Author Topic: Water, Methane, and Oxygen ISRU on Mars  (Read 28746 times)

Offline Warren Platts

Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #40 on: 10/16/2016 12:02 AM »
There might be groundwater in certain places underneath permafrost. Permafrost is impermeable to liquid water, so makes a good cap rock that prevents escape to the surface. As you go deeper, the temperature must of necessity increase to a point that is not subfreezing anymore. At such depths, the overburden pressure is over an atmosphere, so liquid water would necessarily form.

It is much easier to drill for such water--assuming it exists and can be found--than practically any other option on the table IMHO. It would take some prospecting for sure, but maybe not a whole lot, relatively speaking.

The other strategy extreme seems to be to engineer for average conditions. That way the entire prospecting step can be eliminated, while success is guaranteed. But the latest round of studies has mainly succeeded in showing how difficult that is.

YMMV

"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."--Leonardo Da Vinci

Offline Warren Platts

Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #41 on: 10/16/2016 12:05 AM »
Very old school (1970) study of groundwater in permafrost regions in Alaska. Of relevance to Mars ISRU however, IMO.

http://pubs.usgs.gov/pp/0696/report.pdf
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."--Leonardo Da Vinci

Offline lamontagne

  • Full Member
  • ****
  • Posts: 1226
  • Liked: 1666
  • Likes Given: 273
Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #42 on: 10/16/2016 12:19 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.
Using compression to extract water from the air is a really kind of silly.  I don't feel their investigation into atmospheric water was serious or complete.  However, this in not very important as mining for water is by far more effective than extracting it from the atmosphere, even if we use the best atmospheric extraction system, rather than the worst ;-)

Online AncientU

  • Senior Member
  • *****
  • Posts: 6233
  • Liked: 4055
  • Likes Given: 5567
Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #43 on: 10/17/2016 12:59 AM »
I believe the compression is needed to get sufficient flow rate through the zeolite beds to achieve the water extraction rate needed.  Cannot just open a canister of desiccant and expect a significant capture rate by diffusion alone -- gotta pump 250,000cubic meters of Martian atmosphere through the beds to get one liter of captured water.
"If we shared everything [we are working on] people would think we are insane!"
-- SpaceX friend of mlindner

Online Robotbeat

  • Senior Member
  • *****
  • Posts: 28466
  • Minnesota
  • Liked: 8331
  • Likes Given: 5479
Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #44 on: 10/17/2016 02:08 AM »
I believe the compression is needed to get sufficient flow rate through the zeolite beds to achieve the water extraction rate needed.  Cannot just open a canister of desiccant and expect a significant capture rate by diffusion alone -- gotta pump 250,000cubic meters of Martian atmosphere through the beds to get one liter of captured water.
There may be ways to use natural flow to extract water from the atmosphere.

In fact, you could mine gypsum, extract water from the gypsum, and dump the anhydrite back onto the surface where it will slowly reabsorb water from the atmosphere and become gypsum again. In fact, you could have sheets of something like gypsum or other hydrated minerals that you harvest periodically, dehydrate, then place back onto the Martian surface to reabsorb water. Perhaps arranged vertically along with the direction of the wind to maximize flow rates and areal density of plates.

I bet that'd be more energy efficient.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Online AncientU

  • Senior Member
  • *****
  • Posts: 6233
  • Liked: 4055
  • Likes Given: 5567
Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #45 on: 10/17/2016 11:14 AM »
I believe the compression is needed to get sufficient flow rate through the zeolite beds to achieve the water extraction rate needed.  Cannot just open a canister of desiccant and expect a significant capture rate by diffusion alone -- gotta pump 250,000cubic meters of Martian atmosphere through the beds to get one liter of captured water.
There may be ways to use natural flow to extract water from the atmosphere.

In fact, you could mine gypsum, extract water from the gypsum, and dump the anhydrite back onto the surface where it will slowly reabsorb water from the atmosphere and become gypsum again. In fact, you could have sheets of something like gypsum or other hydrated minerals that you harvest periodically, dehydrate, then place back onto the Martian surface to reabsorb water. Perhaps arranged vertically along with the direction of the wind to maximize flow rates and areal density of plates.

I bet that'd be more energy efficient.

Would b much more efficient... that's exactly what 'mining' the regolith is.  It will naturally (gradually) recharge by condensing the atmosphere's load of water each sol.
"If we shared everything [we are working on] people would think we are insane!"
-- SpaceX friend of mlindner

Online Robotbeat

  • Senior Member
  • *****
  • Posts: 28466
  • Minnesota
  • Liked: 8331
  • Likes Given: 5479
Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #46 on: 10/18/2016 02:36 AM »
It's really more like farming, isn't it? If you just had fields of these hydrating minerals, it'd be more efficient than raw regolith, since you have to heat up all the regolith, but only part of it yields water.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline Chris_Pi

  • Full Member
  • *
  • Posts: 182
  • Wisconsin
  • Liked: 74
  • Likes Given: 84
Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #47 on: 10/18/2016 04:15 AM »
It's really more like farming, isn't it? If you just had fields of these hydrating minerals, it'd be more efficient than raw regolith, since you have to heat up all the regolith, but only part of it yields water.

Very flexible on when/if processing steps are done as well. Once the stuff's spread out it can be picked back up early if you want some water at lower yields, Just left there if there's no need for it or collected and dumped into a storage pile if a new batch is ready to go back out.

Of course somebody making maps is going to have to label the area Tatooine. It's practically mandatory.  :D

Offline redliox

  • Full Member
  • ****
  • Posts: 1932
  • Arizona USA
  • Liked: 376
  • Likes Given: 64
Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #48 on: 10/18/2016 09:19 AM »
Of course somebody making maps is going to have to label the area Tatooine. It's practically mandatory.  :D

Or Arrakis, Vulcan, Geonosis, Korhal...

Desert planets are a surprisingly overdone theme in sci-fi I realize.  :P
"Let the trails lead where they may, I will follow."
-Tigatron

Offline Chris_Pi

  • Full Member
  • *
  • Posts: 182
  • Wisconsin
  • Liked: 74
  • Likes Given: 84
Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #49 on: 10/19/2016 06:09 AM »
Of course somebody making maps is going to have to label the area Tatooine. It's practically mandatory.  :D

Or Arrakis, Vulcan, Geonosis, Korhal...

Desert planets are a surprisingly overdone theme in sci-fi I realize.  :P

It's not the desert planet reference, It's the moisture farm one. Maybe Arrakis can kind of squeeze in there too if if a structure that increases airflow over the anhydrite beds makes sense. Some sort of windtrap or something...  :P

Offline john smith 19

  • Senior Member
  • *****
  • Posts: 7572
  • Everyplaceelse
  • Liked: 1164
  • Likes Given: 7798
Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #50 on: 10/19/2016 11:24 AM »
Of course somebody making maps is going to have to label the area Tatooine. It's practically mandatory.  :D

Or Arrakis, Vulcan, Geonosis, Korhal...

Desert planets are a surprisingly overdone theme in sci-fi I realize.  :P
Well in that case I'd suggest calling the place Beta Colony except for the issues around such a name.
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C apply. Believe no one. Run your own numbers. So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Offline sevenperforce

  • Full Member
  • ****
  • Posts: 873
  • Liked: 250
  • Likes Given: 267
Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #51 on: 04/28/2017 03:25 PM »
Seems like a good a thread as any for this question:

Is there any concrete idea about sizing a reusable soil-mining ISRU unit? Suppose you have a vehicle which can deliver and deploy up to 40 tonnes of payload to the surface of Mars, in a cross-section roughly the size of the Falcon 9 fairing. Is that enough for a reusable LOX/CH4 ISRU system -- one which can be deployed by the vehicle, process regolith to extract water, convert the water and collected atmosphere into LOX+CH4, fill the vehicle's prop tanks, dump the used regolith, and start again?

Kicker: it needs to be re-stowable in the vehicle, so that the vehicle can head back up to orbit, transfer the collected propellant to a tanker, and then return to the Martian surface in another location to start again.

Doable?

Offline Steven Pietrobon

  • Member
  • Senior Member
  • *****
  • Posts: 16626
  • Adelaide, Australia
    • Steven Pietrobon's Space Archive
  • Liked: 5428
  • Likes Given: 678
Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #52 on: 01/23/2018 03:19 AM »
This looks very interesting. One step production of carbon dioxide (CO2) and water (H2O) into ethylene (C2H4) and oxygen (O2).

CO2 + H2O → 0.5C2H4 + 1.5O2

http://pubs.acs.org/doi/abs/10.1021/acssuschemeng.7b02110

Compare this trying to make methane (CH4):

CO2 + 4H2 → CH4 + 2H2O (Sabatier)
4H2O → 4H2 + 2O2 (electrolysis)

Overall reaction is

CO2 + 2H2O → CH4 + 2O2

That is, making methane requires twice as much water as ethylene as well as having a lower density and Isp compared to ethylene!

Propellants  MR   dp (kg/L)  ve (m/s) Id (Ns/L)
O2/CH4       3.6   0.8376     3656     3062
O2/C2H4      2.7   0.9007     3678     3313
« Last Edit: 01/23/2018 03:21 AM by Steven Pietrobon »
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Online speedevil

  • Senior Member
  • *****
  • Posts: 2814
  • Fife
  • Liked: 1384
  • Likes Given: 1592
Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #53 on: 01/23/2018 05:59 AM »
Propellants  MR   dp (kg/L)  ve (m/s) Id (Ns/L)
O2/CH4       3.6   0.8376     3656     3062
O2/C2H4      2.7   0.9007     3678     3313


I note the above paper contains the phrase
Quote
When liquid fuels such as ethanol and n-propanol were included, the total solar-to-fuel efficiency was 2.9%.

Then you've got more exotic stuff, like CO/acetylene / O2.
Acetylene (C2H2), and CO to stabilise it, and reduce the fierce combustion temperature a little, while getting rather better ISP than CO alone.
https://arc.aiaa.org/doi/abs/10.2514/3.26350?journalCode=jsr ( https://ntrs.nasa.gov/search.jsp?R=19920049575 )

Under half the hydrogen of C2H4/O2.

Plus, at least one process for C2H4 begins with CH4, so 'flex fuel' generation might be possible, tuned to available water and power.
« Last Edit: 01/23/2018 03:57 PM by speedevil »

Offline oldAtlas_Eguy

  • Senior Member
  • *****
  • Posts: 3479
  • Florida
  • Liked: 1887
  • Likes Given: 223
Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #54 on: 01/23/2018 08:48 PM »
Although Ethylene may not be used for prop it still is useful in the creation of synthetic materials fibers such as polyester. I am sure that the Colony will find the mass manufacture of polyester based materials cloths/ropes/etc will be very useful. Plus ground equipment may use Ethylene and LOX to power heavy mobile equipment via ICE (internal combustion engines) or Fuel Cells. Using less energy to make also means that less energy is stored in the liquids and released when burned. For Rockets that is a bad thing but for rover/ground equipment that is not a major concern.

Offline Russel

  • Full Member
  • ****
  • Posts: 987
  • Liked: 93
  • Likes Given: 1
Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #55 on: 01/25/2018 06:43 AM »
Forgive me for not reading the whole thread but has there been discussion of extraction of atmospheric water.

I do believe this was studied using adsorption and has the advantage of being relatively simple.

Edit: The paper I'm thinking of is here

https://www.google.com.au/url?sa=t&source=web&rct=j&url=https://www.lpi.usra.edu/publications/reports/CB-955/washington.pdf&ved=2ahUKEwjTz7Gt0fTYAhUJv7wKHVX4AtAQFjABegQIBhAB&usg=AOvVaw0rs4OMSQRlfZ81Mx5L_q-O

Edit: Apologies but ny earlier skim missed the posts on water vapor. The volumes of air needed to be processed are large but they don't particularly bother me. The real question is how reasonable/unreasonable you wish to be regarding your target quantity water/hydrogen
« Last Edit: 01/26/2018 02:14 AM by Russel »

Offline Russel

  • Full Member
  • ****
  • Posts: 987
  • Liked: 93
  • Likes Given: 1
Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #56 on: 01/26/2018 01:49 AM »
Another issue I don't think has been mentioned is that food imported from Earth will contain carbon and more interestingly hydrogen. Ordinary metabolism creates CO2 and H2O. In a well sealed environment with water reclamation, humans will actually generate an excess of H2O and this H2.

This may not help if you want hundreds of tonnes of propellant, but if you want a few tonnes, that bit of H2 might be usefull.

It certainly qualifies how much water you think you might need for life support.
« Last Edit: 01/26/2018 02:16 AM by Russel »

Offline Russel

  • Full Member
  • ****
  • Posts: 987
  • Liked: 93
  • Likes Given: 1
Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #57 on: 01/26/2018 02:33 AM »
Although discussion of importation of hydrogen may be seen as OT, I think it is relevant given the sheer cost/difficulty of going after ISRU hydrogen (versus Oxygen). And in the context of the relative ease of importing hydrogen.

One way to import hydrogen is to land amonia (NH3) which is 17% hydrogen by mass and is is dense, stable and storable. The bonus is that you've also got a reserve of Nitrogen.

16 tonnes of CH4/O2 propellant is about 12 tonnes of Oxygen (relatively easy) and about 4 tonnes of CH4. That's 1 tonne of Hydrogen or 5.6 tonnes of NH3 (from which you get 4.6 tonnes of usefull N2)

That cuts the problem down to a third. Yes you need power/mass to process NH3 but you then don't need power/mass to extract native Nitrogen/Argon.

Offline Russel

  • Full Member
  • ****
  • Posts: 987
  • Liked: 93
  • Likes Given: 1
Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #58 on: 01/27/2018 02:48 PM »
One thing I'd like to ask here. Fairly simple.

If you only consider sites on Mars that are of relevance for exploration. Which I presume tends to limit things to under 20-25 degrees from the Equator.

What do we actually know about the presence of water, how deep and in what form and quantity?

In other words, given realistic landing sites, what are we dealing with and also how probable is it? In other words do we need to land a probe beforehand to be certain of the resource?

It seems to me that ISRU for water on Mars comes on one of the following forms:

1. Water vapour
2. Hydrates and other forms of water bound to soil.
3. Thin layers of ice of some reasonable purity of unpredictable depth and possibly localised scope near surface (1-2m at most)
4. Thicker ice, but with some certainty and located deeper (up to about 30m).

Lets consider those in turn.

1. Water vapour varies by season and and location but is to some extent predictable. It also requires relatively non complicated and robust equipment. It is certainly capable of producing life support quantities (hundreds litres to several tonnes or more depending on power source). I dispute the need to source local hydrogen for small scale exploratory missions so I'm happy to simply have a local source of life support water. However this method can in theory supply enough hydrogen for a bare-bones ascent.

2. This method is limited to areas where there is reasonable depth of soil that is not too rocky and not too compacted. One can imagine relatively robust scrapers. Not exactly high-throughput by Earth standards but sufficient to accumulate enough soil (hundreds of tonnes) for the extract of a modest quantity (5-20 tonnes) of water. Like any activity that engages soil this is subject to unknowns. Uneven depth. Uneven consistency. Clogging. Damage. Repair. I cannot see this being done as an automated process. However it could be semi autonomous with day by day radar imaging and sampling. Having said this, any scale implies robotic maintenance and replacement of ground engaging tools (blades, teeth). It is by no means straight forward. Another issue that comes with scale is that if you have thin soil you have to cover a sizeable area and you start dealing with specialised transporters.

3. I concede this might be a possibility near a site of interest. Firstly as a matter of engineering this ups the scale by at least an order of magnitude since you're interested in the ice, not the overburden. You have major issues with wear and damage and replacement of parts. It also takes time and a lot of energy. When you get to the ice you may only be dealing with a thin layer. You also have to deal with very hard ice which is laced with abrasives and which you have to recover quickly. Besides the engineering issue you are now skating close to planetary protection issues.

4. I have reservations that any substantial thickness of ice will be found at a site of interest at a depth that can be reached by realistic boring machinery (say 30m, but even 100m may not find this type of ice deposit). In theory this is an easier process than the above. You just drill a hole and inject hot air and recover the water vapour. Although it does not require the same kind of machinery for open cut work, its still a difficult process even on Earth. The worst thing is that when you find a deep source of ice you are almost certainly running into planetary protection issues - until that area has already been subject to very careful study and deemed not just sterile but incapable of being infected with Earth organisms.

I haven't even begun to talk about all the other engineering issues including what happens to hydraulics and bearings in near vacuum. The erosive and corrosive nature of the materials involved. And the demands for power, power transmission, batteries or chemical fuels. I feel this sort of thing belongs in a specialised thread.

So. All I'm saying here is that my belief is that ISRU on the scale that would sustain a settlement or a SpaceX style launch requires a lot of hardware and a lot of stuff that needs maintenance/repair and quite probably human control if not localised tele-operation. In short, any mission that requires a lot of return-to-earth fuel is begging for so much mas to be landed on Mars that you might as well land the hydrogen or methane you need instead.

On the other hand, if you're purpose is scientific/exploratory life gets a lot easier. For a start it makes sense to limit the amount of ISRU propellant you need (in other words an indirect return). Secondly what methane/hydrogen you do need for the ascent might as well be landed as part of the cargo (which will be a lot bigger than the few tonnes of methane needed). And thirdly to the extent that you are game enough to make some of the hydrogen you need, its going to require a lot less plant and equipment to use atmospheric water vapour.

Since my background is in electronics for mining machinery I'd welcome a separate thread on the mining hardware front. Its just not that easy, even on Earth.
« Last Edit: 01/27/2018 02:53 PM by Russel »

Offline Lar

  • Fan boy at large
  • Global Moderator
  • Senior Member
  • *****
  • Posts: 10629
  • Saw Gemini live on TV
  • A large LEGO storage facility ... in Michigan
  • Liked: 7485
  • Likes Given: 5249
Re: Water, Methane, and Oxygen ISRU on Mars
« Reply #59 on: 01/29/2018 12:58 AM »
I would love to see a mining machinery thread. I don't think we have one at this time.
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Tags: