Extracting moisture from Martian atmosphere

Impaler · 2014-12-01 04:45:15

This paper http://www.uapress.arizona.edu/onlinebk … rces28.pdf seems to have a nice Acetylene/CO/O2 propellent mix which is just 1% Hydrogen by weight and hits the same impulse as Metho-Lox. They even recommend extracting moisture from the atmosphere (10^6 m^3 of atmosphere would yields 1 kg water by simply compressing it). A big industrial size fan doing 700 m^3 a minutes would move that volume in a day (as far as I know the volumetric efficient of a fan should be unaffected by the low pressure on Mars).

That is probably going to be too large a compressor and too slow an extraction rate for any kind of initial mission, but when were talking about a long-term sustained fleet of reusable Mars Taxi's that need to be fueled entirely on Mars using some hydro-carbon fuel it may be simpler then an ice mining operation as it is just a static machine that won't be breaking down the way mining equipment inevitably dose.

In this paper https://www.google.com/search?q=moistur … channel=sb the design of a zeolite moisture absorber optimized for Martian atmosphere is discussed, as the process is passive the energy requirements are just that to push the the air-stream through the zeolite which should be manageable. A more detailed design is here http://www.lpi.usra.edu/publications/re … ington.pdf which claims to be able to get several kg a day with just the a small fraction of reference mission available power provided that altitude is low, in the north polar zone the rate of production shoots op an order of magnitude due to humidity.

Finally this http://www.uapress.arizona.edu/onlinebk … rces29.pdf (again from my old school UofA) looks at the whole spectrum of atmospheric separation and the energy costs their of. For human life-support the energy costs are reasonable as people only need on the order of 1 kg of these inputs per day.

Air-moisture extraction in the desert like environment of Mars reminds one of Arakis from the Dune novels dose it not. The fact that you can just drop the base anywhere without scouting for ice and have high confidence in the equipment because we can test it so thoroughly here on earth is very attractive. Their would also be no issue with ever running out of what ever glacier your mining. A base that exhausts resources like that is going to become a ghost town.

Last edited by Impaler (2014-12-01 04:57:01)

louis · 2014-12-01 19:05:32

Impaler wrote:

This paper http://www.uapress.arizona.edu/onlinebk … rces28.pdf seems to have a nice Acetylene/CO/O2 propellent mix which is just 1% Hydrogen by weight and hits the same impulse as Metho-Lox. They even recommend extracting moisture from the atmosphere (10^6 m^3 of atmosphere would yields 1 kg water by simply compressing it). A big industrial size fan doing 700 m^3 a minutes would move that volume in a day (as far as I know the volumetric efficient of a fan should be unaffected by the low pressure on Mars).
That is probably going to be too large a compressor and too slow an extraction rate for any kind of initial mission, but when were talking about a long-term sustained fleet of reusable Mars Taxi's that need to be fueled entirely on Mars using some hydro-carbon fuel it may be simpler then an ice mining operation as it is just a static machine that won't be breaking down the way mining equipment inevitably dose.
In this paper https://www.google.com/search?q=moistur … channel=sb the design of a zeolite moisture absorber optimized for Martian atmosphere is discussed, as the process is passive the energy requirements are just that to push the the air-stream through the zeolite which should be manageable. A more detailed design is here http://www.lpi.usra.edu/publications/re … ington.pdf which claims to be able to get several kg a day with just the a small fraction of reference mission available power provided that altitude is low, in the north polar zone the rate of production shoots op an order of magnitude due to humidity.
Finally this http://www.uapress.arizona.edu/onlinebk … rces29.pdf (again from my old school UofA) looks at the whole spectrum of atmospheric separation and the energy costs their of. For human life-support the energy costs are reasonable as people only need on the order of 1 kg of these inputs per day.
Air-moisture extraction in the desert like environment of Mars reminds one of Arakis from the Dune novels dose it not. The fact that you can just drop the base anywhere without scouting for ice and have high confidence in the equipment because we can test it so thoroughly here on earth is very attractive. Their would also be no issue with ever running out of what ever glacier your mining. A base that exhausts resources like that is going to become a ghost town.

Couple of thoughts:

1. Whilst not opposed to atmospheric extraction, sending robots to scout for water shouldn't be too difficult. So far none of the space agencies have chosen to send robots to where water is most likely to be found.

2. I think there is a strong possibility quite a young Mars community could build Armadillo style rockets that could get to LMO.

SpaceNut · 2014-12-01 21:13:40

Zeolites Used as Desiccants
Desiccants are of four types, silica gel, montmorillonite clay, molecular sieve (zeolites), and calcium oxide of which I believe Mars does have clay as well as gypsm.

System you described...I think

The water vapor of highest concentratio would be found at latitudes 60 north in the spring at low altitude and 60 latitude in the southern hemisphere such as Hellas Basin which is 4km below planetary reference which would aid water vapor creation with its hugher pressure. The same spring thaw also leads to brine water flows...

Impaler · 2015-01-04 00:03:28

More examination, the UofA system is aiming for 3.3 kg of water per day at Viking landing site conditions (which are rather dry relative to many other sites), and has a mass of 1200 kg, meaning such a system needs exactly 1 year to collect it's own mass in water under worst case conditions. This dose not include mass for power, but power requirements are low compared to the remaining chemical fuel synthesis and electrolysis steps in Propellent production.

If a reusable Mars Ferry capsule will have some ratio between propellent needed per trip and cargo delivery mass to the Martian surface. Numerous factors in the EDL profile chosen, the height of the Martian orbit from which cargo is picked up, and how much if any additional marginal cargo offload done by the vehicle on orbit will all have impacts on this ratio. Ballpark we could estimates the ratio to be between 5:1 and 15:1

The Propellent type will also determine the Propellent production ratio relative to water, as water is only 11.8% Hydrogen the commonly stated Hydrogen leverage ratios can be multiplied by 0.118 to get the 'true' water ratio which are what the actual feedstock is here. The best leverage ratio is Acetylene at 53, which when adjusted for water use is 6.25, mixing CO in with any Hydrocarbon can raise the leverage ratio at the cost of ISP, the more CO used the better the ratio and the worse the ISP as you linearly approach the performance of the CO rocket which is generally considered not viable for the reusable DeltaV mission requirement, it MAY be desirable as way to cool the exhaust of the Acetylene rocket as they are very hot.

These two offsetting ratios, between Ferry propellent needs and water propellent leverage give us the combined water leverage needs of the Propellent production system. At the high end of performance the ISPP system needs to make 80% of it's mass in water to refuel to Ferry, at the low end 2.4 times as much, CO mixing could bring these numbers down further.

Now multiply that water ratio by the days needed for a system to produce the necessary water, the UofA systems one year time would thus translate to either 290 days or 875 depending on the Ferry propellent/down-mass ratio. These are rather long but well within the kinds of time-frames needed for a unmanned pre-fueling Mars-Direct style missions.

The ratio matters because it ultimately determines how much propellent production equipment is needed to give any particular launch cadence to the Ferry. The word Ferry is suggestive of a rapid cadence and this would indeed be the ultimate goal to get good amortization even if initial propellent forces a lower rate. When the first Propellent production equipment is landed it will be unaccompanied by crew and need to operate while sitting in the cargo hold of the Ferry, at most one Solar-Power module could be unloaded from the Ferry and placed onto the surface to power everything but the rest of the equipment remains loaded with all attachments/pipes/cabling having already been made when they were loaded. Over about 1 year a Ferry so equipped is refueld, then when crew arrive on a future Ferry they can complete the unloading of the Production equipment and take the Ferry back to orbit.

If 2 Ferries are landed, one with Propellent production equipment, one with surface habitats, and the crew lands in a 3rd which has a vehicle for moving equipment and additional Propellent storage tanks and piping needed to establish a farm then the crew can have a 2nd lander being fueled during their surface stay. This can be a redundancy for the first Ferry, but if not used before the crew returns to orbit the Ferry can ascend unmanned and then be loaded with another set of Propellent producing equipment and sent back to the surface to bootstrap propellent again. Now each subsequent landing can refuel two Ferries and land 2 sets of equipment, then 4, and then your into the fueling time being short enough that rather then waiting till the end of the crew stay your rolling them over every few weeks and eventually days to bring down propellent production equipment and adding it to the farm at an exponentially increasing rate. Starting with just 1 Ferry and ISPP unit that takes 1 synod to refuel a lander and allowing duplicate units to be brought down from orbit and immediately put to use would in just 6 synods or ~13 years result in over 100 trips per synod being possible, though obviously 100 copies of the ISPP equipment are needed.

This should be seen as a near worst case scenario though, in all likelihood moisture extractor based system will benefit from scaling-up, placement at wetter sites on Mars, mixing some CO for better leverage rate, and will be even faster and need lower numbers of duplicate units. As their are virtually no other risks in a moisture extractor other then premature break-down due to a design over-site (a very hard over-site to make in such a simple device) this moisture based approach is already vastly safer and more reliable then mining could ever hope to be. And it's mass is very likely to be competitive with the ice mining equipment, particularly the practically unbounded upper end of the mining equipment estimate (assuming their is even an estimate that can put any kind of upper limit on the mass).

Last edited by Impaler (2015-01-04 00:06:06)

RobertDyck · 2015-01-04 04:13:26

Interesting. However, Mars has a lot more water than scientists thought just 2 decades ago. Here is an image of ice deposits discovered by SHARAD on MRO:

The Shallow Radar instrument on NASA's Mars Reconnaissance Orbiter has detected widespread deposits of glacial ice in the mid-latitudes of Mars.
This map of a region known as Deuteronilus Mensae, in the northern hemisphere, shows locations of the detected ice deposits in blue. The yellow lines indicate ground tracks of the radar observations from multiple orbits of the spacecraft.
The ice, up to 1 kilometer (0.6 mile) thick, is found adjacent to steep cliffs and hillsides, where rocky debris from slopes covers and protects the ice from sublimation into the atmosphere.
The base map of this image is shaded relief topography obtained by the Mars Orbiter Laser Altimeter on NASA's Mars Global Surveyor. The image is centered at 42.2 degrees north latitude and 24.7 degrees east longitude. It covers an area 1050 kilometers by 775 kilometers (650 miles by 481 miles).

Of course there's lots of water ice at or near the poles. This famous image:

28 July 2005 These images, taken by the High Resolution Stereo Camera (HRSC) on board ESA’s Mars Express spacecraft, show a patch of water ice sitting on the floor of an unnamed crater near the Martian north pole.
The HRSC obtained these images during orbit 1343 with a ground resolution of approximately 15 metres per pixel. The unnamed impact crater is located on Vastitas Borealis, a broad plain that covers much of Mars's far northern latitudes, at approximately 70.5° North and 103° East.
The crater is 35 kilometres wide and has a maximum depth of approximately 2 kilometres beneath the crater rim. The circular patch of bright material located at the centre of the crater is residual water ice.

And closer to the equator:

23 February 2005 This image, taken by the High Resolution Stereo Camera (HRSC) on board ESA’s Mars Express spacecraft, shows what appears to be a dust-covered frozen sea near the Martian equator.
It shows a flat plain, part of the Elysium Planitia, that is covered with irregular blocky shapes. They look just like the rafts of fragmented sea ice that lie off the coast of Antarctica on Earth. This scene, taken during orbit 32, is a few tens of kilometres across, and is centred on latitude 5º North and longitude 150º East.
The water that formed the sea appears to have originated beneath the surface of Mars, and to have come out through a series of fractures known as the Cerberus Fossae, from where it flowed in a catastrophic flood.
It collected in a vast area about 800 kilometres long and 900 kilometres wide with a depth of about 45 metres. As the water started to freeze, floating pack ice broke up into rafts. These became later covered in ash and dust from volcanic eruptions in the region.
...
The question remains as to whether the frozen body of water is still there, or whether the visible floes are just the remains of the sublimation process. Two observations suggest that the ice is still there: first, the submerged craters are too shallow, indicating most of the ice is still in the craters; and second, the surface is too horizontal – if the ice had been lost, there would be a greater height variation.

Antius · 2015-01-04 15:56:10

Acetylene is a monopropellant with explosive instability problems. Ethylene would be a safer choice and achieves most of the benefits you are looking for.

Impaler · 2015-01-04 18:01:55

It looks like we have an old thread on Acetylene rockets, http://www.newmars.com/forums/viewtopic.php?id=6993 lets revive that for discussion of the rocket and stick to atmospheric moisture extraction here on this thread.

Robert: While I can certainly agree that ice presence on Mars is much firmer then it was just a few decades ago, I don't think this is sufficient to displace the pure-atmosphere approach, at least not for a critical bridge phase of any infrastructure build-up.

The 3 Hydrogen methods (Bring from Earth, Moisture Extraction, Ice Mining, BFE, ME, ICEM for short), each clearly fall along a spectrum of scale-appropriateness. The BFE option is dominant at the small scales when you need a few tons of Hydrogen, the ICEM solution clearly needs to be very large scale to be effective, probably hundreds of tons per year and ongoing for years to justify the setup costs. ME is somewhere in between the two.

If we were to graph these solutions with equipment mass to hydrogen mass ratio on one axis and hydrogen needs on the other we would get 3 different sloping curves with two key cross-over points. If we allow multiple time-periods to be considered then ME and ICEM can have multiple curves, where as BFE looks the same all the time. The cross-over between BFE and ME is probably much lower then most people suspect, I think it basically relegates BFE to situations in which less then 1 ton of Hydrogen is needed or time is very short, thus it is inferior on any manned mission concept. The real question is at what Hydrogen mass goal and time-frame is ICEM going to over-take ME, is it 10 mt? Is it 10,000 mt?

I don't doubt that eventually at SOME scale ICEM will be more effective, taking apart a glacier like we take apart a coal seam here on Earth is going to move a lot of mass and have some very nice scaling as you go bigger and bigger, where as ME is going to be fully scaled up at at maximum efficiency likely at much lower production rates, I'd estimate by the time the ME is building sized and massing 100 mt it is likely as efficient as it could get, where as mining infrastructure can have individual TRUCKS and SHOVELS that size.

The problem I have with ICEM is that it's mass needs are sooooo wide open, I've never seen any kind of credible estimates of what it takes to produce just the first ton of water or how it scales after that, how long the equipment service life might be etc etc. Rather then a well defined line on our comparison graph we have a huge error band. It would be unwise to put all your eggs in the mining basket with that kind of risk, you would want to develop and use use the smaller scale solution until the Hydrogen need actually outstrips it and the investment in the new equipment is justified on the EXISTING demand, also having gotten to Mars we will have been able to narrow that ICEM error band a huge amount.

So in summary, our present course of development should drop Hydrogen storage attempts and and go all in for Moisture Extraction because it's the clearly best solution for first landing and autonomously refueling vehicles. Moisture Extraction would be validated on a robotic mission, then relied upon for initial manned missions. On the side methods to characterize and study the Martian ice without depending on any net production, these would be purely experimental attempts and would be employed by the early exploration crews to try to characterize the ice and narrow the error band as much as possible. Then we would re-asses, if ice is hard to mine then we invest in scaling Moisture Extraction out to it's effective maximum and rely on it for ongoing expansion, or if ice is vastly easier and our expansion needs are close to the cross-over point we would invest in mining development.

SpaceNut · 2015-01-04 20:30:56

So lets look at Moisture Extraction (M.E.) First up is where is the best concentration levels of moisture in the Mars air to obsorb and at what altitude is the moisture.

Researchers create map of water vapor distribution in Mars' atmosphere

The content of water vapour in the atmosphere reaches a maximum level of 60-70 microns of released water in the northern regions during the summer season. The summer maximum in the southern hemisphere is significantly lower, about 20 microns.

http://marsanomalyresearch.com/evidence … sphere.htm

WATER VAPOR IN THE ATMOSPHERE OF MARS: FROM PATHFINDER TO MARS POLAR LANDER.

Mars_B4_Moon · 2022-09-01 03:50:36

Chaotic crust contains clues to Mars’ watery past
https://www.esa.int/Science_Exploration … atery_past

New Mars Forums

Announcement

#1 2014-12-01 04:45:15

Extracting moisture from Martian atmosphere

#2 2014-12-01 19:05:32

Re: Extracting moisture from Martian atmosphere

#3 2014-12-01 21:13:40

Re: Extracting moisture from Martian atmosphere

#4 2015-01-04 00:03:28

Re: Extracting moisture from Martian atmosphere

#5 2015-01-04 04:13:26

Re: Extracting moisture from Martian atmosphere

#6 2015-01-04 15:56:10

Re: Extracting moisture from Martian atmosphere

#7 2015-01-04 18:01:55

Re: Extracting moisture from Martian atmosphere

#8 2015-01-04 20:30:56

Re: Extracting moisture from Martian atmosphere

#9 2022-09-01 03:50:36

Re: Extracting moisture from Martian atmosphere

Board footer