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?
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.
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.
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.
... effectively turning the mine into a radiation shelter and storage room, with the additional benefit of being refrigerated.
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)
Quote from: lamontagne on 05/17/2016 07:41 pmWhy 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)
Failure to even consider atmospheric water collection is a major over-site in the paper.
Quote from: Impaler on 07/10/2016 08:48 amFailure 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.
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.
1 kg water is contained in 250,000m3 of atmosphere
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.