Slashdot Mirror
NASA Developing Nuclear Reactor For Moon and Mars
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."
Yeah, until the fuel runs out. I'm pretty sure that with solar panels, the sun never runs out. I wonder how much it costs to call up Uranium-R-Us and have them run up some more nuclear fuel. I suppose they'd be smart and bring enough for like 100 years but still, it's a bit more dangerous than solar and results in a radioactive byproduct. I saw with the recent advances in solar energy, why not just put some really efficient solar panels up there instead?
Google's Super Secret Search Algorithm: SELECT @search_results FROM internet WHERE @search_results = 'good'
Nuclear power is actually one of the safest, cleanest, and most reliable forms of power ever invented. So long as no meteroites hit it, we should be fine. Huh. Wonder what caused all those craters on the moon.....
My blog
That's one standard kitchen outlet in North America. You could run a coffee maker and a microwave, but not a whole lot more...
How much does it weigh in total (including shielding etc)?
Ian Ameline
All of our inhibitions about nuclear power is why we are doomed. Actually even wrote about this previously... the real danger to the west is not nuclear proliferation from atomic bombs, but from third world countries adopting nuclear mining, nuclear aircraft, nuclear ships, and nuclear spacecraft and pretty much leaving the west behind in a windmill driven green feel good stone ages.
This is my sig.
Why not re-open research into nuclear thermal rockets? They were able to get them up to 40% efficiency back in 1972, I'm would hope we can do better than that now. Use the reactor to heat a propellant to get you to the moon, then use the reactor on the moon to power the base. If it's time to head home, you only need to ship a relatively stable propellant up, rather than actual rocket fuel.
Why isn't NASA looking into technology to exploit the temperature difference between lit and shaded areas on the moon to generate electricity? That should be an excellent source of power most of the time.
With such endeavors there is the internal opinion issue: in case of a failed take-off (think Challenger or Columbia) what happens with the nuclear reactor? NASA will have to prove even in such situation the reactor is going to be 100% safe.
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. No, it's not about atomic bombs - but nuclear reactors can easily be used as energy sources for powerful lasers.
NASA might be able to persuade the American public, but will never persuade the Russians and the Chinese about somethign that indirectly can obliterate their satelites and misiles.
Catalin Braescu
Ofaly.com
Ok, great, they put the heat in one side of the Sterling Cycle Engine, and it moves to the other side and we get motion, but what do they do with the heat? There's no air/water to bump against a cooling fin to get the activity of the molecules. Does the "icy vacuum of space" actually cool things very well?
Yeah, it does. An infinitely large radiator protected from the sun and from the surface would cool to around 2.7 degrees kelvin, pretty chilly. When you understand why it won't cool any further, then you'll know a lot more than you need for this engineering problem, although it is interesting. There are engineering limitations where adding another kilometer of radiator tubing to drop from 4K to 3K just isn't worth the cost of tubing, and/or the power required to pump the refrigerant thru the tubes. Radiation power increases as a pretty high power of temperature.
If it did, why wouldn't a sterling cycle engine with one side in the shade and one side in the sun work pretty darn well anyhow?
Look up the rotation period of the moon. Very roughly, Dark for 2 weeks, Light for 2 weeks. Unless you make a engine thats about 1/2 the circumference of the moon (or, just the diameter, if you were REALLY hard core). Which is not totally out of the question, although it would be a heck of an amazing civil engineering project.
"Science flies us to the moon. Religion flies us into buildings." - Victor Stenger
Why would you send the reactor up *activated*? The only part of the reactor that's really of any concern is the fuel - enriched uranium. So, maybe the answer is to send the uranium up in little bits, so that even if it *did* blow up, there's such a small amount of non-reacted fuel (I might be wrong, but if I understand the nuclear fuel cycle, it shouldn't be very dangerous if it hasn't been reacted yet, and there's not a sufficient quantity to start a reaction?)
Can someone who knows more comment on whether I'm right or not? My understanding is that small quantities of unreacted uranium scattered in the atmosphere would pose essentially zero risk to life on earth?
If so, then you only assemble the reactor, insert the fuel, and initiate fission once it reaches the moon, at which point, who cares? I'm sure, having little atmosphere and no magnetic field to protect it, the moon must be subjected to a heck of a lot of radiation all the time, anyhow, no?
Well,
of course the first few power plants should be nuclear. However with a stirling engine like that it would make more sense to have the following plants sun powered (mirrors focusing sun light on the engine). You need to find a way to store the energy created during "daytime", ofc (which is ot that hard).
angel'o'sphere
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
Ok, great, they put the heat in one side of the Sterling Cycle Engine, and it moves to the other side and we get motion, but what do they do with the heat? There's no air/water to bump against a cooling fin to get the activity of the molecules. Does the "icy vacuum of space" actually cool things very well?
Heat is only transferred through conduction or radiation, with radiation being the most efficient, convection is a movement of heated materials, but the heat itself is only ever conducted or radiated away.
If it did, why wouldn't a sterling cycle engine with one side in the shade and one side in the sun work pretty darn well anyhow?
I suspect that it DOESN'T, in which case they'll need to bore a big hole to put the heat in via fluid transferring to lunar dirt.
The key to the operation of any type of thermo-electric device is temprature differential, the greater the difference in temperature from one end to the other, the greater the power output. Sitting in the sun on earth, there would be a maximum of about 20-30 degrees difference in the most ideal situations from the sunny side to the shaded side.
Ignorance is Bliss -- And the Opposite is True -- Genius is Madness
On an outpost that is hopefully* going to be permanently manned, 8 years seems a little short sighted. And if we're honest with ourselves, even those 8 years are not a realistic estimate. Consider that this thing has lots of movable parts and a very volatile coolant system all of which needs to withstand the extraordinary stress of launch and landing.
Consider RTGs on the other hand. They have no moving parts, a much longer lifespan, and a very well known failure mode (continuous degradation of the fission core and thermoelectric elements). While they do degrade considerably over several decades, they do not ever need maintenance and they don't fail suddenly like this very expensive and complex reactor will. Of course 40kW is an energy budget that could only be satisfied by several of these modules, but on the plus side this would promote a decentralized power architecture for the presumed offworld base. The reactor behemoth on the other hand will just fail spectacularly one day (probably after a long series of notorious problems that started on launch day) and Earth will need to ship a fucking big replacement package all the way up there while the Mars ground crew sits in the dark and with minimal life support, taking very shallow breaths.
* the reason I use that word here is because we probably will have just one phenomenally expensive mission that lasts a few weeks at the outset and after that we won't ever go there again. If the Moon mission era is any indication.
Okay, can someone tell me if I'm full of it or if this is a good idea?
The big 'excuse' of why we don't want a reactor in space is because the rocket might blow up and it'll cause cancer..
Why not use a large 'gun' (rail/coil/whatever) to launch the fuel into orbit instead of rockets?! Unlike a rocket which may fail anytime during it's ascent, a ballistic projectile is pretty much fool proof as long as the initial launch works properly and it doesn't hit anything.
But the best part is, I'm pretty sure nuclear fuel can't be damaged by the high G forces of launch so unlike astronauts or complex instruments we don't have to worry about excessive acceleration damaging the payload.
And if you want to get really crazy, if the launcher was electrically powered by a nuclear breeder reactor, you could manufacture the fuel on site instead of having to transport it.
And for the final thought, what if you build a gun like this for EVERY reactor? But instead of putting it into orbit make it powerful enough to launch it into the sun or out of the solar system, or into Jupiter. No more worrying about how to bury used nuclear fuel....
U-235 has a half life of 703,800,000 years. It's not very radioactive. If you think everyone else is wrong, go find your own citation.
Not so much speed as efficiency, VASIMR is a great old technology because it has a high specific impulse, basically acceleration per unit fuel, not because it can go from 0-60 in 4 seconds flat (which it could).
Unfortunately, 40kW is hardly sufficient for a VASIMR system, which requires many MW of power to operate at high SI. For example, all together the ISS right now produces something like 130kW of power with solar, meaning it will have to charge a battery to be able to use the VASIMR they intend to install on it sometime around 2012.
When you're afraid to download music illegally in your own home, then the terrorists have won!
14 days without light IS the problem. Assuming the 40kW power of the nuclear reactor and calculating the equivalent requirements: If they use a 160V DC bus, like on ISS, then they'd need 84,000 Amp-hours worth of batteries. To give you an idea of how big that is (and recalculating for a specific battery type), using Nickel Hydrogen batteries (also like the ISS) which are 75 Wh/kg, you'd need 179,200kg = 394,240lb = 197 tons of batteries.
Because we have VASMIR coming. Combine that with a nice nuclear reactor and we are looking at some good speeds.
The 2.3kW of this sterling engine doesnt speak to that promise. The 40kW they hope to have a ground system producing doesnt instill much confidenc either. ISS produces around 130kW, via a colossal truss-work of solar panels. These are all far short of the 400kW power needed for the target baseline VASIMR engine, and well short of the multi MW power levels VASIMR really is designed for.
Nuclear power generates heat. Heat differential is then used to drive turbines. In space, you may be able to make heat, but what is there for the other end of this power generation equation; where does the cool body of mass come from, the essential other integral to power generation?
VASIMR itself, at high ISP's, is generating 10 megakelvin plasma. That itself has cooling challenges.
Right now, I dont see how these ideas are practical.