Don't de-orbit ISS ! Pull it higher!

[John Furber]

"NASA wants more 'space tug' ideas to deorbit the International Space Station."

I think that NASA and the rest of ISS partners are missing a big opportunity, and making a big mistake, by planning to de-orbit the ISS in 2030.

My reasoning is that it costs a lot of money and energy to put that much material into orbit.

Even if ISS were totally unusable after 2030 (which I doubt), it should be pulled up to a higher orbit to be used for spare parts and materials for power satellites, other space missions, and space colonies. ISS contains refined metals and other materials, already up there!

Could we talk about this to any decision-makers we might know? Hopefully, we can influence the people in charge to change their minds before they make a huge mistake and throw away a bunch of very valuable resources that are already in orbit, able to be used by future missions.

https://www.space.com/nasa-international-space-station-tug-deorbit-ideas

[Keith Henson]

On Thu, Sep 28, 2023 at 3:36 PM John Furber <johnf...@gmail.com> wrote:
>
> "NASA wants more 'space tug' ideas to deorbit the International Space Station."
> I think that NASA and the rest of ISS partners are missing a big opportunity, and making a big mistake, by planning to de-orbit the ISS in 2030.

> My reasoning is that it costs a lot of money and energy to put that much material into orbit.
> Even if ISS were totally unusable after 2030 (which I doubt), it should be pulled up to a higher orbit to be used for spare parts and materials for power satellites, other space missions, and space colonies. ISS contains refined metals and other materials, already up there!

I think the ISS should be pushed up to a higher orbit and saved as a
historical object. But there are problems with the idea. For a
start, the ISS is less than 500 tons. Power satellite designs are
typically 32,000 tons, so we are talking about 1/64. The other
problem is that putting it in a storage orbit above 2000 km puts it in
a high radiation zone where people can't work and even electronics has
a hard time.

Pushing the ISS to about 12,500 km, the gap in the radiation belts,
would work better and make for a very long storage orbit. But even
with high exhaust velocity (electric propulsion) this would take an
awful lot of reaction mass. I could put numbers on it if anyone wants
them.

KeithH

> Could we talk about this to any decision-makers we might know? Hopefully, we can influence the people in charge to change their minds before they make a huge mistake and throw away a bunch of very valuable resources that are already in orbit, able to be used by future missions.
> https://www.space.com/nasa-international-space-station-tug-deorbit-ideas
>

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[John Furber]

Thanks for these insights, Keith!

I would be interested in how much reaction mass would be required, if it would not take too much of your time to calculate it.

How would the cost of sending up an ion engine and a tank of reaction mass from earth compare with the value of not deorbiting the ISS?

I was not even thinking of keeping it habitable, so I wasn't thinking about the radiation environment. I was just thinking about having those materials available to build or repair other vehicles or habitats or even to use on the Moon.

[Keith Lofstrom]

On Thu, Sep 28, 2023 at 05:26:51PM -0700, Keith Henson wrote:
> I think the ISS should be pushed up to a higher orbit and saved as a
> historical object. But there are problems with the idea. For a
> start, the ISS is less than 500 tons. Power satellite designs are
> typically 32,000 tons, so we are talking about 1/64. The other
> problem is that putting it in a storage orbit above 2000 km puts it in
> a high radiation zone where people can't work and even electronics has
> a hard time.
>
> Pushing the ISS to about 12,500 km, the gap in the radiation belts,
> would work better and make for a very long storage orbit. But even
> with high exhaust velocity (electric propulsion) this would take an
> awful lot of reaction mass. I could put numbers on it if anyone wants
> them.

Let's turn the problem 180 degrees, into an "insurmountable
opportunity".

IIRC, three ISS astronaut years is $1B, combined with the
enormous cost/risk of a lethal accident killing all crew
onboard - arguably a much higher amortized cost, given the
political funding damage to the world's space programs.

NASA might find its budget "touching the face of God"
(zeroed), with the US Space Force and SpaceX dividing
up a subset of NASA's goals and budget.

----

Instead, if funding allows, redesign a new LEO space station
with 21st century technology, smaller, safer, healthier, and
more staff efficient. Perhaps a partial gee "dumb-bell
tethered centrifuge, with a small crew habitat in one "bell",
and robotic stuff (perhaps a power reactor) on a tether at
the other end of the centrifuge arm and power cable.

Lower inclination orbit, optimized for KSC and Kagoshima,
less delta-V from Kourou and Satish Dhawan. Orbiting
south of North Korea's suborbital interceptors.

----

All that is a distraction from my main focus: re-purposing
and orbit-boosting the "old relic ISS" to the CENTER of the
inner van Allen Belt, inclination near-equatorial, for four
new ROBOTIC missions:

1) High-radiation-tolerant electronics test.

2) High(er) orbit earth observation. Note that optical CCD
camera imagers must be inside heavy shielding, with mirrors
bending optical light, but not protons and electrons.

3) Measuring the inner Van Allen Belt as it disappears.

3a) ... what the heck?

The inner belt is about two grams of relativistic protons,
trapped for months to centuries, in cyclotron "orbits" that
bounce between north and south in the Earth's magnetic field.

Protons scatter as they penetrate solid mass. Some bounce
altitudes will shift lower. If a proton's bounce altitude
drops into the upper atmosphere, it collides a flash of
X-rays and absorption of the proton.

With enough target mass orbiting through it, most of the
inner radiation belt can be scattered this way, and the
radiation flux to a transiting spacecraft will be reduced.

More importantly, the inner belt is "diamagnetic"; it
reduces Earth's field strength. Eliminating much of it
can expand the "magnetopause" (the boundary between Earth
field and the solar wind) beyond GEO. Good news for the
cost and survivability of comsats - and SSPS - and SSPS
delivery.

The puny target mass of ISS will have a small effect;
however, there are measurable small reduction effects
from many tonnes of derelicts already orbiting through
the inner Van Allen belt.

----

4) The fourth (and IMHO most important) mission is high
mutation rate bioengineering tests. As genetic engineering
advances, we will produce some pretty wild lifeforms, and
I want a safe place to watch them mutate and evolve FAST.
I would prefer the lunar far side. Second best might be
shielded boxes surrounded by a lethal environment, so that
bugs escaping containment will get fried before they reach
the top of the atmosphere.

Or perhaps not. Still, we MUST LEARN how these processes
occur in controlled conditions, rather than learn the hard
way, by unplanned accident in our one and only atmosphere.

----

So yes, keep much of ISS intact for a very long time,
observable from the outside, full of robots and labware
and microbes rather than air and astronauts.

If folks want to see the inside of ISS as it was, START
RECORDING, then start simulating. Then let people explore
the 3D+T "former" ISS in a simulation. Myself, I'd rather
watch the robots and the scanning-tunneling-microscope
images. Some people watch birds; I prefer molecules,
suitably hyper-slowed to match human senses.

Note, I HAVE watched a fluorescent-tagged dynein molecule
"climb" a microtubule in a time-lapse ultra-microscope
image made by a friend. It's robots ALL THE WAY DOWN.

----

The current internal pressurized volume of ISS is 900
thousand liters, almost a billion cubic centimeters.
I'd like to rent 1 cc.

My smallest chip design, decades ago, was 50 by 50 by 10
micrometers ... I could fit 40 million of those chips in a
cubic centimeter. With modern bleeding edge technology,
MANY TRILLIONS of transistors. Moore's Law isn't quite
dead yet, current plans are nanometer wires and spacings,
stacked MANY layers deep. My Samsung 870 1TB solid state
drive has a chip with 4 trillion transistors (stacked 8
high) on a cm², sub-mm-thick chip.

In case you haven't noticed, WEIRD HAS ALREADY HAPPENED.

----

In summary: keep the macroscopic external ISS intact as
a visual relic, as Keith Henson suggests. Move it to a
"lethal" high orbit, and do "dangerous" nano-tasks inside.
Not stupid tasks. Public tasks, with lots of open access
telemetry, so we can all watch for excess "dangerous".
Then argue with each other, not distractable scientists.

Thanks again to Furber and Henson, who led us in a good
vector direction (with an adjustable magnitude). Ball's in
your court, people, please help convert my trillion dollar
value biotech notion into a quadrillion dollars of value.
A few molecules in the right place can save the Earth.

Keith L.

P.S. And now back to HP4100n laser printer wrangling for
Debian 11/12. Any sysadmins reading this, who moonlight
as underpaid Linux consultants? I can pay with ancient
space books, for example "Table of Supersonic Flow
Around Cones", MIT Technical Report No. 1, 1947, computed
and typeset electro-mechanically, with cams and levers.
Some hypersonics text and math, though Allen and Egger's
work after 1953 taught us that Pointy Cones Is STOOPID.

--
Keith Lofstrom kei...@keithl.com

[Gary Barnhard]

Dear Colleagues,

Perhaps in some senses, we are all a bit right.

Time and circumstances permitting, I crawl through this entire thread and respond accordingly.

For now, I will tilt at the highest level of abstraction before I dive into the weeds.

The ISS is not only about what we have learned to do right; it is also about the multitude of things we must learn to do better.

One thing we should be able to find some common ground on is that there are many things that can be done that are far more valuable than splashing the ISS at Point Nemo.

Please check out the following paper and presentation I wrote on the subject for IAC 2022, reprised at ISDC 2023 Dallas/Frisco, and discussed on The Space Show with David Livingston . . .

https://2farchived.thespaceshow.com/file/9692/download?token=PEBo3GNB

https://drive.google.com/file/d/1q5al9f3DuCHSgprc7AepiU4k8xmOxUzw/view?usp=sharing

IAC 2022 Presentation

Barnhard, Gary; C3. IAF SPACE POWER SYMPOSIUM, 2. Wireless Power Transmission Technologies and Application IAC-22,C3,2,5,x73968

Space Station Freedom Redux: Rearchitecting ISS as a Space Solar Power Technology Development and Demonstration Platform

https://drive.google.com/file/d/18cl-DqN-psclT16fYrJx9BLFW880ePTq/view?usp=sharing

IAC 2022 Paper

Barnhard, Gary; C3. IAF SPACE POWER SYMPOSIUM, 2. Wireless Power Transmission Technologies and Application IAC-22,C3,2,5,x73968

Space Station Freedom Redux: Rearchitecting ISS as a Space Solar Power Technology Development and Demonstration Platform

https://drive.google.com/file/d/1tuZLt9EM4kJ7h7YufSk3jmNrThWrlV9A/view?usp=sharing

Ad Astra!

- Gary

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[Keith Henson]

On Thu, Sep 28, 2023 at 5:39 PM John Furber <johnf...@gmail.com> wrote:
>
> Thanks for these insights, Keith!

> I would be interested in how much reaction mass would be required if it would not take too much of your time to calculate it.

Delta V to move the ISS to 12500 km is around 2880 m/s, ignoring plane
change. It's about 760 m/s to take it up to 2000 km.

m0 = mf e^(ΔV/Ve) for LH2 and LOX, Ve is 4.5 km/s. ΔV/Ve is about .169

e to that power is about 1.18 so initial mass would be 1.18 x final.
If the final is 450 tons, the initial would be 533 tons of which 83 is
reaction mass. Assuming I got the math right (not a sure thing as I
get older) that's a starship tanker full. However, the ISS is higher
than the LEO target for tankers.

Pushing the ISS up to the gap would take a lot more reaction mass if
you use chemicals. mf/mo would be around 1.9 so the reaction mass
would be around 400 tons.

Electric thrusters with a 15 km/s Ve would get the reaction mass down
to around 100 tons but it would probably take months to move the ISS,
and after that long in the Van Allen belt, I don't know how well the
PV would be working after that much radiation exposure.

On the other hand, this exercise might be worth it as a test for
moving power satellites or big space-based lasers.

Ke = 1/2 mV^2, a kg of mass per second would need about 112 MW.
1/1000th of a kg/sec would need about the capacity of the ISS solar
arrays. It would eat 3.6 kg/hr, of reaction mass and take about 3
years to use up 100 tons. probably several times that much as a series
of Hohmann transfers.

I guess if someone was really serious about this an idea would be to
get the ISS declared a historical landmark. Then NASS would not be
allowed; to destroy it. :-)

KeithH

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[James Benford]

With my son Dominic Benford, we made a quick estimate of approaches to raising the ISS orbit by several hundred kilometers to ensure its long-term availability. We concluded that they were two approaches that were viable:

 

The first is to use ion rockets to gradually raise the orbit over the next decade. Note that the present Chinese space station, which is only ~20 percent of the mass of ISS, is using ion rockets to stabilize its orbit now. They estimate that they can keep it in the same orbit, about the same altitude as ISS, for the next 15 years with these rockets, which is the lifetime of the station itself.

 

The second approach is to use a series of Starship launches to first attach a coupling to ISS that would allow a Starship boost to higher orbit over a period of about half an hour. This will require a refueling Starship mission. There are six raptor engines on the second stage of Starship. One could use only one engine with the entire fuel load to boost the ISS to 600 km in about half an hour. It would require an acceleration of 1/6^th of a gee, which the station is likely to be able to accommodate.

 

So in principle, is possible to save the ISS for later use.

 

Jim Benford

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[Keith Henson]

You got essentially the same solutions I got. Thanks.

Keith

[Tim Cash]

I believe James Bedford is a genius.  The primary lift should be electric propulsion engines, using waste stock from ISS itself for propulsion stock.  A close friend is an electric propulsion expert, and I helped him get a job within Northrop Grumman Space, where we both work.  The point is there are multiple solutions to lift ISS to any desired orbit, and since I helped build and test most of the US modules on this space station, I am willing to donate my engineering time for a solution to the lift to higher orbit problem.  I may even suggest a temporary high orbit in Earth orbit with the permanent solution for ISS on the lunar surface.  Crazy you might say, but definitely more permanent and tourist friendly long term.  That would most likely require total disassembly of ISS, building the lunar space elevator, and taking the pieces down a little at a time?  Really crazy idea, yes?

Timothy Cash

cash...@gmail.com

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[Gary Barnhard]

Greetings all,

Circumstances permitting, it is my intention to sponsor/co-sponsor a moving analysis party convening at various venues ranging from virtual, to the XISP-Inc facilities in Cabin John, Maryland, to various national and international conferences, to wherever it makes sense to be.  I will invite a collection of trajectory-curious souls from the XISP-Inc rolodex (e.g., Ed B., Chris C., Seth P., et al.). and anyone else inclined to puzzling alternate minimum energy trajectory manifolds (a.k.a., ballistic trajectories, weak stability boundary transitions).  The last similar problem we tilted at in such a manner brought the delta-V requirements for Alpha Cube Sat down by over an order of magnitude. While no one can make any promises, given a willingness to allow time to be variable, a low thrust long duration propulsion capability, a comparatively high thrust short duration propulsion capability, and a willingness to do the math -- chances are we can find a non-null solution space.

The bottom line is that given some target orbits/destinations of interest, we can do the math to recover the set of trajectories (i.e., manifolds) that can get us there.  Paraphrasing Ed B. in the midst of being hornswoggled into working with me on a project -- To do this kind of work, you need the engineers and scientists to frame the problem space, the resources to do the calculations, and the tenacity to contend with the fact that there is still significant art in knowing where in the possible search space to look.  While XISP-Inc can not write anybody checks at this point, I can gather a gaggle of seriously clueful people, provide a hospitable physical and virtual work environment, bring some of the best software available to bear on the problem space, provide the computational capacity to run the analysis in our lab locally and via remote control, tasty adult beverages, perhaps some fresh baked goods, and the audacity and means to publish the results.

For good measure, the Space Development Foundation Inc. would be happy to initiate the application for historic landmark designation for the ISS.  ;-) 

In addition to the https://www.spacedevelopmentfoundation.org web resources, several other domains I own that could be set up immediately include: 

	spacestationfreedom.com	GaryBarnhard	Active
	spacestationfreedom.net	GaryBarnhard	Active
	spacestationfreedom.org	GaryBarnhard	Active
	spaceways.org	GaryBarnhard	Active

All who are interested should let me know, at gary.b...@spacedevelopmentfoundation.org

Ad Astra!

- Gary

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[Keith Henson]

On Fri, Sep 29, 2023 at 5:19 PM Tim Cash <cash...@gmail.com> wrote:
>
> I believe James Bedford is a genius. The primary lift should be electric propulsion engines, using waste
stock from ISS itself for propulsion stock.

Keith

I don't know everything about this topic, but I don't think electric
propulsion engines operate on solid reaction mass. If I am
wrong on this point, please post a URL.

[John K. Strickland, Jr.]

Using electric propulsion, some of the most recent Station modules could have their orbits changed to Low Equatorial over a period of months.
They could then be attached to a very modern station core.
The older (museum quality) parts should be put in a higher orbit.
It should have a maneuvering module so it can dodge.

I have advocated for the use of electric propulsion for a long time to slowly move heavy items in LEO as well as de-orbiting them.
The slow transition speed gives time to verify that the multiple intermediate orbit positions would not create temporary collision hazards along the way.
The electric module would detach once the object was in an orbit where it would deorbit within a short time.
The electric tug would then go to another item to deorbit.

It seems that there are people high in NASA who still reject good new and practical ideas for no good reason.
If a FREE super-heavy launcher were offered to NASA they would turn it down in favor of the SLS.

John S

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[Gary Barnhard]

Electric propulsion typically uses ions from sources such as Cesium, Mercury, Xenon, Argon, etc. 

Other systems use substances such as iodine, indium,

A third class is resistojets which typically push additional energy into a reactive gas, fluid, or components thereof to increase its energy and Isp.

A recent paper on the same entitled  Electric Propulsion and Electric Satellites, by Vincent Camilleri, Aerospace Engineering Sciences, University of Colorado, Boulder, CO, 80309, May 11, 2017 is attached.

- Gary

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[Keith Lofstrom]

The notion of lifting ISS orbit into the "gap" between
the radiation belts fails because ISS is in a 51.4 degree
inclined orbit. The gap follows the field lines to the
magnetic poles, reducing radius as it approaches the poles.

An ISS inclination orbit will be in the upper belt at high
latitudes, and in the lower belt near equatorial latitudes,
because "gap radius" varies with latitude, maximum at the
equator, dropping to Earth surface near the poles.

Dipole magnetic field lines ... duh.

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

Plane-changing ISS to an equatorial orbit near LEO (with a
constant-radius van Allen belt gap) would take a hell of a
large delta V, almost as much as launching a new ISS-sized
space station to a low inclination orbit.

Plane change at transfer orbit apogee requires lifting the
propellant to apogee, paying Tsiolkovsky tax to do so.

Far less propulsion could launch a new-technology 2023-
miniaturized small space station to a KSC-inclination orbit.

----

We paid the "Russia" tax for 51.4 degrees ISS inclination
during the Yeltsin era. We continue to do so, exposing
ISS to overflight destruction by the current Moscow maniac
many times per day. When the last cosmonaut goes home,
ISS may be prematurely doomed.

When the maniac is gone someday, never to be replaced by
another, it may make sense to invest more resources in
another high inclination space station, or a modification
of ISS orbit radius.

As things stand today, it is way too easy to suborbitally
launch a small can of dynamite and ball bearings to ISS
altitude (steered by GPS, with a small change to GPS
receiver software), from any of dozens of bugnuts nations
below, creating another large space debris field.

Funding, designing, and then raising ISS altitude requires
far more time and money than Bugnutstan creating a ball
bearing booster. A truly fiendish adversary will do so
after most of the engineering and construction cost of the
orbit-raising mission, near the maximum expenditure time,
just before the orbit-change mission launch.

The fewer countries overflown by a space station, the safer
it will be. Guiana launch (5.2°N) is safest, Satish Dhawan
(13.7°N) the next safest.

Keith L.

--
Keith Lofstrom kei...@keithl.com

[Tim Cash]

Keith et al,

Here is a link to the microCAT thruster electric propulsion paper which I referred to:

https://www.academia.edu/81570168/Electric_propulsion_for_small_satellites

You will see the mention of metal as propellant feed stock as efficient.

Now, this is micro Newton level thrust magnitudes per thruster, but there is no limit on the number of thrusters one can use, and the time frame one can leverage to accomplish the orbital change.

Yes, using a Starship to accomplish the thrust to final orbit may be the quickest solution, but we have to first fly a successful orbital mission!

The question is what orbit would be optimum for ISS tourism?

We have to get the tourists there, as well as returning them to Earth.  Unless we have many space tugs in service, the point of a high earth orbit or lunar surface ISS final resting point is moot.

You may recall we were debating similar solutions when Skylab decided to re-enter Earth Orbit with pieces landing in Australia before we could get a space shuttle into orbit to effect a rescue.

If we start NOW, we may have the time to manage a move to another orbit before the ISS decides to re-enter on it's own accord.

Sitting around and twiddling our thumbs is NOT a solution.

Tim Cash

cash...@gmail.com

--

Tim Cash

cash...@gmail.com

[Keith Henson]

On Fri, Sep 29, 2023 at 8:35 PM John K. Strickland, Jr.
<jkst...@sbcglobal.net> wrote:
>
> Using electric propulsion, some of the most recent Station modules could have their orbits changed to Low Equatorial over a period of months.

I don't think the physics and math works. My Hohmann calculator says
6675 m/s to change the orbital inclination from 51.64 deg to zero.
That's a lot of delta-V.

Keith

[Keith Henson]

On Sat, Sep 30, 2023 at 7:07 AM Tim Cash <cash...@gmail.com> wrote:
>
> Keith et al,
>
> Here is a link to the microCAT thruster electric propulsion paper which I referred to:
> https://www.academia.edu/81570168/Electric_propulsion_for_small_satellites
> You will see the mention of metal as propellant feed stock as efficient.
> Now, this is micro Newton level thrust magnitudes per thruster, but there is no limit on the number of thrusters one can use,

.
You need a million of them to get up to a Newton level of thrust.
Each has mass and needs power. Practical, I don't think so, but if
you want to work the math and convince me, go ahead.

> and the time frame one can leverage to accomplish the orbital change.

That's not quite true, you need more thrust than the orbital decay rate.

Keith

[John K. Strickland, Jr.]

The high delta-V is why it takes a sustained effort with electrical propulsion or the equivalent of one or two starship stage payloads.
People seem to be focused only on the propulsion cost, while the actual issue is saving what should become a very historical location, the ISS.
If the cost issue is paramount to the decision makers, just put it into a temporary higher orbit, radiation zone or not.
The radiation level must be low enough so that electronic systems would not be damaged.

Such high inclination orbits are a poor location for a manned space station anyway, since the current orbit frequently passes near the South Atlantic Anomaly.

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[Keith Henson]

On Sat, Sep 30, 2023 at 9:06 AM John K. Strickland, Jr.
<jkst...@sbcglobal.net> wrote:
>
> The high delta-V is why it takes a sustained effort with electrical propulsion or the equivalent of one or two starship stage payloads.
> People seem to be focused only on the propulsion cost, while the actual issue is saving what should become a very historical location, the ISS.

These interact. You can make a rational case for what to do if you
can put a value on saving the historical artifact. Even at a fraction
of what the ISS cost, that's a large number. The downside is that the
cost would go into the future. The upside is that the cost to space
can be expected to go down.

The Hubble telescope is a 100 km higher, and that is not high enough
to prevent reentry this side of 2040.

> If the cost issue is paramount to the decision makers, just put it into a temporary higher orbit, radiation zone or not.
> The radiation level must be low enough so that electronic systems would not be damaged.

Eventually, cosmic rays kill the electronics, not to mention that they
die eventually without radiation. But short of 2000 km, the radiation
is tolerable for electronics at least for decades. Kieran Carroll has
(I think) experience with satellites in higher radiation environments.

Keith

[John K. Strickland, Jr.]

Considering that it cost over $100 BILLON to build, launch and assemble it, I am sure that Elon could move it in to a 500 or 600 mile high orbit with a Starship stage and a tanker launch, this does not seem too much. They even could ask Elon how much it would cost if "THEY" were interested.

John S.

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[Keith Henson]

On Sat, Sep 30, 2023 at 1:54 PM John K. Strickland, Jr.
<jkst...@sbcglobal.net> wrote:
>
> Considering that it cost over $100 BILLON to build, launch and assemble it, I am sure that Elon could move it in to a 500 or 600 mile high orbit with a Starship stage and a tanker launch,

You need to work the numbers before saying "I am sure."

Did you intend to use miles? 500 miles is a little over 800 km.

I worked out what it would take to push the ISS up to 2000 km and that
took about a tanker load. But even that high, the orbit will decay
eventually.

Hubble needs to be reboosted, but that's 11 tons, not 450.

this does not seem too much. They even could ask Elon how much it
would cost if "THEY" were interested.

SpaceX needs to test the tanker system. But the timing may not work out.

Keith

[John K. Strickland, Jr.]

I am not quite sure what you are worried about.
The ISS will presumably be reboosted in its current orbit until they decide to retire it.
In any orbit where the object is not about to undergo entry , it can still be reboosted.
It could be equipped with a plasma drive to keep it in the new orbit, where the drag would be a lot less.
Regardless of the numbers, I think that Elon could solve the problem.
I am also sure that the tanker system will be tested far in advance of the ISS retirement date, even without a "working" crystal ball, which we will never have.

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[Narayanan Komerath]

I have heard in the past that NASA objection to keeping STS external tank in orbit is the liability issue. If you find someone to insure I think they will be happy. 

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[John K. Strickland, Jr.]

Do you refer to the higher risk of a large object being hit by other space debris?

The object in question would be able to dodge based on data from an Earth orbit traffic control system.

The components of such a system already exist but it needs integration and authority.

 

If this is the problem, how then could we build any large object in Earth Orbit?

 

John S

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[Paul Werbos]

Years ago, when NSS debated the same issue (and there were plans to deorbit sooner), we discussed the UNESCO world heritage site designation. I don't know whether it might be used here.. but who knows?

[Narayanan Komerath]

Just relaying what I have heard, during discussions on precisely that topic: building large infra in orbit. The STS Main Tank was the obvious LEGO Block: Each had more space inside than the ISS at least as it was then, inside each tank. Some insulation. Could attach 2 such tanks and have a nice station with partial gravity and an atmosphere inside. And most had some fuel left over. They had "nearly" enough delta V to stay in a low orbit, but were deliberately brought down into the ocean to eliminate risk.

As I heard, NASA HQ was all in favor of building such stations, but asked who was taking the liability risk and promising to maintain it, because NASA could not justify that from its budget. Which is the same, I suspect, as their probable reaction to ideas of NASA paying to maintain for a Museum in orbit.

As we know, Owner (Nation) Pays, for any damage per Space Law.

Dodging collisions etc requires a good fuel resupply program too. NASA would probably demand a 30-year guarantee with a guarantee/escrow of costs to de-orbit any time the owners get tired of it.

A discussion on finding an answer to that, might find friends at NASA HQ as well. I am sure they have people who feel very attached to the ISS, which IIRC, was originally intended to be much higher in order to do real MICRO gravity science, not milligravity.

[Narayanan Komerath]

What such a discussion would do, is to restart the WHY and HOW of building a real Space Economy. UNESCO Heritage sites make good money for the local economy from tourism, which somehow I don't see the ISS doing, enough to break even on maintenance and insurance.

So it could be sold to NASA under its original purpose: MICRO Gravity labs plus the nucleus of much more extensive infrastructure in orbit such as refueling, oxygen from the Moon, processing asteroid material, etc. And those will require In-Space power supplies which may be under an SSP organization if that is better than each facility having its own PV. Maybe power facilities on the Moon through lunar nights as a first step. And as precursor of the bigger L-4/L5 stations.

nk

[Robert Poor]

I'm well in over my head here, but would it be possible to launch a relatively small hunk of technology that would "eat" the existing ISS and use the resulting raw material to build a new ISS or to launch it into higher orbit?  Since we've gone to the trouble to get all that mass into orbit, it could make sense to reuse its materials rather than burn them up.  (I'm reminded of how caterpillars almost entirely deconstruct themselves inside their cocoon on their way to becoming butterflies...)

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[Keith Henson]

On Sun, Oct 1, 2023 at 10:27 AM Robert Poor <rdp...@gmail.com> wrote:
>
> I'm well in over my head here, but would it be possible to launch a relatively small hunk of technology that would "eat" the existing ISS and use the resulting raw material to build a new ISS

Eventually, yes. Full-on nanotechnology should be up to this. But we
are not there yet.

> or to launch it into higher orbit?

Suitable engines that could use the ISS structure for reaction mass
don't exist.

> Since we've gone to the trouble to get all that mass into orbit, it could make sense to reuse its materials rather than burn them up. (I'm reminded of how caterpillars almost entirely deconstruct themselves inside their cocoon on their way to becoming butterflies...)

Nature has been evolving things for a long time. Humans are working
on it, but we have a long way to go.

Keith

[Gary Barnhard]

As multiple colleagues have pointed out in this thread, due to its mass, altitude, and inclination, Hofmann transfers are hard to make tractable in the instance.   

Alternate minimum energy trajectory solutions (a.k.a., ballistic escape trajectories, weak stability boundary transitions, etc.) are far more likely to be tractable, provided suitable manifolds can be calculated and time is not a driving issue.

- Gary

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[Keith Henson]

On Sun, Oct 1, 2023 at 1:37 PM Gary Barnhard <barn...@barnhard.com> wrote:
>
> As multiple colleagues have pointed out in this thread, due to its mass, altitude, and inclination, Hofmann transfers are hard to make tractable in the instance.

True. They are however the minimum propulsion methods.

> Alternate minimum energy trajectory solutions (a.k.a., ballistic escape trajectories, weak stability boundary transitions, etc.) are far more likely to be tractable, provided suitable manifolds can be calculated and time is not a driving issue.

I seriously doubt this. Among other reasons is that such methods are
not likely to even counter atmospheric drag.

Keith

[Tim Cash]

Let us be practical, rather than emotional on the topic of ISS reuse.  There are specific materials that could and do have a relative high value for reuse in earth orbit, highly refined metals and other materials.

However, how do we place a value on the raw material reuse from ISS in order to harvest said materials?  There must be a practical basis for assigning such values, and of course, there should be a market with potential buyers for such material.

If we add the cost of replacing each kilogram of material reuse from ISS to the capture value, say on a new space station, we may get an idea of the replacement cost for any specific application.

If there ever is a salvage market for on orbit materials, it could start with ISS, but no one has as yet stepped forward with such a proposition.  First, we must address the issue of whose present property is ISS and what are the details for salvage rights on ISS materials?  Until these issues are addressed, ISS will go nowhere but into the drink.

--

Tim Cash

cash...@gmail.com

[Kevin Parkin]

I think it would make a pretty awesome museum for future space travelers to visit. Otherwise, count me in the “it’s not worth the cost of recycling” category.

Did anyone suggest electrodynamic tethers yet?

Kevin

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[Keith Lofstrom]

On Sun, Oct 01, 2023 at 03:51:57PM -0700, Keith Henson wrote:
> On Sun, Oct 1, 2023 at 1:37 PM Gary Barnhard <barn...@barnhard.com> wrote:
> >
> > As multiple colleagues have pointed out in this thread, due to its mass, altitude, and inclination, Hofmann transfers are hard to make tractable in the instance.
>
> True. They are however the minimum propulsion methods.
>
> > Alternate minimum energy trajectory solutions (a.k.a., ballistic escape trajectories, weak stability boundary transitions, etc.) are far more likely to be tractable, provided suitable manifolds can be calculated and time is not a driving issue.
>
> I seriously doubt this. Among other reasons is that such methods are
> not likely to even counter atmospheric drag.

Gary is right, but his suggestion would be more understandable
to more of us if he provided references, so we know what he
has in mind, or the books he cultivated his fertile mind with.

Ballistic escape trajectories (and other trajectory miracles)
imply a large delta V, somewhat less than "LEO to escape
velocity" or (1-sqrt(2)) * (LEO velocity) = 0.414 * 7670 m/s
= 3170 m/s.

For comparison, an ISS plane change from 51.6⁰ Putin-target
inclination to 0⁰ equatorial inclination requires
2*sin(51.6⁰/2)*7670 m/s = 6670 m/s, almost as much delta V
as the initial launch did. Exponentially more expensive
than ballistic escape.

Instead, a properly timed "near escape delta V" puts the
vehicle (in this case, ONLY the useful components of ISS)
in a 3 body or 4 body dynamic/gravitational Twilight Zone,
where trajectories can do surprising things, strongly
influenced by lunar and solar gravity.

An amusing popsci book about this subject is "Fly Me To The
Moon" by Edward Belbruno. Belbruno's "Capture Dynamics and
Chaotic Motions in Celestial Mechanics" has the bigger-than-
my-brain math. At higher-than-my-budget cost, but readable
in a good university library.

That said, we can accomplish AMAZING things where gravity
sums get complicated. When I am not upgrading computers
to Debian Linux, I ponder some of those amazing things.

Multi-kilowatt-per-kilogram applications, combined with the
fantastic things I know how to do with silicon and other
semiconductors. Space power, as if obscene profitability
and rapid exponential growth is a desirable goal.

Maybe not. Space power deployment seems to be gated by
preserving ancient ISS. Perhaps there is another ISS fan
club list, which I can hijack to discuss power satellite
economics. Perhaps an obscenely wealthy fan on that
hypothetical list can pay for either or both projects.

[Keith Henson]

On Mon, Oct 2, 2023 at 12:55 PM Keith Lofstrom <kei...@keithl.com> wrote:

snip

> Maybe not. Space power deployment seems to be gated by
> preserving ancient ISS.

I suppose that might be possible, but I am not aware of it. The two
projects differ by a factor of 10,000 or more. It would take one or
two Starship launches to move the ISS to a storage orbit whereas a
serious power satellite deployment takes something like 25,000
launches a year.

> Perhaps there is another ISS fan
> club list, which I can hijack to discuss power satellite
> economics. Perhaps an obscenely wealthy fan on that
> hypothetical list can pay for either or both projects.

You might try the guy who is funding CalTech.

This is not related to your concepts of free-floating computer
systems, but I think PV is a poor choice for power satellites of the
bulk power type. Thermal designs will give about twice as much power
per unit area and are not degraded by radiation.

In the long run, perhaps 1000 years, I would look at whatever is going
on at Tabby's Star. I suspect that optimizing for computation
involves going out much beyond Earth orbit where the equilibrium
temperature is much colder. (The low temperature reduces the error
rate.)

KeithH

> Keith L.
>
> --
> Keith Lofstrom kei...@keithl.com
>

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[Gary Barnhard]

Keith L. -

You pretty much nailed it; however, my adventures in alternate trajectories started with the work of Robert W. Farquahar concerning the "Explorer-class heliocentric spacecraft, ISEE 3 (International Sun-Earth Explorer 3), 

which was part of the mother/daughter/heliocentric mission (ISEE 1, ISEE 2, and ISEE 3). In 1982 it was re-purposed as a cometary probe and renamed ICE (International Cometary Explorer)".  

This work and his other trajectory exploits are documented in his memoir (Fifty Years on the Space Frontier: Halo Orbits, Comets, Asteroids, and More) V2, 2011

Informed by Dr. Farquhar's work, as the lead systems engineer for the NASA Cubequest Challenge Team Alpha Cube Sat (ACS), I proposed that Team ACS baseline the use of an alternate minimum energy trajectory so the ACS could participate in both the Deep Space Derby and the Lunar Derby.  The idea was that if we could complete the trajectory with non-negative systems-level margins using an alternate minimum energy trajectory, we could reduce the delta-V requirement allowing ACS to claw back a substantial operations margin.  Since Dr. Farquhar had passed away, I sought after the remaining rock star in the field of orbital dynamics, Dr. Edward Belruno, and managed to negotiate his assistance as an ongoing advisor to Team ACS.

My Team ACS colleagues and I gave a presentation for the AIAA Space Operations Workshop 2016 in Pasadena, California, which we subsequently reprised as a paper and presentation for AIAA Space 2016, Long Beach, California.  

1700 hrs AIAA-2016-5302 Halfway to Anywhere -- Cislunar and Deep Space CubeSats Missions From ISS, G. Barnhard, Xtraordinary Innovative Space Partnerships, Inc., Cabin John, MD; E. Dahsltrom, International Space Consultants, Menlo Park, CA

Both the paper and presentation are attached.  There are multiple additional references included.

The Belbruno books are both germane and should be in the library of anyone entertaining this subject.

Subsequently, Christopher Cassell and Seth Potter joined the Team ACS effort to assist as well.

As noted previously, the analysis effort reduced the ACS delta-V requirements by over an order of magnitude.

The bottom line is that Team ACS did some real work here and earned the respect and support of one of the leading experts in the field.

Alas, despite our best efforts, Team ACS has not and will not get the opportunity to prove it.

The clock has effectively run out on the contest.

Some Moons ago, when the leader of Roscosmos declared that the USA should use a trampoline to get to the International Space Station and that Russia NASA was utterly dependent on Russia providing the necessary boost propulsion for ISS, I looked into the matter.

As circumstances would have it, I found the flight-qualified Interim Control Module (ICM) built/repurposed for ISS sitting in its crate in a certain government warehouse. Thinking a better fate could befall it, and I immediately sent a formal request to the Director of the Lab to open discussions on transferring the same back to NASA for emergency flight purposes if it was viable (it turns out there were issues) or to XISP-Inc/elsewhere for testing purposes (hydrazine to green propellant option evolution). The very next day, I was invited to appear first thing in the morning at NASA Headquarters to discuss my request. After multiple discussions that evidently went to the highest levels within the agency, the Associate Administrator of NASA HEOMD at the time asked me to stand down, intonating in no uncertain terms that NASA had this issue under control.

Truth be told, you were right; I just stated the facts with no color commentary or explanation of how I came to know such things.

Thanks to your thoughtful intervention, our colleagues are better informed should they choose to look into such things.

If you can suspend disbelief and consider that a pragmatic robotic space systems engineer is not an oxymoron, arguably, I am the embodiment of the same.

If our colleagues were convinced that my comments were borne of ignorance, perhaps the issue in question is not with me. ;-)

Ad Astra!

- Gary

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[Kevin Parkin]

Further to Jim, Keith, and everyone else's calculations, I took a look at moving ISS up to 700 km the old fashioned way and it turns out it's just about possible using a single ~$150M Falcon Heavy:

https://parkinresearch.com/engineering-inference-engine/orbit-transfer/#Hohmann

Cheers,

Kevin

[Gary Barnhard]

Kevin -

Thanks for sharing the calculation setup on this.  My contention is not that a Hohmann will can not work, as you clearly demonstrate the numbers say otherwise. 

Rather, that alternate minimum energy trajectoriy solutions with resistojets and other ways to work your way around the phase diagram for the H2O (1) are possible,  (2) are more flexible for altitude raising and plane change, and (3) allow for lower induced loading on the structure.  

My gambit was to find a solution that could not only save ISS, but also allow us the flexibility to do what we want with it while minimizing cost, schedule, and technical risk.  I look forward to proving it.  I see your Falcon heavy with a advanced propulsion testbed (a prototype resistojet testbed was built by McDonald Douglas in the early 70's for Mars applications; we can likely do better but I wanted to dispose of the TRL argument) and raise you an Ed Belbruno and open access to the STK space bundle ;-)

My bet is we can keep the induced loads equal to or lower than any other currently used or proposed ISS reboot solution. 

Ad Astra!

- Gary

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[Tim Cash]

I am positive some backer will step forward and open their wallet to rescue ISS. The real question being the legality and permission to sell ISS from NASA perspective.  An orbital location makes ISS fat more accessible, of course, than anywhere else.  Can you imagine a weekend at ISS hearing Frank Sinatra and Elvis Presley impersonators, wow!  Talk about a popular venue!

[Jay Lewis]

So many great threads on this topic!

The assumption higher orbits are better may doom consensus that deorbiting is best.

My understanding is once above the atmosphere (>600km) there is not much drag.  The debris at higher orbits also don't change much (isn't 800km >200 years?), shouldn't that mean less dodging required than 400km?  

It currently dodges once a month, which is always up which it would do anyway if there was no debris.

If it was moved to 800km it would still need the ability to dodge whenever LeoLabs warned them, but I suspect this might be closer to once a year than once a month, requiring much less energy.  

Jay

[John K. Strickland, Jr.]

I want to emphasize that an initial higher orbit for the ISS does not have to be the final storage orbit.

All that is needed is to keep it high enough from de-orbiting and out of the way of the densest orbital paths and planes.

It can then be moved later to a display or storage orbit.

 

John S

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