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NASA has released a long-awaited Nuclear Power Assessment Study that examines the prospects for the use of nuclear power in civilian space missions over the next 20 years.
The Study concludes that there is a continuing demand for radioisotope power systems, which have been used in deep space exploration for decades, but that there is no imminent requirement for a new fission reactor program.
The 177-page Study, prepared for NASA by Johns Hopkins University Applied Physics Laboratory, had been completed several months ago but was withheld from public release due to unspecified "security concerns," according to Space News. Those concerns may have involved the discussion of the proposed use of highly enriched uranium as fuel for a space reactor, or the handling of plutonium-238 for radioisotope power sources.
"The United States has spent billions of dollars on space reactor programs, which have resulted in only one flight of an FPS [fission power source]," the new NASA report noted. That was the 1965 launch of the SNAP 10-A reactor on the SNAPSHOT mission. It had an electrical failure after a month's operation and "it remains in a 1300-km altitude, 'nuclear-safe' orbit, although debris-shedding events of some level may have occurred," the report said.
In any case, specific presidential approval is required for the launch of a nuclear power source into space, pursuant to Presidential Directive 25 of 1977.
Original Submission
(Score: 2) by looorg on Friday June 05 2015, @11:02AM
I don't know enough about physics or engineering and I can't see anything easily mentioned in the linked report. What would happen in a Challenger/Columbia type event -- catastrophic failure and disintegration upon exit or re-entry? Would that be like setting of a nuke in the atmosphere? Which sounds kinda bad.
What are the other space nations stand on this? Russia? China? ESA? India? ...
(Score: 3, Informative) by Gravis on Friday June 05 2015, @11:20AM
I don't know enough about physics or engineering and I can't see anything easily mentioned in the linked report. What would happen in a Challenger/Columbia type event -- catastrophic failure and disintegration upon exit or re-entry? Would that be like setting of a nuke in the atmosphere? Which sounds kinda bad.
first off, you got it all wrong. when you thing of nuclear you are thinking of a controlled nuclear reaction that is used to heat water to turn turbines to generate power. the problem with these systems is that if they run unchecked, they will run out of control and get radiation everywhere. this isn't that. this is a passive system that is powered by radioactive decay. basically, something that is radioactive is always putting out radiation, so why not capture some and use it for power?
we already power a LOT of sats and even the latest mars rover with it. remember, mars rovers Spirit? [xkcd.com] that one had issues because it's solar panels got too dusty. well check out Curiosity, it has no solar panels. [nasa.gov]
so yeah, check out all our sweet nuclear sats. [wikipedia.org]
(Score: 2) by bob_super on Friday June 05 2015, @10:44PM
Hem... [wikipedia.org]
Not a decay device.
(Score: 0) by Anonymous Coward on Saturday June 06 2015, @03:52AM
well, shit. global warming mystery solved.
(Score: 2, Informative) by khallow on Friday June 05 2015, @12:50PM
I don't know enough about physics or engineering and I can't see anything easily mentioned in the linked report. What would happen in a Challenger/Columbia type event -- catastrophic failure and disintegration upon exit or re-entry? Would that be like setting of a nuke in the atmosphere? Which sounds kinda bad.
As I understand it, there are three things a RTG capsule would have to withstand. First, the forces tearing apart a rocket in flight. This isn't actually that hard to survive. Then there's the thermal input from being for a short time in the middle of a fireball, possibly combined with some heating from reentry into the atmosphere. The latter can be difficult, if the vehicle was almost to orbital velocities when it failed. Finally, there's the impact from hitting ground or water. They have RTGs that are thought to survive all that without releasing their plutonium cargo.
The plutonium (or other radioisotope component) is subcritical (well below what it would need for a self-sustaining cascading fission reaction( with a well known and nearly fixed heat output. It won't blow up or melt down.
(Score: 2, Interesting) by AnonymousCowardNoMore on Friday June 05 2015, @02:17PM
It's happened before. E.g. the USSR lost the nuclear-powered satellite Kosmos 954 [wikipedia.org] over Canada. That's a satellite with a "real" nuclear reactor, not the plutonium-238 RTGs you see in some probes. As per treaty the Russians paid for the material to be cleaned up and that's really all there's to it. While unplanned reentry cannot be fully controlled, rockets launches target sparsely populated trajectories to begin with and any nuclear reactors that have ever been sent into space, or are likely to be in the near future, are far smaller than a terrestrial power plant.
There's nothing special about nukes compared to the nasty chemical poisons used in the aerospace industry. Nuclear waste may last ten thousand years, but beryllium is forever. (Wikipedia does not state the reason why only $3M of the $6M Kosmos cleanup was eventually paid. The Russians argued that the cleanup was needlessly thorough because of the remote location, which the Canadians accepted.)
(Score: 3, Insightful) by gnuman on Friday June 05 2015, @06:19PM
I don't know enough about physics or engineering
Then don't worry about it, because you got your concerns wrong in the first place!
Space nukes are solid devices. All they do is make heat, and not much at that. Maybe a few hundred watts. Your walmart space heater makes more heat than that. They are designed that if they have to return from orbit, or rocket literally explodes, that they will land intact. They are basically a large slug of lead-like-substance wrapped in a protective steel coating.
I don't think anyone is sending real nuclear reactors up into orbit anymore. But USSR sent up quite a few up there and many are still orbiting. By this I don't mean RTG, what I described above, but real nuclear reactors. And none of those things will withstand re-entry. But don't worry too much about that anyway. People have blown up thousands of nuclear weapons for "testing", many in atmosphere, spreading a thin plutonium layer worldwide. A small nuclear reactor shouldn't be much of a problem.