New Mars Forums

Official discussion forum of The Mars Society and MarsNews.com

You are not logged in.

Announcement

Announcement: We've recently made changes to our user database and have removed inactive and spam users. If you can not login, please re-register.

#1 2017-04-20 03:13:25

louis
Member
From: UK
Registered: 2008-03-24
Posts: 2,479

Why worry about water?

It appears as if we could make significant amounts of water on Mars through adsorption from the atmosphere.


http://www.lpi.usra.edu/publications/re … ington.pdf

The deal is 45 Kgs of water per sol for 15 Kws constant of power and 885 Kgs of mass...not a bad deal I would say.

I would make this a contender for a Mars first mission. A tonne of water every 22 sols is impressive. Would be very useful for all the industrial experiments/proofs of concept we would like to carry out.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

Offline

#2 2017-04-20 09:42:53

elderflower
Member
Registered: 2016-06-19
Posts: 476

Re: Why worry about water?

They don't account for battery mass but they need to run their fan during the night when the water vapour in the atmosphere is near saturation. This applies for sites away from the north pole. OK if they have a nuclear source but not if they have to depend on solar power.

Offline

#3 2017-04-20 10:53:58

Oldfart1939
Member
Registered: 2016-11-26
Posts: 894

Re: Why worry about water?

This system plus electrolysis might beat the Moxie unit for efficiency, since it also produces Hydrogen as well as Oxygen; feedstock for the Sabatier reactor?

Offline

#4 2017-04-20 11:22:22

Dook
Banned
From: USA
Registered: 2004-01-09
Posts: 1,409

Re: Why worry about water?

They estimate that, because of life support and water recycling system inefficiency, 1.7875 lbs of water will be lost per person, per day, in flight and on Mars.

So they designed a 1,947 lb WAVAR system that uses one very large zeolite bed to absorb water, microwave it out, and store the water.  They admit that this system would only operate during the summer because it just doesn't produce enough water in winter to justify operating it.  They estimate that it would make 13.48 lbs of water a day at a location in the northern hemisphere. 

But you don't need this huge system to get water, all you need is the zeolite panels on a wheeled fiberglass cart that holds the panels vertical.  In summer, you wheel the zeolite panels outside the greenhouse every night and bring it back inside in the morning and let the warm greenhouse outgas the water vapor.  No microwave needed.  Having a fan that blows Mars atmosphere over the zeolite panels while they are outside would help.

About their water loss estimates, all water in urine can be filtered and then boiled to get out the water and a dehumidifier inside the habitat or greenhouse would recapture the water.   

Getting water out of feces is more difficult.  You can microwave it but it won't get all the water out and microwaving it would probably kill the bacteria that break feces down.  Every time you go #2, about 11 million gut bacteria go out with the feces.  Given time those bacteria will break it down. 

We could build an open sludge tank in our greenhouse (maybe build the tank out of bricks made inside the greenhouse so no water is lost) then take all the feces waste and dump it into the sludge tank, add a little water, and let it sit.  The bacteria would break down the feces to a point where it could be used as fertilizer inside the greenhouse and no water would be lost.

Offline

#5 2017-04-21 08:16:26

Antius
Member
From: UK
Registered: 2007-05-22
Posts: 901

Re: Why worry about water?

Dook wrote:

Getting water out of feces is more difficult.  You can microwave it but it won't get all the water out and microwaving it would probably kill the bacteria that break feces down.  Every time you go #2, about 11 million gut bacteria go out with the feces.  Given time those bacteria will break it down. 

We could build an open sludge tank in our greenhouse (maybe build the tank out of bricks made inside the greenhouse so no water is lost) then take all the feces waste and dump it into the sludge tank, add a little water, and let it sit.  The bacteria would break down the feces to a point where it could be used as fertilizer inside the greenhouse and no water would be lost.

A slight variation would be an anaerobic digester.  If thermophile bacteria are used, most gut bacteria will be destroyed by the heat.  The lower temperature variety will leave some alive, but allowing the sludge to dehydrate at low pressure will kill anything remaining.  As a by-product, modest amounts of methane are produced.  That could be a useful propellant or perhaps you could just burn it off in the greenhouse over night.

Offline

#6 2017-04-21 08:30:48

Oldfart1939
Member
Registered: 2016-11-26
Posts: 894

Re: Why worry about water?

Burning off the methane in the greenhouse would also return the H2O to the system, as well as adding needed heat. Adding back consumable (by the growing plants) some CO2. Ultimately, there will be plant wastes to recycle (greens from bean bushes, other non edible stalks, etc.), which all could be composted for soil amendments. Mixed with the fecal residues, we get a very "green" system. Not that it's really needed for control of Mars Warming!

Offline

#7 2017-04-21 09:09:23

louis
Member
From: UK
Registered: 2008-03-24
Posts: 2,479

Re: Why worry about water?

Once you've got your compost going I think you are able to then use it to convert Mars regolith to organic soil. Soil production will be one of our key industries. A few years in and I think the argument for natural light agriculture becomes quite strong. 

Oldfart1939 wrote:

Burning off the methane in the greenhouse would also return the H2O to the system, as well as adding needed heat. Adding back consumable (by the growing plants) some CO2. Ultimately, there will be plant wastes to recycle (greens from bean bushes, other non edible stalks, etc.), which all could be composted for soil amendments. Mixed with the fecal residues, we get a very "green" system. Not that it's really needed for control of Mars Warming!


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

Offline

Board footer

Powered by FluxBB