oxygen-cycle in space?

[Urge]

I read at wikipedia that right now they are using some sort of pellets that create oxygen when burned, but sometimes they have release the C02 into space because it would require a lot of space to turn it into oxygen again using plants.

Are there science on other ways of turning C02 back into oxygen? One way could be to use geneticaly modified plants that can turn more C02 into oxygen then normal plants, or to use some sort of machine that can do it.

If one manages to create a efficient oxygen-producing plant, or a machine it might be used against global warming as well. Oxygenlevels in the atmoshpere have dropped a litte during the last century, while C02 levels have gone up.

Is anny research going on in this field?

 

[Jadzia]

I think there are chemical processes that can do it.

I remember correctly, with a suitable catalyst you can turn water and carbon dioxide into methane and oxygen. I'm not sure what the conditions and energy costs for the reaction are (eg, high pressure), but with enough solar power (or nuclear power) on a space station it should be possible to manufacture a sustainable supply of oxygen with a big enough chemistry set.

Methane of course isn't much use to astronauts -- it basically has its origins in the food that the astronauts ate and metabolised. They'd just discard that and recover the oxygen.

One problem would be getting the CO2 and water out of the air. For that perhaps a kind of air conditioning unit which cools the air passing through it (and warming the exhaust gas). The CO2 and water vapor will freeze when hitting the cold plate and can be scrapped off and passed on to the catalytic process.

 

[JustAFriend]

Plants would be great, but they take up a lot of space, special handling and would need a full-time staff to take care of them. You cant do that in a small capsule or even the ISS.

We dont have anything off-planet big enough (and wont for a while considering they're going to dump the ISS in the ocean in seven years...)

Go watch the 1972 flick "Silent Running" with Bruce Dern.
Here's a bit of it on YouTube.

 

[Alpha_Geek]

Urge, If you're talking about the ISS, the canisters are a back-up for other equipment on board. The primary oxygen generaor is the Russian built "Elektron" device, which seperates hydrogen and oxygen from water. There is also an American built piece of equipment that does the same thing.

Russian automated craft sometimes deliver fresh water as part of their cargo, and American Shuttle flights offload water, which is a waste product of the onboard fuel cells. In addition, a newer piece of ISS gear recycles onboard wastewater and reclaimed atmospheric condensation.

Back to the oxygen cannisters though. They aren't used as a primary system. The cannisters also produce a lot of heat as the oxygen generation process is exothermic. Similar canisters in the cargo hold were a root cause of a ValuJet airliner crash back in 1996.