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He3 on asteroids?
Is there any known or guessed quantity of He3 on asteroids or dead
comets? If an object has been orbitting for 4+ billion years, it should have collected some from the solar wind. It seems that He3 would be easier to obtain from something like Eros than the Moon, if it existed in similar density. If there was a supply, collecting and separating He3 could be much simpler in the micro-G environment. I did a quick Google and found little, but am wondering what you think? Josh |
#2
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He3 on asteroids?
In article ,
Josh Gigantino wrote: Is there any known or guessed quantity of He3 on asteroids or dead comets? If an object has been orbitting for 4+ billion years, it should have collected some from the solar wind. The big uncertainty is that we know essentially nothing about the depth and age of the regolith on asteroids. Yeah, there'd probably be some, but whether it's worth exploiting is another question. ...If there was a supply, collecting and separating He3 could be much simpler in the micro-G environment. Or not, as the case may be. Handling fine powders may well be easier in gravity. -- MOST launched 30 June; science observations running | Henry Spencer since Oct; first surprises seen; papers pending. | |
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He3 on asteroids?
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#4
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He3 on asteroids?
Josh Gigantino wrote: Is there any known or guessed quantity of He3 on asteroids or dead comets? If an object has been orbitting for 4+ billion years, it should have collected some from the solar wind. It seems that He3 would be easier to obtain from something like Eros than the Moon, if it existed in similar density. If there was a supply, collecting and separating He3 could be much simpler in the micro-G environment. I did a quick Google and found little, but am wondering what you think? Josh From pages 204 and 205 of _Mining The Sky_ by John S Lewis "But the circumstances of the asteroids differ from those we have studied on the Moon. First, the intensity of the solar wind drops off roughly with the square of the distance from the Sun. Therefore an asteroid near 3.2 AU from the Sun experiences a solar wind flux that is only a tenth that felt by the Moon. Second, accumulation of solar wind gases on the Moon is aided by 'gardening' of the lunar surface by small impacts, which constantly expose fresh material to the solar wind and constantly bury gas-saturated surface grains out of harm's way. On asteroids, even small impact events can remove regolith material by ejecting it at speeds greater than the asteroid's tiny escape velocity. Thus, "mature" surface grains with high contents of implanted gases are preferentially lost, not preserved. Finally, the total exposed surface area of the asteroids is less than the surface area of the Moon. For all these reasons, extraction of helium-3 from the surfaces of asteroids is not likely to be competitive with that from the Moon." An excellent book in my opinion. http://www.amazon.com/exec/obidos/tg...92717?v=glance Although I think the last part of the paragraph must be in error. Surely the surface area of the asteroids is greater than the Moon's (even though the Moon outmasses the asteroids). -- Hop David http://clowder.net/hop/index.html |
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He3 on asteroids?
Hop David wrote in message ...
From pages 204 and 205 of _Mining The Sky_ by John S Lewis snip MTS quote Although I think the last part of the paragraph must be in error. Surely the surface area of the asteroids is greater than the Moon's (even though the Moon outmasses the asteroids). Thanks Hop! I sometimes forget there are these strange, rectangular things called "books" next to my computer desk. I've got both "Rain of Iron & Ice" and "Mining the Sky", I'll brush up on what Mr. Lewis says. I agree on the surface area issue. Thousands of roughly spherical objects all rotating slowly should have a vast collective surface. For the NEOs that are "rubble piles", there would be that much more surface area, and a method for trapping He3. Josh |
#6
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He3 on asteroids?
Would Mercury, being much, much closer to the Sun, have a much higher
quantity of He3 than the Moon (not that getting there would be a picnic ? How about huge He3 collectors at either a solar orbit closer to the sun, or at one of the LaGrange points, with a surface area of, say, one of the theorized Solar Power Sattelites envisioned in the 70's - would they work, or would the amounts of He3 over a reasonable period of time be too negligable to even consider them? "Josh Gigantino" wrote in message om... Hop David wrote in message ... From pages 204 and 205 of _Mining The Sky_ by John S Lewis snip MTS quote Although I think the last part of the paragraph must be in error. Surely the surface area of the asteroids is greater than the Moon's (even though the Moon outmasses the asteroids). Thanks Hop! I sometimes forget there are these strange, rectangular things called "books" next to my computer desk. I've got both "Rain of Iron & Ice" and "Mining the Sky", I'll brush up on what Mr. Lewis says. I agree on the surface area issue. Thousands of roughly spherical objects all rotating slowly should have a vast collective surface. For the NEOs that are "rubble piles", there would be that much more surface area, and a method for trapping He3. Josh |
#7
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He3 on asteroids?
"Joseph S. Powell, III" writes:
How about huge He3 collectors at either a solar orbit closer to the sun, or at one of the LaGrange points, with a surface area of, say, one of the theorized Solar Power Sattelites envisioned in the 70's - _WAY_ too small, given the miniscule flux of He3 involved. would they work, or would the amounts of He3 over a reasonable period of time be too negligable to even consider them? The latter. -- Gordon D. Pusch perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;' |
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He3 on asteroids?
(Karl Hallowell) writes:
(Gordon D. Pusch) wrote in message ... "Joseph S. Powell, III" writes: How about huge He3 collectors at either a solar orbit closer to the sun, or at one of the LaGrange points, with a surface area of, say, one of the theorized Solar Power Sattelites envisioned in the 70's - _WAY_ too small, given the miniscule flux of He3 involved. Well, what happens if you get really close? That is, you graze the photosphere? Assuming that you have a collector that handles 5000 K temperatures. Hmmm, still bet the He3 concentrations are extremely small. Youbetcha. He3 is a rare isotope, cosmically speaking --- only 1.37 ppm of all helium is He3. Probably makes more sense to use solar cells instead. Especially since we haven't a =CLUE= how to burn He3 in a fusion reactor, and if Todd Rider's Ph.D. Dissertation is correct, there may be be fundamental thermodynamic reasons why =ANY= He3-burning "reactor" smaller than a brown dwarf will consume more energy than it generates... -- Gordon D. Pusch perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;' |
#10
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He3 on asteroids?
In article ,
Roger Stokes wrote: Even at .7 ppb of the Earth's atmosphere, I assume it must still be cheaper right now to refine it on Earth... You don't get it from the atmosphere. Rather, it's a product of tritium decay. Most modern nuclear weapons contain small amounts of tritium for "boosting" fission yield (either of the whole bomb, or of the fission trigger for a fusion bomb), and it must be repurified regularly because He3 poisons the reaction. So the US nuclear arsenal, in particular, generates a steady trickle of He3 as a byproduct of bomb maintenance. and try some fusion experiments, rather than go to the moon to get it - what's the reason it hasn't been done? We don't have a fusion reactor that works even for the D-T reaction, never mind for one involving He3. The basic physics of the He3 reactions have been understood for a long time; it's the engineering details of the fusion reactor that might, or might not, be able to overcome the problems. We can't run meaningful experiments on that until we can build one. -- MOST launched 30 June; science observations running | Henry Spencer since Oct; first surprises seen; papers pending. | |
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