NASA Developing Nuclear Reactor For Moon and Mars 424
Al writes "NASA recently finished testing a miniature nuclear reactor that would provide power for an astronaut base on the Moon or Mars. The reactor combines a small fission system with a Stirling engine to make a 'safe, reliable, and efficient' way to produce electricity. The system being tested at NASA's Glenn Research Center can produce 2.3 kilowatts and could be ready for launch by 2020, NASA officials say. The reactor ought to provide much more power than solar panels but could prove controversial with the public concerned about launching a nuclear power source and placing it on the Moon or another planet."
Shouldn't be that dangerous (Score:5, Informative)
The uranium that goes into a reactor isn't all that radioactive - it's the spent fuel that comes out that's the problem. If a rocket carrying this thing explodes on take off it isn't going to be Chernobyl. In fact, it sounds a good deal safer than all those Pu-238 RTGs that have been sent up there.
Engine (Score:5, Informative)
Sterling engine? (Score:5, Informative)
An engine made out of silver [wikipedia.org]? Or just a generally excellent [merriam-webster.com] one? Ah, a Stirling engine [wikipedia.org].
More quality editing from Slashdot...
Re:mmhmmm (Score:4, Informative)
The specs would have this thing lasting 8 years.
And yeah, the sun does run out. Or at least it isn't useful when it goes through an extended night. Or if it is in a location that doesn't get direct sun (crater).
!Sterling but Stirling (Score:2, Informative)
Stirling from the name of inventor - Dr. Robert Stirling.
Mod parent up please (Score:5, Informative)
Re:That's only 20 Amps at 115V (Score:5, Informative)
Read the article. 2.3 kW is the test version, they want to scale it up to 40 kW for the base:
The recent tests examined technologies that would see a nuclear reactor coupled with a Stirling engine capable of producing 40 kilowatts of energy--enough to power a future lunar or Mars outpost.
40 kW is approximately 17 outlets that can handle 20 A at 115 V. Yeah, it's still not a ton but it's a start and you could potentially put up several of these reactors as you expand the facility. This would also add fault-tolerance to the entire system.
Re:It shouldn't be any more controversial... (Score:5, Informative)
Re:It shouldn't be any more controversial... (Score:5, Informative)
Uranium is "huggably safe" before a reactor is actually turned on. With a half-life of a billion years it's more dangerous as a heavy metal than anything else.
Plutonium is nasty if powdered or vaporized, but NASA designed a "safe" for the Cassini plutonium RTG that would survive being dropped at any point during the launch path.
The hydrazine [wikipedia.org] fuel used in the maneuvering thrusters in spacecraft and the Space Shuttle's APUs is amazingly toxic. In most scenarios a tank of hydrazine is more of a danger than a lump of plutonium. Off-Earth, a hydrazine APU is just exposing astronauts to unneeded danger to avoid "scary nuclear scary scary".
Re:It shouldn't be any more controversial... (Score:3, Informative)
Fission is the splitting of the nucleus into two (or more?) large pieces. It's not a very common decay mode. The release of neutrons and the usual radioactivity of the pieces makes it dirtier.
From the article: 1080 Square feet of cooling (Score:3, Informative)
Ah, the articles says they'll have 1080 square feet of cooling. I'm not sure whether that says the vacuum stinks at cooling or not.
How much would be needed in air?
Re:WHere do they put the heat? (Score:3, Informative)
A heat source on earth is cooled by conduction (a pot transferring heat to the surface its sitting on), convection (air moving over the surface and carrying away heat), and radiation (direct transmission of energy via photons). In the "icy vacuum of space" you get no conduction or convection, so you're limited to radiation as a method of dispensing of heat. If you're on the moon you can conduct a lot back into the ground as you suggest as well.
However, the black cold of space is a pretty good source to radiate towards (since you don't get anything radiated back), so you get more out of radiation than you would on Earth. However, since cooling on earth is dominated by the other two, you still have to have huge radiator constructs. If you look at the ISS a lot of the panels aren't solar panels, but are in fact radiators. Of course, a deep space probe with a nuclear reactor is going to have a simpler system than the ISS, since the heating is dominated by the constantly changing views of the Earth and Sun in LEO.
If you've ever seen any pictures of the proposed nuclear powered JIMO probe, it had huge panels hanging off of the main truss. These were radiator panels as well, since it wouldn't have required solar panels.
Re:mmhmmm (Score:5, Informative)
Actually, Moon dust is a bigger problem on the than Mars dust exactly because there is no weather. Weathering wears down the rough edges of dust particles. Without it, the dust retains jagged edges. It is extremely abrasive, sticks to everything, and is electrically charged. Once it sticks to something, it is extremely difficult to get off. On Mars, however, you can just wipe the dust away. It's weathered and smooth, like the dust we are all familiar with on Earth.
http://www.wired.com/science/space/news/2005/04/67110
http://www.sciencedaily.com/releases/2008/09/080924191552.htm
http://www.space.com/scienceastronomy/090421-st-moon-dust-sunangle.html
Re:It shouldn't be any more controversial... (Score:5, Informative)
Hydrazine is not all that bad compared to the oxidizer used, nitrogen tetraoxide. People used to sniff for hydrazine leaks with their nose (smells like rotten fish) early in satellite development. Nitrogen tetraoxide smell like the inside of your nose being dissolved.
But your general point is correct in that the chemical effects of most of these items are far more problematic than the radioactivity, and the chemical effects can be dealt with reasonable safety as has been proven for decades.
Brett
Re:NUCLEAR IS NEVER THE ANSWER! (Score:4, Informative)
Thorium [technologyreview.com] reactors don't make plutonium. No need for a light water or breeder reactor for it. I'm told that the fission byproducts are an order of magnitude safer as well, but I haven't seen the math for it yet.
Re:mmhmmm (Score:3, Informative)
Chances are, it'll already be on the moon and working before astronauts even get there. This is not the first nuclear-based energy source NASA has launched.
Re:For a start fine, but then - solar! (Score:5, Informative)
"which is ot that hard"
Okay, how?
Batteries are heavy and you have to lift them from Earth. Regolith has a pretty low specific heat capacity. Water works pretty well to store heat, or to make hydrogen, but on the moon you're probably not going to have much and you might want to drink it instead. You can compress gas to store energy, but where are you going to find that on the moon?
Re:That's only 20 Amps at 115V (Score:3, Informative)
It would be silly to use this for loads of growlights, when you have places on the moon where you can obtain near total sunlight. You will have to raise some pipes up and redirect the sun down, but I am certain that a number of spots on the poles can be found to do that with.
Re:Shouldn't be that dangerous (Score:2, Informative)
I said "isn't all that radioactive", which means that it is radioactive, but not very much. I'd happily hold a lump in my hand, which I sure as hell wouldn't do with spent fuel. Please read posts more carefully before accusing people of lying.
Re:Nuclear Power on the Moon FTW! (Score:2, Informative)
Orders of Magnitude (Available Enthalpy) (Score:3, Informative)
Weight is the main factor in the number of things that can go up in a rocket.
Nuclear is inherently a big win, in terms of Available Enthalpy (if scared, just read: Power) versus weight. Chemical reactions can yield 13 megajoules per kilogram. Nuclear fission can get you 82 million megajoules per kilogram. In terms of possible exhaust velocity, you can get 4.5 km/s out of chemical propellants, but a potential 12,800 km/s out of nuclear. Fusion is even better with 347 million MJ/kg of useful energy. But only using present day technology, beamed power sources can match anything out there in the theoretical realm. We'd only need to launch mirrors and reflectors and leave the heavy power generation on the ground. It wouldn't be easy, but the basic physics is very favorable -- tons of equipment could just sit on the ground instead of needing to be accelerated to high speed. (Sources, Zubrin's _Entering Space_)
Re:WHere do they put the heat? (Score:3, Informative)
"Yeah, it does."
No, it doesn't. You can cool things only by radiation in vacuum. And radiation is quite slow, on Earth the major contributor in cooling is convection.
Well OK this is very Slashdot, your point of view is that radiative cooling is pretty bad in comparison to convection cooled cooling towers on earth, or phase change cooling towers (with water misters) or conduction cooling if near a nice cool lake/river. And my point of view is that radiative is pretty good, compared to having to build a reactor cooling tower plus an atmosphere, or build an ocean. Really, radiative cooling is pretty good considering that its dumping heat into "nothing" or into the universe in general. Usually you don't get anything at all for nothing.
For some actual numbers:
http://www.lockheedmartin.com/products/HeatRejectionRadiators/index.html [lockheedmartin.com]
So, the ISS is radiating 1/2 into space and 1/2 into the earth and about ten KW takes about one ton of radiator. Move into a gravity well it'll need to be stronger and heavier, but maybe you can thermosiphon. On one hand, with proper insulation and something to block the sun, you can radiate into the black cold 2.7 degree sky, on the other hand, blocking the sun and moon surface blocks alot of angular area to radiate into. Its looking like radiating a KW takes about 100 pounds of radiator. Not too impressive compared to my car radiator, not too bad for radiating heat away into a vacuum "nothing".
Re:mmhmmm (Score:3, Informative)
Re:Nuclear Power on the Moon FTW! (Score:4, Informative)
What is it about "nuclear" that makes people's brains turn off?
The same mindset, I guess, that prompted the medical profession to quietly change the name of Nuclear Magnetic Resonance Imaging (NMRI) to Magnetic Resonance Imaging (MRI). Nobody wanted an NMRI but now people line up for an MRI, at least here in Canada.
Re:There is only TWO issues (Score:3, Informative)
If the American public will accept the safety assurances of NASA, then the Russians and the Chinese are going to raise HELL about the idea of having nuclear energy in space.
Um, the Russians have actually already launched quite a few nuclear reactors (not just RTGs, although they've launched plenty of those too):
http://en.wikipedia.org/wiki/TOPAZ_nuclear_reactor [wikipedia.org]
http://en.wikipedia.org/wiki/Category:Nuclear_power_in_space [wikipedia.org]
Heck, in the 1970s one of the Russian reactors disintegrated over Canada, and the Canadians billed Russia a few million dollars in cleanup costs:
http://en.wikipedia.org/wiki/Cosmos_954 [wikipedia.org]
Re:From the article: 1080 Square feet of cooling (Score:1, Informative)
In vacuum, the only form of cooling would be radiative - no air for conductive or convective heat transfer. Thus, slower.
Chemistry not physics (Score:3, Informative)
Re:mmhmmm (Score:5, Informative)
Since there is specifically zero atmosphere, the only dust you're going to get on the rover is something directly applying it via ballistic trajectory. That's pretty easy to prevent with simply placement slightly away from drive paths. A wind driven environment will *always* have more dust flying around than the moon. there isn't any atmosphere to push it so it just sits until something imparts energy to it.
That's an impressive and very persuasive bit of reasoning with only the minor flaw that it's entirely wrong from beginning to end. The fact is lunar dust is very pervasive, fine, and troublesome. Here's [space.com] an article about it.
Re:NUCLEAR IS NEVER THE ANSWER! (Score:2, Informative)
Thorium [technologyreview.com] reactors don't make plutonium. No need for a light water or breeder reactor for it. I'm told that the fission byproducts are an order of magnitude safer as well, but I haven't seen the math for it yet.
Please check Kirk Sorensen's Google Talk [youtube.com] about thorium nuclear reactors. And here are the actual slides [energyfromthorium.com] used in the presentation.
From the Introduction and Basic Principles [blogspot.com] of thorium based reactors on Kirk's blog: A liquid-fluoride thorium reactor operating only on thorium and using a "start charge" of pure U-233 will produce almost no transuranic isotopes. This is because neutron capture in U-233 (which occurs about 10% of the time) will produce U-234, which will further absorb another neutron to produce U-235, which is fissile. U-235 will fission about 85% of the time in a thermal-neutron spectrum, and when it doesn't it will produce U-236. U-236 will further absorb another neutron to produce Np-237, which will be removed by the fluorination system. But the production rate of Np-237 will be exceedingly low because of all the fission "off-ramps" in its production.
-k
Re:mmhmmm (Score:4, Informative)
You might kick some up, but unless the stuff is given a decent ballistic velocity it won't go anywhere. Can't exactly hang around in the air, right?
Actually, you couldn't be more wrong [nasa.gov].
The dust particles get a charge off the solar wind and sunlight itself, then repel one another. Result: Dust hanging about in the air (well, mainly lack of air actually).
Re:It shouldn't be any more controversial... (Score:4, Informative)
Hydrazine is a little bit more toxic than you make it out to be.
The F-16's epu uses hydrazine (about 80 lbs of it are in a tank aft of the cockpit). During epu tests, everyone gets upwind (regulation). Our hydrazine response team wear full-protection SCBA spacesuits to clean it up. If a person is exposed, they get regular blood tests for the rest of their lives.
I work closely with a few people who have been exposed, and they are reminded with every passing hour that they cannot breath as well or feel as well. You can say, "yeah, comes with the territory," but it's pretty heartbreaking when you know that these guys have beautiful kids who are probably going to lose their dads within 10 years...
-b
Re:Mod parent up please (Score:3, Informative)
The uranium fuel used in reactors is predominantly U-238 mixed with a small percentage (3-4%) of enriched U-235. U-235 is the fissile material and while it does spontaneously emit neutrons at a low level, it becomes useful for power generation when placed in the presence of other neutron emitting material and a moderator. A moderator slows the velocity of neutrons which makes them more likely to interact with the U-235. Fast neutrons bad, slow neutrons good. The fuel is loaded into tubes in pellets roughly 1/2 inch long by 1/4 inch in diameter. Each tube is about 12 feet long and there are a number of tubes in each fuel assembly. There may be a couple of hundred assemblies in the reactor. Each pellet contains roughly the same potential energy as a ton of coal. This whole paragraph is oversimplified of course, but you get the idea.
It is indeed the spent fuel that is highly radioactive. All work done on spent fuel assemblies and assemblies currently in the core is done under water. Spent assemblies are moved entirely under water from the core to the storage pool, where they will stay for the licensed life of the reactor. Of course, if your reactor gets a license extension, some of the spent fuel will eventually need to be moved off-site.
Contact the community relations or corporate communications group at your local nuke plant. They likely have an introductory video they can send you. Those videos are cool, if for no other reason, because they film place you'll never get to visit in person. I've seen one video that had a shot looking down into the reactor core during a refueling outage. How many people would get to see that in person?