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zebo-the-fat
2007-Jun-30, 10:46 PM
NASA may be considering the old NERVA nuke rocket design for future Moon trips
Link http://space.newscientist.com/article.ns?id=dn12148&feedId=space_rss20

Good idea or not?

Noclevername
2007-Jun-30, 11:25 PM
NASA may be considering the old NERVA nuke rocket design for future Moon trips
Link http://space.newscientist.com/article.ns?id=dn12148&feedId=space_rss20

Good idea or not?

The article doesn't say that NASA is actually considering it. Only that Howe is saying they could.

JustAFriend
2007-Jul-01, 02:40 AM
Nuclear rockets just aren't needed to get to the moon. And they'd leave a lot of junk you don't want around when the next crew went.

...now if you want to send a manned mission to Jupiter or Saturn ala "2001".....

Romanus
2007-Jul-01, 04:30 AM
^
Ditto.

Though I'm a big fan of nuclear-thermal propulsion, its strengths would be wasted for a target as close as the Moon.

manmeetvirdi
2007-Jul-01, 12:03 PM
Perhaps Nuclear power should be and is being used where sun light is not an option,example:Voyager1, Voyager2
Is NASA is still receving the signals from these spacecraft? !!!

Noclevername
2007-Jul-01, 12:34 PM
http://en.wikipedia.org/wiki/Voyager_1
http://en.wikipedia.org/wiki/Voyager_2

Zachary
2007-Jul-04, 02:16 PM
Nuclear rockets just aren't needed to get to the moon. And they'd leave a lot of junk you don't want around when the next crew went.

...now if you want to send a manned mission to Jupiter or Saturn ala "2001".....

True, but getting to the moon is a perfect opportunity to test and develop the technology.

I think it's a great idea, but I'm almost certain the 'anything nuclear is bad' crowd will stop this from happening :(

Nicolas
2007-Jul-04, 02:33 PM
The fact that not all nuclear is bad does not mean that all nuclear is good :).

We need to consider things very well before using this kind of technology.

sts60
2007-Jul-05, 05:53 PM
Perhaps Nuclear power should be and is being used where sun light is not an option

Radioisotope thermoelectric generators* (RTGs) are routinely used for missions to the outer solar system (Jupiter and beyond). Cassini, orbiting Saturn, uses such generators. Galileo, which was intentionally plunged into Jupiter after completing its mission, did as well. Also Ulysses (which swung around Jupiter to go into a solar-polar orbit) and New Horizons (currently on its way to Pluto and points beyond).

...example:Voyager1, Voyager2
Is NASA is still receving the signals from these spacecraft? !!!

Yes indeed, and will for some time. RTGs in general lose power slowly, due to decay of the plutonium fuel (half-life 87.7 years) and degradation of the thermoelectric materials. But no spacecraft RTG has ever failed prematurely.

Other uses for RTGs are closer in. The MSL-09 Mars rover will use a new model of RTG, because it needs more power than solar cells can conveniently provide. The ALSEP experiments placed on the Moon during Apollo used RTGs to operate through the two-week day/night cycle (which tends to kill solar cells anyway). And even the solar-powered Mars rovers (Sojourner, Spirit, Opportunity) use small isotope heat sources to keep their electronics alive during the frigid Martian night.

There are quite a few other spacecraft which have been launched with RTGs or survival heat sources, but you get the idea.

*Note that isotope-powered systems are not reactors, but simply use the heat generated by natural decay of radioisotopes. The Soviets/Russians have used reactors aboard a number of their intelligence satellites, but the U.S. has launched only one experimental reactor (SNAP-10A back in the '60s).

eburacum45
2007-Jul-08, 10:59 AM
Nuclear rockets to the Moon might not be a sensible option, but nuclear rockets from the Moon might. There is a certain amount of uranium in the Moon's crust in the rocks known as KREEP (http://www.lunarpedia.org/index.php?title=KREEP); eventually it could be mined, refined and used to power NERVA-type (or more advanced) nuclear rockets.

I doubt that fissile material will ever be shipped in bulk off the surface of the Earth (the various regulatory bodies will prevent that, to prevent accidents during launch), so fission rockets in space are a non-starter- unless uranium can be extracted from the Moon (or elsewhere).

Graham2001
2007-Jul-08, 03:34 PM
*Note that isotope-powered systems are not reactors, but simply use the heat generated by natural decay of radioisotopes. The Soviets/Russians have used reactors aboard a number of their intelligence satellites, but the U.S. has launched only one experimental reactor (SNAP-10A back in the '60s).

Indeed, but NASA did have plans to use reactors in space, on the NTRS are a couple of documents from 1965/66, dealing with a planned Nuclear-Ion driven Lunar Logistics craft, interestingly the reactor portion of the craft is not dissimilar to the reactor portion of the Soviet RORSATS (See: Svens Space Place (http://www.svengrahn.pp.se/trackind/RORSAT/RORSAT.html) for a picture). However the designers considered it an interim solution until a Solar-Ion driven craft was developed.

For anyone whose interested the two reports are:

1. Electrically-propelled cargo vehicle for sustained lunar supply operations, Final report (http://tinyurl.com/24ewqc)(18.6)

2. Electrically-propelled cargo vehicle for sustained lunar supply operations, Summary report (http://tinyurl.com/ytnmjs)(3.8mb)

The summary report is the one that discusses the option of using Solar-Ion engines instead of/as successors to the Nuclear-Ion engines.

publiusr
2007-Jul-21, 07:05 PM
I like NTR better than NTP myself. Using a Lox afterburner, you combine both chemical and nuclear propulsion with superheated steam as the only exhaust product.

http://www.nss.org/settlement/moon/LANTR.html
http://www.abo.fi/~mlindroo/Station/Slides/sld051p.htm

Ares V's wider core works to the advantage of NTR upper stage diameters, with 12 meter hammerheads not out of the question.

The ultimate Ares V mission is to have a hydro/lox NTR upper stage and an NEP/ion payload for an interstellar precursor mission to go screaming out of the Solar system.

And you thought New Horizons was fast...

John F
2009-Feb-10, 11:38 PM
This article just restated what's been known for decades. Nuclear propulsion makes sense as an investment, but only if you really intend on getting there & getting things done.

JustAFriend(01-July-07): Nuclear rockets just aren't needed to get to the moon. And they'd leave a lot of junk you don't want around when the next crew went. ...now if you want to send a manned mission to Jupiter or Saturn ala "2001".....Romanus ^ Ditto. Though I'm a big fan of nuclear-thermal propulsion, its strengths would be wasted for a target as close as the Moon.
I lean quite a bit the other way, further towards nuclear power than most.
I also remember reading that while the screenplay for 2001 was being written, Clarke was relieved to hear about Orion, because finally he had a plausible way to explain the trip across the solar system as described for the characters. Kubric and the art department's budget nixed the idea of depicting it. Clarke seemed to avoid discussion of what Discovery actually used, in the final form of the book.
Especially LOX Augmented "afterburning" NTRs are just the thing for Cis-Lunar traffic (at least until a full tether transport system is built up from Lunar or asteroid resources. The recent article on LANTRs allowing cheap 24-hour commuter travel to the Moon shows that even if we had a full inner-solar system tether system for small cargo, nuclear power still makes sense for passenger travel. Limit the time for low/micro-G adaptation, and radiation exposure.)
Even better if it's tri-modal, to produce power for emplacements (especially fuel production) and NEP super efficiency rockets.
This range of thrust/isp trade-offs allows performance equal to VASIMR, and is just about good for crewed high fuel mass-fraction trips to Mars, using aerobraking to help get into Mars orbit for a ~90 day trip.
Anything to Jupiter or Saturn, or fast or high cargo mass-fraction to Mars is going to have to be external-pulse plasma rocket (Orion-ish), or solar sails.
LANTR might also suffice for the big slowboat supply emplacement on an NEA, but for crewed travel on interplanetary trajectories, we can't afford to mess around. Time spent in interplanetary space is the threat, which must be avoided.
Also we continuallty hear that we just aren't technically capable of doing trips to Mars or beyond because the travel times are too long. We must wait for medical miracles, or breakthroughs in launch technology to bring the cost down to $1 per kg, or warp speed or Elvis or whatever. No, we just need a "breakthrough" in throwing 40kilo kegs aft every 10 seconds, and spraying a grease-mist over a steel plate in between pulses. Also a "breakthrough" in accepting that a multinational mission of exploration using EPPP is not a threat to treaties against nuclear weapons in space. (seems a bit easier to innovate than nuclear gas core or light bulb or salt water or even VASIMR, which needs extremely hot plasma in close proximity to structural materials, and a large fission reactor.)
A stripped EPPP upper stage sent up on an Ares-V (like the Orion 10 meter upper stages segments for a space-assembled ship) could just jump across interplanetary space ignoring orbital periods and leaving when Mars is directly in opposition, getting the crew transfer hab there in as little as 21 days (~120 km/sec mission Delta-V).
Lower cargo-mass-fraction trips use EPPP for quick jumps, while cargo trips can arrive at Jupiter with ~60% cargo. The Moon's surface (jettisoning the NTR engine and exposing landing rockets) still of around 70% EO departure mass.


And seriously, for interplanetary travel, is radiation leakage or EPPP a problem (blowing off a kilo or so of weapons-grade fissionables every few seconds)? Interplanetary space as a radiation environment makes the Elephant's Foot at Chernobyl #4 look no more than rather toasty.
Put a soccer ball in the middle of the pitch, and a pea at the goal line, and you've fairly accurately modeled the Earth-Sun inner solar system. Now picture solar prominences as Earth-ocean masses of mostly radioactive stuff, blasting out at ~600 km/sec, buffeting Jupiter's mighty magnetosphere at 5AU, which sweeps out and can rattle Saturn at 10AU if Jupiter was sweeping past.
Nothing we can do would affect that.
If we tried to "pollute" space, we could devote all our species' effort to it for a few centuries and vaporize the Earth in the process, and only make a temporary and minor change.

If the objection is brought up of the dangers of launching nuclear materials and possible launch failures, I remind them that the crew of the Challenger survived the break-up of their vehicle. 2.5 minutes later, hitting the ocean 9.5 miles down is what killed them. External parts of the Challenger from near the engines and ET showed no sign of explosive damage, and very little fire. Also the recent report on the survivability of the Columbia crew showed that even they survived a while after the break up, until aerodynamic mechanical & thermal stresses tore the crew compartment apart & killed them. Many parts of Columbia and the crew compartment of the vehicle were practically unaffected, and worms in a science payload package survived. Water tanks from Skylab fell in from orbit, recognizable.

Nuclear material packages for travel on roads are tested by dropping them onto concrete and onto sharpened steel posts, not to mention the stunt of ramming one with a train. Yes, that Soviet RORSat broke up over the Canadian arctic... That's obviously not how we'd build it. If such packaging wastes launch mass, then this is just for the launch of parts that'd need such protection. RTGs & NTRs might not. The fissile material "pits" of the thrust bombs of an EPPP engine are less than 10% of the mass & less of the volume of the total "propellant" of the vehicle.
I remember reading a report of engineer's assessment of the risks of launching the Cassini probe: they were more concerned with the rocket fuels than the dense & fairly rugged core of the RTG.




Space is bad for living things, but we can move around and build up little habitable bubbles, and for getting there you need nuclear power. Freeman Dyson said only nuclear power (and pointedly EPPP) makes sense when contemplating the true scale of the solar system. Something like it still makes sense as the way the species leverages itself up to occupy the whole solar system.
In George Dyson's book on Project Orion, Theodore Taylor is quoted: "When we open the Pandora's Box that nuclear energy is, the first things immediately at the top are horrible, and we must say no, we can't use that. But if we dig a little deeper, under the clutter, you find the real content of the box, which is hope."

If we're going to space for anything more than a temporary exploration base lasting only a couple launch opportunities to Mars, it only makes sense to admit that nuclear power is the natural tool for anything much beyond Earth orbit. The bigger and most boisterous the use of nuclear energy, the better for interplanetary travel.



Human Exploration and Settlement of the Moon Using LUNOX-Augmented NTR Propulsion
http://link.aip.org/link/?APCPCS/324/409/1
http://www.astronautix.com/craft/lannbase.htm





External Pulsed Plasma Propulsion
ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20000021516_2000013018.pdf

mugaliens
2009-Feb-12, 08:23 PM
The fact that not all nuclear is bad does not mean that all nuclear is good :).

No one's saying that all nuclear is good. We're saying that some nuclear is good, and this is a good opportunity to field test some of those designs so that we can improve them.

John F
2009-Feb-14, 02:16 AM
The fact that not all nuclear is bad does not mean that all nuclear is good

We need to consider things very well before using this kind of technology

What's to consider? Poisoning the solar wind?
The only factors are worker & environmental safety on Earth (including clean-up of wastes from manufacturing), and reasonable precautions during launch.
Used engines in space will probably be stockpiled somewhere in a long-term orbit until somebody comes up with an economical plan to reclaim them, or dispose of them. I wonder if a cheap solar powered ED tether unit could be used to take them from Earth orbit to spiral them into the Sun? Tethers.com established that a de-orbiting unit for Earth satellites could be no more than 2% of the mass of the satellite.

Even in the case of a fission-burst powered EPPP rocket, that's all. Precautions about weapons-grade fuels during production of the "bombs" are not too difficult. If the pits aren't even assembled into firing units until they're in orbit, it's even better.


eburacum45:
I doubt that fissile material will ever be shipped in bulk off the surface of the Earth (the various regulatory bodies will prevent that, to prevent accidents during launch), so fission rockets in space are a non-starterNot an issue, if examined realistically.

Nowhere Man
2009-Feb-14, 03:14 AM
Thread necromancy alert!

Not so bad this time, only 1.5 years.

Fred

mugaliens
2009-Feb-15, 02:00 AM
Thanks, Fred. Sometimes it's nice to revisit old threads. I like to, anyway, as the more time that passes and the more I learn, I often find myself being able to contribute where I couldn't 1.5 years ago.

scottlowther
2009-Feb-15, 05:33 AM
...now if you want to send a manned mission to Jupiter or Saturn ala "2001".....

Already thought out. *Fifty* years ago, almost...

http://www.up-ship.com/eAPR/images/v2n2ad8.jpg

publiusr
2009-Feb-20, 07:03 PM
What do you think of the NSWR? I do like the concept of a more constant thrust. Can the constant heat be dealt with? I seem to remember in the book on Orion (and I don't mean the CEV capsule BTW) that urea of all things was a useful substance that moderated radiation a bit. Could that be used for a NSWR cooling system as well?

I also seem to remember reading that Saturn V could put 400 tons above the sensable atmosphere. Ares V would seem to be a better candidate for future mini-mag orion type craft than cramped little shuttle-c, which seems to be emerging as Ares V's "replacement."

cjameshuff
2009-Feb-20, 08:03 PM
What do you think of the NSWR?

"Terrifying" sums it up nicely. The sheer scale of the accidents that the fuel would make possible...

Orion-like systems seem much more feasible. There is the proliferation aspect of mass production of the bomblets, but they can be secured to the point that it is impossible to detonate them without the proper authorization short of dismantling them and building a new device from the parts. And I do think limited ground launch of Orion vehicles from Earth would be acceptable, quite possibly leading to lower environmental impact in the long run if it is used to establish orbital industry. Perhaps an Antarctic launch would limit spread of radioactive fallout. It seems likely that they would be restricted to use well outside of Earth's magnetosphere, though.

I've also seen a concept using particle beam triggered fusion devices without fission primaries. To sum up, the ship builds up an artificial magnetosphere around it, with a large charge difference between the ship and a cloud of electrons around it...several gigavolts. The fusion device is ejected into the negatively charged regions, and hit with a pulsed proton beam from the ship, accelerated using the potential difference between ship and cloud (and fusion device) as a one-stage linear accelerator. The expanding plasma from the detonation is used to both accelerate the ship and restore the charge difference between the ship and magnetosphere. The bomblets themselves would be completely inert without a GeV-energy proton beam to ignite them, possibly not even needing tritium, and there would be no significant radioactive ash. The technology is completely unproven, but I don't see why it wouldn't work...

publiusr
2009-Feb-20, 09:32 PM
With NSWR--
http://en.wikipedia.org/wiki/Nuclear_salt-water_rocket
--you just need fuel injection technology--and would not need to develope what might wind up being micronukes.

Yes the tech shown in the following links might make what you talk about easier:

http://en.wikipedia.org/wiki/Ballotechnics
http://en.wikipedia.org/wiki/Induced_gamma_emission
http://en.wikipedia.org/wiki/Nuclear_isomer
http://en.wikipedia.org/wiki/Pure_fusion_weapon

But I think you are downplaying the proliferation risk.

I remember a NOVA broadcast that explained that while mainstream nuke production required economies of scale that small terror nations couldn't match--bio-warfare agents were easier to do with small budgets. The massive US economy funded such studies, of course resulting in information free to the public. I think the word describing your small bomblets is 'destabilizing.'

Micronukes will make small rockets into big ICBM threats. Yes the particle beam aspect requires TVA tech, not MSN tech--but if the bomblet and not the starship is what you are after...well, the less said the better.

With NSWR technology, you need huge rockets lobbing water and just need to concentrate the nuclear salts. With Sea Dragon construction, a rugged NSWR with simpler pressure-fed systems might be had.

In this way, weapon potential is minimized---big starships are all you could make with it.

I don't ever see Orion launched from the ground--especially in Antarctica.

Talk about warming!

Space initiated NSWRs can be used at smaller scales, and look to be simpler than fooling around with bomblets--which all strikes me as being a bit busy. And by busy--I mean Rube Goldberg.

John F
2009-Mar-07, 08:00 AM
...
But I think you are downplaying the proliferation risk.

I remember a NOVA broadcast that explained that while mainstream nuke production required economies of scale that small terror nations couldn't match--bio-warfare agents were easier to do with small budgets. The massive US economy funded such studies, of course resulting in information free to the public. I think the word describing your small bomblets is 'destabilizing.'Many fail to see why. We're not assuming a nationalistic military ship, if simple production of nuclear explosives is supposed to alarm other nations. Quite the reverse with multinational participation in space these days.
How is the knowledge that thousands of identical bomblets are being made for a space ship "destabilizing"?


I don't ever see Orion launched from the ground--especially in Antarctica.Likewise, though I'd say "even from antarctica -and I don't see any sort of benefit in doing it from there anyway, whether the mythical "clean" primaries existed or not.


Space initiated NSWRs can be used at smaller scales, and look to be simpler than fooling around with bomblets--which all strikes me as being a bit busy. And by busy--I mean Rube Goldberg.
No more so than a rocket!

Starfury
2009-Mar-10, 12:43 AM
A viable alternative between chemical and nuclear rockets could be Dr. Franklin Chang-Diaz's VASIMR (Variable Specific Impulse Magnetoplasma Rocket). From what I've seen, it could cut interplanetary travel times by a tremendous amount. I heard him on TV once saying his engine could propel a spacecraft to Mars in 39 days. Here's the link to info about VASIMR:

http://www.adastrarocket.com/home1.html

VASIMR, or something like it, might prove to be essential to human exploration of the outer solar system.

sanman
2009-Mar-11, 08:40 AM
You need a power source to run VASIMR. It certainly doesn't generate plasma for free. The only power source capable of powering VASIMR is a nuclear reactor. So VASIMR for any meaningful interplanetary mission would effectively be a nuclear rocket.

Starfury
2009-Mar-12, 12:05 AM
Well, that pretty much goes without saying.

sanman
2009-Mar-12, 09:41 PM
you wrote:

A viable alternative between chemical and nuclear rockets could be Dr. Franklin Chang-Diaz's VASIMR (Variable Specific Impulse Magnetoplasma Rocket).

Well, VASIMR is not a distinct option from nuclear rockets, since it is itself a nuclear rocket.

I wanted to start a separate thread on Quantum Nucleonics and Nuclear Isomers, which I feel is a potentially revolutionary power supply for things like VASIMR, etc.

publiusr
2009-Mar-16, 08:48 PM
Ares V/NTR
http://www.csnr.usra.edu/archives/2007%20Fellows/NTR-based%20ESAS%20Architecture.ppt#1

From Mr. Howe's group
http://www.csnr.usra.edu/archives.html

Works better than all "this"
http://en.wikipedia.org/wiki/Anti-gravity
http://en.wikipedia.org/wiki/Ning_Li
http://en.wikipedia.org/wiki/Breakthrough_Propulsion_Physics_Program

__________________________________________________ _____________________

"Space initiated NSWRs can be used at smaller scales, and look to be simpler than fooling around with bomblets--which all strikes me as being a bit busy. And by busy--I mean Rube Goldberg."

'No more so than a rocket!'

You'd be surprised.

http://en.wikipedia.org/wiki/Nuclear_salt-water_rocket

A quote:

"NSWRs share many of the features of Orion propulsion systems, except that NSWRs would generate continuous rather than pulsed thrust and may be workable on much smaller scales than the smallest feasible Orion designs (which are generally large, due to the requirements of the shock-absorber system and the minimum size of efficient nuclear explosives)."



With a huge pressure-fed like Sea Dragon, you would have a little RP at one end (though you might go all hydrolox according to a concept called "Freezerburn", and some nuclear salts at the other. Instand starship--just add water.

http://en.wikipedia.org/wiki/Sea_Dragon_(rocket)
http://catalog.loc.gov/cgi-bin/Pwebrecon.cgi?v1=1&ti=1,1&Search%5FArg=TALL%20%22Space%20energy%20and%20tran sportation%3F%22&Search%5FCode=CMD&CNT=25&PID=GMg-QBFWjElxe1mc9JqGwdWqfkrU&SEQ=20090316161357&SID=1
http://neverworld.net/truax/
http://adsabs.harvard.edu/abs/2002iaf..confE.282T

The key is how you would deal with the terrific heat released by NSWR and that is something I'd like to kick around with some of you today.

I was wondering about the concept of jacketed thrust.

I very large torus containing the water for a NSWR would surround a very thick nozzle.

Inside, there would be a ring of nozzles to generate a 'tube' of more conventional thust products, perhaps magnetically 'pinched'. The outer zone of thrust products would encase the inner, much hotter NSWR flow within--with Mach cones and constriction compressing the NSWR stream towards criticality.

I wonder if the following info would help:
http://en.wikipedia.org/wiki/Soliton
http://dusty.physics.uiowa.edu/~goree/papers/PRE04162.pdf
http://eol.jsc.nasa.gov/sseop/EFS/photoinfo.pl?PHOTO=STS51I-42-40

That and good CFD...

The idea would be that the outer 'cooler' exhaust flow would help block some of the heat of the inner thrust stream.


Note the magnetic nozzle here.
http://www.projectrho.com/rocket/MagneticNozzle7.jpg

If I had a tube of them to form a cyllinder that was the spine of the ship--like joined ovoids--I could slide the tube back to some eating furnace nozzle so that the center of thrust would travel back and forth within the outer main nozzle heating different portions as the frame of the ship was slowly being eaten away. Like the truss-fabricator the shuttle was going to carry for old SPSS only in reverse. Hydrogen metal might form the tubes--and it would be a self eating design like Tsanders self eating rocket.

'Fridrikh Arturovich Tsander of the Soviet Union completes writing his paper,
“Problems of High-Altitude Flight and Preparatory Tasks for Interplanetary Travel,” for the Fifth International Congress on Air Travel.'

"Among the ideas he proposes are a rocket plane that consumes parts of itself as fuel after those parts have fulfilled their function; rocket engine clusters; and high-energy metallic fuels. F. Tsander, NASA TT F-147, Problems of Flight by Jet Propulsion, pp. 30-31, 96-101."

Hydrogen metal closest to the NSWR stream is therefore designed to melt, as opposed to resisting heat. That would be for the outermost nozzle with the pre-salt water.


Yes this is all Rube Goldberg as well--but I like the idea of a slow, self eating design of some kind where I'm pulsing flow as opposed to having hydrolics, springs, joints, and all the mechanics of the blam-blam type Orion where I would have many more moving parts.

Now how I do what I have explained and have it work--I've no idea.

But the idea of jacketed thrust, hydrogen metal that just joins the exhaust product, etc--could all be used in some other combination to make NSWR work while keeping continous flow interactions of some kind to pinch salt water streams to criticality...

When I think of the elegance of the old fictional atomic rockets with steady 1 g thrust--I'm convinced NSWR is the way to go...eventually.

http://www.projectrho.com/rocket/


NOTE---------------------------------------------------------------------------------------------------

I was also thinking about laser propulsion and a way NSWR or other nuclear systems might help pump a laser.

We have chemical pumped lasers. Could a NSWR reaction in a sacrificial chamber also pump a powerful continous laser, rather than the old exploding X-ray laser bomblets?

http://en.wikipedia.org/wiki/Induced_gamma_emission http://www.hafniumisomer.org/cqeseg3.htm

publiusr
2009-Mar-19, 10:40 PM
Nice links
http://www.projectrho.com/rocket/rocket3c2.html#ntrsoliddumbo
http://www.dunnspace.com/00339489.pdf

mugaliens
2009-Mar-20, 10:39 PM
The key is how you would deal with the terrific heat released by NSWR and that is something I'd like to kick around with some of you today.

I was wondering about the concept of jacketed thrust.

I very large torus containing the water for a NSWR would surround a very thick nozzle.

Simply jacketing the very hot thrust with a thin sheath of water bled into the chamber, but along the sides, would create a steam boundary layer that would provide cooling while adding to the thrust.

publiusr
2009-Mar-30, 10:32 PM
I just wonder if that is really enough. That would be used, yes, but having different layers of thrust might have its own advantages as well.

I wonder about progressing mach cones within an elongate nozzle. Something to keep the pulse without the pusher-plate and all the bomblet mechanics. By allowing the exhaust concentration to move around, you can reduce heating to any one area in the nozzle. NSWR is going to be complex in dealing with the heat--but fuel injecton tech is all the rocket itself needs or so I imagine.

With pusher plate orion--the heating is very short, and you don't heat soak the structure. NSWR allows a constant nuke-blast stream. That is a whole 'nother animal altogether. So there has to be something else going on I think.

I could be wrong and hope I am

DUMBO NTR sounds great for right now. With an AIMSTAR payload to go screaming out of the Sol system.

publiusr
2009-May-01, 09:23 PM
Something else I was thinking about. A Bimodal rocket that also had a weaker ion drive (tri-modal) that would be powered by the nuclear engine to slowly move a spent NTR tug back to Earth... A good asteroid mover?

Vultur
2009-May-08, 03:56 AM
It's horribly heretical to say it, but...

Why *couldn't* we launch nuclear rockets from Earth? We did tons of dirty bomb tests in the open air, and I don't think there is that much damage from them. Most of the modern ideas for nuclear rockets would be much less messy.

I'm generally pretty environmental, but I think this is a risk/reward thing. The advantages to human civilization of launching stuff that big are so great that even large risks are quite acceptable.

The problem is the completely irrational paranoia about nuclear stuff. I still wonder why a non-democratic government like China hasn't tried it, though...

Antice
2009-May-08, 06:39 AM
Because even totalitarian regimes generally know better than to mess with the anti nuke crowd.
Only way is to educate people about the real risks. then get a majority to actually aprove of the risks.

galacsi
2009-May-08, 08:38 PM
It's horribly heretical to say it, but...

Why *couldn't* we launch nuclear rockets from Earth? We did tons of dirty bomb tests in the open air, and I don't think there is that much damage from them. Most of the modern ideas for nuclear rockets would be much less messy.

I'm generally pretty environmental, but I think this is a risk/reward thing. The advantages to human civilization of launching stuff that big are so great that even large risks are quite acceptable.

The problem is the completely irrational paranoia about nuclear stuff. I still wonder why a non-democratic government like China hasn't tried it, though...


Testing atomic bombs in the open air has been stopped because of their horrific pollution.

The governments could not lie any more about it and for going on testing they went underground.

Statistics studies by National Cancer Institute and the Centers for Disease Control (CDC) show the scope of the problem. If you don't trust me about that , do a little googling.

I am Happy you are "pretty environmental" but may be China is not the best example to follow !

galacsi
2009-May-08, 08:40 PM
Because even totalitarian regimes generally know better than to mess with the anti nuke crowd.
Only way is to educate people about the real risks. then get a majority to actually aprove of the risks.

Even a totalitarian government don't like receiving radio-active fallout on its head !

PraedSt
2009-May-08, 08:59 PM
I was under the impression that nuclear propulsion was only suitable in space- that there's not enough thrust to launch a rocket from Earth?

Is this wrong?

p.s. controlled propulsion of course. I'm aware that if it goes critical you'll end up on the Moon.

p.p.s. sorry if covered before.

galacsi
2009-May-08, 08:59 PM
[QUOTE=sanman;1451840]You need a power source to run VASIMR. It certainly doesn't generate plasma for free. The only power source capable of powering VASIMR is a nuclear reactor. So VASIMR for any meaningful interplanetary mission would effectively be a nuclear rocket.[/QUOTE

I don't follow you.New generation of solar panels are lighter and I don't see why they could not be used to power a VASIMIR.

Ara Pacis
2009-May-08, 10:47 PM
I was under the impression that nuclear propulsion was only suitable in space- that there's not enough thrust to launch a rocket from Earth?

Is this wrong?

p.s. controlled propulsion of course. I'm aware that if it goes critical you'll end up on the Moon.

p.p.s. sorry if covered before.

The first generations of atomic thermal rocket engines researched and developed looked like they would barely attain a thrust-to-weight ratio of 1 (on Earth's surface), and when you add on everything else it would be even lower. It could, however, be useful on a later stage.

PraedSt
2009-May-08, 11:10 PM
The first generations of atomic thermal rocket engines researched and developed looked like they would barely attain a thrust-to-weight ratio of 1 (on Earth's surface), and when you add on everything else it would be even lower. It could, however, be useful on a later stage.
That's what I thought. Thanks.

cjameshuff
2009-May-09, 07:14 PM
I don't follow you.New generation of solar panels are lighter and I don't see why they could not be used to power a VASIMIR.

They're not that much lighter, and advances can't do anything about the limited power density of sunlight. You need huge areas to collect the amount of power needed to run a high-power VASIMR, and structure to support those panels. And sunlight gets dimmer as you move into the outer system. Perhaps for Mercury, Venus, or low-orbit solar missions...but in general, you need a nuclear reactor to run a VASIMR. (or beam power from a stationary power plant...limited range might require you to run the VASIMR at unusually low Isp and high thrust, but there might still be a benefit)



The first generations of atomic thermal rocket engines researched and developed looked like they would barely attain a thrust-to-weight ratio of 1 (on Earth's surface), and when you add on everything else it would be even lower. It could, however, be useful on a later stage.

They also didn't necessarily have any radioactive exhaust. They had problems with the core being eroded by the hot hydrogen reaction mass, but they were also working on coatings and materials to prevent that.

Orion-style nuclear pulse protection can lift enormous payloads, but does require open-air nuclear detonations. The comparisons with nuclear testing are spurious...politics was heavily involved, and there were incidents with detonations both far larger and far dirtier than anything that would be used for a launch vehicle. I think the environmental cost of a few Orion launches would be quite acceptable given the rapid establishment of space-based industry it would allow, but this isn't a particularly popular view...

Vultur
2009-May-09, 10:58 PM
I think the environmental cost of a few Orion launches would be quite acceptable given the rapid establishment of space-based industry it would allow, but this isn't a particularly popular view...

Exactly. IIRC the environmental costs wouldn't really be that bad, certainly not compared to the industrial pollution we create constantly. There's nothing 'special' about radiation, and from a purely ecological (as opposed to a public health) standpoint, it's not one of the worst forms - look at how well the ecology has recovered at Chernobyl. You wouldn't want to launch one every day, but using a few to set up a Moon base or an L5 colony would be perfectly sane.

galacsi
2009-May-10, 08:42 AM
Exactly. IIRC the environmental costs wouldn't really be that bad, certainly not compared to the industrial pollution we create constantly. There's nothing 'special' about radiation, and from a purely ecological (as opposed to a public health) standpoint, it's not one of the worst forms - look at how well the ecology has recovered at Chernobyl. You wouldn't want to launch one every day, but using a few to set up a Moon base or an L5 colony would be perfectly sane.

I think somebody must state the obvious :

I don't care if the ecology has recovered at Chernobyl , of course it has recovered , when not too hard ,radiations are just a new selection factor. Some animals die ,and those who live they thrive happily without human interference. What motivate me is my health so you can fire your Orion rocket everywhere but not on my planet

galacsi
2009-May-10, 08:51 AM
[QUOTE=cjameshuff;1485646]They're not that much lighter, and advances can't do anything about the limited power density of sunlight. You need huge areas to collect the amount of power needed to run a high-power VASIMR, and structure to support those panels. And sunlight gets dimmer as you move into the outer system. Perhaps for Mercury, Venus, or low-orbit solar missions...but in general, you need a nuclear reactor to run a VASIMR. (or beam power from a stationary power plant...limited range might require you to run the VASIMR at unusually low Isp and high thrust, but there might still be a benefit)/QUOTE]

Time will tell , but I think solar panel can be greatly improved. It is true you need huge areas to collect the power you need but if the panels are light enough I don't see it as a problem. Remember we are in zero gravity so you don't need heavy structure , just a good system to put them in good order.

At your list of potential targets for solar missions you can add the Moon, NEOs , planet Mars and may be the asteroid belt IMO. But I concede that for the outer planet you will need something more powerful. Nuclear energy of one form or another probably.

Ara Pacis
2009-May-10, 12:45 PM
They also didn't necessarily have any radioactive exhaust. They had problems with the core being eroded by the hot hydrogen reaction mass, but they were also working on coatings and materials to prevent that.

Orion-style nuclear pulse protection can lift enormous payloads, but does require open-air nuclear detonations. The comparisons with nuclear testing are spurious...politics was heavily involved, and there were incidents with detonations both far larger and far dirtier than anything that would be used for a launch vehicle. I think the environmental cost of a few Orion launches would be quite acceptable given the rapid establishment of space-based industry it would allow, but this isn't a particularly popular view...

Such is what I've also read. I think NTRs have a bright future. I also agree that a few NPP launches might be okay. The lower atmosphere fallout would fall out in a small area and the stratospheric fallout will tend to stay up there for so long that it will probably decay to relatively safe levels before it drifts back into the turbulent troposphere and gets mixed around. If we were to launch from an ocean location I think it could be safe enough.

publiusr
2009-May-18, 09:19 PM
Here is a thought for a post Mars manned expedition to outer planets. Ares V launches the actual craft with High Value Components. Sea Dragon launches tankage and fuel.

NTR engine blocks would be launched engine-facing up, atop a LV. This would have an escape tower so as to save the nuclear block. The flat bottom of the engine block then faces the flat bottom of the tankage launched by other HLLVs, end to end.

The cockpit of the ship is launched atop Ares V, and needs no shroud being roughly pointed at it stands. Thus the craft has a simdle shap, pointed at both ends. Pointed nose, and pointed tail, with the NTR right there bringing up the rear. Then this entire craft can be reused and refueled, with this assembly being a giant command service module, with landers launched atop Ares V to dock with the nose of this craft and pushed to its destination. Orion capsules dock ahead of time for crew transfer.

Some other examples here
http://www.bautforum.com/space-exploration/33907-nswr.html#post593570

JustAFriend
2009-May-19, 10:20 PM
You can tweak nuclear bombs to give highly reduced fallout.

The book "Project Orion (http://www.amazon.com/Project-Orion-Story-Atomic-Spaceship/dp/0805072845/ref=sr_1_1?ie=UTF8&s=books&qid=1242771532&sr=1-1)" (its a great read) detailed how you can get a nuke-ship off the ground. They even tested a scale model with conventional explosives.

...but that anti-nuke crowd is STILL gonna string you up by the googlies before you can even get it partway built!

aquitaine
2009-May-21, 02:09 PM
I think somebody must state the obvious :

I don't care if the ecology has recovered at Chernobyl , of course it has recovered , when not too hard ,radiations are just a new selection factor. Some animals die ,and those who live they thrive happily without human interference. What motivate me is my health so you can fire your Orion rocket everywhere but not on my planet


Actually a surprisingly small amount of animals (and people) died. While it was bad, it was nothing like what people at the time (and the anti nuke crowd continues to spout) believed it would be, and that was the worst possible thing that could ever happen.

Needless to say I also don't think a nuclear pulse rocket would be a good idea, the NERVA would be much better.

Extracelestial
2009-May-21, 02:45 PM
I was under the impression that nuclear propulsion was only suitable in space- that there's not enough thrust to launch a rocket from Earth?

Is this wrong?

p.s. controlled propulsion of course. I'm aware that if it goes critical you'll end up on the Moon.

p.p.s. sorry if covered before.

No need to be sorry. This is a touchy topic albeit solely from a societal point of view. Technically it is simple.
First, an atomic powered rocket using pure hydrogen for fuel (with an extra oomph if oxygen is added at start) could be used for taking off from Earth.
Second, going critical and ending up on the Moon? Well, isn't that exactly what we want? ;-)
Third, the exhaust (pure hydrogen or pure water) is not radioactive and if the reactor doesn't fail won't be for a long, long time.
From my point of view, nuclear propulsion offers many positive characteristics but as long as we ban nuclear energy in space (with the exception of RTGs) for fear of abusing it for weapons (which, by the way, technically is really hard to achieve) and for "environmental" reasons we won't get very far. Mars with chemical propulsion is hard for the humans and expensive on top. Mars nuclear will be easier and cheaper.

Extracelestial

Extracelestial
2009-May-21, 03:06 PM
Now I'm sorry. I forgot to tie my post to the topic. Nuclear rocket would add benefits for moon missions as well. The variable thrust, variable impulse capabilities allow for some interesting manouvering.
And such a rocket might be easier to be built as a reusable one than a chemical one since weight restrictions are less demanding.
The beauty of a nuclear rocket is that you can use almost anything as fuel as long as it is liquid. Your fuel can be nonexplosive e.g. water but it will suffer in performance. Hydrogen is due to its molecular weight suited best for high specific impulse and with oxygen augmentation, to gain some extra push for high thrust, can be used to lift high masses into orbit. It boils down to the fact that you can lift more when using nuclear.

Extracelestial

Joe Meils
2009-May-21, 08:45 PM
Already thought out. *Fifty* years ago, almost...

http://www.up-ship.com/eAPR/images/v2n2ad8.jpg

I agree! To what better use could nukes be put? I'd sure rather be using this material outside the biosphere than within it!