Author Topic: Scaling Agriculture on Mars  (Read 225455 times)

Offline guckyfan

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Re: Scaling Agriculture on Mars
« Reply #1260 on: 09/11/2018 06:01 PM »
why would it first not heated to high enough temperatures to sterilize it?

Composting is a step in recouping the nutrients. Part of it may be producing gases which can be reprocessed as well. Composting done correctly will make the outflow safe and not need energy expended.

Offline AegeanBlue

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Re: Scaling Agriculture on Mars
« Reply #1261 on: 09/13/2018 08:40 PM »
When I wrote about sleeping in the greenhouse, I had just returned to Fresno from vacation and saw all the homeless of my neighborhood. The greenhouse is not a good, and at times nor a safe (think pesticide sprayings), place to sleep. Be sure though that people bored with the same surroundings (or after a huge fight!) might just take a sleeping bag or a hammock and sleep there.

Composting is a process to treat manure and other organic refuse. After the 6-8 week process, what comes out is not manure BUT organic soil. Of course, this assumes that we will use soil based agriculture, rather than soil less. I envision the composting cycle as this: After a couple of growing cycles we decided to build greenhouse 2. We take organic refuse and put it in the composting piles. After one of the piles has digested everything, we take the compost and mix it with the regolith to create soil for greenhouse 2. Then we put the irrigation system and other automations.

Offline Lar

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Re: Scaling Agriculture on Mars
« Reply #1262 on: 09/13/2018 10:46 PM »
I'm not seeing how composting eliminates all harmful microorganisms and in a closed system that may be problematic. We want intestinal flora and fauna not to carry forward into the soil or drinking water, I would think.
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Offline guckyfan

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Re: Scaling Agriculture on Mars
« Reply #1263 on: 09/14/2018 08:10 AM »
I'm not seeing how composting eliminates all harmful microorganisms and in a closed system that may be problematic. We want intestinal flora and fauna not to carry forward into the soil or drinking water, I would think.

A well built compost pile reaches temperatures well above temperatures killing harmful germs. Especially if they are in isolated bioreactors.

Offline zhangmdev

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Re: Scaling Agriculture on Mars
« Reply #1264 on: 09/14/2018 09:58 AM »
Composting needs a lot of oxygen. Large scale static piles or turned windrows are open-air operations.

https://modernsteader.com/composting-methods/

Or constantly pumps air into the pile to keep it aerated.

http://maf-compostingsystems.de/

Offline AegeanBlue

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Re: Scaling Agriculture on Mars
« Reply #1265 on: 09/14/2018 06:28 PM »
Composting works as such: Aerobic microorganisms (bacteria, fungi etc) start breaking down the organic material, oxygen is consumed, temperature rises to 70-80 degrees C and then it drops off until it reaches room temperature because the microorganisms get neutralized due to high temperature and there is no more oxygen near the organic material. The pile gets overturned, again temperature rises and oxygen is consumed until again it drops. You do this again and again up until when you overturn the pile, the temperature does not rise any more. At this point harmful bacteria have long been destroyed from the high temperature and the cycle. I do not know of any cases of disease transmission from well digested compost, quite the contrary it is often used as a filter to collect harmful bacteria and metals in runoff.

Now the Martian greenhouse will constantly have external CO2 pumped from outside. Staying inside the greenhouse during the pumping is dangerous for people, because CO is available at toxic levels to animals but not plants, but then again you do not quite pump when the sun is not up (except in preparation). Since we only consume something like 5-20% of a plant's biomass, there will be far more O2 produced than we need to breathe. There will be sufficient for composting, at another chamber

Offline Lampyridae

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Re: Scaling Agriculture on Mars
« Reply #1266 on: 09/18/2018 10:50 AM »
Yup. White button mushrooms are grown in compost; even have bits of it sticking to them when you buy them though that's usually potting soil. Not that I've actually tried growing these myself.
« Last Edit: 09/18/2018 11:09 AM by Lampyridae »
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Offline nacnud

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Re: Scaling Agriculture on Mars
« Reply #1267 on: 09/18/2018 11:40 AM »
Interesting note: composting would be a good source of heat for a mars greenhouse. In horticulture this is known as a hotbed or hothouse. In the past this has been used to grow pineapples in Europe, first in the Netherlands then later in the UK.

This is an interesting read, A Taste for the Exotic, Pineapple cultivation in Britain

Offline Lampyridae

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Re: Scaling Agriculture on Mars
« Reply #1268 on: 09/18/2018 12:18 PM »
So should it be possible to have greenhouses on Mars which [would be] transparent enclosed areas where plants with foliage could grow?

As stated many times through the thread, I don't think surface greenhouse(s) on Mars are worth the effort. Too much effort to solve unneeded problems. (And certainly not planting directly into the ground. Even if you could treat the regolith (which seems reasonable), building an open-bottomed pressurised vessel is... not smart.)

If you use artificially lit grow rooms, whether hydroponics or soil-in-container, you would use tuned-frequency LEDs for efficiency. That light is unpleasant to work under. Similarly, plants require varying length dark periods, depending on their grow/flower/fruit cycle, which don't necessarily match human preferences. (And during their dark periods, your white light reduces their recovery.) So I don't think the day-to-day living areas will be actually amongst the plants, beyond perhaps the first "tent settlement" equivalent level of colony that is willing to exchange discomfort for simplicity.

(That said, if you did have white-lit grow-areas, the light levels would be similar to Earth sunlight and thus help settlers reduce depression/schizophrenia/etc.)

But regardless of whether you actually live amongst the plants, the general principle that agricultural areas will dominate over the living areas is true. The seeming lack of awareness amongst even, presumably, pro-Mars enthusiasts is something that annoys me about those moronic "Design a Mars colony" contest: Three stories of living areas, labs, etc, with two small green racks on one floor for food. The pressurised areas in a Mars settlement will be almost entirely agricultural space, with a few small nooks for all other activities. I'd be shocked if you get it below 10:1.

https://pdfs.semanticscholar.org/1053/ae3d668dc7eaba44f937c4242328fa8aa23b.pdf?_ga=2.132553353.601666823.1537270725-1910810296.1537270725

MIT reckons 50m^3 per person. ISS is ~1000m^3 habitable volume for 6 people in microgravity. Of course, that's if you want to eat peanut butter sandwiches for the rest of your life. Yeogong-1 had a proven 105m^3 per person in a rather inefficient layout (wasted ceiling space). I think 100m^3 per person would be a very safe bet and allow stuff like dwarf plums and some limited animal protein like snails and fish.

Dunno if the link's been shared about dwarf plums but here it is:
http://gravitationalandspaceresearch.org/index.php/journal/article/viewFile/680/700

Another thing with the Mars colony proposals is that inhabiting a space in .38g is different from Earth. Working at heights is much easier, you can simply pull yourself up with minimal difficulty. Verticality in design would become more viable and important.

However the biggest argument for (transparent) surface greenhouses is this: you want to show lush stretches of greenery on the Martian surface to make your colony appealing and self-sufficient. Simple as that. It might be more for show, with your real production taking place in bricked-over pressure vessels which would just look like a tank farm.

I kind of like this idea: a small bubble, moveable LEDs to enhance illumination and also to keep plants alive during dust storms. If you have the resources, just make long rows of these if you're not going to worry about radiation.

https://ttu-ir.tdl.org/ttu-ir/bitstream/handle/2346/64489/ICES_2015_submission_224.pdf?sequence=1
« Last Edit: 09/18/2018 01:54 PM by Lampyridae »
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Offline sghill

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Re: Scaling Agriculture on Mars
« Reply #1269 on: 09/18/2018 01:10 PM »
However the biggest argument for (transparent) surface greenhouses is this: you want to show lush stretches of greenery on the Martian surface to make your colony appealing and self-sufficient. Simple as that.


Aaaand, that takes us back to this upthread conversation (which was a good one, IMHO).

https://forum.nasaspaceflight.com/index.php?topic=35877.msg1651890#msg1651890 and
https://forum.nasaspaceflight.com/index.php?topic=41427.msg1757611#msg1757611
« Last Edit: 09/18/2018 01:11 PM by sghill »
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Offline Paul451

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Re: Scaling Agriculture on Mars
« Reply #1270 on: 09/18/2018 07:02 PM »
https://pdfs.semanticscholar.org/1053/ae3d668dc7eaba44f937c4242328fa8aa23b.pdf?_ga=2.132553353.601666823.1537270725-1910810296.1537270725
MIT reckons 50m^3 per person.

[Where did you get 50 cubic metres in that paper?]

It's worth being wary of such figures, as they are often based purely on caloric values, not an actual workable long-term diet. Such figures also rarely include inputs (such as waste-processing, water treatment, etc.) For example:

Yeogong-1 had a proven 105m^3 per person in a rather inefficient layout (wasted ceiling space).

AIUI, they only produced half of the food they consumed. And the facility consisted of a large ag module, a large plant&equipment module for the fermentation of waste, processing of air, etc, and a smaller hab module. Roughly 3:1 rato of ag-related volume to living volume to produce roughly half their food.

And that was just plants and meal-worms, not going through another efficiency-reduction to get to fish, chickens, goats, etc. Plus it seems like the crew did nothing but survive; they weren't trying to expand the facilities as quickly as possible, they weren't expanding their power system, they weren't setting up/maintaining/feeding their ISRU-fuel system, etc etc. So roughly 6:1 Ag:Hab to just feed your ag workers, with no excess for the rest of the necessary settlers.

I don't think my 10:1 "I'd be shocked if"-level was oversold.

in a rather inefficient layout (wasted ceiling space.

I'm not seeing that. You have to allow for ventilation, for adjustment space for the LED-arrays, for adjusting the rack-heights, etc. Any more volume-efficient and you'd introduce other issues.

(It always surprised me how much ventilation plants need. In hindsight it's obvious, there's very little CO₂ in breathable air, even if you augment it, so they can exhaust it much faster than an oxygen-breather can use up oxygen. But still, you just assume that plants are somehow more robust than animals. Similarly, although it varies widely, the maximum tolerance of CO₂ in many plants is merely around the level that humans find air "stale" and drowsy, but below the level that causes serious health issues.)

Offline AegeanBlue

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Re: Scaling Agriculture on Mars
« Reply #1271 on: 09/19/2018 10:05 PM »
A bit more from ESA on the MELISSA technology derived water system on the Concordia station in Antarctica. On related news mentioned in another ESA release, this technology was recently applied for irrigation water in Morocco.

http://www.esa.int/spaceinimages/Images/2018/08/Cool_water

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