Nuclear Orion Memories
Pat Flannery
http://www.theregister.co.uk/2009/11/15/zuppero_solar_system/
"Tony Zuppero, one of [a few] would-be nuclear rocketeers, tells those
stories as he recalls them, with sometimes alarming candor, humor, and
disappointment," opined Steve Aftergood of the Federation of American
Scientists after linking to the memoir on his secrecy blog.
Zuppero's dream begins in 1968 with the scientist inspired by one of
Freeman Dyson's well-traveled crackpot ideas - that of powering a
spaceship to the nearest star at one per cent of the speed of light,
using atomic bombs. (Sci-fi authors Larry Niven and Jerry Pournelle
famously employed one in their alien invasion novel, Footfall.)
Working for a government lab, Zuppero asks to view the classified plans,
called Orion, for the Dyson space ship."
The free pdf of the book is here: http://www.neofuel.com/inhabit/inhabit.pdf
Pat
David Spain
>
> The free pdf of the book is here: http://www.neofuel.com/inhabit/inhabit.pdf
>
> Pat
So I've always wondered what would be easier and more cost effective.
A "fixed fuel" design based on a set number of stored, pre-built bombs,
or flying a production reactor that could produce plutonium and deuterium
and/or tritium on-the-fly as well as generate electricity for the spacecraft?
The bombs get built as needed and it gives the crew something to
do (yes, other than expanding the crew) during the interstellar legs of the
flight.
I'm purposely ignoring all the treaties that'd have to be redone in order
to enable any of this...
Dave
Pat Flannery
>
> So I've always wondered what would be easier and more cost effective.
>
> A "fixed fuel" design based on a set number of stored, pre-built bombs,
> or flying a production reactor that could produce plutonium and deuterium
> and/or tritium on-the-fly as well as generate electricity for the spacecraft?
Way, way, too heavy unless your Orion spacecraft is something the size
of a Space Ark.
Pat
David Spain
Um, I thought the original Orion proposal was exactly that?
Are you thinking of a Goulden (better, faster, cheaper) version?
Dave
David Spain
> On Tue, 17 Nov 2009 21:11:40 -0500, David Spain <nos...@127.0.0.1>
> wrote:
>
>>Um, I thought the original Orion proposal was exactly that?
>>Are you thinking of a Goulden (better, faster, cheaper) version?
>
> ...Grenades tossed out from behind a garbage can lid?
>
> OM
Just a few cost overruns on that garbage can lid design...
:-D
Dave
Pat Flannery
>
> Um, I thought the original Orion proposal was exactly that?
> Are you thinking of a Goulden (better, faster, cheaper) version?
Well, the one in the Orion report from 1964 is designed for use inside
the solar system.
Freeman Dyson may have been playing around with interstellar space ark
ideas for the propulsion system, but those never got funding for any
detailed studies by NASA or the Air Force.
About the time I found out the Dyson Sphere wasn't going to have a solid
shell on it, but consist of hundreds of thousands of little artificial
worlds orbiting a star - with all the fun gravitational interactions
that implied - I knew that Dyson was a world-class loon who had been
drinking herbal tea made with Carl Sagan's bong water. :-D
Pat
American
You're throwing the baby out with the bathwater.
Dyson contributed heavily to the original Orion concept - but no one
seems to recognize the facts that, albeit a few "skew" references to
the actual, circa 50's science-in-the-making, like:
1) ablation and opacity studies
2) ARPA/Air Force/NASA sponsorship
3) AEC security requirements [1]
A nation's right to the free use of a controlled substance such as
plutonium is indeed similar, if not (strangely) proportional to, its
right to protect and defend the Constitution of the United States [2]
American
[1]
In those days, it was the AEC, "... on a tour of nuclear facilities to
evaluate non-proliferation safeguards, ... At Nuclear Fuel Services'
commercial nuclear fuel reprocessing plant in West Valley, New
York, ... several containers with separated plutonium nitrate
solution, enough in the aggregate for at least two atomic bombs, were
in a small shack a few feet away from an ordinary chain-link fence and
more than 100 yards from the plant entrance, where the 'guard' had no
weapon of any kind."
- G. Dyson's book "Project Orion, the True Story of the Atomic
Spaceship
[2]
The "free market" use of plutonium - since plutonium becomes
"internationally inspected", should ONLY become limited w.r.t. a
wartime 'pacifist stance' - a stance that only exists as a failed
ideology, philisophically empty and zero-tolerance policies used by,
technologically starved and wholly bureaucratically dependent,
institutions of academia and over-legislated, co-dependent businesses.
Pacifism and zero-tolerance take away individual judgement and replace
rugged individualism with completely arbitrary, draconian rules and
regulations. The unintended consequences of draconian legislation are
the overly-bureaucratic mandates that punish or financially hurt
innocent entrepreneurs in the free market of ideas, as well as in the
free market of technologically sound scientific entrepreneurialism.
Dr J R Stockton
Nov 2009 16:45:26, David Spain <nos...@127.0.0.1> posted:
>So I've always wondered what would be easier and more cost effective.
>
>A "fixed fuel" design based on a set number of stored, pre-built bombs,
>or flying a production reactor that could produce plutonium and deuterium
>and/or tritium on-the-fly as well as generate electricity for the spacecraft?
>
>The bombs get built as needed and it gives the crew something to
>do (yes, other than expanding the crew) during the interstellar legs of the
>flight.
To go interstellar at a reasonable speed, using only what was launched
from Earth (or the Solar System), one should consider the relativistic
"increase in mass" and where that mass-energy will come from. All your
energy comes from fission; fission generates (IIRC) considerably less
energy per event than fusion does, and a fission event needs of the
order of a hundred times more mass directly involved than a fusion one
does.
To say anything meaningful about interstellar travel, one must be
familiar with the energetics.
<http://www.wolframalpha.com/input/?i=energy+uk> gives UK electric power
gross production as almost 400E9 kWh/yr; 400E12 * 8E3 Joules, say 3E18
Joules. Now c is 3E8 m/s, so to get to 0.1 C (40 years to Alpha
Centauri) with that energy P: E = 0.5 M V^2 or M = 2E/V^2 gives us M =
6E18 / 1E15 kg = 6 tonnes - AT 100% EFFICIENCY. That's the mass of an
Apollo capsule. Check the figures.
--
(c) John Stockton, nr London, UK. ?@merlyn.demon.co.uk Turnpike v6.05.
Web <URL:http://www.merlyn.demon.co.uk/> - w. FAQish topics, links, acronyms
PAS EXE etc : <URL:http://www.merlyn.demon.co.uk/programs/> - see 00index.htm
Dates - miscdate.htm estrdate.htm js-dates.htm pas-time.htm critdate.htm etc.
BradGuth
This is a topic for Willam Mook, and you'd need 0.1 c.
~ BG
Pat Flannery
>
>
> To go interstellar at a reasonable speed, using only what was launched
> from Earth (or the Solar System), one should consider the relativistic
> "increase in mass" and where that mass-energy will come from.
IIRC, the Dyson Orion Ark concept was supposed to top out at only a few
percent of lightspeed, so relativistic mass increase effects were
inconsequential.
Pat
RalphE
Maybe you were thinking of this?
http://en.wikipedia.org/wiki/Mini-Mag_Orion
Ralph
--
Dream of Space? Make it Real.
http://www.OpenAerospace.Org/
BradGuth
wrote:
> In sci.space.history message <6uws1ozuyx....@ws125.sysdef.com>, Tue, 17
> Nov 2009 16:45:26, David Spain <nos...@127.0.0.1> posted:
>
> >So I've always wondered what would be easier and more cost effective.
>
> >A "fixed fuel" design based on a set number of stored, pre-built bombs,
> >or flying a production reactor that could produce plutonium and deuterium
> >and/or tritium on-the-fly as well as generate electricity for the spacecraft?
>
> >The bombs get built as needed and it gives the crew something to
> >do (yes, other than expanding the crew) during the interstellar legs of the
> >flight.
>
> To go interstellar at a reasonable speed, using only what was launched
> from Earth (or the Solar System), one should consider the relativistic
> "increase in mass" and where that mass-energy will come from. All your
> energy comes from fission; fission generates (IIRC) considerably less
> energy per event than fusion does, and a fission event needs of the
> order of a hundred times more mass directly involved than a fusion one
> does.
>
> To say anything meaningful about interstellar travel, one must be
> familiar with the energetics.
>
> <http://www.wolframalpha.com/input/?i=energy+uk> gives UK electric power
> gross production as almost 400E9 kWh/yr; 400E12 * 8E3 Joules, say 3E18
> Joules. Now c is 3E8 m/s, so to get to 0.1 C (40 years to Alpha
> Centauri) with that energy P: E = 0.5 M V^2 or M = 2E/V^2 gives us M =
> 6E18 / 1E15 kg = 6 tonnes - AT 100% EFFICIENCY. That's the mass of an
> Apollo capsule. Check the figures.
>
> --
> Web <URL:http://www.merlyn.demon.co.uk/> - w. FAQish topics, links, acronyms
> PAS EXE etc : <URL:http://www.merlyn.demon.co.uk/programs/> - see 00index.htm
> Dates - miscdate.htm estrdate.htm js-dates.htm pas-time.htm critdate.htm etc.
Correct, and none better for this topic than Willam Mook, and
otherwise we'll need that 0.1 c velocity at the very least, as well as
enough energy for stopping unless it's just a 0.1 c fly-by mission.
~ BG
David Lesher
>>Are you thinking of a Goulden (better, faster, cheaper) version?
>...Grenades tossed out from behind a garbage can lid?
My boss at LeRC wrote a proposal to have a self-reloading
rail gun throw slugs back and thus its craft forwards...
--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433
David Spain
Yes this is the way I remember it too.
FWIW the Wikipedia article has a lot to say about Orion:
http://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion)
Both types of vehicles (interplanetary vehicle and interstellar ark) were
considered during the project study life cycle, which, according to Wikipedia,
ended after the signing of the Comprehensive Test Ban Treaty.
Interesting to contemplate an alternative reality. If Slizard's nightmare were
to have become reality, one could speculate that the Nazi regime coupled to a
hyperactive German military/industrial complex would have quickly established
a totalitarian world government eliminating the nation states of the 19th
century and hence no need for a comprehensive test ban treaty. Then Orion might
have gone forward, planting the Nazi flag on Mars a century before we're actually
likely to see any flag on Mars, with genetically engineered colonists running
around inhabiting the place.
Iron Sky senario in reverse. More like P.K. Dick's 'Man in the High Castle'.
Sometimes progress comes at too high a price...
Dave
Pat Flannery
>
> Both types of vehicles (interplanetary vehicle and interstellar ark) were
> considered during the project study life cycle, which, according to Wikipedia,
> ended after the signing of the Comprehensive Test Ban Treaty.
Even Orion was anemic for the interstellar mission; about the first
design that anyone came up with that looked like it had a real chance of
working (even though the physics were a lot more involved than Orion's
nuclear pulse propulsion) was the BIS' "Daedalus" proposal that used
fusion pulse propulsion: http://en.wikipedia.org/wiki/Project_Daedalus
It was also one of the few multistage starship proposals. ;-)
Pat
David Spain
> To go interstellar at a reasonable speed, using only what was launched
> from Earth (or the Solar System), one should consider the relativistic
> "increase in mass" and where that mass-energy will come from. All your
As I agree with Pat. I don't think at only .1 c we're anywhere close to
having to worry about 'increase in mass', which for this exercise translates
into 'how much energy is needed to achieve velocity X'.
> energy comes from fission; fission generates (IIRC) considerably less
> energy per event than fusion does, and a fission event needs of the
> order of a hundred times more mass directly involved than a fusion one
> does.
>
I don't doubt this, but I don't know the ordering of energies relative to
fusion vs fission, I guess I could look it up. For the sake of argument, let's
assume your estimates are correct.
It's even trickier than this. Since it is very straightforward to enchance
an atomic bomb to become a hydrogen bomb, let's assume that the propulsion
energy is generated by thermonuclear reaction. Maybe the spacecraft brings
along its own supply of lithium for conversion to lithium deuteride for
use as a fuel for the thermonuclear bombs.
> To say anything meaningful about interstellar travel, one must be
> familiar with the energetics.
>
I don't have any quibbles about your math, which btw seem to ignore
relativistic mass increse effects anyway, going with straightforward
Newtonian mass/energy calculations.
But I'm confused by your use of the UK electric power output in your
calculations. Why does that matter? Wouldn't one just build one or
more power reactors of the appropriate energy output to suit the purpose?
It seems more appropriate to consider the (non-relativistic aka) rest
mass of the spacecraft, and then derive an energy budget for getting
that mass to .1c and back to zero within a reasonable time frame
(say 40 years) and then estimate reactor fuel mass based on that.
All the while de-rating for the fact that we're not getting 100%
efficiencies.
So today I thought of perhaps a better way to think about the problem;
if you're using the 'fixed-fuel' design you've actually built a
multi-stage rocket! Based on the fact that the materials used to build
the bombs were left behind on Earth! In that case you only need to
generate via fission enough power to operate only the electrical systems
of the spacecraft, presumably a much smaller reactor.
If you knew that your destination had plenty of reserves of uranium
(either on a planet or on asteroid(s) in orbit around Alpha Centari)
then you'd bring along only enough mass to enable the enrichment of
that uranium at the other end leg of the journey to re-stock your
bomb supply and thus rebuilding the virtual 'first-stage' which is
jettisoned for the return flight. This would halve the number of bombs
needed to be carried for the mission, assuming a previous scouting
mission told you there was enough material available for that purpose.
From these principles alone, it argues in favor of pre-built
bombs, since we all understand the efficiencies of multi-stage rocket
design.
Comments?
Dave
David Spain
> So today I thought of perhaps a better way to think about the problem;
> if you're using the 'fixed-fuel' design you've actually built a
> multi-stage rocket! Based on the fact that the materials used to build
> the bombs were left behind on Earth! In that case you only need to
> generate via fission enough power to operate only the electrical systems
> of the spacecraft, presumably a much smaller reactor.
Pat,
Your Project Daedalus link shows that a variant of this idea was considered
before by Robert Freitas and published in 1980. This is simply self-replicating
the infrastructure that provides the virtual first stage, rather than the
entire vehicle.
Dave
Pat Flannery
> Dr J R Stockton <repl...@merlyn.demon.co.uk> writes:
>> To go interstellar at a reasonable speed, using only what was launched
>> from Earth (or the Solar System), one should consider the relativistic
>> "increase in mass" and where that mass-energy will come from. All your
>
> As I agree with Pat. I don't think at only .1 c we're anywhere close to
> having to worry about 'increase in mass', which for this exercise translates
> into 'how much energy is needed to achieve velocity X'.
There are graphs here: http://www.udel.edu/mvb/PS146htm/146nosr.html
showing the relativistic effects at various fractions of lightspeed.
>
>> energy comes from fission; fission generates (IIRC) considerably less
>> energy per event than fusion does, and a fission event needs of the
>> order of a hundred times more mass directly involved than a fusion one
>> does.
>>
>
> I don't doubt this, but I don't know the ordering of energies relative to
> fusion vs fission, I guess I could look it up. For the sake of argument, let's
> assume your estimates are correct.
>
> It's even trickier than this. Since it is very straightforward to enchance
> an atomic bomb to become a hydrogen bomb, let's assume that the propulsion
> energy is generated by thermonuclear reaction. Maybe the spacecraft brings
> along its own supply of lithium for conversion to lithium deuteride for
> use as a fuel for the thermonuclear bombs.
On orion it wasn't the nuclear blast itself that drove the ship
forwards, but rather superheated tungsten vapor created by the nuclear
blast that was blown into the pusher plate. Each one of the propulsion
bomblets consisted of a small spherical fission device mounted in a
casing that looked like a liquid rocket engine combustion chamber and
nozzle (or the pellet from a pellet rifle)
The fission device proper sat in the combustion chamber part, the nozzle
was filled with beryllium,and a plate of tungsten was secured to the
wide open end of the nozzle.
On detonation, the beryllium "channel filler" absorbs the radiation
emitted and rises to a very high temperature, generating a high energy
shockwave that propagates into the tungsten plate, turning it into very
high velocity vapor that is projected upwards to hit the pusher plate
on the bottom of the vehicle and drive it forward by simple
action-reaction principles.
The whole bomblet-pusher mass assemble was to be housed in a cylindrical
casing that incorporated the fuzzing and firing gear for easy ejection
out the rear of the Orion vehicle.
If you want to read a good overall description of how Orion was supposed
to work, then download this NASA report on the project from 1964 in pdf
format (176 pages):
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19770085619_1977085619.pdf
The drive bomblet is shown in cutaway form on page 23 of the pdf.
Though Orion went nowhere after the test ban treaty and treaty of outer
space, that little nuclear bomblet that could shoot superheated material
in one direction intrigued the military, and they looked into making a
ASAT/ABM weapon out of it under the code name "Casaba Howitzer" - the
idea being to launch one into the high atmosphere or space, aim it at
the enemy target vehicle, set it off, and blast the target with a cloud
of material going at such a high velocity that it would damage or
destroy it.
Casaba Howitzer is still classified, so how close the design was to the
Orion bomblets is open to conjecture.
As to the use of thermonuclear devices to do the same thing in regards
to propulsion, it's certainly possible to make very small ones nowadays,
but you will still need small fission devices to detonate them, and you
run into the problem of getting the fusion bomblets so powerful that
they damage the pusher plate on detonation, despite the bomblet weight
vs. energy released advantages of moving up to fusion rather than
fission explosions.
On the Orion design, the pusher plate had to deal with initial impact
forces from the tungsten vapor of 50,000 g's, and I think that they
would have had their hands full trying to figure out how to get it to
survive that without seeing what little H bombs could do in that regard. :-)
Pat
Pat Flannery
> Your Project Daedalus link shows that a variant of this idea was considered
> before by Robert Freitas and published in 1980. This is simply self-replicating
> the infrastructure that provides the virtual first stage, rather than the
> entire vehicle.
Robert Enzmann proposed huge fusion powered starships back in 1969 also:
http://www.centauri-dreams.org/?p=9961
Here, Robert W. Bussard (of Bussard Ramjet fame) discusses Enzmann's
design and Daedalus:
http://www.askmar.com/Robert%20Bussard/A%20Starship%20is%20Born.pdf
As well as antimatter and other ideas.
That article was from 1983, when fusion powerplants were right around
the corner.
Pity the car broke down in the middle of the block. ;-)
Pat
David Spain
> If you want to read a good overall description of how Orion was supposed to
> work, then download this NASA report on the project from 1964 in pdf format
> (176 pages):
> http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19770085619_1977085619.pdf
Cripes Pat, I'm nowhere near finishing off the Augustine Report and now you
fire another 176 page report at me!
But thanks for that link! It's a fascinating first glance. I've stashed it
away for a future read.
You find a bit of irony in the scope of plans between this and what Augustine
lays out? Times they are a changin'....
> The drive bomblet is shown in cutaway form on page 23 of the pdf.
Yep. Size-wize I think the W88 would drop in nicely here and would boost the
yield from ~30kT to well over 300. That puts the effective thrust off the
scale at way way over 200 Newtons (see fig 2.14 which appears to be log/log
scaling), and likely too much for the shock absorber / pusher plate system
to handle.
> Though Orion went nowhere after the test ban treaty and treaty of outer space,
> that little nuclear bomblet that could shoot superheated material in one
> direction intrigued the military, and they looked into making a ASAT/ABM
> weapon out of it under the code name "Casaba Howitzer" - the idea being to
> launch one into the high atmosphere or space, aim it at the enemy target
> vehicle, set it off, and blast the target with a cloud of material going at
> such a high velocity that it would damage or destroy it.
> Casaba Howitzer is still classified, so how close the design was to the Orion
> bomblets is open to conjecture.
So Star Wars w/o the X-Rays?
> As to the use of thermonuclear devices to do the same thing in regards to
> propulsion, it's certainly possible to make very small ones nowadays, but you
> will still need small fission devices to detonate them, and you run into the
> problem of getting the fusion bomblets so powerful that they damage the pusher
> plate on detonation, despite the bomblet weight vs. energy released advantages
> of moving up to fusion rather than fission explosions.
Yup see above.
> On the Orion design, the pusher plate had to deal with initial impact forces
> from the tungsten vapor of 50,000 g's, and I think that they would have had
> their hands full trying to figure out how to get it to survive that without
> seeing what little H bombs could do in that regard. :-)
>
Quick someone fetch some more bong water! And make that heavy water!
;-)
Dave
Pat Flannery
>
> Cripes Pat, I'm nowhere near finishing off the Augustine Report and now you
> fire another 176 page report at me!
>
> But thanks for that link! It's a fascinating first glance. I've stashed it
> away for a future read.
Their cost estimates are a riot.
They think the whole works can be done on the cheap.
>
> You find a bit of irony in the scope of plans between this and what Augustine
> lays out? Times they are a changin'....
Henry Spencer once wrote that around the time period of that report it
seemed like no matter how wild a spacecraft related idea seemed to be,
it was considered doable if you threw enough money and effort at it.
And if you look back, the period around 1962-1966 is indeed where all
the really crazy space ideas seem to come from.
>
>> The drive bomblet is shown in cutaway form on page 23 of the pdf.
>
> Yep. Size-wize I think the W88 would drop in nicely here and would boost the
> yield from ~30kT to well over 300. That puts the effective thrust off the
> scale at way way over 200 Newtons (see fig 2.14 which appears to be log/log
> scaling), and likely too much for the shock absorber / pusher plate system
> to handle.
Unfortunately, section 2 of the report that goes into all the specifics
of the drive bomblets is still classified, as for starters it gives the
cost per bomblet, which would have let the Soviets figure out a lot
about our nuclear weapons production efficiency.
>
>> Though Orion went nowhere after the test ban treaty and treaty of outer space,
>> that little nuclear bomblet that could shoot superheated material in one
>> direction intrigued the military, and they looked into making a ASAT/ABM
>> weapon out of it under the code name "Casaba Howitzer" - the idea being to
>> launch one into the high atmosphere or space, aim it at the enemy target
>> vehicle, set it off, and blast the target with a cloud of material going at
>> such a high velocity that it would damage or destroy it.
>> Casaba Howitzer is still classified, so how close the design was to the Orion
>> bomblets is open to conjecture.
>
> So Star Wars w/o the X-Rays?
Hard to say what exactly it was, as there is very little to be found on
it anywhere.
There's a basic description of it here:
http://www.projectrho.com/rocket/rocket3x.html#shapedcharge
Neutron bombs, which were a big topic of conversation back in the 1980's
but which you hear almost nothing about today (they let a fairly small
nuclear detonation generate a mass of neutrons that will quickly kill
people exposed to the detonation even if they are inside tanks or
structures, while not causing much blast damage to buildings) were a
offshoot of ABM warhead development, in this case the warhead for the
Sprint missile that killed its target via neutron flux (Spartan killed
via X-rays).
Pat
Pat Flannery
>
> Unfortunately, section 2 of the report that goes into all the specifics
> of the drive bomblets is still classified, as for starters it gives the
> cost per bomblet, which would have let the Soviets figure out a lot
> about our nuclear weapons production efficiency.
Out of curiosity, I got out the calipers and figured out the size of the
drive bomblets based on the drawings on pages 10, 11, and 27 of the
report; I knew they couldn't be very large based on the statement that
they were expected to weigh only 311 pounds each, and depleted uranium,
tungsten, and plutonium ain't light.
The results though were a real eye-opener even given that.
The bomblets are only about a foot in diameter by two feet tall, with
the actual nuclear device in their core being around ten inches in
diameter (that's the explosive lens and all).
Given that their yield is to be around 30 kilotons each (half again as
powerful as the bomb dropped on Nagasaki) you can see by 1964 we had
made some huge strides in nuclear weapon design.
Given its small size and low weight I suspect that the bomblet is based
on the primary fission igniter that was normally used on a ICBM or SLBM
thermonuclear warhead, such as Minuteman 1 or 2 or Polaris.
References in the Orion report to uprated versions using bomblets
employing fusion suggest that the original version doesn't use tritium
gas boosting to up yield, and is a pure fission device.
Pat
Dr J R Stockton
Nov 2009 08:49:18, David Spain <nos...@127.0.0.1> posted:
>Dr J R Stockton <repl...@merlyn.demon.co.uk> writes:
>> To go interstellar at a reasonable speed, using only what was launched
>> from Earth (or the Solar System), one should consider the relativistic
>> "increase in mass" and where that mass-energy will come from. All your
>> energy per event than fusion does, and a fission event needs of the
>> order of a hundred times more mass directly involved than a fusion one
>> does.
>>
>
>I don't doubt this, but I don't know the ordering of energies relative to
>fusion vs fission, I guess I could look it up. For the sake of argument, let's
>assume your estimates are correct.
>
>It's even trickier than this. Since it is very straightforward to enchance
>an atomic bomb to become a hydrogen bomb, let's assume that the propulsion
>energy is generated by thermonuclear reaction. Maybe the spacecraft brings
>along its own supply of lithium for conversion to lithium deuteride for
>use as a fuel for the thermonuclear bombs.
You say it is straightforward; I've never done it. The basic method,
however, is to add fusion fuel and other mass. Perhaps someone here
knows the figures for the ratio of overall mass to reacted mass for a
well-designed bomb. The effective fuel mass is increased in that ratio.
One needs a reusable bomb design; one which can be retained and
refuelled after use. Daedalus had that.
>> To say anything meaningful about interstellar travel, one must be
>> familiar with the energetics.
>>
>
>I don't have any quibbles about your math, which btw seem to ignore
>relativistic mass increse effects anyway, going with straightforward
>Newtonian mass/energy calculations.
>
>But I'm confused by your use of the UK electric power output in your
>calculations. Why does that matter? Wouldn't one just build one or
>more power reactors of the appropriate energy output to suit the purpose?
It just provides an idea of the power available from a fairly large
generating system.
>It seems more appropriate to consider the (non-relativistic aka) rest
>mass of the spacecraft, and then derive an energy budget for getting
>that mass to .1c and back to zero within a reasonable time frame
>(say 40 years) and then estimate reactor fuel mass based on that.
>All the while de-rating for the fact that we're not getting 100%
>efficiencies.
No need. If it's impractical at 100% efficiency, it's impractical with
anything less.
--
(c) John Stockton, Surrey, UK. ?@merlyn.demon.co.uk Turnpike v6.05 MIME.
Web <URL:http://www.merlyn.demon.co.uk/> - FAQish topics, acronyms, & links.
Proper <= 4-line sig. separator as above, a line exactly "-- " (SonOfRFC1036)
Do not Mail News to me. Before a reply, quote with ">" or "> " (SonOfRFC1036)
Pat Flannery
>
> refuelled after use. Daedalus had that.
Daedalus had a very hypothetical system for initiating fusion in a
deuterium/helium 3 pellet via electron beams that we have never gotten
to work in a laboratory, much less in a actual vehicle.
Matter-antimatter annihilation for spacecraft propulsion is actually
based on a lot less iffy physics from a engineering viewpoint than the
Daedalus propulsion system.
The Daedalus Drive was a concept of Professor Friedwardt Winterberg, who
you can read more about here:
http://en.wikipedia.org/wiki/Friedwardt_Winterberg
He has had a "interesting" career. :-)
Pat
Pat Flannery
>
It's straightforward if you just want to up the yield via a limited
fusion reaction on detonation; you inject tritium gas just as detonation
starts (I always suspected that this goes into the space between the
explosive lens and the plutonium pit in a "levitated" warhead, but have
no firm proof of that). Such a warhead is is referred to as "boosted"
but isn't considered a true H-bomb.
To make one of those, you need a lot of mathematical work and some very
fancy internal geometry and materials, as you have to take the energy
released from a fission primary and focus it on a "sparkplug" - a
assembly that houses the lithium-6 deuteride that will generate the
majority of the energy released by the weapon via nuclear fusion.
As far as efficiency vs. weight goes, that's difficult to figure out.
In either type of device, you have certain things of fairly fixed weight
that they share in common: plutonium pit, explosive lens, U-238 tamper,
neutron emitter, safety and fuzzing systems. With the H-bomb you add
the weight of the sparkplug and the case and other goodies that reflect
and focus the energy to activate it.
Also, there is probably a upper limit here in regards to what your
pusher plate can tolerate - you are relying on the mass and velocity of
the tungsten vapor hitting the pusher plate to drive it forward, and at
some point the combo of the two is going to damage or destroy the pusher
plate after a few detonations, oil covering or no.
Frankly, I'm leery of their 50,000g impact energy in the Orion design,
as I suspect all you are going to do is generate a very severe shockwave
in the steel pusher plate that will propagate right through it and cause
the front surface to blow clean off of it.
There's a antitank weapon that works on that that principle (HESH, or
High Explosive Squash Head) by sticking a chunk of plastic explosive on
the exterior of the tank's armor and detonating it...the exterior of the
tank looks undamaged after the blast goes off, but the shockwave travels
through the armor and causes its inside surface to detach and go flying
around the inside of the tank at very high velocity:
http://en.wikipedia.org/wiki/High_explosive_squash_head
Pat
BradGuth
wrote:
> In sci.space.history message <6uhbspl31d....@ws125.sysdef.com>, Fri, 20
> Web <URL:http://www.merlyn.demon.co.uk/> - FAQish topics, acronyms, & links.
> Proper <= 4-line sig. separator as above, a line exactly "-- " (SonOfRFC1036)
> Do not Mail News to me. Before a reply, quote with ">" or "> " (SonOfRFC1036)
Get feedback from William Mook, because he knows everything about
nuclear rocket thrusters.
~ BG
David Spain
> Pat Flannery wrote:
>>
>> Unfortunately, section 2 of the report that goes into all the specifics of
>> the drive bomblets is still classified, as for starters it gives the cost
>> per bomblet, which would have let the Soviets figure out a lot about our
>> nuclear weapons production efficiency.
>
Or what it used to be. Stockpiles are now being re-cycled rather than
manufactured from scratch.
>
> Out of curiosity, I got out the calipers and figured out the size of the drive
> bomblets based on the drawings on pages 10, 11, and 27 of the report; I knew
> they couldn't be very large based on the statement that they were expected to
> weigh only 311 pounds each, and depleted uranium, tungsten, and plutonium
> ain't light.
Yeah, it's all in the recipe. A better recipe and you don't have to
over engineer and that saves space and weight. You don't want to use depleted
uranium in a bomb if you want to leverage fast fission, you'll stick with
natural uranium.
> The results though were a real eye-opener even given that.
> The bomblets are only about a foot in diameter by two feet tall, with the
> actual nuclear device in their core being around ten inches in diameter
> (that's the explosive lens and all).
> Given that their yield is to be around 30 kilotons each (half again as
> powerful as the bomb dropped on Nagasaki) you can see by 1964 we had made some
> huge strides in nuclear weapon design.
Um, I think you mean twice as powerful as the Nagasaki bomb, IIRC a weaponized
version of the Trinity test device, which yielded around 15kT (ok Wikipedia
says 20-21).
By 1964 we'd moved from solid initiators to electrically driven neutron guns
(zippers), switched to evacuated shells and levitated cores, considerably
reducing the size and mass.
http://en.wikipedia.org/wiki/Fat_Man
http://en.wikipedia.org/wiki/File:Sanborn_Critical_Assembly_Installation.jpg
> Given its small size and low weight I suspect that the bomblet is based on the
> primary fission igniter that was normally used on a ICBM or SLBM thermonuclear
> warhead, such as Minuteman 1 or 2 or Polaris.
I agree.
> References in the Orion report to uprated versions using bomblets employing
> fusion suggest that the original version doesn't use tritium gas boosting to
> up yield, and is a pure fission device.
Using core (pit) tritium gas boosting would needlessly complicate the bomblet
design. Since you aren't worried about varying the yield of each bomblet,
I suppose you could seal the tritium within the pit at assembly time, but it
would put a shelf life limit on the boosted yield of the bomblet. Maybe best
to not bother.
The big push on thermonuclear happened in the 60's when we went to MIRVed
warheads but didn't get a corresponding increase the rocket throw weight.
Minaturization really counts on MIRV, esp. on sub launched missiles.
A lot of that came with the development of the spherical secondary, which
I suspect involves a lot of highly classified work in x-ray dispersion
within the hohlraum.
http://en.wikipedia.org/wiki/W88
When SLBMs moved over to the Trident configuration, the distinction between
ICBM and SLBM was largely erased.
Dave
Pat Flannery
>> Given its small size and low weight I suspect that the bomblet is based on the
>> primary fission igniter that was normally used on a ICBM or SLBM thermonuclear
>> warhead, such as Minuteman 1 or 2 or Polaris.
>
> I agree.
Doesn't 30 kt seem awfully high yield for a initiator?
I thought they were in the 3-5 kt range.
>
>> References in the Orion report to uprated versions using bomblets employing
>> fusion suggest that the original version doesn't use tritium gas boosting to
>> up yield, and is a pure fission device.
>
> Using core (pit) tritium gas boosting would needlessly complicate the bomblet
> design. Since you aren't worried about varying the yield of each bomblet,
Actually, there are some bomblets aboard that only generate 1/2 yield
that are used to get the shock absorption system moving in a cyclic
manner at engine start-up or after a misfire.
> I suppose you could seal the tritium within the pit at assembly time, but it
> would put a shelf life limit on the boosted yield of the bomblet. Maybe best
> to not bother.
>
> The big push on thermonuclear happened in the 60's when we went to MIRVed
> warheads but didn't get a corresponding increase the rocket throw weight.
> Minaturization really counts on MIRV, esp. on sub launched missiles.
> A lot of that came with the development of the spherical secondary, which
> I suspect involves a lot of highly classified work in x-ray dispersion
> within the hohlraum.
>
> http://en.wikipedia.org/wiki/W88
I was wondering about that; I saw a drawing of a H-bomb with a
egg-shaped primary and spherical secondary and thought they had got the
parts reversed.
Frankly, the thought of having the ovoid primary explosive lens need
only two ignition points is a bit spooky from the safety viewpoint,
although they may have come up with this fairly early on, as it matches
the shape of the warhead on the Genie air-to-air nuclear rocket:
http://commons.wikimedia.org/wiki/File:Genie_Nuclear_Unguieded_Missile.jpg
Pat
Pat Flannery
> Actually, there are some bomblets aboard that only generate 1/2 yield
> that are used to get the shock absorption system moving in a cyclic
> manner at engine start-up or after a misfire.
Keep forgetting, here are links to a whole pile of Orion-related
reports:
http://web.archive.org/web/20071022133749rn_1/www.mfbb.net/nuclearrockets/nuclearrockets-about12.html
Pat
David Spain
> David Spain wrote:
>>> Given its small size and low weight I suspect that the bomblet is based on the
>>> primary fission igniter that was normally used on a ICBM or SLBM thermonuclear
>>> warhead, such as Minuteman 1 or 2 or Polaris.
>>
>> I agree.
>
> Doesn't 30 kt seem awfully high yield for a initiator?
> I thought they were in the 3-5 kt range.
>
Pat,
Careful with the terminology, it matters. Initiators don't have fission yields,
just produce copious amounts of neutrons.
You mean primary. Wikipedia seems to rely fairly heavily on the Chuck Hansen
material, which was for a number of years the best source of unclassified
information in this area.
A quick review of Wikipedia gives this description of the Swan device that
was later weaponized into the Robin primary:
http://en.wikipedia.org/wiki/Robin_primary
According to Hansen ( aka Wikipedia :-) ) the Robin primary had a variety
of configurations and yields ranging from .5 to 15 kT.
It saw application as a primary in the W47 warhead used on Polaris-I
and I suspect likely adopted in subsequent Polaris configuration, which would
have been known at the time of the Orion study.
http://en.wikipedia.org/wiki/W47
So yeah, you're right, 30kT is awfully high for a device of this size
even with boosting. At a more realistic 15kT applied to the curve in
figure 2.14 you've dropped from a best case of 40 Newtons to about
30 Newtons if you assume you're on the same curve as the one used in
the case study. The study admits uncertainty over the yields of the
pulse units, but the banding in figure 2.14 seems to promote a highly
optimisitc view. It would imply a possibility that you would get the
same effective thrust over nearly a 4X range of bomblet yields.
I don't see how that is possible unless you're varying the rate of
bomblet explosions or some such.
FWIW, the half-life of tritium is about 12 years, which is ok for an
interplanetary mission, but won't work for a 40 year interstellar
space ark w/o replentishment.
Dave
Pat Flannery
> Pat,
>
> Careful with the terminology, it matters. Initiators don't have fission yields,
> just produce copious amounts of neutrons.
>
> You mean primary.
Okay, primary from now on.
This Wikipedia page I stumbled on a few days back has so much info on
nuclear weapon design that I'm surprised there haven't been requests
that it be censored:
http://en.wikipedia.org/wiki/Nuclear_weapon_design
> So yeah, you're right, 30kT is awfully high for a device of this size
> even with boosting. At a more realistic 15kT applied to the curve in
> figure 2.14 you've dropped from a best case of 40 Newtons to about
> 30 Newtons if you assume you're on the same curve as the one used in
> the case study. The study admits uncertainty over the yields of the
> pulse units, but the banding in figure 2.14 seems to promote a highly
> optimisitc view. It would imply a possibility that you would get the
> same effective thrust over nearly a 4X range of bomblet yields.
> I don't see how that is possible unless you're varying the rate of
> bomblet explosions or some such.
> FWIW, the half-life of tritium is about 12 years,
I was hoping it was less than that, so any boosted nuclear weapons that
leaked out of the Soviet Union would be dead a few years later, but
maybe by now they are.
At least that may be the case if all those Walmart signs didn't fall
into the wrong hands:
http://www.nrc.gov/reading-rm/doc-collections/news/2009/09-011.html
Pat
David Spain
> The fission device proper sat in the combustion chamber part, the nozzle was
> filled with beryllium,and a plate of tungsten was secured to the wide open end
> of the nozzle.
> On detonation, the beryllium "channel filler" absorbs the radiation emitted
> and rises to a very high temperature, generating a high energy shockwave that
> propagates into the tungsten plate, turning it into very high velocity vapor
> that is projected upwards to hit the pusher plate on the bottom of the vehicle
> and drive it forward by simple action-reaction principles.
>
Does the study give any indication why this scheme rather than one that relies
strickly on reflecting the radiation from the explosion? Not enought thrust
available this way for a given number of bomblets?
Dave
David Spain
>
> My boss at LeRC wrote a proposal to have a self-reloading
> rail gun throw slugs back and thus its craft forwards...
>
On a similar note, I've wondered if astronauts should
be allowed to carry side arms during EVAs. These things
would be auto-loading cartridge based CO2 air pistols
firing blanks or real firearms if the powder contained
its own oxidizer in the mix. If you're worried about
orbiting spent cartridge debris, use revolvers instead.
Need to be modified to allow firing with suit gloves
on or remotely by wire perhaps.
Besides looking really cool in the Wild West sense,
would these things actually generate enough thrust to
manuever in an emergency? Or is it easier just to install
thrusters in the suit for this purpose?
I can't believe this idea wasn't considered in the past,
Pat?
Dave
David Spain
> [snip]
> causing much blast damage to buildings) were a offshoot of ABM warhead
> development, in this case the warhead for the Sprint missile that killed its
> target via neutron flux (Spartan killed via X-rays).
See prior post about radiation enhanced propulsion using a reflector.
Would the neutron flux be dense enough to provide propulsion using a
chilled reflector?
This might save literally tons of mechanical complexity in the pusher system
at the expensive of a much lower effective thrust. But could a large enough
bomblet supply make up for the difference?
Dave
David Spain
> There's a antitank weapon that works on that that principle (HESH, or High
> Explosive Squash Head) by sticking a chunk of plastic explosive on the
> exterior of the tank's armor and detonating it...the exterior of the tank
> looks undamaged after the blast goes off, but the shockwave travels through
> the armor and causes its inside surface to detach and go flying around the
> inside of the tank at very high velocity:
> http://en.wikipedia.org/wiki/High_explosive_squash_head
How effective is that against Cobham (sp?) armor, which is not a uniform
material?
Tom Clancy has lots to say about 'spall' in his book 'Armored Cav',
which is a great read:
http://www.amazon.com/Armored-Cav-Clancys-Military-Reference/dp/0425158365
Dave
Pat Flannery
The idea is to have as little radiation as possible get to the pusher
plate. The crew still has to be in a heavily shielded area of the ship
when the bombs are going off, but that doubles as a solar storm shelter.
This is shown having very thick shielding on it, particularly on the
bottom facing the pusher plate, and I suspect it was supposed to be
similar to the radiation armor that was going to be attached to tanks
from the time period, which varied in composition - including high
density polyethylene, lead, boronated polyethylene, and a epoxy/boron
carbide mixture to be applied to the exterior of the tank to prevent
capture of thermal neutrons by the tank's steel armor.
I assume the concern was the high radiation of the detonations so close
to the rear of the ship would cause the metal in the ship to start to
become radioactive (they state that the crew can't approach the pusher
plate for a few hours after the pulse drive is shut down, so I assume
some short half-life isotopes are formed during operation).
The pusher plate is made out of steel rather than some exotic radiation
reflecting substance like beryllium.
The channel filler is beryllium oxide BTW, not pure beryllium.
Getting out the calipers again indicates there is around 7-8 inches of
it between the nuclear device and the tungsten plate, and that the
tungsten plate is around 1.5 inches thick.
To prevent the superheated tungsten plasma from either ablating or
sticking to the steel pusher plate on impact, a thin layer of oil was
ejected onto it just before each detonation.
That's one of the things in the design that looks iffy, as there is
going to be a detonation every .8 seconds, so getting the oil onto the
plate is going to have to happen very fast.
BTW, the cutaway of the bomblet shows the nuclear device itself to be a
sphere, but surrounding it is a unidentified container that comes to a
point at the bottom like a egg, point downwards. I assume this is where
one of the detonation points for the ovoid explosive lens is located,
but there is no corresponding one at the top, so how it works is a bit
of a mystery.
Pat
Pat Flannery
I'd be concerned that the radiation flux would be so high that chilled
or not, the outer layer of the pusher plate would be converted into
plasma when the radiation penetrated it. Instead of going anywhere, it
would just melt...although I guess you could push something forward via
having repeated plasma explosions occur on its back surface, but that
means carrying a large weight in material to be converted into plasma as
well as your nuclear bomblets.
Maybe that was what was supposed to drive the giant Aldebaran spaceship
design, with its huge engine nozzle:
http://3.bp.blogspot.com/_VyTCyizqrHs/SaXNtUFqGaI/AAAAAAAAC3Q/aU_86B7K_Hw/s400/aldebaran2.jpg
On Daedalus, the fusion explosions were contained by a electromagnetic
field inside the drive bell to both protect it and generate electrical
power by something like a MHD effect.
In the Orion report, they speak of moving up from fission bomblets to
ones employing both fission and fusion (tritium boosted, I assume) and
finally to ones using pure fusion with no fission component...though how
that was to work is anyone' guess.
Pat
David Spain
> I'd be concerned that the radiation flux would be so high that chilled or not,
> the outer layer of the pusher plate would be converted into plasma when the
> radiation penetrated it. Instead of going anywhere, it would just
> melt...although I guess you could push something forward via having repeated
How 'bout this variation:
Reduce the bomblet yeild substantially and devise the bomblet mainly to
supply EMP. Set it off much, much further away and use the EMP to power
a 'traditional' low specific impulse ion drive by using an antenna and
capacitor bank to collect the energy from the EMP?
A nuclear-electric ion drive on the cheap using surplus stockpile!
OK, I don't believe there is enough stockpile (or political latitude)
for this, but you get the idea...
Dave
Pat Flannery
>
> How effective is that against Cobham (sp?) armor, which is not a uniform
> material?
Probably not much, as I suspect the Chobham's internal structure would
dissipate the shockwave rather than transmitting it to the interior
surface.
I don't think it is in use anymore, as the warheads had to be large and
heavy.
The British made a 105 mm shell for the Centurion tank that used this
concept.
Two antitank missiles that used it were the US Dart and the Australian
Malkara, both big clumsy things (and Dart used to have trouble with its
wings running into trees on the way to the target in wooded areas):
http://www.designation-systems.net/dusrm/app1/ssm-a-23.html
http://en.wikipedia.org/wiki/Malkara_missile
HEAT warheads gave better penetration at less size and weight.
Pat
> Tom Clancy has lots to say about 'spall' in his book 'Armored Cav',
> which is a great read
Yeah, I've read that one.
Pat
Pat Flannery
> Reduce the bomblet yeild substantially and devise the bomblet mainly to
> supply EMP. Set it off much, much further away and use the EMP to power
> a 'traditional' low specific impulse ion drive by using an antenna and
> capacitor bank to collect the energy from the EMP?
Remember though, total firing time on the Orion engine wasn't going to
be that long on a space mission... they were going to carry around 1,000
bomblets along and with one firing every .8 seconds, so total engine run
time was around 13 minutes.
Since ion drive uses very long firing times at low thrust, a standard
fission reactor would be a lot better usage of your fissionable materials.
Pat
Pat Flannery
> Two antitank missiles that used it were the US Dart and the Australian
> Malkara, both big clumsy things (and Dart used to have trouble with its
> wings running into trees on the way to the target in wooded areas):
> http://www.designation-systems.net/dusrm/app1/ssm-a-23.html
That source says it had a shaped charge warhead instead of HESH, so I
may have made a slip there.
Gunston's book on rockets and missiles states the Dart warhead weighed
nearly 30 pounds, which seems high for a HEAT warhead of that size though.
Pat
David Spain
Such a kill joy! OK, try this:
Don't reduce the bomblet yield substantially, rather increase it substantially
and devise the bomblet mainly to supply EMP. Set it off much, much, (much, much, ... :-)
... and use the EMP to power a 'non-traditional' VASIMR engine at high specific
impulse by using an antenna and capacitor bank to collect the energy from the EMP?
Handwave handwave handwave. Boy my wrist is getting tired! There is some
math needed here. How much EMP energy do I get if I boost the bomblet up, say
its now a full thermonuclear at 300kT? Will that give me enough EMP to charge a
capacitor bank powerful enough to keep a VASIMR fed?
There are distinct advantages. Like needing only a reactor big enough to
supply electrical power to the space craft or none at all if solar cells
will do the job. Since irradiation by the bomblets fall off as the inverse
square law, by keeping them distant we don't need heavy-duty shielding of
a massive fission power reactor, nothing about the drive makes the ship
radioactive, and bye, bye heavy duty pusher plate, ablation troubles and
springs or hydraulics to make it all work.
?
Dave
Pat Flannery
> Such a kill joy! OK, try this:
>
> Don't reduce the bomblet yield substantially, rather increase it substantially
> and devise the bomblet mainly to supply EMP. Set it off much, much, (much, much, ... :-)
> ... and use the EMP to power a 'non-traditional' VASIMR engine at high specific
> impulse by using an antenna and capacitor bank to collect the energy from the EMP?
>
> Handwave handwave handwave. Boy my wrist is getting tired! There is some
> math needed here. How much EMP energy do I get if I boost the bomblet up, say
> its now a full thermonuclear at 300kT? Will that give me enough EMP to charge a
> capacitor bank powerful enough to keep a VASIMR fed?
You are going to have a hard time beating the performance on the stock
Orion drive mechanism, which they predicted would start at a specific
impulse 10,000 on the initial version and they were confident could be
raised to 16,000 by 1980, with the possibility of getting it up to
20,000 at some point in the future with the use of the fusion bomblets.
For comparison, the Shuttle main engine has a isp of 465, and although
VASIMR can theoretically get up to a isp of 50,000 its thrust isn't all
that high, so you are going to spend a lot of time accelerating up to
speed, which will affect your overall trip time.
> There are distinct advantages. Like needing only a reactor big enough to
> supply electrical power to the space craft or none at all if solar cells
> will do the job. Since irradiation by the bomblets fall off as the inverse
> square law, by keeping them distant we don't need heavy-duty shielding of
> a massive fission power reactor, nothing about the drive makes the ship
> radioactive, and bye, bye heavy duty pusher plate, ablation troubles and
> springs or hydraulics to make it all work.
Well, maybe.
VASIMR is sure the most interesting thing on the table at the moment,
and I think NASA should be spending more time and effort on it.
Pat
David Spain
> For comparison, the Shuttle main engine has a isp of 465, and although VASIMR
> can theoretically get up to a isp of 50,000 its thrust isn't all that high, so
> you are going to spend a lot of time accelerating up to speed, which will
> affect your overall trip time.
>
More than 13 minutes I presume? Will I (still) exhaust my bomblet supply?
>> Since irradiation by the bomblets fall off as the inverse
>> square law, by keeping them distant we don't need heavy-duty shielding of
>> a massive fission power reactor
And the gigantic cooling fins it needs. What's also appealing about this approach
is the fact that it would be the one path to a FUSION powered (ok assisted) rocket
where we already know how to do the fusion part.
OTOH no country is going to sign off on the idea of putting real EMP nuke bombs
in orbit, let alone >1,000 of them. And existing space treaties would have
to be rewritten correct?
> Well, maybe.
> VASIMR is sure the most interesting thing on the table at the moment, and I
> think NASA should be spending more time and effort on it.
No argument from me. NACA should get on with funding Diaz to develop it and
then let him license it to whomever wants to use it!
Dave
Rick Jones
> VASIMR is sure the most interesting thing on the table at the
> moment, and I think NASA should be spending more time and effort on
> it.
Just how much NASA (which means Congress) hands-on do we really want
for VASIMIR? These days NASA/Congressional involvement isn't exactly
a good thing is it?
rick jones
--
Wisdom Teeth are impacted, people are affected by the effects of events.
these opinions are mine, all mine; HP might not want them anyway... :)
feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH...
Pat Flannery
> Pat Flannery <fla...@daktel.com> writes:
>> For comparison, the Shuttle main engine has a isp of 465, and although VASIMR
>> can theoretically get up to a isp of 50,000 its thrust isn't all that high, so
>> you are going to spend a lot of time accelerating up to speed, which will
>> affect your overall trip time.
>>
>
> More than 13 minutes I presume? Will I (still) exhaust my bomblet supply?
Unless you have a whole pile of storage batteries aboard, or maybe some
sort of superconductor energy storage system.
>
>>> Since irradiation by the bomblets fall off as the inverse
>>> square law, by keeping them distant we don't need heavy-duty shielding of
>>> a massive fission power reactor
>
> And the gigantic cooling fins it needs. What's also appealing about this approach
> is the fact that it would be the one path to a FUSION powered (ok assisted) rocket
> where we already know how to do the fusion part.
>
> OTOH no country is going to sign off on the idea of putting real EMP nuke bombs
> in orbit, let alone >1,000 of them. And existing space treaties would have
> to be rewritten correct?
At the moment, yes.
Until we started discussing this, I hadn't thought the Orion drive
bomblets were that high of yield; they were indeed powerful enough to
have a EMP effect on the Earth's surface under the point of detonation
in orbit, something the ship's designers missed (or didn't know about
due to it being classified).
They also missed the Argus Effect...those detonations driving the ship
out of orbit would create areas of electrons in orbit that would damage
satellites: http://en.wikipedia.org/wiki/Starfish_Prime
"While some of the energetic beta particles followed the Earth's
magnetic field and illuminated the sky, other high-energy electrons
became trapped and formed radiation belts around the earth. There was
much uncertainty and debate about the composition, magnitude and
potential adverse effects from this trapped radiation after the
detonation. The weaponeers became quite worried when three satellites
in low earth orbit were disabled. These man-made radiation belts
eventually crippled one-third of all satellites in low orbit. Seven
satellites were destroyed as radiation knocked out their solar arrays
or electronics, including the first commercial relay communication
satellite ever, Telstar.[4] Detectors on Telstar, TRAAC, Injun, and
Ariel 1 were used to measure distribution of the radiation produced
by the tests.[5]
In 1963, Brown et al. reported in the Journal of Geophysical Research
that Starfish Prime had created a belt of MeV electrons, and Bill Hess
reported in 1968 that some Starfish electrons remained for five years.
Others reported that radioactive particles from Starfish Prime descended
to earth seasonally and accumulated in terrestrial organisms such as
fungi and lichens."
Yield on Starfish Prime was 1.4 mt, but of course Orion would be doing
multiple detonations as it pulled out of orbit.
The place to crank up a Orion is way out in space, say at one of the
Lagrange points.
I've never read up on what the Soviet reaction was to Starfish Prime,
but it must have damaged or destroyed a lot of their satellites also.
Pat
Pat Flannery
> In sci.space.history Pat Flannery <fla...@daktel.com> wrote:
>> VASIMR is sure the most interesting thing on the table at the
>> moment, and I think NASA should be spending more time and effort on
>> it.
>
> Just how much NASA (which means Congress) hands-on do we really want
> for VASIMIR? These days NASA/Congressional involvement isn't exactly
> a good thing is it?
NASA did fund the prototype that is presently undergoing tests.
Pat
Sam West
> Pat Flannery <flan...@daktel.com> writes:
>
> > The free pdf of the book is here:http://www.neofuel.com/inhabit/inhabit.pdf
>
> > Pat
>
> So I've always wondered what would be easier and more cost effective.
>
> A "fixed fuel" design based on a set number of stored, pre-built bombs,
> or flying a production reactor that could produce plutonium and deuterium
> and/or tritium on-the-fly as well as generate electricity for the spacecraft?
>
> The bombs get built as needed and it gives the crew something to
> do (yes, other than expanding the crew) during the interstellar legs of the
> flight.
>
> I'm purposely ignoring all the treaties that'd have to be redone in order
> to enable any of this...
>
> Dave
David Spain
> David Spain <nos...@127.0.0.1> wrote:
> :These things
> :would be auto-loading cartridge based CO2 air pistols
> :firing blanks or real firearms if the powder contained
> :its own oxidizer in the mix.
>
> You mean like, say, gunpowder?
>
Well sure. I don't see any reason why gunpowder would not
conflagrate in the vacuum of space, but I'm no expert in
that area either.
> :
> :Besides looking really cool in the Wild West sense,
> :would these things actually generate enough thrust to
> :manuever in an emergency? Or is it easier just to install
> :thrusters in the suit for this purpose?
> :
>
> If you want thrust, just use a nitrogen bottle with a nozzle.
OK, that sounds very reasonable. Maybe holster it just as you
would a side arm for convenience sake.
The trick would be to hold and 'fire' it near your CG so as
not to induce unnecessary yaw, roll and pitch, but give you
propulsion in the direction you want to go.
I suspect the way you'd probably hold the device or firearm
would be very different if trying to maneuver in space vs
trying to shoot something on the ground.
How did that handheld item that Ed White used in Gemini ?
work for him? Was that a nitrogen bottle? IIRC it had two
nozzles at the ends of a small pipe in the shape of a T?
Dave
Jeff Findley
"David Spain" <nos...@127.0.0.1> wrote in message
news:6ud430k...@ws125.sysdef.com...
> OK, that sounds very reasonable. Maybe holster it just as you
> would a side arm for convenience sake.
>
> The trick would be to hold and 'fire' it near your CG so as
> not to induce unnecessary yaw, roll and pitch, but give you
> propulsion in the direction you want to go.
>
> I suspect the way you'd probably hold the device or firearm
> would be very different if trying to maneuver in space vs
> trying to shoot something on the ground.
>
> How did that handheld item that Ed White used in Gemini ?
> work for him? Was that a nitrogen bottle? IIRC it had two
> nozzles at the ends of a small pipe in the shape of a T?
That thing didn't work very well at all. As for the details, they are,
quite literally, history, so maybe you should read up on that topic, hmmmmm?
Also, try reading about other Gemini experiments in that area, as well as
Skylab and the development of the shuttle MMU and SAFER.
Knowledge... it makes you look smarter than ignorance.
Jeff
--
"Take heart amid the deepening gloom
that your dog is finally getting enough cheese" - Deteriorata - National
Lampoon
Pat Flannery
> Well sure. I don't see any reason why gunpowder would not
> conflagrate in the vacuum of space, but I'm no expert in
> that area either.
I'm pretty sure both black and smokeless powder will detonate in a vacuum.
> How did that handheld item that Ed White used in Gemini ?
> work for him? Was that a nitrogen bottle?
It used two nitrogen bottles.
>IIRC it had two
> nozzles at the ends of a small pipe in the shape of a T?
Three nozzles; one faced forward:
http://history.nasa.gov/SP-4002/images/fig99.jpg
It only worked in a mediocre manner.
The problem with any system using only compressed gas in tanks is that
your compressed gas reserves run out fairly quickly, and your delta v is
fairly limited.
IIRC, they later ran a air line down the EVA umbilical connected to a
gas supply inside the Gemini.
Pat
William Mook
> Dr J R Stockton <reply0...@merlyn.demon.co.uk> writes:
>
> > To go interstellar at a reasonable speed, using only what was launched
> > from Earth (or the Solar System), one should consider the relativistic
> > "increase in mass" and where that mass-energy will come from. All your
>
> As I agree with Pat. I don't think at only .1 c we're anywhere close to
> having to worry about 'increase in mass', which for this exercise translates
> into 'how much energy is needed to achieve velocity X'.
The Lorentz dilation factor is 1.05038 at v = 0.1c
1/(sqrt(1-(v/c)^2) = 1.05038
Medusa has a specific impulse of 100,000 seconds at most.
http://en.wikipedia.org/wiki/Nuclear_pulse_propulsion#Medusa
This translates to an exhaust speed of 908.2 km/sec which is 0.3027%
light speed.
So, to accelerate to 0.1 c (or 10% light speed) using a Medusa style
nuclear pulse rocket requires a propellant fraction of
u = 1 - 1/exp(0.1/0.003027) = 0.999999999999996
which is impractically large.
To accelerate to 0.01c (or 1% light speed) using a Medusa style
nulcear pulse rocket requires a propellant fraction of
u = 1 - 1/exp(0.01/0.003027) = 0.96325
which is about the mass ratio of a multi-stage rocket like the Saturn
V moon rocket. The Lorentz factor is even smaller than the previous
calculation - so its not really a factor.
To accelerate a tonne of payload to 1% light speed requires expelling
27.21 tonnes at 0.3027% light speed. The minimum energy needed
(assuming no losses) in the jet is;
E = 1/2 m^v^2 = 0.5 * 27,210 * 908,200 ^2 = 11,221,958.33 giga-
joules.
The energy contained in 1.8 million barrels of oil.
or that contained in 17.4 metric tons of hydrogen fully fused.
So, a ton of payload may be accelerated to 1% light speed by a ball of
hydrogen 9.06 meters in diameter. The shell might be less than half
the total mass.
>
> > energy comes from fission; fission generates (IIRC) considerably less
> > energy per event than fusion does,
Anti-matter generates 88,876,000 million MJ/kg
Fusion generates 645 million MJ/kg
Fission generates 88 million MJ/kg
Burning hydrogen generates 143 MJ/kg
Burning gasoline generates 46.4 MJ/kg
> > and a fission event needs of the
> > order of a hundred times more mass directly involved than a fusion one
> > does.
No it doesn't. The specific energy of a fission bomb is only slightly
less than the specific energy of a fusion bomb.
> I don't doubt this,
You should since it isn't true.
> but I don't know the ordering of energies relative to
> fusion vs fission,
Fission is 1/8th as energetic and has reaction products that are 40x
heavier (on average - see table below) so exhaust speeds of a fission
bomb powered spaceship is 1/2,500x as fast (about 400 m/sec or 4,000
seconds Isp) than a fusion bomb powered spaceship (about 1,000,000 m/
sec or 100,000 sec)
Source Average energy released [MeV]
Instantaneously released energy
Kinetic energy of fission fragments 169.1
Kinetic energy of prompt neutrons 4.8
Energy carried by prompt γ-rays 7.0
Energy from decaying fission products
Energy of β−-particles 6.5
Energy of anti-neutrinos 8.8
Energy of delayed γ-rays 6.3
Sum 202.5
> I guess I could look it up.
yes, you could.
> For the sake of argument, let's
> assume your estimates are correct.
Why? Since they are not.
> It's even trickier than this. Since it is very straightforward to enchance
> an atomic bomb to become a hydrogen bomb, l
Yes, a micro-fission 'bomblet' is ideally suited to be used as a
'sparkplug' for a fusion bomb. That fusion bomb's fragments are then
deflected by a suitable pusher which captures most of the fragments
and reflects them to form a jet. The jet pushes the entire system
forward. Speeds of 1% light speed are achievable.
> let's assume that the propulsion
> energy is generated by thermonuclear reaction. Maybe the spacecraft brings
> along its own supply of lithium for conversion to lithium deuteride for
> use as a fuel for the thermonuclear bombs.
Yes. An aneutronic reaction is preferred. Boron is plentiful, so is
lithium and deuterium. Boron and lithium deuteride are both dense
solids. So, a sphere of lithium deuteride 4 meters in diameter would
propel 1 tonne to 1% light speed. A sphere of boron 3 meters in
diameter would propel 1 tonne to 1% light speed.
> > To say anything meaningful about interstellar travel, one must be
> > familiar with the energetics.
among other things.
> I don't have any quibbles about your math,
why not since its wrong?
> which btw seem to ignore
> relativistic mass increse effects anyway, going with straightforward
> Newtonian mass/energy calculations.
At 1% or even 10% light speed they are minor corrections.
> But I'm confused by your use of the UK electric power output in your
> calculations. Why does that matter? Wouldn't one just build one or
> more power reactors of the appropriate energy output to suit the purpose?
Bombs detonated in a way that directs the reaction products in the
desired direction to form a jet is the best way known, and the
energetics and so forth are well known as well.
> It seems more appropriate to consider the (non-relativistic aka) rest
> mass of the spacecraft, and then derive an energy budget for getting
> that mass to .1c and back to zero within a reasonable time frame
> (say 40 years) and then estimate reactor fuel mass based on that.
At 1/10th gee it takes a month to achieve 1% light speed and a year to
achieve 10% light speed.
> All the while de-rating for the fact that we're not getting 100%
> efficiencies.
Correct, but dealing with high temps and pressures with an impulse
based system is pretty efficient energetically.
> So today I thought of perhaps a better way to think about the problem;
> if you're using the 'fixed-fuel' design you've actually built a
> multi-stage rocket! Based on the fact that the materials used to build
> the bombs were left behind on Earth! In that case you only need to
> generate via fission enough power to operate only the electrical systems
> of the spacecraft, presumably a much smaller reactor.
The 'reactor' is a bomb otherwise you get really low power levels and
carry huge mass penalties.
> If you knew that your destination had plenty of reserves of uranium
> (either on a planet or on asteroid(s) in orbit around Alpha Centari)
> then you'd bring along only enough mass to enable the enrichment of
> that uranium at the other end leg of the journey to re-stock your
> bomb supply and thus rebuilding the virtual 'first-stage' which is
> jettisoned for the return flight. This would halve the number of bombs
> needed to be carried for the mission, assuming a previous scouting
> mission told you there was enough material available for that purpose.
It will take 430 years to get to Alpha centauri at 1% light speed.
43 years to get to alpha centauri at 10% light speed.
> From these principles alone, it argues in favor of pre-built
> bombs, since we all understand the efficiencies of multi-stage rocket
> design.
Your considerations make little sense in light of real engineering
analysis.
>
> Comments?
>
> Dave
Laser light sails are preferred. Consider
http://students.cec.wustl.edu/~ktr1/Solar_Sail_GTO_RESSLER.pdf
Sunlight at 1,380 W/m2 produces 4.56e-6 N/m2
A square meter of GBO film
William Mook
>
> Laser light sails are preferred. Consider
>
> http://students.cec.wustl.edu/~ktr1/Solar_Sail_GTO_RESSLER.pdf
>
Sunlight at 1,380 W/m2 produces 9 micro-Newtons per m2 when fully
reflected
A square meter of GBO film 8 microns thick of PET plastic contains 100
milligrams of material.
To accelerate this film at 1 gee requires 908.2 milli-Newtons of
force. About 1.4 million Watts per square meter.
GBO film is nearly 100% efficient reflecting bandgap matched light
from a laser tuned to operate at the same color the GBO film is
designed to reflect.
http://www.sciencemag.org/cgi/content/abstract/287/5462/2451
To accelerate 1 tonne with 27 tonnes of mirror material fabricated
into 8 micron thick GBO reflective layer means 10 square meters of
mirror are produced per gram. That's 10 square kilometers per ton.
270 square kilometers of film to accelerate 1 tonne of payload. A
disk some 10 miles in diameter.
Each square meter of film requires 1.5 MW of laser energy to
accelerate the system at one gee. It takes a month of beaming to
accelerate the system to 1/10th light speed at 1 gee. 270 million
square meters times 1.5 MW per square meter is 405 trillion watts for
about 3 million seconds. That's 1,250 million trillion joules to get
the 28 tonne system up to 1/10th light speed.
28 tonnes (28,000 kg) moving at 1/10th light speed (30,000,000 m/sec)
contain
E = 1/2 * m * V^2 = 0.5 * 28,000 * 900 trillion = 1.26 million
trillion joules
About 1/1000th the energy in the beam.
At 625,000 trillion joules per metric ton of boron, only 20 tons of
boron are needed to fuse in a fusion powered laser system. A beam
formed with a similar film to create a 10 mile wide beam - focuses a
500 nm wavelength beam 500 million miles - the distance a sail moves
over a month executing a 1 gee acceleration to 1/10th light speed.
A solar powered system operating 3 million km from the sun, intercepts
3.4 MW per square meter. At 40% efficiency, the system produces 1.5
MW per sq meter of collector area. So, the same system- without
solving the problem of fusing boron to form a beam efficiently - could
be orbited. A 30 ton payload as the 'target' and a 30 ton payload as
the laser. Both are launched into orbit and deploy. They use
sunlight to sail into a tight orbit around the sun 3 million km
radius. The laser beams energy at the target for a month - which is
driven at 10% light speed in the desired direction.
A trip to alpha centauri takes 43 years.
A slight increase in system parameters allow the attainment of 30%
light speed and a reduction of trip times to alpha centauri in 14.3
years. Which is about the experience of sending probes to the outer
planets using chemical rockets.
Launching a 30 ton payload every few months, allows reuse of the
launch system over several years.
William Mook
Laser light sails are practical for interstellar voyages at 1/3 light
speed.
Nuclear pulse rockets can only attain 1/300th light speed at best.
Laser light sails that travel between nearby stars augmented by laser
powered plasma thrusters for planetary operations is ideal.
A mobile solar (star) powered laser beam with thin film optics - very
similar to the light sail - is transported to the target star to
deploy a network of beams to support a steady traffic between nearby
stars.
David Spain
> That thing didn't work very well at all. As for the details, they are,
> quite literally, history, so maybe you should read up on that topic, hmmmmm?
>
> Also, try reading about other Gemini experiments in that area, as well as
> Skylab and the development of the shuttle MMU and SAFER.
>
> Knowledge... it makes you look smarter than ignorance.
>
When one asks a simple question a simple answer will suffice.
I didn't ask for the complete history of EVA propulsion.
Smugness doesn't tend to want me to follow any of your suggestions
regardless of their merit. How about a degree of civility?
Dave
David Spain
I have only a few comments in response to your response:
You picked the Medusa configuration for Orion, presumably because
the Wikipedia article claims this yields the highest efficiency
of the various nuclear pulse proposals, while ignoring the problem
of irradation of the spacecraft. Perhaps handled by placing shielding
at the front of the space craft rather than the pusher plate?
In any case I agree it's probably more useful to consider the best-case
design senario.
I don't have issues with your presentation of Lorentz dilation, specific
impulse or exhaust speeds. They seem OK to me. However, I'm no expert
in this area, I could be wrong to not have issues when perhaps I should
have as you pointed out in my response to Stockton. I choose not to
investigate this further as a matter of priorities on my time.
> Correct, but dealing with high temps and pressures with an impulse
> based system is pretty efficient energetically.
>
>> So today I thought of perhaps a better way to think about the problem;
>> if you're using the 'fixed-fuel' design you've actually built a
>> multi-stage rocket! Based on the fact that the materials used to build
>> the bombs were left behind on Earth! In that case you only need to
>> generate via fission enough power to operate only the electrical systems
>> of the spacecraft, presumably a much smaller reactor.
>
> The 'reactor' is a bomb otherwise you get really low power levels and
> carry huge mass penalties.
>
Well you do carry a mass penalty, but for electrical operation of the
ship's systems, having to set off bombs while the thing is not in
transit just to power a spacecraft seems like overkill to me, IMO.
>> From these principles alone, it argues in favor of pre-built
>> bombs, since we all understand the efficiencies of multi-stage rocket
>> design.
>
> Your considerations make little sense in light of real engineering
> analysis.
>
I don't see how that follows from what you presented. I'm not saying you
are wrong, I just don't see justification for that statement in what you
posted.
> Laser light sails are preferred. Consider
>
I don't disagree. On their face, light sails definitely have advantages,
however, I think light sails based systems have their own set of issues.
This topic was on nuclear pulse, however, not light sails.
Dave
William Mook
rockets. This is impractical with fission rockets or fusion rockets.
So, another method must be found. I detailed a few before and a few
more below.
Enjoy.
On Dec 1, 7:48 pm, David Spain <nos...@127.0.0.1> wrote:
> Greetings WilliamMook
>
> I have only a few comments in response to your response:
>
> You picked the Medusa configuration for Orion, presumably because
> the Wikipedia article claims this yields the highest efficiency
> of the various nuclear pulse proposals,
Because it is highest performing on fundamental principles which I
related in my post. The wiki post is accurate about this, but it was
my knowledge of the fundamentals that caused me to point to it as an
easily accessible reference.
> while ignoring the problem
> of irradation of the spacecraft.
What sources of radiation are you supposing exist? At worst a micro-
fission 'trigger' blast for a fusion pulse unit uses milli-grams of
fissile material. At best, an anti-matter trigger for a fusion pulse
unit uses no fissile material. Anti-matter radiation is primarily
pions and gamma rays, which are efficiently absorbed by the fusion
bomblet body at high compression. All radiation effects are prompt -
and well below what is naturally encountered in interplanetary and
interstellar space anyway. The use of boron or lithium deuteride as a
fusion energy source is aneutronic, producing only alpha particles
(helium 4) which are easily shielded and again well below the
background radiation given the size of the exhaust jet.
> Perhaps handled by placing shielding
> at the front of the space craft rather than the pusher plate?
No more shielding than is needed for any long-duration spacecraft.
> In any case I agree it's probably more useful to consider the best-case
> design senario.
I am making no unsupported assumptions. Remember, I did graduate work
under Dr. Turchi at the OSU working with U of Penn and USAF Phillips
Lab and CERN regarding microfission back in the day. So, I know what
I'm talking about.
> I don't have issues with your presentation of Lorentz dilation, specific
> impulse or exhaust speeds. They seem OK to me.
That's good, since they are accurate.
> However, I'm no expert
> in this area,
Understood. I am.
> I could be wrong to not have issues when perhaps I should
> have as you pointed out in my response to Stockton.
I have pointed out obvious errors in earlier posts where it was useful
to do so.
> I choose not to
> investigate this further as a matter of priorities on my time.
Yes, I spent many years in graduate school studying these topics, I
hope that you can benefit without putting in the same amount of effort
I have! lol.
> > Correct, but dealing with high temps and pressures with an impulse
> > based system is pretty efficient energetically.
>
> >> So today I thought of perhaps a better way to think about the problem;
> >> if you're using the 'fixed-fuel' design you've actually built a
> >> multi-stage rocket! Based on the fact that the materials used to build
> >> the bombs were left behind on Earth! In that case you only need to
> >> generate via fission enough power to operate only the electrical systems
> >> of the spacecraft, presumably a much smaller reactor.
>
> > The 'reactor' is a bomb otherwise you get really low power levels and
> > carry huge mass penalties.
>
> Well you do carry a mass penalty,
Yes, and that penalty is tremendous! It scales as the inverse of
fourth power of temperature by operation of Stephan-Boltzman (we are
in vacuo recall) So, the mass of a system operating at 500K is 10,000x
as massive per unit power as a system operating at 5,000K and 100
million x as massive per unit power as a system operating at 50,000K
and 1 TRILLION x as massive per unit power as a system operating at
500,000K
> but for electrical operation of the
> ship's systems, having to set off bombs while the thing is not in
> transit just to power a spacecraft seems like overkill to me, IMO.
?? Setting off propulsive units to power the ship is totally
inefficient and I never suggested that. For power in transit a beamed
energy system or small nuclear source is appropriate.
Small nuclear light bulbs are the best solution. Basically, think of
an old-style incandescent lamp. Filament temperatures are about
3,000K. These can be boosted if nuclear powered to reduce nuclear
mass. Highly enriched uranium or plutonium oxide and is mixed with
another moderating material in the right proportion formed into a
sufficiently thick wire and coated with a neutron reflecting material
whose neutron opacity varies with temperature. A short segment of
this wire once fabricated will rise to 3,000K or more and continue to
glow like that for hundreds of years without any active control, all
control is built into the way its fabricated.
The wire is placed into a tube of molten lithium sandwiched between
two dichroic windows at an appropriate distance to maintain ideal
operating temperature. At an appropriate distance, a cylinder of high-
intensity photocells surrounds the glowing wire segment. The PV cells
also have an appropriate window to reflect ineffective photons back to
the center. The PV cells are spaced so that their area allows
radiating all the waste heat at 300K junction temperature.
In this way I create a 'power tube' - a nuclear light bulb - that is
about 1/10,000th the mass of a conventional nuclear generator per watt
of output, and in vacuum is very highly efficient and provides
tremendous electrical power for hundreds if not thousands of years
with no moving parts.
>
> >> From these principles alone, it argues in favor of pre-built
> >> bombs, since we all understand the efficiencies of multi-stage rocket
> >> design.
>
> > Your considerations make little sense in light of real engineering
> > analysis.
>
> I don't see how that follows from what you presented. I'm not saying you
> are wrong, I just don't see justification for that statement in what you
> posted.
Well, if you won't take the trouble to educate yourself, and you don't
understand the comments of someone who is educated and has troubled
themselves to explain to you where you got it wrong, I don't know what
else to say. I don't mean any disrespect, you said it at the outset,
you haven't put in the time, and I have.
Multi-stage rockets have nothing to do with bombs being pre-built or
otherwise. Multi-stage rockets are called for whenever travel to many
times the exhaust speed of the rocket is desired. The exhaust speed
of a nuclear fission pulse rocket is 50 km/sec. The exhaust speed of
a nuclear fusion pulse rocket is 1,000 km/sec. The exhaust speed of
an anti-matter rocket varies from 10,000 km/sec to 300,000 km/sec
depending on storage method (we used Penning traps). The exhaust
speed of a photon rocket is the speed of light 300,000 km/sec.
So, if you want to travel at 10% the speed of light 30,000 km/sec you
cannot do it with nuclear rockets. 1% the speed of light 3,000 km/sec
is achievable with multi-stage nuclear rockets of the fusion variety
(not the fission variety) A nuclear ramjet (Bussard ramjet) *IS*
capable of speeds exceeding 1% the speed of light with low exhaust
speeds, because it is a jet, not a rocket strictly speaking. The
speed depends on a number of factors, not the least of which is the
density of fuel, its speed relative to the spacecraft, and so forth.
Combined systems are interesting. For example, ejecting fuel pellets
from Saturn at very high speeds so they arrive in front of a fusion
powered rocket that scoops them up and ejects them.
Also, there are rocket free systems. Like laser light sails and other
methods.
One interesting method is two massive objects orbiting one another at
very high speed - an object falling into the pair can be ejected at
very high speed along any line in the plane of rotation - and even
along a wedge with a narrow opening angle around the plane of rotation
- by controlling the timing and direction of their arrival. A
computer with detailed timing data from each of the moving masses can
compute the rocket thrust needed to fall through the pair at high
speed and be ejected at 10% or more the speed of light with very
little fuel.
The cool part, is that a similar system at the 'target' star would be
monitored and the precise arrival time and direction would be
programmed to slow spacecraft from its high speed to planetary
speeds!
Here rockets would be used as course correction only.
Another cool feature is that the kinetic energy in the vehicle would
be stored in the rotating masses and retrieved by the original system
at Earth when the vehicle returned.
And a yet another cool feature is that the bulk of the acceleration
would occur in seconds to hours and the vehicle would be in free fall
- with only tidal forces acting.
> > Laser light sails are preferred. Consider
>
> I don't disagree. On their face, light sails definitely have advantages,
Yes, and unlike the super-dense objects imagined above we can build
them with technology we know how to build today.
> however, I think light sails based systems have their own set of issues.
All engineering, like all productive skills, have a set of issues.
Mastery of those issues, like playing a piano well, or doing anything
well, takes time and effort and imagination.
> This topic was on nuclear pulse, however, not light sails.
The topic was getting to 10% light speed. You cannot do it even with
multi-stage nuclear rockets. You can do it with appropriately
designed SYSTEMS involving fusion rockets and electromagnetic
launchers that toss fusion pulse units TO the rockets. But this is
clearly a variant of beamed power. Shooting nuclear fusion pulse
units at 10% the speed of light accurately toward a receding
spacecraft - and getting it to blow up behind the pusher plate in a
way that delivers useful thrust - would involve a short range version
of laser light sail. So, this is what I described.
I think 30% light speed is the magic figure. Even at this speed
dilation is only 4.8% - which means Newtonian mechanics dominates.
But, trip times only 3x the distance in light years - which is a
reasonable figure for nearby stars since trip times are on the order
of present-day trips to the outer planets by Hohmann Transfer orbits.
> Dave
I didn't mean any disrespect in what I've said to you - however,
politely accepting balderdash isn't useful if we want to really
understand what is possible.
The Superconducting Supercollider - if it were to have been built -
may have been able to bring in a new age of physics. Things it would
be capable of doing is;
1) detailed fundamental physics at a very high energy giving new
understanding of fundamentals
2) expanded our understanding of building practical anti-matter
machinery
a) low cost antimatter would be able to trigger tiny fusion
blasts making tiny
ICF (perhaps even sized to home use) a reality.
3) expanded our understanding of high-energy phenomenon -
a) creating minature black holes on demand
which would allow us to gain the basics of black hole
engineering.
When I attended the switch-on ceremony for Paul Horowitz's project
BETA back in the '80s, I spent a fruitful week of discussion with
Robert Forward, Carl Sagan, and others, detailing what might be
possible with black hole 'dusts' - collections of charged, spinning,
and moving black holes made on demand. Some of the outcomes of making
only a few tiny black holes were;
a) black hole 'forge' - that absorbed iron-56 and efficiently
produced a stream of engineered black holes.
b) black hole 'reactor' - that absorbed any material and efficiently
produced a stream of engineered photons, or neutrinos, or other
particles - that allowed efficient conversion of bulk matter into a
variety of energy forms. A neutrino stream makes a very interesting
variant of photon rocket - whose exhaust is invisible to normal
matter! - thrust but no exhaust port! This inspired Barnie Oliver to
work out the details of relativistic rocketry.
http://frontal-lobe.info/boliver/space.html
And conclude radio was far more efficient!
calteches.library.caltech.edu/357/01/extraterrestrial.pdf
c) black hole 'gun' - which I described above. Basically, two or more
super-dense objects orbit one another at optical speeds, and a
spacecraft navigates through the system to be ejected at optical
speeds with very little input of energy. The engineered collection of
black holes that form each of the rotating masses can be fed iron-56
to power rockets on board to keep them from over-spinning or under-
spinning. Of course in a robust system of transport, 'gateways'
receive energy from moving ships slowing to planetary speeds and
expend energy ejecting ships at interstellar speeds. Time dilation at
90% the speed of light or more makes journeys on board very short for
the travellers.
Speed Dilation Trip Time Trip Time
c factor Earth Ship
years years
0.90000 0.4359 4.778 2.083
0.99000 0.1411 4.343 0.613 (7.4 mos)
0.99900 0.0447 4.304 0.192 (2.3 mos)
0.99990 0.0141 4.300 0.061 (3.1 wks)
0.99999 0.0045 4.300 0.019 (1.0 wks)
So, we can imagine three to six gateways in orbit out in the Kuiper
belt. Ships use neutrino rockets to leave Earth or other centers of
human development in the solar system, and accelerate to about 3% the
speed of light - continually at 1 gee - taking about 10 days to reach
one of the gateways. Thrust is varied slightly over the 10 day period
so that the timing and direction of arrival tosses the ship at 99.999%
the speed of light. The occupants feel a little squeeze inside from
the intense but exceedingly brief tidal pulse. The ship continues its
1 gee acceleration for the 10 ship board days of the journey - adding
another 3% light speed to its speed - but the DIRECTION if varied so
that it arrives precisely at the time - speed and direction of the
'target' star's gateway - so that the ship slows to interplanetary
speeds (below 3% light speed) around the target star. The ship then
navigates along a 1 gee trajectory coming to rest at the remote star's
human habitation centers.
Total delta vee of the neutrino rocket portion is 9% to 10% the speed
of light, which for a neutrino rocket that efficiently converts matter
to energy requires a propellant fraction (which could be bulk iron
evaporated into a beam that is 'processed' by an engineered collection
of minature black holes) of 9.5% - So a 20 ton spacecraft need only
carry 1.9 tons of iron which is a cube only 0.5 meters (1.8 ft) on a
side. In practice it would be a spool of wire fed to an evaporator
that interfaced with the bhd array.
These highly speculative imaginings require only construction of a
superconducting supercollider or some larger variant - and funding the
research programs outlined. The moon, being airless, has been
proposed as a site of a very large - moon encircling - particle
accelerator - that would be surprisingly inexpensive - relative to a
moon base cost - and produce astounding engineering and scientific
benefits - which likely will have the benefits outlined here in some
shape or form.
It is important to note none of these speculations violate the known
laws of physics, or even require anything outlandish in the way of
engineering or scientific development.
William Mook
sphere 7 cm (2.75 inches) in diameter! At 3,000K this radiates with a
power rating slightly in excess of 70,000 watts. This is 10 kW per
kg!
A PV shell 10 x larger than the nuclear 'filament' converts the
effective photons to DC electricity efficiently with no moving parts.
This means a 7 cm filament requires a 0.7 meter diameter PV shell
assuming 90% net efficiency.
2,744 of these spheres are packed into a 10 meter cube massing 19.2
tons and produce 193 megawatts electrical with no moving parts.
Increasing operating temperature to 5,000K increases power output per
unit weight 7.77 x but total size of the system is increased since
more PV is needed. even while system mass falls below 3 tons for the
nearly 200 MW system.
Nuclide Critical Mass Diameter
(kg) (cm)
protactinium-231........750±180? 45±3?
uranium-233...............15 11
uranium-235...............52 17
neptunium-236............ 7 8.7
neptunium-237............60 18
plutonium-238............. 9.04–10.07 9.5-9.9
plutonium-239.............10 9.9
plutonium-240.............40 15
plutonium-241.............12 10.5
plutonium-242 75–100 19-21
americium-241 55–77 20-23
americium-242m 9–14 11-13
americium-243 180–280 30-35
curium-243 7.34–10 10-11
curium-244 (13.5)–30 (12.4)–16
curium-245 9.41–12.3 11-12
curium-246 39–70.1 18-21
curium-247 6.94–7.06 9.9
californium-249 6 9
californium-251 5 8.5
William Mook
I see the following development arcs;
MEMS based rockets, MEMs based inertial guidance, MEMS based life
support, etc.
Conventional liquid fuel rockets built with MEMs components around
existing aeroshell and tankage technology.
Creation of fully reusable cryogenic and non-cryogenic liquid fuel
rockets with aforementioned components.
1) commercial moon tourism flights
2) development of global wireless hotspot
Meanwhile, large terrestrial solar arrays using ultra-low-cost solar
energy technology produce hydrogen (200 kg per acre per day) to
displace coal in coal fired power plants, and also to combine with
stranded coal to make synfuels (gasoline, diesel fuel, jet fuel) to
displace conventional fuels.
3) development of space based solar pumped IR laser operating at 1,000
nm - This increases hydrogen production at terrestrial sites to 4,000
kg per acre per day - far surpassing carbon based synfuel and
supporting a hydrogen economy.
4) use of space based solar pumped IR lasers to drive MEMs based
plasma engine array powered spacecraft expanding presence in space and
use of spacecraft in every day life.
http://www.nasa.gov/centers/ames/research/technology-onepagers/arcjetcomplex.html
Development of super energetic super-collider to explore anti-matter
and minature black hole production (possibly on the lunar surface)
5) solar power satellite optics for beaming IR energy interplanetary
distances
6) use of solar sail technology to move power sats into close solar
orbit rising to TW levels
7) beam high intensity laser energy around solar system in support of
interplanetary commerce
8) solar power satellite optics for beaming IR energy interstellar
distances
9) expand size of solar orbiting infrastructure to quadrillion watt
level.
10) develop laser driven light sail technology
11) multi-stage laser light sail
12) dispatch laser beaming systems to remote star systems for two-way
interstellar commerce.
At this point we have achieved a transport system that allows commerce
between stars at 1/3 light speed.
If the development of black hole based technology is successful along
the lines described (or others) then we can imagine building black
hole forges at Sol and any star system we have reached, and with these
support 30 day journeys between star using extreme dilation to good
advantage.
So, we have an expanding shell moving outward at 1/3 light speed and a
network of high speed 'gates' consisting of two black hole bodies
orbiting one another at near light speed - large enough to dispatch a
reasonably sized ship at very nearly light speed.
Period Number Spanning time
50 years 1,200 stars 5 months
100 years 9,200 stars 11 months
150 years 33,500 stars 16 months
200 years 79,400 stars 21 months
250 years 155,100 stars 27 months
300 years 268,100 stars 32 months
Assuming we started expanding along these lines in 2050 - a three year
journey to the 'rim' and back in 2350 that took three years ship time,
would return the crew and passengers to Earth in 2650 - so travel deep
into space and back would also be travel into the future as Einstein
predicted.
Doug Freyburger
>
> 12) dispatch laser beaming systems to remote star systems for two-way
> interstellar commerce.
>
> At this point we have achieved a transport system that allows commerce
> between stars at 1/3 light speed.
>
> If the development of black hole based technology is successful along
> the lines described (or others) then we can imagine building black
> hole forges at Sol and any star system we have reached, and with these
> support 30 day journeys between star using extreme dilation to good
> advantage.
>
> So, we have an expanding shell moving outward at 1/3 light speed and a
> network of high speed 'gates' consisting of two black hole bodies
> orbiting one another at near light speed - large enough to dispatch a
> reasonably sized ship at very nearly light speed.
The black holes orbitting each other would have tides strong enough to
atomize any ship. Building them big enough to not have that problem
would take many solar masses.
> Period Number Spanning time
>
> 50 years 1,200 stars 5 months
> 100 years 9,200 stars 11 months
> 150 years 33,500 stars 16 months
> 200 years 79,400 stars 21 months
> 250 years 155,100 stars 27 months
> 300 years 268,100 stars 32 months
>
> Assuming we started expanding along these lines in 2050 - a three year
> journey to the 'rim' and back in 2350 that took three years ship time,
> would return the crew and passengers to Earth in 2650 - so travel deep
> into space and back would also be travel into the future as Einstein
> predicted.
If a species developed interstellar travel, how long would it take to
span a galaxy? Depending on the numbers it ends up anywhere in the 1
million to 20 million year range. That's long enough for species to
differentiate but short in comparison to the lives of stars.
The fact that we have not seen aliens suggests that no species has
developed interstellar travel, or they are now extinct and we have
evolved since thei last visit (consistant with the 20 million year time
span), or they do not visit planets like Earth routinely.
I have considered fusion drives that can propel ships to well under %1
of C. Such ships would give us access to the comets in the Kuiper belt
and Oort cloud. The Oort cloud is far enough from the Sun that solar
radiation would require much less shielding than travel in the inner
systems. The comets in the Oort cloud are so far apart that fusion
drives would be needed for commerce, but once out there the total
resources available there would be far larger than the total resources
available on the surfaces of planets. Also comets may thinly fill all
of interstellar space not just be bound to stars.
When I think that through I think that once out away from the Sun
there's no longer much incentive to go star to star. Comet to comet is
closer, less resource intensive, and less limited. I suspect that
interstellar civilizations end up nearly ignoring inner solar systems,
if any such civilizations exist.
If civilizations use comets in interstellar space, they would span a
galaxy in a time scale of 10s of millions of years. They should be
visible from there fusion flames, shouldn't they? We don't see fusion
flames.
That's as far as I had considered until you mentioned neutrino jets for
propulsion. We would not see such flames without a lot more effort than
pointing telescopes and looking for light or looking for X-ray and gamma
ray bursts with satellite telescopes. Satellite telescopes do see X-ray
and gamma ray burst that are currently attributed to natural events.
Could they be fusion flames? But if neutrinos could be used for
propulsion there would be no fusion flames.
How to focus both the neutrinos and anti-neutinos to eject in the same
direction to make neutrinos into a rocket flame? They would tend to be
created in matched pairs going in opposite directions so they would tend
to cancel out. Solve that problem, find a way to generate lots of them,
and neutrino rockets could work very well. Extremely advanced science
and technology compared to our current level - Using fusion torches to
go comet to comet is much closer to our current level.
BradGuth
Mook doesn't like iron thrusters either, especially radon ion
thrusters that can obtain an exit velocity of 0.5 c. Our moon has
radium, but we can't seem to safely get ourselves to/from our moon.
A sizable reactor for making energy that's intended for large area ion
thrusters, seems viable.
~ BG
William Mook
Brad means ion thrusters. Brad doesn't know what he's talking about
either. Like? What does liking a thing have to do with its utility
or workability? A thing works or doesn't work. What Brad describes
cannot work. That has nothing to do with whether I like it or not!
lol. Brad worries about his popularity when he should worry about
feasability based on clear engineering analysis.
> especially radon ion
> thrusters that can obtain an exit velocity of 0.5 c.
Radon ion-thrusters? Have any been made? Operated? No. Why not?
Because what Brad claims about this process isn't true.
In addition, Brad obviously doesn't know the difference between
radioactive decay and a self-sustaining nuclear reaction. Radioactive
decay is a spontaneous natural process that cannot be modified in any
way known to humanity. Nuclear reactions are controllable and achieve
the power levels useful for nuclear propulsion.
http://www.radonguide.com/radon-decay-chain.html
http://en.wikipedia.org/wiki/Radioactive_decay
http://en.wikipedia.org/wiki/Nuclear_fission
Brad in stating that electrons are emitted at 1/2 light speed is
referring to a synthetic radon isotope weighing 224 atomic mass units
that decays naturally into Francium also weighing 224 atomic mass
units after emitting a pair of electrons each massing 1/1836th atomic
mass unit at 0.8 MeV.
This occurs by natural radioactive decay of this isotope of Radon gas
with a half-life of 1.8 hours.
Brad is right about the electron is moving at nearly half the speed of
light. Sure the electrons are easily collimated by external fields.
But as a rocket, it sucks for three reasons;
1) the power level is too low, declining and uncontrollable;
2) the ratio of masses between the ejected material and stationary
material is too low;
3) electrons are not very penetrating, so the film of radon must be
thin enough to let the electrons escape.
An array of very thin tubes containing radon gas at high pressure,
each contained in an electret reflector in back of it to collimate
electrons moving at half light speed, provides the lightest system
possible.
http://en.wikipedia.org/wiki/Electret
Not counting the weight of the tubes, and field generators, just
imagining 1 gram of radon-218 no more than 10 micro-grams of electrons
are available to be ejected over the history of the universe - with
half of them ejected in 1.8 hours, and 1/4 of them ejected in the next
1.8 hours, and 1/8th of them ejected in the third 1.8 hours, and so
forth...
So, imagine we assemble this contraption in zero-gee and send it on
its way all in far less than 1.8 hours - because of the unalterable
decay rate... and so, without counting the mass of the tubes and
field generators, we have as an estimate;
MV = mv
1 gram * V = 1/100,000 gram * 0.5 c
V = 1/200,000 c = 1.5 km/sec
Given the density of the GAS and the requirement to contain it in
tubes, and deflect it with electric or magnetic fields - and the fact
that the tubes will absorb a fraction of the electrons - and the rate
of decay drops to half every 1.8 hours - any real system is likely to
be reduced by a factor of 1,000 so; the top speed, would be 1.5 meters
per second... under even the best of conditions.
> Our moon has
> radium,
So? Brad is talking about Radon 218 - which is a MINOR decay product
synthesize by a nuclear reaction of Plutonium.
> but we can't seem to safely get ourselves to/from our moon.
Brad's fixed belief that Apollo program didn't send twelve American
heroes to the moon is clear evidence of his mental instability and
abject lack of patriotism.
Name Mission Lunar EVA dates Employer
1. Neil Armstrong Apollo 11 Jul 21, 1969 NASA
2. Buzz Aldrin Apollo 11 Jul 21, 1969 Air Force
3. Pete Conrad Apollo 12 Nov 19–20, 1969 Navy
4. Alan Bean Apollo 12 Nov 19–20, 1969 Navy
5. Alan Shepard Apollo 14 Feb 5–6, 1971 Navy
6. Edgar Mitchell Apollo 14 Feb 5–6, 1971 Navy
7. David Scott Apollo 15 Jul 31 – Aug 2, 1971 Air Force
8. James Irwin Apollo 15 Jul 31 – Aug 2, 1971 Air Force
9. John W. Young Apollo 16 Apr 21–23, 1972 Navy
10. Charles Duke Apollo 16 Apr 21–23, 1972 Air Force
11. Eugene Cernan Apollo 17 Dec 11–14, 1972 Navy
12. Harrison Schmitt Apollo 17 Dec 11–14, 1972 NASA
> A sizable reactor for making energy that's intended for large area ion
> thrusters, seems viable.
No it doesn't. Brad's talking about carrying along a reactor to MAKE
radon 218! haha - Radon 218 is a MINOR constituent of any reaction.
The addition of a reactor to make radon 218 and flood the system
mentioned with the gas, at a rate needed to replace the spent gas
following its natural decay REDUCES speed by increasing the mass of
the system 10x to 100x.
Also, the POWER of the reactor is far far greater than the power of
the electron beam. So much greater that if you're going to the
trouble to carry a reactor with you, it is far better used to generate
thrust by radiating HEAT the reactor makes. HEAT which uses photons
that move AT THE SPEED OF LIGHT! Twice as fast as the electrons.
http://en.wikipedia.org/wiki/Nuclear_photonic_rocket
Here black body radiation from a hot nuclear reaction is collimated by
a mirror to produce thrust. The THRUST is higher, the system can
actually be engineered and built, and the FINAL speed is higher.
This system, using nuclear fission, the same reaction Brad wants to
tap into to gather Radon 218 to make a very inefficient rocket, allows
rockets that travel up to 300 km/sec - instead of 1.5 m/sec Brad's
proposed system. A fusion reaction allows rockets that travel up to
3,000 km/sec. Taking a store of anti-hydrogen and beaming it into a
tungten block, allows travel up to 30,000 km/sec.
These are all more interesting than Brad's unworkable proposal, but
far less interesting than laser light sail and laser propulsion
methods which are capable of attaining 100,000 km/sec speeds.
http://en.wikipedia.org/wiki/Laser_propulsion
http://www.youtube.com/watch?v=LAdj6vpYppA
> ~ BG
I have repeated these facts to Brad over several years. Brad has
ignored these facts and refused to educate himself preferring to spin
along in ignorance.
William Mook
world today. The United Nations could enter into an agreement to rid
the world of this material and convert it into non-threatening anti-
matter catalyzed trigger units to detonate lithium-deuteride
propulsive units.
This fuel supply would dispatch a large fleet of nuclear pulse
spacecraft and erect a large industrial infrastructure off-world.
Nuclear material production within Earth's biosphere would end and be
transferred to an international organization that would operate on the
moon. The nuclear pulse fleet would return to the moon, for
refueling, to sustain a solar system wide network of bases and
operations. After their initial launch, all operations and support
would be transferred to the moon - and nuclear vehicles would not
operate within 3 Earth radii of Earth's surface without special
permission. Transport from Earth surface to the moon would occur by
chemical rockets or laser rockets.
Off world infrastructure includes; power satellite network, orbiting
solar-powered tele-operated factory network, return of rich asteroid
feedstock to Earth orbit, global wireless hotspot, lunar mining, lunar
factories, lunar research reactors, (in support of nuclear pulse
fleet), mars base, venus base (floating in venus atmosphere) mercury
base, Ceres base, Jovian base (on moons), Saturn base (on moons),
Neptune base (on moons and floating in atmosphere) Pluto base, 50000
Quaor base (etc.)
A steady stream of rich materials flowing from the asteroid belt to
Earth orbit, is processed into goods and products by an orbiting
teleoperated factory infrastructure. Products, food, clothing, all
manner of things rain down from this orbiting network. Satellite
telephones and satellite telerobotics allow people to place orders and
to obtain work, anywhere in the world. The same technology that
allows GPS guidance, also guides products from orbit directly to end
users. As a result, all factories, all refineries, all processing
plants, all mines, all industrial forests, all farms, are removed from
Earth, and the only remaining thing on Earth is a planetwide
residential park and nature preserve. Waste is gathered and returned
to orbit using low cost laser propelled light craft - obtaining energy
from orbit.
http://www.youtube.com/watch?v=LAdj6vpYppA
A fleet of 60 super-Orion spacecraft is proposed by the USA, and
participation in this program is offered to anyone who signs an
enhanced non-proliferation treaty. This turns over nuclear materials
to an international body, for conversion into nuclear pulse units, and
limits the rights of signers to make more on Earth, while giving them
rights to make more materials on the lunar surface, within the context
of an international nuclear research center. Signers also have rights
to operate nuclear pulse vehicles beyond Earth, and own property off-
world in contravention to existing outer space treaties, and agree to
abide by certain rules of the road for interplanetary development.
Doug Freyburger
>
> Name Mission Lunar EVA dates Employer
> 1. Neil Armstrong Apollo 11 Jul 21, 1969 NASA
> 2. Buzz Aldrin Apollo 11 Jul 21, 1969 Air Force
> 3. Pete Conrad Apollo 12 Nov 19–20, 1969 Navy
> 4. Alan Bean Apollo 12 Nov 19–20, 1969 Navy
> 5. Alan Shepard Apollo 14 Feb 5–6, 1971 Navy
> 6. Edgar Mitchell Apollo 14 Feb 5–6, 1971 Navy
> 7. David Scott Apollo 15 Jul 31 – Aug 2, 1971 Air Force
> 8. James Irwin Apollo 15 Jul 31 – Aug 2, 1971 Air Force
> 9. John W. Young Apollo 16 Apr 21–23, 1972 Navy
> 10. Charles Duke Apollo 16 Apr 21–23, 1972 Air Force
> 11. Eugene Cernan Apollo 17 Dec 11–14, 1972 Navy
> 12. Harrison Schmitt Apollo 17 Dec 11–14, 1972 NASA
Current score - Navy 6, Air Force 4, civilians 2. Fly Navy!
BradGuth
>
> Brad means ion thrusters. Brad doesn't know what he's talking about
> either. Like? What does liking a thing have to do with its utility
> or workability? A thing works or doesn't work. What Brad describes
> cannot work. That has nothing to do with whether I like it or not!
> lol. Brad worries about his popularity when he should worry about
> feasability based on clear engineering analysis.
>
> > especially radon ion
> > thrusters that can obtain an exit velocity of 0.5 c.
>
> Radon ion-thrusters? Have any been made? Operated? No. Why not?
> Because what Brad claims about this process isn't true.
>
> In addition, Brad obviously doesn't know the difference between
> radioactive decay and a self-sustaining nuclear reaction. Radioactive
> decay is a spontaneous natural process that cannot be modified in any
> way known to humanity. Nuclear reactions are controllable and achieve
> the power levels useful for nuclear propulsion.
>
>
> > ~ BG
>
> I have repeated these facts to Brad over several years. Brad has
> ignored these facts and refused to educate himself preferring to spin
> along in ignorance.
I intentionally ignore nothing. I just selectively elect to filter
out or exclude all the usual negatives and perpetual or systematic
naysay by those that continually believe in and otherwise hype each
and every faith-based and government published word, as though it were
the one and only interpretation in town (even though the best
available independent science is not supportive).
btw; our moon(Selene) has lots of radium, not that Earth is without
its fair share. So, there's no shortage of sufficient radium for
creating a continuous supply of radon gas that can be utilized as
Rn222/ion thruster fuel.
What's needed on the moon is a reasonably large scale robotic tunnel
boring machine, and of course a fleet of actual fly-by-rocket landers
that should have existed as of decades ago.
Going after rogue asteroids is crazy business (even if it's headed our
way), especially when we have one that's worth 7.35e22 kg that's
currently in a stable orbit as is, not to mention its nifty L1 that
should be fully utilized.
~ BG