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#1 2018-03-29 16:46:14

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,796

Mars Soil Factory

What is the best way of providing soil for soil based agriculture on Mars?

I am of the view that a dedicated soil factory probably makes sense. Here you could produce various grades of soil: grind down rocks, and then mix in Mars sand and clay, water, imported compost and nutrient solutions from Earth, human faeces from Mars colonists, waste food, and waste plant material to create perfect soils for plant growth. These factory soils could then be put into raised beds or dug outs in the farm habs. Worms and other organisms could be introduced, to begin the process of creating healthy productive soils.

Another approach might be to begin with poor soils, basically just Mars regolith, and then gradually condition and improve it. But that seems like a v. slow process to me.  The factory process could probably create viable soils within a matter of weeks or months.


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

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#2 2018-03-30 04:18:52

elderflower
Member
Registered: 2016-06-19
Posts: 1,219

Re: Mars Soil Factory

Earth soils generally involve a lot of assorted organisms, bacteria, fungi, slime molds, nematodes, insects and arthropods. Not just earth worms. These break down waste and render it suitable for uptake by plants- some with assistance by symbiotic organisms.
For decent soil you will at least need mineral dust, faeces and compost and soil organisms. A warm compost heap takes several weeks to work its magic but you have to avoid overheating it.
I would be concerned that you might bring a species from earth, without also bringing its competitors and predators. That hasn't gone well in isolated parts of this planet. So a prolonged isolated testing program must be used before risking your hab being overrun by such a species.

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#3 2018-03-30 04:55:39

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,796

Re: Mars Soil Factory

I think the issue of soil ecology is very important and what organisms are required and which ones can safely be deployed.  This is why we do really need a Mars analogue facility on Earth where this could be tested. 

elderflower wrote:

Earth soils generally involve a lot of assorted organisms, bacteria, fungi, slime molds, nematodes, insects and arthropods. Not just earth worms. These break down waste and render it suitable for uptake by plants- some with assistance by symbiotic organisms.
For decent soil you will at least need mineral dust, faeces and compost and soil organisms. A warm compost heap takes several weeks to work its magic but you have to avoid overheating it.
I would be concerned that you might bring a species from earth, without also bringing its competitors and predators. That hasn't gone well in isolated parts of this planet. So a prolonged isolated testing program must be used before risking your hab being overrun by such a species.


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

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#4 2018-03-30 12:39:40

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 5,933
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Re: Mars Soil Factory

We have a facility: MDRS has a greenhouse. And MDRS has other donations: a small observatory with telescope, and a dome. The dome was intended to be the new greenhouse, but those running GreenHab want a transparent greenhouse, they can't use an opaque dome. So it's now the "Science Dome".

The Science Dome is a 7-meter in diameter geodesic dome that contains our solar system’s control center and is a functional microbiological and geological laboratory.

I am concerned. MDRS is supposed to simulate a Mars Direct mission. The more we add, the less it is Mars Direct. Before MDRS was built, I expressed concern that it isn't "Mars Direct". You realize a real Mars Direct habitat has only the upper deck. The lower deck is rocket engines used to land on Mars, propellant tanks (fuel & oxidizer) to feed the landing engines, RCS thrusters used to manoeuvre in space during transit from Earth to Mars, propellant tanks for RCS thrusters, life support equipment to recycle air & water and large batteries to store power from solar panels, the airlock and stairway to the upper deck, storage compartment for a rover capable of carrying all 4 crew up to 1,000km, that same storage compartment also houses surface science equipment and the greenhouse deflated, folded and stored. The storage compartment will be the size of a single car garage, pack full of stuff during transit so that space cannot be used until on Mars. However, once on Mars all that stuff will be unpacked, so the storage compartment can be used a workshop or laboratory. If you're very lucky, there will be room for a small EVA prep room. That's all. Remember, life support equipment on the US size of ISS was designed to support 3 crew, Mars Direct will have 4. And ISS life support equipment filled 3 full-size science racks, not including the CO2 sorbent or batteries. Including all that, that means 5 full size-science racks. You could build life support equipment into one wall of the lower deck storage compartment, but also remember that compartment will be depressurized when the rover and other stuff are unpacked on Mars. That means you need a pressurized enclosure around the life support racks. All this means the EVA prep room will have to double as the landing at the foot of the stairs, and at most half the size of the one in MDRS. And there won't be a "Battery Charging & Work Table" outside the EVA prep room, but on Mars there won't be any "outside". The lower deck will be nothing but airlock, storage compartment, and landing at the foot of the stairs. That's it, nothing more.

I post this here because the "Science Dome" has "a functional microbiological and geological laboratory". A real Mars Direct hab has only 2 options: contain it all in the upper deck, or store laboratory equipment in the upper deck to be deployed in the lower deck storage compartment. And again, that storage compartment will only be the size of a single car garage.

So where do you compost soil? In early days of GreenHab, they talked about recycling waste from the toilet for use in the greenhouse. That wasn't done. Another issue is soil ecology, as elderflower said (in other words). If crew have E. coli (Escherichia coli) in their gut, it will be in feces. Actually, everyone has it. It colonizes babies within 40 hours after birth. It's the primary "probiotic". But you don't want it in food. The city sewage waste treatment plants in my city use settling tanks to remove feces, which are then taken to "digester" tanks to be broken down. After a series of steps to decompose it, this can be used as manure to fertilize crops; it's called "night soil". However, "night soil" can only be used for crops fed to livestock, not food for humans. Manure from livestock is used to fertilize food crops for people. On Mars you won't have that luxury. So feces has to be carefully decomposed before using it as compost. But one critical step is to ensure Mars crew don't have diseases to start with.

MDRS changes crew every 2 weeks. It can't isolate crew. And crew on Mars will exchange each other's diseases very quickly. So this work can't be done at MDRS. At least not sewage recycling. They could do soil analysis.

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#5 2018-03-30 16:06:08

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 18,570

Re: Mars Soil Factory

We have talked lots about how to make mars soils better in a number of topics and once it came down to a shouting match in on topic with regards to just use the clean sand and do a hybrid hydroponic feeding system to nourish the plants.

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#6 2018-04-04 06:11:31

elderflower
Member
Registered: 2016-06-19
Posts: 1,219

Re: Mars Soil Factory

Night soil (sewage sludge) can be conditioned in a compost heap so long as the heap is large enough to attain 70 degrees C at least. It can then be safely dug into the soil of a vegetable plot. It becomes a valuable fertilizer.

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#7 2019-01-18 20:47:04

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 18,570

Re: Mars Soil Factory

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