haaheim <mikkel...@gmail.com> wrote:

>Depends upon the scales. In your fantasy scenario (NOT SciFi, because a "universe" filled with atmosphere will rather quickly collapse on itself),

Grin. I don't read fantasy, so I'm forced to call Sea Wasp's uch
universe SF.

[Mikkel Haaheim]

Le vendredi 16 septembre 2016 02:33:04 UTC+2, Rick Pikul/Chakat Firepaw a

> You did notice that this discussion was a month and a half ago, right?

Sorry. My wife imposed an incommunicado during our vacation in order for us to do some work on our house and rental properties.

>
> You do not understand because I never said anything about the opposing
> orbital point: "...the other point the initial and final orbits
> intersect."

Okay, you will have to explain this a little, then. For a point burn, there is only one point where the orbits intersect, and that is at the point of the burn. If you are using a continuous sail manoeuvre, there IS no intersection, because you are either spiralling in or spiralling out. Once a manoeuvre is completed, the only point of intersection is with the point where you withdrew the sail, unless you were constantly changing the angle of the sail in order to circularise the final orbit... but, again, there would be no common point with the initial orbit. You CAN NOT oppose a radial out burn with another radial out burn.

>
> >> Not really, hitting the platforms involves firing shots that saturate a
> >> target area at least one hundred _million_ square kilometres in size.
> >> Cheap, unguided, shot means a minimum of about one 'pellet' per square
> >> metre.
> >
> > This is not a problem. Yes, I have suggested 1 pellet/m^2, but you
> > actually only need 1 pellet per sensor. The sensors will have to be
> > large in order to obtain useful info. 1 pellet/10m^2 would likely be
> > more than sufficient.
> > Furthermore, pellets can be small. The impact of even a single gram will
> > likely sufficiently damage the sensors.
>
> And what will be the total mass of those pellets?
>
> 10,000,000 km^2 = 1e14 m^2

10^13, actually... However, I think you might have meant 100 000 000 km^2, which would roughly match the 10 000 km spread I meantioned; although I no longer remember if I intended that "spread" to refer to diameter or area.

>
> For a 1g pellet every 10 m^2 that's:
>
> 1e14 m^2 * 0.1 g/m^2 = 1e13g
>
> That's ten _million_ _TONNES_. For a shot that isn't even certain to
> connect, (perfectly spaced they're 5.77m apart).

Actually, the shot is pretty certain to connect. The Hubble has a minimal cross section of over 17m^2. But I suppose that I can concede an insignificant probability that all the pellets will miss.
You have a point that that is a lot of mass (and energy) to dedicate to a single target, although it might still be worthwhile for strategic purposes. based on the original discussion, 10 000 km^2 should be more than sufficient. That brings us down to 10^9 g, or 1000 tonnes. This would be about the size of a backyard pool of material. This would also be the mass equivalent of the bomb load of an average WWII sortie of B-17s (6 combat boxes of 12 aircraft each), generally dedicated against a single target (actually, this count is small... typical sorties used anywhere from 100 to 600 bombers, not counting support aircraft).

>
> > You don't even need pellets...
> > sensors are VERY sensitive to any kind of impact. Even high velocity
> > dust will scour the collector dishes and optics, rendering them
> > unusable. Given the size of the pellets or dust in question, the mass
> > required to do sufficient damage, results in high arial coverage
> > actually yielding fairly low actual masses or volumes.
>
> You obviously either didn't do the math or made rather unrealistic
> assumptions.
>
> Or are you jumping around between units again: Using one figure as the
> radius of your shot cloud when claiming it will hit, then using the same
> number as the area when claiming you can connect using a sane amount of
> material.

The area originally discussed was probably overkill. However, the mass discussed is NOT unreasonable for important strategic targets. Still, I have demonstrated that the mass can be significantly reduced for more reasonable strikes. You can even decrease the mass below 1g, especially if you decide to use an explosive shell or armour piercing design.
In war, "sane" amounts of material is quite subjective.

>
> Um, no. You need on the order of 10km/s for escape trajectories, and
> that's if you eject prograde from the body orbiting the sun. For these
> kinds of shots think 15-20km/at least.

Again, easily achievable with small pellets. Existing rail gun design will fire a 3.5 kg projectile at over 2.5 km/s. The same energy will fire 100 1g pellets at 15 km/s. BTW, your 10 km/s delta v estimate applies to launch from Earth orbit. From the asteroid belt, you only need on the order of 3 km/s delta v.

>
> > Also, dust and pellets will continue to disperse, leaving them no more a
> > hazard than currently existing meteoroids.
>
> Actually, they don't. They just transform into a stream, meteor showers
> are annual for a reason.
>

Actually, relative to each other, they DO. Even if they are locked into respective orbits, they will disperse within that orbit (actually, a band of orbits). But, yes, you now have another region of meteor showers.
Largely irrelevant... it would not be difficult to impart sufficient momentum for solar escape velocity; or, alternatively, to have a programmed detonation to reduce the shells to dust.

>
> Actually, yes you do: All of the stations can see almost everywhere, you
> have no horizon to hide behind.

If you scan, yes. However, if you scan, you leave open large windows where you can sneak manoeuvres in.

>
> >> Remember that 'cold-running' means turning everything off, including
> >> things like life support and any computer systems. If you have
> >> anything running you will have waste heat to get rid of.
> >
> > Incorrect. Cold running simply means that waste heat will have to be
> > limited to what can be safely absorbed by the internal heat sink
> > (cryogenic supply)
>
> Which isn't that much, expect no more than a few months under ideal
> conditions.

This depends upon the object, the amount of heat sources, the amount of cryogenic supply or other heat sink material, and the amount of surface area for low level radiation of waste heat.
If I have time, I will try to draw up some scenarios.

>
> > or what can be emitted without allowing for detection.
>
> Which also isn't that much

Fairly safe to emit quite a lot of radiation normal to the solar plane. Even with your imaginary solar polar orbits, you are not going to get a significant measurement unless you are passing almost directly "overhead".

>
> > Let's say you ere emitting 2.25 watts/s IR radiation.
>
> So you are a tiny ship cooled to under 150K.

Who said anything about a tiny ship?

>
> Even at a chilly 200K your hull is emitting 9 W/m^2, not the waste heat
> from your systems, the hull itself, (and that's assuming you optimize for
> minimal blackbody radiation).

Which is not significant, considering all the other bodies in space that are emitting blackbody radiation. It is also quite insignificant compared to the energy from reflected sunlight. Again, stealth is NOT about not being detected, but not being noticed.
Also, I was using the 2.25 watt value out of convenience when I was working through my calculations. Those calculations actually result in 126 W allowing a maximum of 1 photon/s striking a 35m sensor. Even if you could detect such low yields, these are likely to be disregarded as unreliable. Even if considered reliable, it will likely be disregarded as a probable meteoroid/small asteroid. Such emissions are far to small for Hubble. Even WISE might have some difficulty.

>
> (Psst: W/s would be how fast your emissions are increasing, you simply
> want W.)

Quite correct. Sorry. I was actually thinking J/s, but then decided it would be easier just to go with watts.

>
> Multiple sensor platforms, remember? Not simply orbiting a single
> planet, remember? Besides, controlling the direction your heat goes
> takes energy and quickly becomes a Red Queen's race.

If the radiation is directed off the solar plane, and outward from the sun, it is unlikely to be detected even by your imaginary solar polar platforms... even if these extend beyond the orbit of jupiter. Unless you have invested the resources to build and deploy at least 360 such platforms. Considering that the resources to deploy such a platform even in a 1 AU solar orbit do not exist, and barely exist even in theory (even GC-NTR propulsion would require multiple staging), that is not very likely.
Controlling the direction of radiation does not require energy. It is a question of architecture. Well, okay, you probably will need a little energy to pump the coolant through the radiators.

>
> > Furthermore, although electronics can produce significant waste heat, as
> > can human bodies, life support generally will not.
>
> Life support means you have portions of your ship heated to 280K or more.

Yes. A question of architecture and engineering. The body heat of the crew, and the operational systems, are quite sufficient to provide the necessary environmental heating. The trick is to balalnce the rate of heat loss.

>
> > Actually, much of the
> > human and electronics generated waste heat will be absorbed in the
> > processof bringing cryogenic oxygen supplies to usable temperatures.
> > Properly handled, waste heat will actually be the sole source of
> > environmental heating.
>
> Think about why you need environmental heating.

The why is irrelevant. All that is relevant is that you have sufficient environmental heating and (often more importantly) cooling.
However, in response, you need thermal energy to maintain metabolism (this means that you want sufficient insulation to prevent the loss of metabolic generated heat... already a common practice since the development of the shuttle). You need sufficient heat to avoid freezing working liquids and condensing gases such as atmospheric supply. You need sufficient heat to avoid moving parts freezing together. You need sufficient heat to avoid joint seals from ontracting to the point that they start leaving gaps. Etc.

>
>
> >
> > Platforms for searching for asteroids DO exist, but you are correct that
> > there are very limited numbers of such platforms.
>
> Congratulations, you managed to repeat the very caveat I made.
>
> Describing that sensor platforms looking for interplanetary objects don't
> really exist is as correct as saying that passenger aircraft didn't
> really exist in 1914.

And both statements would be equally incorrect. You did not say the capabilities were underdeveloped. You said they did not exist. You then qualified this statement to correct the error, but it does not refute Emmett's statement.

> > The cost of putting
> > such platforms into space is rather the issue.
>
> Right now it is, right now we aren't looking at even setting up the
> preconditions of an interplanetary war being possible in the first place.

Cost, in terms of resources, will ALWAYS be an issue. Yes, more resources will become available... but more resources will also be in demand. Populations will continue to increase. These populations will continue to demand an increase in standards of living, which means an increase in the availaility of resources dedicated to meating those standards. The number of different services and products offered will increase, also increasing the demand on resources. Automated labour might very well replace manual labour, but increasing populations will continue to mean increasing demand of resources, especially since automation requirements will be adding their own demands on resources.
You are ALWAYS going to have to balance out the use of available resources, and your populace is not likely to consider establishing your Big Brother Net as justified.

>
> Nope, not false. Your later simply shows that you still don't understand
> how a sensor system like this would work.
>
> (Hint: Think about why radar dishes move and why they can get away with
> not constantly staring at things.)

Nope, still false. You can get away with terrestrial radar scanning because the gaps created during military radar sweeps are generally not large enough to slip aircraft through, at least not at the ranges where you have reliable detection.

>
> >> Second, most of the oceans are places where deploying those sensors is
> >> hard, (contrast with space, where there are harder spots that you want
> >> to use, but the limitation for those is really deployment time, (you
> >> have to wait for the slingshot that kicks your inclination up), and the
> >> easy spots are still usable).
> >
> > Slingshots are of very limited use in kicking up inclination.
>
> Nope, they can do quite a bit of it. You can get plenty of (anti)normal
> in a slingshot and that's what you need for a plane change.

Jupiter's orbital inclination to the ecliptic is currently about 1.31°. It has about a 6° inclination off the plane of the sun's equator, while Earth has just over a 7° inclination. Using Jupiter's gravitational pull, you could drag an object launched along the plane of the ecliptic, achieving an inclination of perhaps 8.5°... perhaps you can manage to convert a little of Jupiter's orbital momentum to boost this diflection a few more degrees. You would probably have much better results using the Oberth effect during a deflectional burn.

>

> So you think trailing a 4km long cable to the bottom that can survive for
> years is the easy way to do it?

No. There are even easier methods. Rather supports my point.

>
> > Until you have colonies claiming regions of space. The entire reason for
> > a space navy is to protect assets. Current space law will no longer
> > apply in such settings.
>
> Space does not work that way. The only thing you could meaningfully
> claim is the orbital space around your own planets/moons, the oceanic
> equivalent would be things like the White Sea or the Gulf of St.
> Laurence. Claiming solar orbits would be like claiming the Pacific Ocean.

You are not thinking future. You can claim any territory you are willing and able to defend. It will be much easier for established belt and outer planet communities to enforce and develop outer planet territories than for an Earth based organisation. While independent outer planet communities might not be able to enforce territorial "ownership" outside their immediate sphere of influence from each other, a united organisation of developed outer planets communities would sure as hell be able to block out any spy satellite development from Earth.

>

>
> Um, picking out new signals against a known background is _easy_. Heck,
> there is a good chance that your _car_ is doing the kind of filtering
> needed.

Um, no... it really isn't, which is why astronomers are still pooring over 50 year old (and older) photographic plates, along with all the newer observation data, trying to locate and identify the rest of the uncatalogues stars, asteroids, etc... not to mention more remote dwarf planets and similar objects. They have been looking for asteroids specificly for over thirty years, and of the 150 million plus estimated 100m+ asteroids, they have only identified 500 000 (1/3%).
You can try to filter out all light sources brighter than the expected target signal. The danger with this is that with over 4 000 000 such sources in a single square degree (this is for magnitude 12 objects... if you are looking at higher magnitude objects, there will be many times this number), you have a very good chance of filtering out the target signal itself, because its signal will (possibly) be in front of or immediately adjacent to the light of a filtered source (it will then be interpreted as part of that filtered source). Even if you manage to filter all the brighter sources, the distribution of sources is such that you will have a number of sources of the same magnitude as the target as the total number of sources brighter than the target. Good luck with that.
You can try to filter out sources by spectral analysis, but spectral analysis is pretty much limited to one source at a time. At 4 000 000 + objects to sort through, that will take a long while. You can try to filter out all the known sources... but you still have to identify them, and there is an excellent chance that the target source will be in front of, overlapping, or adjacent to the known source, and might therefor be filtered out as part of the signal from the known source.
Keep in mind that tracking all these known sources is not quite so easy either. You will have to calculate their positions relative to the current position of the platform. All these apparent positions will be moving, relative to the platforms FOV, so you will need to be able to track multiple millions of moving targets.
Oh, yes... once you have actually found a legitimate target (a spacecraft), you are then going to have to filter through all the other spacecraft... ALL of which must be tracked.

>
> > Let's say that you have the means to filter out all this background.
>
> Yes, let's say we can do something that we could do before you were born.

Again, no, this is simply not true. If it were anywhere near to being true, we will already have filtered everything out in order to dentify ALL of the projected 150 million 100m+ asteroids. We are nowhere near completing this task, exactly because we do not have the means to filter out all the background stars.

> Have you missed the whole bit about how you place these things in _solar_
> orbits?
>

Have you missed the bit that even theoretical GS-NTR rockets would not be able to place platforms of the required mass into even 1AU solar polar orbits, without a hell of a lot of expendable staging?

>
>
> Dude: Stop talking about how we might launch such things from the
> surface of the Earth. In any scenario where this kind of thing matters
> you will have to have cheap access to space as the very minimum and are
> more likely going to be engaging in orbital manufacture. You won't be
> launching them into orbit, you're going to be _building_ them there.

You might be constructing these things in space, but you will first have to transport all the raw materials from either the Earth or the moon (perhaps Mars, if you still control Mars space). Also, cheap access into space is realtive, and is not entirely relevant in this case. The notion that LEO is halfway to anywhere (in the solar system, at least) is only applicable to transit along the solar plane. For solar polar orbits, not only do you have to start from scratch, but you also have to negate the velocities along the solar plane.

>
>
> Wrong, you don't need to look at everything at all times. This is one of
> the two constant errors pro-stealth people make.
>
> Instead you look at any given direction periodically, using a search
> pattern that makes it impossible to manage to 'sneak though' by moving
> from areas about to be scanned to ones that were just scanned.

Remember, stealth is not about not being seen, but about not being noticed. Looking all the time means that you have more opportunity of spotting intermittent burns that might indicate something worth paying attention to. When you scan, the holes are not places where a ship is not detected so much as they are occasions where the activities (burns) of that ship do not send up flags.
Seaarch patterns are okay, but you are not going to see what is actually happen. You are not going to see the energy spikes produced by a burn, or the launch of an assault force of drones from an NEA or common cargo transport.
Scans also make it much more likely that two intermittent spikes will be interpreted as anomalies, rather then manoeuvres from a single object.

>
> > A single degree field
> > of view is MUCH more likely (still probably somewhat generous),
>
> Getting a 0.8 degree field of view with a single sensor that could do 1.5
> FOV/s was possible _TWENTY YEARS AGO_. That gives you two whole sky
> surveys, (not a band, the full 4pi steradians), per day using hardware
> that isn't as good as the phone in your pocket.

1.5 FOV/s is possible with small sensors. It is not possible with the 35m dishes required for detecting weak signals. But that doesn't matter, because you are forgetting that you will be dealing with a developed community of spacefarers. Local traffic between moons is going to be on the level of city street traffic. Traffic between adjacent planets will be on the level of interstate traffic. Even traffic between Jupiter and Earth will be on the level of international traffic between Europe and the US (several flights per day... or, if you prefer, several departures per day of ocean vessels).
Again, stealth is not about not being seen... it is about not being noticed. You are going to have thousands of legitimate targets to sort through to look for possible threatening activities, and if you aren't looking all the time, you are going to easily miss such activities.

>
> Combine an array, (let's say a 3x3), with faster CCDs and processors,
> (let's say 5 FOV/s), and an out of plane sensor platform that only looks
> at half of the sky, (because everything interesting is either staying in
> the plane of the ecliptic or coming from it), and you are down to one
> full scan every 12 minutes.

Given the bulk of data (and poverty of input), faster CCDs and processors will be insufficient. You need more processors (or processors capable of much greater loads, or both), and more sensitive CCDs (if you run the CCD too fast, it will not accumulate enough energy to register). Actually, you need that anyway. Astronomers are STILL looking at 50+ year old data, running them through newer, faster, higher capacity computers, trying to extract useful info from the data that is already there, just trying to count and catalogue the stars and other objects already present on those plates.

>
> > but that
> > would require 540 to 720 platforms... well, assuming that you want full
> > coverage. You could reduce the requirement through scanning.
>
> Oh man can you ever reduce it.

Yes. You can reduce it all you want. But say goodbye to your notion of stealthless space.

> pointed out to you earlier:
>
> That you use one type of sensor to do the whole thing.
>
> You start with one that scans fast, gives limited angular detail and
> generates false positives left, right and centre.

A fast scanner is not going to help you if it can't receive sufficient energy input. Detectors require a sufficient number of photons of sufficient energy in order to register. Energy is not usually difficult, but photon count is important. There are three options for increasing sensitivity here: find something that can sense a lower number of photons; increase reception area; and/or, increase exposure time. If you scan too fast, you are going to miss your input.

>
> You pass off its potential detections to a narrow FOV, higher resolution
> system that confirms the detection.
>
> That then hands off to other platforms to confirm with their narrow FOV
> systems and lock in the location.
>
> At this point you know where it is and where it's heading and can also
> start looking at it with the really high resolution stuff.

At the ranges being discussed, resolution is not exchanged with FOV. Resolution is a function of baseline, and FOV is a function of the sensors you are using. Sensitivity is a function of sensor collection area and exposure time. You can try to use planar array sensors, which will give you vastly improve FOV at the cost of much larger required collection area; or you can use parabolic arrays that collect much more energy in a much smaller area (because, unlike planar arrays, you can reflect and focus the energy in a smaller area). Optical lenses and reflectors do the same job as parabolic arrays, but are much more sensitive to damage.
Since a minimum 35m collector will be required just to have a chance to detect low level emissions from 1AU+, you might as well just rely on these. However, you can run them individually for the initial detection, if you prefer; and then coordinate the data for high res interferometric telescopy if you find something of interest.
But here's the problem: you are going to ind objects of interest. Lot's of them. Tens of thousands of them. But you are not going to know which ones are commuter traffic, which ones are routine shipping, which ones are pleasure cruises, which ones are military on routine patrol, which ones are military on training exercises, and which ones are military on possible stealth missions until you track and observe them. ALL of them. ALL the tens of thousands of them. If you stop observing the wrong ones at the wrong time, you give them the window to perform their task without you noticing. That is stealth.

>
> > Please keep in mind that these platforms make REALLY easy targets.
>
> This claim of yours has been repeatedly shown to be false. You have to
> either engage in a massive effort, telegraph your attack months in
> advance or accept a probable failure.

There is always the possibility of failure. ALWAYS. Military planners know this. Possibility, and even probability, of failure is not a deterent.
There is a difference in planning and telegraphing. Properly shielded rail and coil guns do not telegraph. However, in space, it could be months before the shells arrive on target. Not useful against targets under constant manoeuvre, but quite effective against fixed or cyclic targets. This is just one option.
"Massive" is quite relative when it comes to effort.
Platforms are really easy targets because they tend to be cyclic. Random motions tend to get in the way of cooperative processing. The required platforms will also be large, as a function of physical law. Tech limitations will tend to make them larger. This makes them easy to see and to hit. There are numerous options for hitting: buckshot, sniper, small drone attack, automated (homing) missile attack, etc. Nothing prevents several methods from being used at once. Nothing prevents one method from being used to trap the target in a position optimal for another.

>
>
> Um, you don't go out and fix these kinds of platforms unless you are past
> what would be plausible midfuture technologies, (IOW, you have reached
> the point where the entire discussion is as moot as would be one Pliny
> the Elder might have about WWII naval tactics). You assume they will
> last about 50% of their MTBF and use that for their replacement schedule.

Perhaps. Perhaps not. You might decide that it is easier to send up a new platform instead of fixing a malfunctioning platform. In which case, replacement platform construction and deployment would be part of the infrastructure I am talking about.

[Mikkel Haaheim]

Le vendredi 16 septembre 2016 12:10:12 UTC+2, Sea Wasp (Ryk E. Spoor) a écrit :
> On 9/15/16 2:27 PM, Mikkel Haaheim wrote:
> > Le jeudi 15 septembre 2016 17:57:19 UTC+2, Mikkel Haaheim a écrit :
> >
> >
> >> Once detected, you need processing power to identify a source as a "legitimate" target. You need to eliminate all background sources. To understand how many sources have to be eliminated: someone had calculated that a "torchship" (fusion powered rocket) at full thrust would have a magnitude of +12 (he did not specify if this were absolute magnitude, or apparent magnitude at 1 AU or so, so I will assume apparent, which would actually yield a brighter absolute). This roughly coincides with the detection limit of a 5" to 10" telescope. Now, consider the hundreds to thousands of stars visible to the naked eye on a clear, dark night (the milky way)... and consider the tens to hundreds of thousands of stars and galaxies that become visible with a 5" telescope. This is the background you have to elliminate before detecting an unsheilded fusion drive.
> >
> >
> > Right. I actually have a little more precise information.
> > I found a source that reports 156 182 070 295 stars catalogued with apparent magnitudes of 12 or brighter.
>
>
> And if you have them catalogued, a modern computer will be able to
> notice "hey, that sucker just appeared out of nowhere and isn't in the
> catalogue" in less time than a human can notice.

Not when you are talking about tracking billions of these sources. Not even when you are talking about tracking millions. Those computers you mention are still trying to extrapolate information from 50+ year old photographic plates, trying to track all those known sources in order to identify and catalogue the unknown ones. Various computers and astronomers have been doing this for 30 years, and they STILL have only been able to catatlogue a small fraction.

>
> This is a trivial job. You include the catalogue as part of your scan,
> and look for *change*, not analyzing everything from scratch.
>
>

No. It is NOT a trivial job, as evidenced by the fact that these sources sontinue to make it difficult to identify the remaining sources that have already been recorded for nearly 100 years.

>
>

[Mikkel Haaheim]

Human sight is good for up to about magnitude 6 objects. The human brain is by far the most capable computer for complex visual analytic calculations.

[Mikkel Haaheim]

SciFan, at best. A stable universe filled with atmospheric density gas is only as realistic as pixie dust and fairies. Actually, much less so.

[Mikkel Haaheim]

Le vendredi 16 septembre 2016 02:33:04 UTC+2, Rick Pikul/Chakat Firepaw a écrit :

I should point out that your method of observation is entirely realistic, and is most likely how arrays would actually be deployed... mostly. Your expectations of what they would be able to achieve, however, are not.
Your proposed system is the equivalent of a beat cop or security officer. When they find something uspicious, they will call in more resources. It is a system that has worked for millenia.
The problem is, you don't quite understand what stealth really is, or how it is, or might be, used.
Take the scenario from whence stealth derived its name: you could have a cop on every city block, and that cop might actually see the two pedestrians bump into one another. However, this cop is unlikely to see the thief pick the wallet any more than the victim noticed. Stealth is NOT about not being seen. It is about not being noticed.
The catburglar will also likely be seen dozens of times, perhaps even hundreds of times, during the night. Passing patrol cars will see the catburglar. But then they drive on. No one sees the catburglar when s/he goes behind a hedge or over a fence, into the back yard, and then through the window. No one sees the moment s/he leaves the property. Dozens or hundreds of people, and the passing patrol car, WILL see when the catburglar is back on the street going to the next target, or going home. But these observers will never stop the thief, or suspect the illegal activity.

[Mikkel Haaheim]

Le vendredi 16 septembre 2016 02:33:04 UTC+2, Rick Pikul/Chakat Firepaw a écrit :

> >
> > Incorrect. Cold running simply means that waste heat will have to be
> > limited to what can be safely absorbed by the internal heat sink
> > (cryogenic supply)
>
> Which isn't that much, expect no more than a few months under ideal
> conditions.
>

Right... here's a worked example.
A single person, running a high fever, will emit a little shy of 500 W (or 500 Joules each second). This translates to 43 200 Joules (43.2 kJ) / day.
A single tonne of ice (a little over 1 m^3) will absorb well over 700 MJ in transitioning from ice at 73°K to water at 290°K (actually, this would be closer to 735 MJ or more).
This means that your tonne of water will serve as a nice heat sink for a crew of 16 for 1 day, or a crew of 1 for 16 days. Well, that doesn't sound like much. However, let's go on to a supply of 1 kT of ice (a little over 10m x 10m x 10m) at 73°K. This will absorb 700 GJ. This would absorb 8.3 kW waste heat emissions for 1000 days (a little under 3 years), or about 25 kW emissions over 333 days (11 months).
Please note that these 25 kW are waste heat emissions. 1 kW is the equivalent of 2 crew; or the waste heat from a 2 kW device running at 50% efficiency, or the waste heat from a 5kW device running at 80% efficiency. A theoretical device running at 100% efficiency would be converting all energy to work, and would emit no energy to be detected.
If you are hard pressed, you could let the water (and the atmosphere) warm up to 35°. For each tonne of water, you absorb an extra 60 kJ (actually, a little bit more).
A sufficient layer of aerogel will prevent the bulk of this waste heat from escaping. This should prevent emissions of over 6 or 7 W/m. Proper architecture should further limit detectability.

[Alie...@gmail.com]

On Monday, September 19, 2016 at 5:49:17 AM UTC-7, Mikkel Haaheim wrote:
> Le vendredi 16 septembre 2016 02:33:04 UTC+2, Rick Pikul/Chakat Firepaw a écrit :
>
> > >
> > > Incorrect. Cold running simply means that waste heat will have to be
> > > limited to what can be safely absorbed by the internal heat sink
> > > (cryogenic supply)
> >
> > Which isn't that much, expect no more than a few months under ideal
> > conditions.
> >
>
> Right... here's a worked example.
> A single person, running a high fever, will emit a little shy of 500 W (or
> 500 Joules each second). This translates to 43 200 Joules (43.2 kJ) / day.
> A single tonne of ice (a little over 1 m^3) will absorb well over 700 MJ in
> transitioning from ice at 73°K to water at 290°K (actually, this would be
> closer to 735 MJ or more).

(Why did you take 290 K as your endpoint?)

At rest, your average (not feverish) human emits only ~100W. Notice that means not doing anything useful or entertaining, not even exercising to maintain physical health let alone mental health. Your 500W is typical of a trained athlete, say a bicyclist, going all-out, but that can't be sustained for very long.

Depending on how physically robust the crew needs to be, an average of ~150W over some months is more reasonable, less for longer terms.

Bottom line, IMO your 500W does leave headroom for exercise and whatnot, but inflates the heat budget unnecessarily.

> This means that your tonne of water will serve as a nice heat sink for a crew
> of 16 for 1 day, or a crew of 1 for 16 days. Well, that doesn't sound like
> much. However, let's go on to a supply of 1 kT of ice (a little over 10m x
> 10m x 10m) at 73°K. This will absorb 700 GJ. This would absorb 8.3 kW waste
> heat emissions for 1000 days (a little under 3 years), or about 25 kW
> emissions over 333 days (11 months).

Tech quibbles:

The warmer the ice gets, the less easily heat will transfer to it, and eventually the ice will reach skin temperature (310 K) and heat won't transfer at all.

Also, unless the ice completely surrounds the crew, extra machinery and plumbing are required to "steer" heat from crew to ice and prevent it escaping through the hull, and the machinery generates heat which means even more ice is needed per person.

Also also, life support machinery is required (fans and air scrubbers at the minimum, maybe video games to forestall insanity) which also generates heat -> still more ice per person.

Also^3, there's standby power for all of the machinery that makes a warship a warship, -> even still more ice. If you have radioactive materials (e. g.nuke warheads), more ice.

(I say "standby" because even such a stealthed craft may be discovered at any time and should be able to go to combat readiness as quickly as possible. That means you can't let critical systems or subsystems get too cold.)

All of the above can be quantified given a specified tech level.

> Please note that these 25 kW are waste heat emissions. 1 kW is the equivalent
> of 2 crew; or the waste heat from a 2 kW device running at 50% efficiency, or
> the waste heat from a 5kW device running at 80% efficiency. A theoretical
> device running at 100% efficiency would be converting all energy to work, and
> would emit no energy to be detected.

The most efficient device ever made is the transformer, reaching 99.9% efficiency in some applications, but you can't do everything a warship needs doing with just transformers, even in standby mode.

> If you are hard pressed, you could let the water (and the atmosphere) warm up
> to 35°. For each tonne of water, you absorb an extra 60 kJ (actually, a
> little bit more).

With heat pumps you can take the water all the way to steam (given room for expansion), but heat pumps produce their own waste heat, meaning yet more ice per person.

> A sufficient layer of aerogel will prevent the bulk of this waste heat from
> escaping. This should prevent emissions of over 6 or 7 W/m.

I like that, but structurally strong aerogels aren't particularly good insulators:

http://www.aerogel.org/?p=1058

There's a lot of current interest in carbon nanofoams for that reason. They're stronger, lighter, and better thermal insulators than silicon-based aerogels and have interesting electric and magnetic properties not present in silicon-based aerogels:

http://www.google.com/#q=carbon+nanofoam

> Proper architecture should further limit detectability.

This is where my biggest quibble comes in. No matter how strong the insulator, unless it's as strong as the spaceframe (in which case you make the spaceframe out of it) you're going to need structural members running through the insulation, and that structure will leak heat making hot spots on the outermost hull that will shine like infrared flares.


Mark L. Fergerson

[Greg Goss]

"nu...@bid.nes" <Alie...@gmail.com> wrote:

>On Monday, September 19, 2016 at 5:49:17 AM UTC-7, Mikkel Haaheim wrote:
>> Le vendredi 16 septembre 2016 02:33:04 UTC+2, Rick Pikul/Chakat Firepaw a écrit :
>>
>> > >
>> > > Incorrect. Cold running simply means that waste heat will have to be
>> > > limited to what can be safely absorbed by the internal heat sink
>> > > (cryogenic supply)
>> >
>> > Which isn't that much, expect no more than a few months under ideal
>> > conditions.
>> >
>>
>> Right... here's a worked example.
>> A single person, running a high fever, will emit a little shy of 500 W (or
>> 500 Joules each second). This translates to 43 200 Joules (43.2 kJ) / day.
>> A single tonne of ice (a little over 1 m^3) will absorb well over 700 MJ in
>> transitioning from ice at 73°K to water at 290°K (actually, this would be
>> closer to 735 MJ or more).
>
> (Why did you take 290 K as your endpoint?)

close to room temperature. If you're soaking up the output of
residents, then that's the limit of simple cooling without going to
fancy equipment.

[Mikkel Haaheim]

Le lundi 19 septembre 2016 23:54:02 UTC+2, nu...@bid.nes a écrit :
Hi Mark,

>
> (Why did you take 290 K as your endpoint?)

This was actually a typo. I meant to say 293°. Although Greg is correct about the room temperature limitation, which you alude to later with skin temp, the actual reason was much more spontaneous and practical: the first source for heat of fusion that I came to gave a figure of 333 J/g for transitioning H2O from 0°C to 20°C.

>
> At rest, your average (not feverish) human emits only ~100W. Notice that means not doing anything useful or entertaining, not even exercising to maintain physical health let alone mental health. Your 500W is typical of a trained athlete, say a bicyclist, going all-out, but that can't be sustained for very long.

Thanks for the correction. I did not have the info for radiation from human metabolism immediately on hand, so I derived my calculations directly from a black body heat source at body temp in a vacuum. However, I then purposefully inflated this figure, both for ease of calculation and to avoid someone arguing that my figure would be unrealisticly low.

> Tech quibbles:
>
> The warmer the ice gets, the less easily heat will transfer to it, and eventually the ice will reach skin temperature (310 K) and heat won't transfer at all.

Yes. This is why I limited the emergency reserve figure to 35°C instead of 37°C.
Your point also highlights the reason for, and importance of, my condition of suitable insulation. Although your point does not affect the amount of heat that will be absorbed, the insulation is to ensure that the ice/water layer has time to absorb the heat, rather than to emit it into space.

>
> Also, unless the ice completely surrounds the crew, extra machinery and plumbing are required to "steer" heat from crew to ice and prevent it escaping through the hull, and the machinery generates heat which means even more ice is needed per person.

My intent was that it would be surrounding the crew and (virtually) all working equipment, yes.

>
> Also also, life support machinery is required (fans and air scrubbers at the minimum, maybe video games to forestall insanity) which also generates heat -> still more ice per person.

Which is why I gave raw figure for waste heat, and not per capita allowance. When you determine the crew and equipment you want to include, and the waste heat they will be generating, you will be able to determine how many kT of ice you will need.

>
> Also^3, there's standby power for all of the machinery that makes a warship a warship, -> even still more ice. If you have radioactive materials (e. g.nuke warheads), more ice.

Yeeeeessss...

However, I did not actually have a full sized warship in mind. Mind you, if you wanted a full size warship, you scale up the amount of ice... but such a warship quickly becomes observable from reflected sunlight. Warships will not be undergoing stealth missions. Stealth measures on warships are only intended to make the enemy work a little harder, tying up the required resources.
I was actually thinking of a fairly small craft, by comparison. Perhaps the equivalent of a zodiac ferrying a SEAL team.

>
> (I say "standby" because even such a stealthed craft may be discovered at any time and should be able to go to combat readiness as quickly as possible. That means you can't let critical systems or subsystems get too cold.)

Yes, which means you will want self contained weapons requiring very little support. Guns and missiles. Purely chemical.

>
> The most efficient device ever made is the transformer, reaching 99.9% efficiency in some applications, but you can't do everything a warship needs doing with just transformers, even in standby mode.

Again, I actually was not intending warship applications. It is also why I gave example conversions at 50% and 80% (a fairly optimal range... 25% and lower is possible, and they waste heat figures can be easily calculated).

>
> With heat pumps you can take the water all the way to steam (given room for expansion), but heat pumps produce their own waste heat, meaning yet more ice per person.

Yes. Which is why I was opting to limit the transfer to air temp or skin temp.

> I like that, but structurally strong aerogels aren't particularly good insulators:
>

The aerogel will not be supporting structure, and will not have to be structurally strong.

>
> There's a lot of current interest in carbon nanofoams for that reason. They're stronger, lighter, and better thermal insulators than silicon-based aerogels and have interesting electric and magnetic properties not present in silicon-based aerogels:
>
> http://www.google.com/#q=carbon+nanofoam

Thanks for the reference.

>
> > Proper architecture should further limit detectability.
>
> This is where my biggest quibble comes in. No matter how strong the insulator, unless it's as strong as the spaceframe (in which case you make the spaceframe out of it) you're going to need structural members running through the insulation, and that structure will leak heat making hot spots on the outermost hull that will shine like infrared flares.

Exept for the (propbable) forces from an EM catapult launch, acceleration will generally be limited to less than 1 mm/s^2 (even this allows for an 8.62 km/s delta v after a continuous 100 day burn). Aerogel plates will be affixed to the structural hull, with no protrusions (at most, bolts will be fitted to the inside surface of the aerogel plate, reducing the amount of insulation at that point... but that just means using slightly thicker plates than absolutely necessary). But there is not even the ned for plate. Aerogel is currently available in flexible fabric that can essentially be "wrapped" around the hull.
In any case, most of the structural support (especially catapult for launch) will actually come from the thick plates of ice. Perforated ice will be sandwhiched between thin semi-structural hull layers. The perforations will allow for expansion and water melt. Some structural strength will, of course, be lost when the ice melts; but again, VERY little structural support is actually required.

[elie....@gmail.com]

Why use water? Liquid hydrogen is bulkie, but it will be a dramatically better heat sink.
Paint your ship with superblack, give it a tiny cross-section so it has minimal sun exposure, and use the heated hydrogen as propellant to gain some small but not negligible delta-V while keeping the whole thing at 3K.
This is the basis of a working stealth design by Isaac Kuo: https://plus.google.com/+IsaacKuo/posts/CCXEHEK7wHN

He also points out that star occulting is limited by diffraction limits, so it will be undetectable beyond short range.

An interesting point is that the endurance of such a ship increases with size: heat sink capacity increases with (liquid hydrogen) volume, while waste heat is mostly from Sun irradiation, which depends on surface. For once, the Square Cube law works in its favour. Even more, a larger ship may have a relatively smaller Sun cross-section if the main limitation is the size of internal components.

Now, launch those with a shrouded gun as unmanned missiles and you got yourself a first-strike WMD.
Just remember that the gun station itself won't be stealthy, so anyone will know you are building a first-strike WMD and react accordingly.
This is why I compared it with the Death Star elsewhere: only a dominant military power will be able to build this world-killer.

[Alie...@gmail.com]

On Tuesday, September 20, 2016 at 3:00:08 AM UTC-7, elie....@gmail.com wrote:
> Why use water? Liquid hydrogen is bulkie, but it will be a dramatically
> better heat sink.

Why do you say that? The latent heat of fusion and vaporization for water are larger than the values for hydrogen. That means you can get rid of more than six times as much heat melting water ice than you can by melting hydrogen ice (assuming you can make that in the first place), and almost five times as much by boiling:

https://en.wikipedia.org/wiki/Latent_heat#Table_of_specific_latent_heats

Granted, hydrogen absorbs more heat per degree raise in temperature as a gas than water does, but by that time it's already exhaust in the Isaac's example.

> Paint your ship with superblack, give it a tiny cross-section so it has
> minimal sun exposure, and use the heated hydrogen as propellant to gain some
> small but not negligible delta-V while keeping the whole thing at 3K.
> This is the basis of a working stealth design by Isaac Kuo: https://plus.google.com/+IsaacKuo/posts/CCXEHEK7wHN

He's using the hydrogen as propellant, not just a heat sink. Could do the same with water/steam, but large clouds of water are rarer than hydrogen.

For that matter, hydrogen is also more generally available anywhere in the Solar system, and water is likely to be too precious to use as reaction mass, but as a potentially recoverable (and drinkable!) heat sink, no biggie.

OTOH handling LH2 requires specialized pressurized tankage and pumps, and it *leaks* out of everything. Water can be handled at any pressure humans can tolerate (assuming there's a crew) and water ice doesn't even need tankage since it can even tolerate vacuum without much trouble. From this:

https://people.nwra.com/resumes/andreas/publications/Icarus_Moon.pdf

the sublimation rate of water ice below 70 K is "much less than one molecule of water vapor lost per square centimeter of surface per hour." That's way less than the leakage rate of even LH2 right through stainless steel tank walls.

> He also points out that star occulting is limited by diffraction limits, so
> it will be undetectable beyond short range.

That's not what I got from what he wrote. The long, skinny shape takes most of the credit.

> An interesting point is that the endurance of such a ship increases with
> size: heat sink capacity increases with (liquid hydrogen) volume, while waste
> heat is mostly from Sun irradiation, which depends on surface. For once, the
> Square Cube law works in its favour. Even more, a larger ship may have a
> relatively smaller Sun cross-section if the main limitation is the size of
> internal components.

Same applies to water used as a heat sink.

> Now, launch those with a shrouded gun as unmanned missiles and you got
> yourself a first-strike WMD.

How are fighters WMDs?

> Just remember that the gun station itself won't be stealthy, so anyone will
> know you are building a first-strike WMD and react accordingly.

Point defense sites (railguns, lasers, whatever) don't have to be stealthy either.

> This is why I compared it with the Death Star elsewhere: only a dominant
> military power will be able to build this world-killer.

Fighters aren't world-killers even if you launch them from, say, Neptune's orbit with a constant acceleration of a few gees.

And, why can't any space-capable economy build such things?


Mark L. Fergerson

[Mikkel Haaheim]

Le mardi 20 septembre 2016 12:00:08 UTC+2, elie....@gmail.com a écrit :
> Why use water? Liquid hydrogen is bulkie, but it will be a dramatically better heat sink.

Simple answer: I knew the approximate data for water at the top of my head.

That said, there are advantages and disadvantages of using either.

The bulk of hydrogen is a serious problem.
First, for a given H2 vs H20 mass, you need much more structural mass to contain LH (much more than the 1400% required to simply coontain the volume). This is because ice can act as its own structural support, while LH can not (it is even possible to use ice without ANY additional structure... until the moment it melts). This added mass means more thrust is required to attain the same acceleration. You might want to argue that you will not need as much H2 mass because of its better performance. I will explain shortly why this is wrong.
Second, more bulk means more surface area. By using LH, you are increasing your chances of being detected by 1400%. I will point out that skin temp is a function of insulation efficiency... and that there is no reason you can't use 14°K (the melting point of H2) as the starting ice temperature. I will also point out that reflectivity is a function of outer coat material.
Third, at a very low boiling point, H2 will expand explosively to over 55 times its volume, converting from liquid to gas. Attempting to contain this (which was not suggested), would require either much greater volume or much heavier containment mass (in any case, you have increased mass).

For a given temperature range, H2 greatly outperforms H20 as a heat sink. However, in the given proposal, a mass of H2 can only perform as a heat sink up to 19°K. At best, you MIGHT be able to extract 600 J/g, even assuming you start with "solid" H2 at 4°K. Otherwise, ou can only extract 569 J/g assuming that you start with "solid" H2 at its melting point of 14°K (taking advantage of the heat of fusion), or 511 J/g if you start with LH at its melting point. After that, you have no choice but to expel the gas at the moment it boils. H2O is effective as a heat sink up to a much higher boiling point. I presented a functional load of 733 J/g from 73°K to 293°K. This increases to 793 J/g if you allow room temperature to rise to just below skin temp (310°K). If you also begin with a common starting temp of 14°K, the useful load increases to 911 J/g. If you take it a bit further, and use heat pumps, the useful load increases to 3420 J/g at its boiling point, where it, too, must finally be ejected. Thus, the useful load of H20 is anywhere from 150% to 500% the useful load of H2 (this is why I say that H2O has a better heat sink performance).
If you combine useful load with volumetric efficiency, H2O offers 70 times greater load per volume performance.

H2 is very dfficult to contain, as Mark states. Not only does H2 leak through smaller seams, there is also loss through a quantum effect called "tunneling" (I think this is why Mark puts "leak" in quotes). It is also much more susceptible to containment rupturing. Furthermore, the extreme low temperatures required tend to render most materials extremely brittle, so tankage does not survive as long before it needs to be completely replaced.
Containment aside, H2 is extremely volatile. Overheating can take place at very low temperatures (below 20°K), and can result in explosive expansion. It is also quite reactive, creating a risk of combustive explosion.

H2O is somewhat rare in space... although there ARE places with considerable high quantities (the martian poles, Europa, etc.). Additionally, H2 is quite abundant... s is oxygen. Both can be readily extracted from just about anywhere, and very easily combined into water. I would say availability is not much of an isue.

It is somewhat debatable which is a better propellant. H2 is, of course, extremely superior as a combustive propellant. Also, given its low boiling point, it has a considerable advantage in thermal expansion rate, driving its Isp. However, it is very low mass, which is a marked disadvantage in thrust, in principle.
My understanding is that thermal expansion of all gases is 1/T per °K. This means that the thermal expansion of H2 at 20°K (1°K above boiling point) is 1/20, as it is heated to 21°K. The expansion of H2O at 1°K above its respective boiling point (374°K) would then be 1/374, as it is heated 1°K to 375°K. This should give H2 an Isp performance benefit of 1870% (18.7x)over H20 Taking into account the atomic mass, you would need to expand 18 molecules of H2 to achieve the same thrust as a molecule of H2O. This would reduce thrust performance benefit to about 104% (1.04x) over H2O. So far, H2 is still superior... but at this point, heat capacity becomes a disadvantage, as it takes 7x the amount of energy to heat gaseous H2 as it does to heat water vapour.
This is all very rough calculation, so I might have made some mistakes in the previous paragraph... notably in the particulars of the analysis. Take it with a grain of salt, and feel free to correct me on any of these points.

[elie....@gmail.com]

> He's using the hydrogen as propellant, not just a heat sink. Could do the same with water/steam, but large clouds of water are rarer than hydrogen.

This is one of the two main reasons for using liquid hydrogen: it gives you some nice delta-V, allowing for essentially invisible en route course-correction, and giving you extended range.

In addition, due to how common it is, a detector somehow getting hydrogen spectral lines from the middle of nowhere will probably ignore it (I am not even sure it would be detected at all from star occulting, due to the star itself being full of hydrogen), while H2O detection may occasionally raise an alarm.
Note: I have no idea how hard it is to detect the plume of a solar-thermal craft.

The other reason is that at a few K (so you can keep the surface of your ship at 3K, which makes it invisible), hydrogen is way better: has the best heat capacity per mass, about 7 times better than water. (Also, it is not a solid)
https://en.wikipedia.org/wiki/Heat_capacity#Table_of_specific_heat_capacities
Once you reach water fusion, water fusion latent heat helps balance it, but hydrogen is still competitive at this point. You'll have to reach boiling temperatures for water to really stand out, and in a stealth design, you probably don't want to reach such high temperatures.

Ice can make for a good heat sink, depending on what it is used for. But for a stealth design, liquid hydrogen is by far a superior option, as you want to keep extremely low surface temperatures, where hydrogen is superior.

Note that in this design, solar energy is concentrated and used to flash-vaporise hydrogen, so for this water or other materials would be more efficient, mass-wise.
Temperature theoretically get close to the surface of the Sun, a few thousand K, but maybe you want a colder plume to keep it from being detected. (Again, I have no idea how low it has to be to become undetectable.)

But this is also used for propulsion, so you would cripple your dV, which is probably not worth it in most cases - in addition to the added complexity of having two different heat sinks.

> > it will be undetectable beyond short range.
>
> That's not what I got from what he wrote. The long, skinny shape takes most of the credit.

That's what he answered me when I asked about detecting it by star occulting (see comments below).


> How are fighters WMDs?
Remove crew, weapons and brakes. At interplanteary speed, you may not even need a warhead.
This is a stealth KKV missile instead of a stealth spaceship, but this is mostly a change of payload anyway.

> Fighters aren't world-killers even if you launch them from, say, Neptune's orbit with a constant acceleration of a few gees.

It's probably not what you meant, but I first read it as "a few g from Neptune to Earth" - in which case it is definitely a WMD, as in "high-relativistic kill vehicle".
That said, when I said "world-killer", it was for space colonies: Mars, space habitats, asteroids, Jovian/Saturnian moons... Those will be fragile enough that one or a few interplanetary KKV without warning will kill them. Earth itself will probably not be killed with a few of those (it survived the Dinosaur Killer asteroid, after all), but it would be crippled with a big enough one.

> And, why can't any space-capable economy build such things?

For the same reason the USAF gave up on their plans for a 3000 MT [sic] Orion-propelled orbital nuclear bomb (apart from the Orion-propelled part, that is). It could have literally wiped the entire Soviet Union out on the push of a button.
Even if it was possible, engineering-wise, how would the Soviet Union react to efforts from the US in putting such a doomsday device in the sky? They would have had no choice but to strike first, even if it means risking a nuclear exchange (where their survival chances would still have been better).
So unless you can build such weapon in the utmost secrecy (and don't count on it, leaks will happen), everyone else will launch pre-emptive strikes against you, even if it means (conventional) war.
The only way for a space polity to build such weapon is if it is already the dominant military power, so other powers simply don't have the strength to stop them. Again, like the Galactic Empire with the Death Star.



For thermal expansion of hydrogen, I don't think that's much of a problem.
The liquid hydrogen used for solar-thermal propulsion/getting rid of solar energy is immediately vented through the nozzle.
Before being flashed, liquid hydrogen can be used to cool the surface of the craft at below evaporation point (ideally 3K), so it won't expand yet. If you have to cool internal elements down faster, it may be worth it to go above fusion on those, but the gaseous hydrogen obtained can be vented through the nozzle as well.
Ideally, the ship should be designed to avoid that as much as possible, though. The simplest way is to make the ship bigger: the increased solar cross-section gives a bigger hydrogen flow, compensated by bigger tanks. (On bigger ships with the same proportion, acceleration is lower but tanks will last longer.)

[elie....@gmail.com]

Side notes:

Having no nuclear power, it will not be detected by neutrino detectors.

On the other hand, I have no idea how feasible a long-range gravimetric detector is, and at which point it can detected all ship-sized objects in the solar system (and track them to see if one is not following its orbit as it should). I've vaguely heard about prototype gravimetric devices used to detect masses across a wall (useful for disaster relief or SWAT teams), but I doubt their range can easily be extended to interplanetary range.
In the far enough future, this may limit this design to smaller crafts, with lower autonomy.

Active systems like radar or lidar could be used to detect those, but technologies like featureless shapes and radar-absorbent material are already available to counter those.

I am not sure how much more complex it would become to adapt it to multiple star systems. Good luck if your system has four stars.

Getting rid of warm-blooded human crew would extend autonomy, but not that significantly: the most energy you have to get rid of comes from the Sun. The biggest contributor may be by allowing a smaller cross-section.
That is, until you start operating in the Kuiper Belt or the Oort Cloud.

The further you are from the Sun, the lower your acceleration and the higher your autonomy.

Close enough from the Sun and the disk is big enough to be a problem: the ship needs to be cone-shaped to keep in the shadow of its solar-thermal engine, and at some point the cone will be too short to be practical. (Not much of the black surface can reasonably be lit by the Sun.)
But at that point, your autonomy may be too low anyway.

If you are even closer to the Sun (as in, right above its atmosphere, you are better off just putting a mirror on its side: it's not as if the Other Side(s) would put outward-pointing sensors even lower, right?
Right?

[elie....@gmail.com]

>So far, H2 is still superior... but at this point, heat capacity becomes a disadvantage, as it takes 7x the amount of energy to heat gaseous H2 as it does to heat water vapour.

I am not sure how this is a disadvantage. Given that the ship has weeks, months or even years of coast time, low acceleration is not a problem: small, constant acceleration is about as good as high point acceleration, as seen with probes using ion drives.
In specific short-duration missions, or on the outer reaches of the system where solar-thermal simply don't have enough energy, higher thrust may be needed for the entire course, though. Maybe Kuiper Belt models would use water for that reason. They might still keep liquid hydrogen to cool the hull down, though.

[Mikkel Haaheim]

Le mercredi 21 septembre 2016 18:50:47 UTC+2, elie....@gmail.com a écrit :

> I am not sure how this is a disadvantage. Given that the ship has weeks, months or even years of coast time, low acceleration is not a problem: small, constant acceleration is about as good as high point acceleration, as seen with probes using ion drives.

I am not refering to the low acceleration. I take that as a granted. I am refering to the fact that 7x as much energy is required to heat gaseous H2 by 1° as is required to heat water vapour by the same amount. A savings of 85% energy (approximately), means that you have that much energy available for other tasks. It is that much energy that you don't have to generate, meaning less waste heat to dissipate/absorb. It means you have that much more constant acceleration, vastly decreasing the amount of time for someone to observe you. It also means you have that much extra delta-v available for course corrections or other manoeuvres.
Low acceleration is not a problem. Wasting energy is.

LH is not what is going to keep the outer shell temperature low. A good insulator is. The heat sink is for absorbing all the extra heat being generated by whatever systems you are using. It is NOT for cooling the outer shell. Insulation helps to funnel the heat flow into the heat sink, and to prevent that heat from flowing to the outer shell. Even LH will be ineffective in preventing heat emission if you don't use an appropriate insulator, no matter how cold that LH is.

[Mikkel Haaheim]

Le mercredi 21 septembre 2016 18:50:47 UTC+2, elie....@gmail.com a écrit :

After reading through your earlier posts, I have one modification to make to my response. You are correct that LH would be better suited exclusively for the specific task of actively cooling the outer skin in order to prevent blackbody emissions from your low-albedo coating. However, this assumes that you are not using heat pumps. The consequence of this assumption means that you will NOT be able to maintain the shell temp below 14°K to 19°K (the LH will only absorb the heat of the shell if the shell is warmer than the temperature of the LH). IF you ARE using a heat pump, then the temperature range of H2O will again render it better suited to the task of absorbing the shell temp.

[Mikkel Haaheim]

Le mercredi 21 septembre 2016 18:50:47 UTC+2, elie....@gmail.com a écrit :

Actually, thinking it through some more, neither H2 nor H2O will be suitable if you want to try to suppress shell temp to 3°K, as both will be solid at this temperature. You will probably need Helium, which (according to my sources) does not have a solid phase.

[Mikkel Haaheim]

Le mercredi 21 septembre 2016 18:50:47 UTC+2, elie....@gmail.com a écrit :

I find that I DO have a correction to make in my calculations:
I neglected to take into account the effect of the diverse BP temperatures on the molar mass densities. At their respective BPs, H2 actually has slightly better than 2x the density of H2O. This would actually yield a thrust advantage of about 38x in favour of H2. Even with the energy disadvantage, the overall advantage up to this point would still be about 6.5x in favour of H2.
OTOH, as a function of thrust efficiency per volume, H2O still yields a slightly better than 2x advantage.

[Mikkel Haaheim]

Le mercredi 21 septembre 2016 18:31:46 UTC+2, elie....@gmail.com a écrit :

> On the other hand, I have no idea how feasible a long-range gravimetric detector is, and at which point it can detected all ship-sized objects in the solar system (and track them to see if one is not following its orbit as it should). I've vaguely heard about prototype gravimetric devices used to detect masses across a wall (useful for disaster relief or SWAT teams), but I doubt their range can easily be extended to interplanetary range.
> In the far enough future, this may limit this design to smaller crafts, with lower autonomy.

Negligent. Gravity is a fairly weak force, and the mass of even a relatively large vessel would likely be virtually undetectable at much more than a few meters, regardless of sensitivity. The masses of planets even thousands of light seconds away would interfere with any sensitive gravimetric readings.

>
> Active systems like radar or lidar could be used to detect those, but technologies like featureless shapes and radar-absorbent material are already available to counter those.

Distance would render radar and lidar pretty useless at distances much over 100 000 km, unless you are using a 35m radar dish with a multi-MW transmitter source... something you would not be able to fit on any non-dedicated platform. Even then, the return signal might be questionable with stealth tech.

>
> I am not sure how much more complex it would become to adapt it to multiple star systems. Good luck if your system has four stars.

Last I heard, a system with four stars would most likely have rendered any additional mass into dust... thus, virtually no resources worth defending, and virtually no possibility for life to evolve. Even visiting life forms would probably find it difficult to survive in such a system for more than a few days.

[Mikkel Haaheim]

Le mercredi 21 septembre 2016 18:50:47 UTC+2, elie....@gmail.com a écrit :

I just considered another factor:
Although the latent heat of vaporisation of H2O is about 5x that of H2, which makes it a better heat sink at the mtime of boiling, but requires more energy to boil; the expansion of water during boiling is 22x greater than that of H2. Assuming that you are ejecting both (as thrust) at their respective boiling points, H2O provides a clear advantage over H2.

[Mikkel Haaheim]

Le mercredi 21 septembre 2016 18:10:30 UTC+2, elie....@gmail.com a écrit :
> > He's using the hydrogen as propellant, not just a heat sink. Could do the same with water/steam, but large clouds of water are rarer than hydrogen.
>
> This is one of the two main reasons for using liquid hydrogen: it gives you some nice delta-V, allowing for essentially invisible en route course-correction, and giving you extended range.
>
> In addition, due to how common it is, a detector somehow getting hydrogen spectral lines from the middle of nowhere will probably ignore it (I am not even sure it would be detected at all from star occulting, due to the star itself being full of hydrogen), while H2O detection may occasionally raise an alarm.
> Note: I have no idea how hard it is to detect the plume of a solar-thermal craft.

First, you are will not be dealing with large clouds of water. You will have very low trace amounts of water (much lower than even the trace amounts of H2). Because water/ice absorbs so much more heat from a given starting temp (13°K, for best H2 performance) to respective boiling points, much less water will be ejected over the same time span. Because it has so much more molar mass, there will be that much less molecules emitted to detect. Since you are beginning with values of tens of kg/day (for H2... this will be reduced to hundreds of g/day for H2O), there will be less than 1g of H2 (less than 10mg H2O) emitted per second (on average). Given interplanetary velocities on the order of km/s, the gas density will be well under 1 mg/m^3 (a few micrograms/m^3 for water, even assuming zero dispersion... with dispersion, the molecular count for either will be scarcely more than a few ng/m^3.
Given the low molecular density, and the point source background illumination (which is itself not conducive for absorbtion spectral analyis)... and the fact that I forgot to take into account the multiple-km/s exhaust velocity of the gas... detection is highly improbable at any range. Even IR scanning presents too low of a surface area to render 375°K blackbody radiation detectable.

> The other reason is that at a few K (so you can keep the surface of your ship at 3K, which makes it invisible), hydrogen is way better: has the best heat capacity per mass, about 7 times better than water.

Per degree, yes. NOT when you consider the effective temperature range for absorbtion. Also, at 3K, the outer shell will not conduct heat to the LH (instead, the LH, even at 14°K -it's melting point, will heat the shell instead). Helium, or perhaps nitrogen, would be required to maintain a liquid flow at 3K. The exception to this is superfluid hydrogen, but that has a tendancy to violently explode at the drop of a pin... I would not suggest using it.
You COULD use the helium or nitrogen primary loop with a heat pump. However, heat pumps gain efficiency at higher temperatures. Such a system would be MUCH more efficient in a thermal exchange with H2O, at an exchange temp of about 50°C to 100°C.

>(Also, it is not a solid)

It IS a solid at 3°K... or at any temperature below 13°K.

> https://en.wikipedia.org/wiki/Heat_capacity#Table_of_specific_heat_capacities
> Once you reach water fusion, water fusion latent heat helps balance it, but hydrogen is still competitive at this point. You'll have to reach boiling temperatures for water to really stand out, and in a stealth design, you probably don't want to reach such high temperatures.

Only in small increments. If you consider the capacities from a common starting temp to their relative boiling points, H2O is FAR superior in performance.
These temperatures are pretty much rendered irrelevant when you take insulation into account.

>
> Ice can make for a good heat sink, depending on what it is used for. But for a stealth design, liquid hydrogen is by far a superior option, as you want to keep extremely low surface temperatures, where hydrogen is superior.

Not when you take system volume into consideration... and the resultant surface area poses much more of a threat to detection than other concerns (it increases the amount of solar absorbtion, blackbody radiation, reflected radiation -even at extremely low albedo, occultation -which DOES become a concern when you use 100 000 km arrays, such as we have been discussing here; etc).

>
> Note that in this design, solar energy is concentrated and used to flash-vaporise hydrogen, so for this water or other materials would be more efficient, mass-wise.
> Temperature theoretically get close to the surface of the Sun, a few thousand K, but maybe you want a colder plume to keep it from being detected. (Again, I have no idea how low it has to be to become undetectable.)

At this point, density of the plume is much more of a concern... particularly particle count density.

>
> But this is also used for propulsion, so you would cripple your dV, which is probably not worth it in most cases - in addition to the added complexity of having two different heat sinks.
>

Actually, it probably won't cripple the dV much at all.

> That said, when I said "world-killer", it was for space colonies: Mars, space habitats, asteroids, Jovian/Saturnian moons... Those will be fragile enough that one or a few interplanetary KKV without warning will kill them.

Not likely, unless if you are talking about pre-industrial colonisation. The infrastructure required to make them viable in the first place will also harden them against any point attack. Space habitats especially will be spread over large volumes.

>
> > And, why can't any space-capable economy build such things?
>
> For the same reason the USAF gave up on their plans for a 3000 MT [sic] Orion-propelled orbital nuclear bomb (apart from the Orion-propelled part, that is). It could have literally wiped the entire Soviet Union out on the push of a button.
> Even if it was possible, engineering-wise, how would the Soviet Union react to efforts from the US in putting such a doomsday device in the sky? They would have had no choice but to strike first, even if it means risking a nuclear exchange (where their survival chances would still have been better).
> So unless you can build such weapon in the utmost secrecy (and don't count on it, leaks will happen), everyone else will launch pre-emptive strikes against you, even if it means (conventional) war.
> The only way for a space polity to build such weapon is if it is already the dominant military power, so other powers simply don't have the strength to stop them. Again, like the Galactic Empire with the Death Star.

Again, this is only an issue for pre-industrial colonies. Once you have colonies of sufficient size to build their own military forces, it would be far easier for them to protect their "space" than it will be for Earth to maintain its control.

> Before being flashed, liquid hydrogen can be used to cool the surface of the craft at below evaporation point (ideally 3K),

No. It can't. At least, not directly... and indirectly, H2O becomes much more efficient.

[elie....@gmail.com]

Oops, I completely forgot that hydrogen would be solid at 3K...

At this temperature, heat pumps are too inefficient to be useful. Theoretical max efficiency is Thot/(Thot-Tcold), which for liquid hydrogen is 14/(14-3) = 1.28, meaning you produce several more watts of waste heat per watt of heat removed, and that's at the most perfect theoretical performance.

helium will be neither good enough at absorbing heat per kg, per m^3 nor even that good as a propellant, so it won't cut it by itself.
So you will need solid hydrogen (as cold as possible, let's arbitrarily say 1K), and a liquid helium loop to keep the surface of the ship at 3K. This complicates the design.
On the other hand, wouldn't solid hydrogen be less prone to escape and embrittle everything?

So as long as we have a (initially) solid heat sink and a liquid helium loop, it is probably not that much more complicated to have one type or another, or even several at the same time.
Still, I would stick with hydrogen, at least for the most part, for its capacity to absorb more heat per kg at low temperature, and for its performance as a propellant.

Hydrogen absorbing more energy per kg is a feature, not a liability: energy is free at as great a quantity as needed with the Sun, thanks to solar-thermal propulsion. If you need more energy for a given dV, simply increase the mirror aperture.
This may not hold in the outer reaches of the system, though I am not sure how the design should be adapted for those conditions, and it probably depends on the required mission.
But in the inner Solar System, pretty much the only important factor is dV per kg, regardless of how much energy it requires. (As long as the plume itself is not visible, so light sail or photon drive is out)

Bulk is a drawback, but not such a big one I suspect. By far the most energy received is from the Sun, and this is taken care of with the solar-thermal engine. For the rest, you end up with a long, thin cone, but this craft doesn't have to manoeuvre anyway.
A numerical analysis would be necessary to see how this plays out, but with the better dV of hydrogen, I suspect it still holds the advantage.

As for an insulated heat sink where heat is bottled instead of released, how good would insulation need to be for long-term storage? how good are existing/theoretical insulators? How well can you insulate the coolant loop itself?

One case where such a heat sink could be useful is, for the brief moment the mission becomes active and you have to start a high-power engine, you want to keep things cold just a little bit longer (until right when the attack is launched).
Here, compactness may be useful as it requires less insulation material, but again, I can't tell what would be best.

> Not likely, unless if you are talking about pre-industrial colonisation. The infrastructure required to make them viable in the first place will also harden them against any point attack. Space habitats especially will be spread over large volumes.

We are talking about a stealth impactor massing at least several tons (possibly much more) closing in at interplanetary speeds, so probably dozens of km/s. Kinetic energy is going to be counted in kT eq. TNT
Being stealthy, the defenders will probably have only a few seconds at best to react, if they detect it at all before impact. So neither time to intercept it nor to brace for impact or evacuate for shelters.

Unless this is dispersed shirt-sleeve environment (e.g. the countryside surrounding cities), no civilian installation will survive. Space stations and surface domes stand no chance. Even hardened habitats (like a hollowed asteroid) won't be safe: not only can it aim at a weak point, and being a long thin cone it can be built as an armour-piercing projectile, but it can even pack a hydrogen bomb to detonate once the armour is passed (similarly to present-day bunker-busters on a larger scale).
I suspect even if Mars has started terraforming, a few well-placed impacts could break those efforts.

> Again, this is only an issue for pre-industrial colonies. Once you have colonies of sufficient size to build their own military forces, it would be far easier for them to protect their "space" than it will be for Earth to maintain its control.

The point is precisely that you can't intercept it, as you don't see it coming.
Even if other sides can build their own, this wouldn't work as a MAD system, as MAD requires second-strike capability. With this, your opening salvo can destroy the other side's launchers/attempts at building a launcher.
The only way to have second-strike is to already have stealth impactors flying around, ready to change course and impact, but they have limited autonomy so you have to keep launching them every few years. It requires several sides to develop the capability at about the same time (or the first one will be able to destroy the other sites before completion), but building one in the first place is probably going to cause a (non-stealthy) war before completion.

[Mikkel Haaheim]

Le vendredi 23 septembre 2016 14:35:48 UTC+2, elie....@gmail.com a écrit :

> At this temperature, heat pumps are too inefficient to be useful. Theoretical max efficiency is Thot/(Thot-Tcold), which for liquid hydrogen is 14/(14-3) = 1.28, meaning you produce several more watts of waste heat per watt of heat removed, and that's at the most perfect theoretical performance.

Is there a reason you are inverting your expression of efficiency? With maximum efficiency expressed as "1", the formula for theoretical maximupm efficiency is (Thot-Tcold)/Thot. This is multiplied by 100 if you want to express efficiency in percentage, with max efficiency being 100%.
You are making my point regarding the preference of water/ice over H2. However, I find it rather silly to limit your "hot" temperature to 14°K. Your H2 is suitable to absorb heat up to 20°K, so this should be your "hot" temp. Still, your heat pump efficiency will be limited to 0.85 (or 85%). However, using H2O as the heat sink, you can bring the hot operating temperature of the pump to 373°K, yielding a maximum theoretical efficiency of 0.99 (99.2%).
Actually, it occurs to me that the efficiency of both would be slightly better, as the He coolant loop would have to be chilled BELOW 3°K in order for heat to flow from the shell to the coolant. Given that you don't want the coolant to get above 3°K outside the insulation layer, and that the shell would not be able to heat it further anyway, you would then want the coolant to circulate through hotter sections of the craft to bring up its "hot" temp. The good news about this is you may not actually need to pump it (add heat).

>
> helium will be neither good enough at absorbing heat per kg, per m^3 nor even that good as a propellant, so it won't cut it by itself.

No. I did not intend that helium should be used as either heat sink or propellant, but rather as a closed-loop primary coolant transfering heat to the heat sink.

> So you will need solid hydrogen (as cold as possible, let's arbitrarily say 1K), and a liquid helium loop to keep the surface of the ship at 3K. This complicates the design.

Correct. Except that H2O would be a better choice.

> On the other hand, wouldn't solid hydrogen be less prone to escape and embrittle everything?

Actually, it is much more prone to embrittlement, but I think you are probably correct that it would be less prone to escape (although I don't know how this would affect it's propensity toward quantum tunneling loss). It might even provide some structural reinforcement. However, it will still underperform H2O.
A little bit of intellectual honesty: most of the problem with embrittlement is due to temperature, so H2O would produce some of the same problems here. OTOH, much of the problem with H2 is it's volatility. H2O is far less volatile... unless you go in the opposite direction and superheat it at high pressure.

>
> So as long as we have a (initially) solid heat sink and a liquid helium loop, it is probably not that much more complicated to have one type or another, or even several at the same time.

Correct.

> Still, I would stick with hydrogen, at least for the most part, for its capacity to absorb more heat per kg at low temperature, and for its performance as a propellant.

Except this is more heat per kg PER °K. The fact that H2O has a much greater useful temperature range means that it has far superior performance per kg itself.

>
> Hydrogen absorbing more energy per kg is a feature, not a liability: energy is free at as great a quantity as needed with the Sun, thanks to solar-thermal propulsion. If you need more energy for a given dV, simply increase the mirror aperture.

Energy absorption is a feature, not a liability, FOR A HEAT SINK. It becomes a liability when you are trying to use it for propulsion. This is why Argon is actually a prefered propellant for thermal propulsion. It has considerable mass for thrust, and requires 1/4 the energy to heat than water. It is not so good as a heat sink, though, which is why H2O would be a better candidate for such a hybrid function.

> But in the inner Solar System, pretty much the only important factor is dV per kg, regardless of how much energy it requires. (As long as the plume itself is not visible, so light sail or photon drive is out)

H2O converting at BP will produce much greater thrust per mass than H2, at a ower enrgy cost. This means a higher dV per kg, whether you are looking at it as a function of energy per unit of thrust or a function of thrust per unit of mass.

>
> Bulk is a drawback, but not such a big one I suspect. By far the most energy received is from the Sun, and this is taken care of with the solar-thermal engine. For the rest, you end up with a long, thin cone, but this craft doesn't have to manoeuvre anyway.

Maybe, maybe not. You would probably be correct if the crat is used strictly as a ferry... but you have to take into account ALL of the internal systems. Life support, etc, probably would not add considerable waste heat... at least that has also been MY argument. However, other military systems, or even recreational systems (or... lights, anyone?) can add up.
A little extra bulk might, or might not, be a significant drawback. 1400% extra bulk poses a drawback for many reasons. It absorbs 14x as much energy... which is an advantage if you can use that energy, a disadvantage if it goes into waste heat. It reflects 14x as much energy. It is easier to see because it reflects more energy (14x), but also because it fills up 14x more FOV. It provides a 14x bigger target to hit. It is also 14x more likely to suffer accidental damage from stray objects. The extra bulk also means extra structural support and shielding, which means extra mass, which means less dV. It also means a larger coolant loop, which means a greater length of piping to suffer damage. Etc.

> A numerical analysis would be necessary to see how this plays out, but with the better dV of hydrogen, I suspect it still holds the advantage.
>

The dV of H2 is actually worse. H2O molecules have 9x the mass of H2 molecules (I might have misstated this elsewhere... H2O is 18x the mass of an atom of H, but hydrogen usually appears in molecules of H2), and therefor 9x the thrust for the same exhaust velocity. H2O has 22x the expansion rate of H2 at BP, and therefor greater exhaust velocity. H2O requires 5x more energy to convert liquid to gas, but this is easily compensated for by the otherwise superior performance, and it requires much LESS energy for each additional °K, meaning that you can give it a much greater temperature boost (and thus greater Isp) during the course of its ejection.

> As for an insulated heat sink where heat is bottled instead of released, how good would insulation need to be for long-term storage? how good are existing/theoretical insulators? How well can you insulate the coolant loop itself?

First, you don't want to insulate the coolant loop, because that will prevent the loop from absorbing heat. Instead, you have to cool the loop below the temperature of whatever it is meant to cool, and then remove the coolant flow once it attains the target temp for the item to be cooled.
Scientists have discovered materials (developed from "photon crystals") that have better insulation performance than the vaccul of space, because it also blocks out radiation. However, I don't know if it is possible to produce these in the sizes or volumes required for architectural use (insulating spaceframes). As I understand it, they are being researched for the nsulation of computer chips. In any case, this probably represents the theoretical limit.
Existing aerogels are capable of reducing heat conductivity to 0.014 W/m*°K. My understanding is that there are even better insulators being researched, and possibly already on the market.

> We are talking about a stealth impactor massing at least several tons (possibly much more) closing in at interplanetary speeds, so probably dozens of km/s. Kinetic energy is going to be counted in kT eq. TNT

Except that impactors do not simply "blow up". To give you an idea, a typical 9mm shell has much more kinetic energy than a .45 shell. However, the 9mm shell is likely to just pass through a target, limiting damage to the physical hole it has made. The .45 shell, on the other hand, has less energy, but will distribute more force throughout the body. The 9mm shell passing through the head might simply result in minor brain damage... or a bad facial scar if it just goes through the jaw. The .45 shell will more than likely tear off at least half of the head.
Your impactor is likely to leave a very deep hole, assuming it does not pass through entirely; but its kinetic energy will be used up drilling that hole (at least if it has the same needle configuration we've been discussing here).

> Unless this is dispersed shirt-sleeve environment (e.g. the countryside surrounding cities), no civilian installation will survive. Space stations and surface domes stand no chance. Even hardened habitats (like a hollowed asteroid) won't be safe: not only can it aim at a weak point, and being a long thin cone it can be built as an armour-piercing projectile, but it can even pack a hydrogen bomb to detonate once the armour is passed (similarly to present-day bunker-busters on a larger scale).
> I suspect even if Mars has started terraforming, a few well-placed impacts could break those efforts.

Most constructions are going to be compartmentalised. Constructions are going to be widely dispersed. A high energy kinetic impactor will cut through a station like a toothpick going through hot butter... but a toothpick reallt doesn't do much damage to the block of butter.

>
>
> The point is precisely that you can't intercept it, as you don't see it coming.
> Even if other sides can build their own, this wouldn't work as a MAD system, as MAD requires second-strike capability. With this, your opening salvo can destroy the other side's launchers/attempts at building a launcher.
> The only way to have second-strike is to already have stealth impactors flying around, ready to change course and impact, but they have limited autonomy so you have to keep launching them every few years. It requires several sides to develop the capability at about the same time (or the first one will be able to destroy the other sites before completion), but building one in the first place is probably going to cause a (non-stealthy) war before completion.

It would not be a MAD system anyway. Kinetic impactors are great for making holes, not blowing things up. UNLESS you give up stealth and go for a nice, blunt impact with something soft, giving off lots of shrapnel.