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Space gas harvesting

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(+2, -6)
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The vacuum of space is not really empty, gas particles (mostly hydrogen) are abundant. Why not harvest these particles using some sort of molecular sieve, which allows particles to entr the containment vessel but not leave? After several years there might be enough to make hydro/oxy to make fuel out of, a sort of deep space refuleing depot.
simonj, Jan 08 2009

Molecular sieve http://en.wikipedia...iki/Molecular_sieve
[simonj, Jan 08 2009]

Bussard Ramjet http://en.wikipedia...wiki/Bussard_ramjet
Theoretical spacecraft propulsion that does sort of what you describe. [sninctown, Jan 08 2009]


       Hm, what's this molecular sieve?   

       This needs a pump of some sort and would have to use energy. Could be solar - this isn't a showstopper. But "molecular" sounds like something you can just put out there and forget, and I don't think that's thermodynamically possible.
jutta, Jan 08 2009

       abundant? really?   

       Even if H2 were "abundant" in the "near" vacuum of space collecting it would be damn near impossible. A one way valve for H2 atoms is beyond dreaming. If there was enough to be substantial then the drag on space craft (and all other solar bodies, planets, etc.) would make space travel impossible.
WcW, Jan 08 2009

       Why would space travel be impossible? We travel through the air don't we? We even travel underwater sometimes. I'd suggest the drag underwater would be much more than the drag in space.
simonj, Jan 08 2009

       Yes, but the distances we travel here on earth through relatively dense fluid media, are insignificant when compared to any type of space travel. The distances we're talking about in space are only made possible because drag is approximately zero. You spend enough energy getting in/out of gravity wells, etc you don't need to fight your way through every inch of space.   

       IIRC the density of "far" space is dorn to only a few hydrogen atoms per cubic metre. Not so sure about "near" space.
Custardguts, Jan 08 2009

       for you non science types 1 molecule per cubic meter is. very. low.
WcW, Jan 08 2009

       Molecular seives are fine, and they are not that dissimilar to a regular seive. However, they can't be used to actively pump anything, as far as I know, any more than a seive can.   

       However, perhaps it would be possible to adsorb or absorb hydrogen from space. I have no idea of the relevant ab[or ad]sorbent, but I can imagine a material which would bind hydrogen sufficiently tightly (and it would have to be very, very tightly indeed) to sequester it from space.   

       The only problem would be getting the hydrogen back off again, but perhaps heating would achieve this. Whether the whole process would be useful or not is another kettle of worms.
MaxwellBuchanan, Jan 08 2009

       I agree with all the above issues and add on more, slowing them down. The scant atoms filling space are not moving with you and you are always MOVING. I think this would be like catching a ping pong ball bouncing in the 4 lane highway from a speeding car. With the right net you may get the first one, but the second one may knock the first one out. Oh and you need 6x10^23 balls to make a gram. Still we should do this, we just need a REALLY good net. Till then (-).
MisterQED, Jan 08 2009

       Good point [MrQED] - I did a quick google and found a figure of about 100 hydrogen atoms per cubic metre. So, to get a mole, you'd need to filter 6x10^15 cubic kilometres, or about four times the volume of Jupiter (without Jupiter actually being there, obviously).
coprocephalous, Jan 08 2009

       [simonj] as noted, you've described "Bussard Ramjet" (which puts you in some pretty lofty company).   

       Dr. Bussard gave a talk to Google on alternative fusion power a couple years ago... well worth the watch.
FlyingToaster, Jan 08 2009

       //about 100 hydrogen atoms per cubic metre//   

       I stand corrected. 2 orders of magnitude out. Hmmm. Maybe I should go post an idea about fusion.
Custardguts, Jan 08 2009

       //I stand corrected. 2 orders of magnitude out//
I shouldn't worry too much - it was a _very_ quick google, and I just did the sums to indicate the magnitude (no pun intended) of the problem.
coprocephalous, Jan 08 2009

       To up your density A LOT, you should move the net closer to the Sun. This is especially handy because in the solar wind you then get a lot more ions and less H2, then you can use magnetic nets like the Bussard Ramjet does without the need for the ionizing laser to catch the ions and you will get a lot more tritium, duterium and other fusion fuels that are a LOT more usefull than H2.
MisterQED, Jan 08 2009

       If one could build a device that emitted some long distance force that could pull these gas particles towards it, all nearby particles should accumulate by or in the device - maybe even held next to the device by this force. I think it should be possible to devise a way that this force is actually emitted without expending any energy. No sieve necessary, except for the radiatore.
bungston, Jan 08 2009

       I suppose gravity could act as such a force? Would a device of enough mass attract nearby individual atoms in space? Just a thought.
simonj, Jan 09 2009

       I'm a little disappointed that there hasn't been any mention of nanobots to do some kind of H2 pumping (like tiny little ants). Whatever happened to nanobots round here? Seems like they've been forgotten about amongst the GM and Bluetooth ideas. Maybe they've been drowned in custard...
Jinbish, Jan 09 2009

       fishbone, because of mention of nanobots. Damn nanobots.
bungston, Jan 09 2009

       // fishbone, because of mention of nanobots. Damn nanobots   

       No fair!!! I never mentioned them, [Jinbish] did!
simonj, Jan 09 2009

       Oops! Sorry [simonj].   

       Tell you what, here's a bun. {The nanobots might get hungry anyhow}
Jinbish, Jan 09 2009

       //Whatever happened to nanobots round here?//
Work has been discontinued on nanobots pending world-encompassing grey goo FDA approval.
FlyingToaster, Jan 09 2009

       /Would a device of enough mass attract nearby individual atoms in space?/   

       One might seek out extant devices or other objects in space, on the theory that over time they might have accumulated space gas. The local area around such objects might be enriched for gas and so facilitate collection.
bungston, Jan 09 2009


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