Author Topic: Obtaining water from the Martian atmosphere  (Read 10540 times)

Offline Slarty1080

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Obtaining water from the Martian atmosphere
« on: 12/03/2018 10:09 am »
I believe that extracting water from the Martian atmosphere would be quite possible but entirely impractical due to its very low concentration, the huge amounts of Martian atmosphere that would need to be processed and the large energy requirements for pumping pressurization and heating.
 
I vaguely remember reading a NASA paper a while back that rejected the prospect of obtaining water from the Martian atmosphere, but I can’t find it. Does anyone know of such a study? Alternatively if I am mistaken, is there a paper that shows obtaining water from the Martian atmosphere is likely to be a practical proposition?
My optimistic hope is that it will become cool to really think about things... rather than just doing reactive bullsh*t based on no knowledge (Brian Cox)

Offline KelvinZero

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Re: Obtaining water from the Martian atmosphere
« Reply #1 on: 12/03/2018 10:28 am »
It has been brought up here a few times

https://forum.nasaspaceflight.com/index.php?topic=33716.msg1145185#msg1145185

https://en.wikipedia.org/wiki/WAVAR

(google also returned this link, not sure what message it was attached to)
http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=33716.0;attach=567424

I think the conclusion here was that it was doable. The energy requirement is high but only a fraction of the energy to turn the water and CO2 into propellant.. I think the reason discussion moved away from it is that extraction from the ground is looking very promising. (on that topic, I noticed the Insight mission plans to dig 5 meters into the ground with what looks to me like a pretty small device. This makes something like a Rodriguez well sound pretty straight forward to me.. in the right location  http://www.gdargaud.net/Antarctica/Water.html#Well )

Offline Slarty1080

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Re: Obtaining water from the Martian atmosphere
« Reply #2 on: 12/03/2018 12:54 pm »
It has been brought up here a few times

https://forum.nasaspaceflight.com/index.php?topic=33716.msg1145185#msg1145185

https://en.wikipedia.org/wiki/WAVAR

(google also returned this link, not sure what message it was attached to)
http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=33716.0;attach=567424

I think the conclusion here was that it was doable. The energy requirement is high but only a fraction of the energy to turn the water and CO2 into propellant.. I think the reason discussion moved away from it is that extraction from the ground is looking very promising. (on that topic, I noticed the Insight mission plans to dig 5 meters into the ground with what looks to me like a pretty small device. This makes something like a Rodriguez well sound pretty straight forward to me.. in the right location  http://www.gdargaud.net/Antarctica/Water.html#Well )
Thanks for this - a very interesting paper. As you say the power requirements are a bit steep but that might be manageable. Not sure how much additional water they would need to manufacture all of the Methane required to LMO / TEI ? Any idea? If it’s a big number then the power requirements might start to get a bit out of hand.

The Rodriguez well idea also looks interesting, but like the above is still unproven or more to the point the water quantity, quality, depth and substrate are not known in sufficient detail yet. It would seem that a robot mission (unmanned Starship?) might be required to try out all of these technologies and see how they work before sending a crew who would rely on them as a matter of life and death.
My optimistic hope is that it will become cool to really think about things... rather than just doing reactive bullsh*t based on no knowledge (Brian Cox)

Offline KelvinZero

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Re: Obtaining water from the Martian atmosphere
« Reply #3 on: 12/03/2018 08:01 pm »
Power shouldn't be a show stopper because it was some fraction. I forget what, but it should in any case less than double your power requirements for each ton of liquid methane and liquid oxygen*. Apparently it was also region dependent. More atmospheric water was available in some regions.

Every ISRU plan I am aware of has a robotic component. For example the SpaceX plan lands two unmanned ships a synod ahead of sending crew. It has to assure the availability of the water. It would be nice if the fuel itself was generated ahead though SpaceX implies more ISRU setup is done after crew arrive. Perhaps the robotic BFS could actually gather the water before the crew arrive, so they only need to set up a larger solar power farm.

* If my memory of people's claims in the earlier conversations are correct.
« Last Edit: 12/03/2018 08:03 pm by KelvinZero »

Tags: Mars atmosphere water 
 

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