Author Topic: Water, Methane, and Oxygen ISRU on Mars  (Read 8252 times)

Offline lamontagne

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Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #20 on: 05/17/2016 07:41 PM »
Why do they condemn atmospheric extraction of water?  The method they propose, using compressors, on page 26, is not the most likely one, IMHO.  Shouldn't it should be possible to use regeneration of zeolite beds, or another strongly adsorbent material, to extract the water, as in the joined paper?  Or has that technology been disproven?
I don't doubt there would be a lot of modifications required, but here is a catalog of commercial desiccant systems.  84 000 cfm is not that much in ventilation equipment terms.  a big machine, but nothing extraordinary.  And at the very low air densities, the fan power required should be tiny.  The main power drain would be the regeneration heat.
Similar methods can be used to extract the CO2 from the atmosphere as well.
If we are making CH4 from atmosphere, we might have heat from the Sabatier reaction to use for regeneration.
The power would still be fundamentally solar though, unless the Sabatier used hydrogen from Earth.


Offline redliox

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Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #21 on: 05/17/2016 09:37 PM »
Why do they condemn atmospheric extraction of water?  The method they propose, using compressors, on page 26, is not the most likely one, IMHO.  Shouldn't it should be possible to use regeneration of zeolite beds, or another strongly adsorbent material, to extract the water, as in the joined paper?  Or has that technology been disproven?

Matter of practicality not so much technology.  The dry, thin air of Mars makes the Mohave Desert look like a rain forest.  To the point, the dehumidifiers would have to run for hours...and hours...and likely weeks if not months to yield much.  A shovel load dug from a gypsum deposit would give you the same amount of water in less time; weeks versus a single day, which is more economical?

Similar methods can be used to extract the CO2 from the atmosphere as well.
If we are making CH4 from atmosphere, we might have heat from the Sabatier reaction to use for regeneration.
The power would still be fundamentally solar though, unless the Sabatier used hydrogen from Earth.

Carbon dioxide pretty much is the Martian atmosphere, with nitrogen and argon the only others with significance, and ubiquitous; hence why both fuel cells and Sabatier reactors are viable because their resource is everywhere.  Water vapor sadly doesn't have this advantage, hence why it was turned down in the M-WIP study.  If you want water on Mars, digging for it is the best option; I will say near the Martian poles (particularly the northern one) would be the region to consider this...but only if you don't have the means to mine the water literally under your feet there.
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Offline lamontagne

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Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #22 on: 05/18/2016 12:26 AM »


Matter of practicality not so much technology.  The dry, thin air of Mars makes the Mohave Desert look like a rain forest.  To the point, the dehumidifiers would have to run for hours...and hours...and likely weeks if not months to yield much.  A shovel load dug from a gypsum deposit would give you the same amount of water in less time; weeks versus a single day, which is more economical?

Carbon dioxide pretty much is the Martian atmosphere, with nitrogen and argon the only others with significance, and ubiquitous; hence why both fuel cells and Sabatier reactors are viable because their resource is everywhere.  Water vapor sadly doesn't have this advantage, hence why it was turned down in the M-WIP study.  If you want water on Mars, digging for it is the best option; I will say near the Martian poles (particularly the northern one) would be the region to consider this...but only if you don't have the means to mine the water literally under your feet there.

The air extraction paper suggested 3 kg per day, or about 1,5 tonnes for the 480 days of the study cited in the first post, for 880 kg of equipment.  To get the 16 tonnes requires as per the first post would require about 8 to 9 tonnes of equipment.  The reference site was the Viking lander site.
How does that compare to mining?  The mining equipment seems rather light, good, but I see no mass numbers for ore processing.
It's not that I don't believe in mining, it's just that the paper's dismissal of atmospheric mining seems wrong.  It's using the wrong comparison base. The conclusions may be the same.
« Last Edit: 05/18/2016 12:27 AM by lamontagne »

Offline TakeOff

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Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #23 on: 07/09/2016 06:28 PM »
KISSCaltech has a few presentations of ISRU on Mars, just a week old, on their youtube channel.
https://www.youtube.com/user/KISSCaltech

I'm surprised to learn that solar panel power production varies so very much (on the MER rovers). Some kind of cleaning mechanism would help. Why not a set of layers of thin plastic foils that could be removed and discarded? Still 45% change of insolation over a Martian year and blocking dust in the atmosphere varies too. Solar power is not so easy on Mars as I thought.

Online guckyfan

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Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #24 on: 07/09/2016 10:00 PM »
Still 45% change of insolation over a Martian year and blocking dust in the atmosphere varies too. Solar power is not so easy on Mars as I thought.

Not easy true. Possible that the base value for production is just good enough to keep the colony running. Fuel ISRU and other energy intensive activities may need to be limited to times when enough power is available. It is a calculation what is more efficient. Having more solar power and keep the ISRU equipment running all the time or having more mass in ISRU equipment and run it only when energy is available.

Constant supply from nuclear power would make things easier. You could keep ISRU running all the time, even at night.

Offline Bob Shaw

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Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #25 on: 07/09/2016 10:32 PM »
There's lots of easily accessible, crushed up ice on Mars; just land your demo ISRU plant next to a nice, fresh impact crater somewhere on the northern plains. There are fresh craters each year - no need to worry about finding one that's not suffered too much sublimation. Land either in the ejecta field, or even *inside* the crater, and shovel up the goodies!

Offline Impaler

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Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #26 on: 07/10/2016 08:48 AM »
Failure to even consider atmospheric water collection is a major over-site in the paper.  It is clearly the source which is most widely distributed and most easily processed, the technical challenge is basically just a sufficient power supply which is something that needs to be cracked anyway.

Offline Hotblack Desiato

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Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #27 on: 09/05/2016 05:50 PM »
Regarding a glacier as water source, how about underground mining?

One entrance at the side, with airlock to have a higher air pressure inside, and then dig tunnels and caverns into the glacier.

Excavating these tunnels will provde lots of water and more importantly, it's several 10s of meters below the surface. That layer will block any radiation, effectively turning the mine into a radiation shelter and storage room, with the additional benefit of being refrigerated.l

The sides and bottom layers of the glacier can then be used for testing other excavation methods for larger underground structures inside the bedrock (again with perfect radiation shielding).


Offline CuddlyRocket

Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #28 on: 09/05/2016 10:56 PM »
... effectively turning the mine into a radiation shelter and storage room, with the additional benefit of being refrigerated.

I see the advantage of being refrigerated for a storage room; less so for a radiation shelter! :)

Offline Dalhousie

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Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #29 on: 09/06/2016 07:42 AM »
Why do they condemn atmospheric extraction of water?  The method they propose, using compressors, on page 26, is not the most likely one, IMHO.  Shouldn't it should be possible to use regeneration of zeolite beds, or another strongly adsorbent material, to extract the water, as in the joined paper?  Or has that technology been disproven?
I don't doubt there would be a lot of modifications required, but here is a catalog of commercial desiccant systems.  84 000 cfm is not that much in ventilation equipment terms.  a big machine, but nothing extraordinary.  And at the very low air densities, the fan power required should be tiny.  The main power drain would be the regeneration heat.
Similar methods can be used to extract the CO2 from the atmosphere as well.
If we are making CH4 from atmosphere, we might have heat from the Sabatier reaction to use for regeneration.
The power would still be fundamentally solar though, unless the Sabatier used hydrogen from Earth.

The best estimate of water concentration in the martian atmosphere in your reference is 10e-5 kg/m3, so to get the 16 tonnes of water recommended in the most recent studies for ISRU will need the processing of 1.6 km3 of atmosphere.  That 2.7 million m3 per sol for 600 sols.  Or 74 m3 a second for 10 hours per sol (when solar power can be used)
« Last Edit: 09/06/2016 07:46 AM by Dalhousie »
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Offline KelvinZero

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Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #30 on: 09/06/2016 08:14 AM »
The best estimate of water concentration in the martian atmosphere in your reference is 10e-5 kg/m3, so to get the 16 tonnes of water recommended in the most recent studies for ISRU will need the processing of 1.6 km3 of atmosphere.  That 2.7 million m3 per sol for 600 sols.  Or 74 m3 a second for 10 hours per sol (when solar power can be used)
Finding a way to run at night would be good, but how insurmountable is that value?

http://quest.nasa.gov/aero/planetary/mars.html
"The maximum wind speeds recorded by the Viking Landers in the 1970's were about 30 meters per second (60 miles an hour) with an average of 10 m/s"

That implies 70m3 pass through a given 7 square-meter area per second on average.

(obviously I am brushing over the fact that you need to somehow sieve this wind for every atom of moisture. I have no idea of the efficiency or drag of that)

I think there are also canyons with notorious winds.. Are those also the ones speculated to have ice ten meters down, ie good long term targets?
« Last Edit: 09/06/2016 08:16 AM by KelvinZero »

Online guckyfan

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Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #31 on: 09/06/2016 08:21 AM »
I think water content in the atmosphere will vary a lot with location and season.

Offline Robotbeat

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Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #32 on: 09/06/2016 01:38 PM »
Why do they condemn atmospheric extraction of water?  The method they propose, using compressors, on page 26, is not the most likely one, IMHO.  Shouldn't it should be possible to use regeneration of zeolite beds, or another strongly adsorbent material, to extract the water, as in the joined paper?  Or has that technology been disproven?
I don't doubt there would be a lot of modifications required, but here is a catalog of commercial desiccant systems.  84 000 cfm is not that much in ventilation equipment terms.  a big machine, but nothing extraordinary.  And at the very low air densities, the fan power required should be tiny.  The main power drain would be the regeneration heat.
Similar methods can be used to extract the CO2 from the atmosphere as well.
If we are making CH4 from atmosphere, we might have heat from the Sabatier reaction to use for regeneration.
The power would still be fundamentally solar though, unless the Sabatier used hydrogen from Earth.

The best estimate of water concentration in the martian atmosphere in your reference is 10e-5 kg/m3, so to get the 16 tonnes of water recommended in the most recent studies for ISRU will need the processing of 1.6 km3 of atmosphere.  That 2.7 million m3 per sol for 600 sols.  Or 74 m3 a second for 10 hours per sol (when solar power can be used)
If the batteries are lighter than the equipment they'd be powering, then you might want to run the entire sol.
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Offline Norm38

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Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #33 on: 10/11/2016 08:39 PM »
If Curiosity isn't allowed to go anywhere near water, then how will anyone be allowed to use ice/water to make fuel?  Wouldn't that cause microbe contamination just the same?

Or would any human base just fundamentally have to be considered tainted and contamination allowed?

http://www.nature.com/news/mars-contamination-fear-could-divert-curiosity-rover-1.20544

Offline Impaler

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Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #34 on: 10/11/2016 11:22 PM »
Peak atmospheric moisture occurs during the northern summer near the poles as the ice cap is actively sublimating away and air temperatures are highest which gives the atmosphere maximum moisture holding capacity.  Solar power is naturally maximized during a polar summer, but you have the difficulty of surviving during the polar winter unless your doing a brief surface stay in which case the north pole is clearly the best location as you can get to have your cake and eat it too.

The WAVAR concept described here http://www.lpi.usra.edu/publications/reports/CB-955/washington.pdf would produce several times it's mass in water over a martian year at most sites on mars and at the simulated average martian moisture level, only at particularly dry locations like Viking-2 would it be inadequate.  The system proposed here was for life-support water but multiplying it a few times would get the desired water quantity of 16 tons.
« Last Edit: 10/12/2016 04:11 AM by Impaler »

Offline savuporo

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Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #35 on: 10/12/2016 05:55 AM »
Failure to even consider atmospheric water collection is a major over-site in the paper. 
Ask yourself why isn't every desert settlement on earth littered with "atmospheric water collection" plants.
The tech exists by the way, Fraunhofer and Simon Fraser university have active R&D programs for various methods of absorption and refrigeration.
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Offline john smith 19

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Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #36 on: 10/12/2016 06:52 PM »
Reading the thread I can't quite shake the idea people seem to think they are building a well by hand

IIRC in several parts of the US people get their water from individual boreholes. Pulling some numbers off the web gives figures around a 200-600 feet with an 8 inch diameter.  Such boreholes can be drilled in less than 10 days. A quick check on eBay suggests these run 16Hp

This suggests a borehole of < 32 feet is well within the SoA. Building a drilling rig that can do this would be a high energy task by space probe power levels, around 12Kw. You're also looking at quite a heavy package once the drill pipe is included. Obviously the shorter length helps and lowering the drill rate should reduce the Hp requirements.

But that's the easy part  :(

Phase changes release and absorb huge amounts of energy and water is among the highest (behind LH2). That said the very low atmospheric pressure suggests any water will immediately vaporize, once that energy has been added.

The joker in the pack is what state such glacier water will be in. Will be be (more or less) pure ice or more like permafrost IE frozen mud? This sounds like a case of "Hope for the best, plan for the worst" as the worst will need to shift a lot more mass to recover the same volume of water.

One thing I have not seen anything about is the use of focused sunlight to provide most of the heating. This would replace PV arrays with reflectors and concentrators with minimal conversion losses.   

Just my $0.02

I quite like the University Of Washington concept of water recovery from the atmosphere. yes it is low density and quite variable but accessing it is mechanically simpler and enough is known about the Mars atmosphere to predict the best sites for collection.
« Last Edit: 10/12/2016 07:01 PM by john smith 19 »
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Offline lamontagne

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Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #37 on: 10/12/2016 07:48 PM »
Why do they condemn atmospheric extraction of water?  The method they propose, using compressors, on page 26, is not the most likely one, IMHO.  Shouldn't it should be possible to use regeneration of zeolite beds, or another strongly adsorbent material, to extract the water, as in the joined paper?  Or has that technology been disproven?
I don't doubt there would be a lot of modifications required, but here is a catalog of commercial desiccant systems.  84 000 cfm is not that much in ventilation equipment terms.  a big machine, but nothing extraordinary.  And at the very low air densities, the fan power required should be tiny.  The main power drain would be the regeneration heat.
Similar methods can be used to extract the CO2 from the atmosphere as well.
If we are making CH4 from atmosphere, we might have heat from the Sabatier reaction to use for regeneration.
The power would still be fundamentally solar though, unless the Sabatier used hydrogen from Earth.

The best estimate of water concentration in the martian atmosphere in your reference is 10e-5 kg/m3, so to get the 16 tonnes of water recommended in the most recent studies for ISRU will need the processing of 1.6 km3 of atmosphere.  That 2.7 million m3 per sol for 600 sols.  Or 74 m3 a second for 10 hours per sol (when solar power can be used)

The Washington paper, for 3,3 kg/day, proposed a velocity of 8 m/s over the Zeolite beds for 95% separation efficiency. The required fan power was 12 kW.
In our case, at 27 kg/day, That would mean an area of about 10m2 for the Zeolite beds. 
They also proposed using a fan, at 20m/s, so about 4m2.  That would be about 1.2m in diameter.
In our case the required fan power would be almost 100 kW.  That's a big motor!

Wind alone could not provide enough energy to push the air through the Zeolite bed.

The solar panel area would be 600 W/m2 x .2eff = 150 W/m2 = 665 m2.  At 10 kg/m2, almost 6 tonnes.

Doesn't seem insurmountable, but not very good at our scale of operation.

However, looking all the way to the conclusion of the report, there are emplacements where the average concentration of water is higher, and their simulations achieved 46 kg per day with 15 kW.  That would be OK for our needs, and avoid the humongous motor I just calculated.  Location is key.

As far as melting water goes, 335 kJ/kg x 27 kg/day = 8736 kJ/day = 0,24 kJ/s or 240 Watts.  Melting is the clear winner here, by I to2 orders of magnitude!  So we have a lot of energy difference available for digging up the ice.  On that basis, digging wells is the more energy efficient solution.  And the well digging equipment will probably weigh less than the extra solar panels...

So I would conclude that atmospheric is possible, but well digging is much better.
« Last Edit: 10/12/2016 08:01 PM by lamontagne »

Offline KelvinZero

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Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #38 on: 10/14/2016 03:53 AM »
Failure to even consider atmospheric water collection is a major over-site in the paper. 
Ask yourself why isn't every desert settlement on earth littered with "atmospheric water collection" plants.
The tech exists by the way, Fraunhofer and Simon Fraser university have active R&D programs for various methods of absorption and refrigeration.
Earth has bodies of fresh water, roads, pipes, cheap trade with near and distant neighbours, and is nervous about giving every desert settlement it's own nuclear capability? :)

Online AncientU

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Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #39 on: 10/14/2016 10:55 AM »
Failure to even consider atmospheric water collection is a major over-site in the paper.  It is clearly the source which is most widely distributed and most easily processed, the technical challenge is basically just a sufficient power supply which is something that needs to be cracked anyway.

Atmospheric extraction was considered and ruled out.  See p26 of presentation.
Quote
1 kg water is contained in 250,000m3 of atmosphere

Quote
The air handling system implied by these calculations would be on the same order of magnitude as the largest air compressors known on Earth: ~600,000 CFM, requiring 65 megawatts to run, and roughly 5x5x10m in size.
CONCLUSION: The mass, power, volume, and mechanical complexity of the system needed for this approach are far outside of what is practical for deployment to Mars.

And here they didn't even include the power required to get water back out of the zeolite... which is far from trivial.
« Last Edit: 10/14/2016 11:00 AM by AncientU »
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