Author Topic: Scaling Agriculture on Mars  (Read 232168 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

Offline AegeanBlue

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Re: Scaling Agriculture on Mars
« Reply #1272 on: 09/25/2018 06:41 PM »
Antarctica Greenhouse Produces Cucumbers, Tomatoes and More in Mars-Like Test

https://www.space.com/41863-antarctic-greenhouse-eden-iss-project.html

Peppers and strawberries failed, most likely due to lack of pollinators. It is a DLR project and it has a website in German

Offline Lampyridae

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Re: Scaling Agriculture on Mars
« Reply #1273 on: 09/26/2018 03:40 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?]


Page 9 of 35.

While the 200m^3 area required for this crop selection is four times larger than that
originally stated by the Mars One Foundation, a computer aided design analysis indicates that it is still
possible to fit this into a portion of the Inflatable unit if a high density packing scheme is employed, such as that originally planned for NASA’s BIO-Plex(27) - a proposed integrated habitation - BPS test facility that was developed throughout late 1990s, but never operated.


It seems to be a typo, but if you assume that the growth area is 1 cubic metre per square metre... say 75cm overhead, with the rest of the volume being for accessways, ventilation etc, then you get a cubic metre. 200m^2 for four people (how to cook fo(u)r humans) yields about 50m^3 per person. This is further supported by the volume of the Mars One inflatable habitat being 500m^3 (from their comment about packing the growing volume taking up 40% of the hab and the packed inflatable is 33.33m^3 packing efficiency being 15:1).

Quote
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.

That 50% figure in Wikipedia is from 2014. According to the on-site interview, the closure rate was 98%. http://ev.buaa.edu.cn/info/1081/1585.htm

YMMV as to what the real figure was, but that's the university website writeup.

The South Pole Food Growth Chamber delivers about 9 Calories per cubic metre, including all the ducting etc. So an equivalent chamber on Mars would be about 200m^3 per person. Improved lighting, CO2, cultivars would only improve that, offset against the unknowns on Mars. All the NASA literature I've come across indicates that 50m^3/50m^2 per person is suitable for a bland but nourishing diet. So we could consider that the "floor." We could easily double, quadruple that for a more diverse food supply, including aquaculture and maybe chickens (questionable - they stink something terrible but provide feathers & eggs). Vat-grown meat would probably account for the rest.

Quote
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.)

Presumably the ventilation efficiency would be improved by making taller modules with higher stacks of plants? Gravity affects convection as well so there may be some extra volume, maybe more than Earth. I know that lunar habitat studies for large bases figure in extra room height for people to walk in low gravity without cracking their head on a pipe.

I understand your skepticism but disagree on the 10:1; whilst there will be increased varieties of crops, including low-yield ones for flavour and variety which will require increased volume, as well as lower-cost, lower efficiency greenhouses, colonists will also simply demand more volume. No sane person is going to raise a family in ISS volumes per person. Once ISRU construction of new habitats begins, there will be a strong push for more elbow room. How much depends on how easy it is to build safe, comfortable habs.

Nobody has really taken a good crack at how much volume is required per person in a permanent community since the 1975 NASA Ames study. That estimated ~800m^3 per person, based on US building standards, and ~900m^3 for food (including meat animals).

http://space.nss.org/settlement/nasa/75SummerStudy/Chapt3.html

So, personally, I would say that the agricultural scaling would look like this (generous thumbsucking):


First expeditions (4 crew): 25m^3 ag : 50m^3 hab (50% closure, 100% O2 recycling, salad crops, potatoes, bleeding edge tech)

First outpost (8 crew): 50m^3 ag : 50m^3 hab (98% closure, boring but nutritious diet, mealworms, bioreactor sludge, somewhat matured tech)

Outpost expansion / colony core (16 crew) : 75m^3 ag : 75 m^3 hab (99% closure, aquaculture, dwarf fruit trees, well understood tech)

Colony growth (? colonists) : 100+m^3 ag : 100+m^3 hab (now it's a matter of economics as to which is preferred. Elbow room or expanded menu? Also, the tech becomes less cutting edge with locally manufactured trays, rock wool, etc as the ags are geared towards profitability)
« Last Edit: 09/27/2018 09:14 AM by Lampyridae »
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Offline AegeanBlue

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Re: Scaling Agriculture on Mars
« Reply #1274 on: 09/26/2018 09:04 PM »
Carbon dioxide is denser than (the rest) of atmospheric air and has a tendency to have higher concentrations near the bottom of a greenhouse. Using taller plants does not increase ventilation efficiency, which is also an issue of removing high humidity air which makes plants more susceptible to diseases. You need stronger pumps, or in Mars' case introduce higher CO2 concentration Martian atmosphere. Again though you would need to remove H20 and trace gasses that act as plant hormones (e.g. ethylene) from the greenhouse atmosphere. It is nice to see an independent source noting the 200-250 m2 growing area  (which is a figure that includes working space) to support a person on hydroponics.

Online Tulse

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Re: Scaling Agriculture on Mars
« Reply #1275 on: 09/27/2018 01:43 PM »
Are algae or similar foodstuffs practical for Mars?  I would think the nutrition per unit volume of cultivation for algae would be far higher than plants where only a limited part is edible, and it would be far easier to engineer algae to have whatever nutritional profile one wanted, compared to modifying traditional food crops.

I know, spirulina tastes like a swamp, and having familiar and tasty food is important for morale.  But could algae (or related foods) serve as an efficient bulk of a human diet?

Offline Lampyridae

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Re: Scaling Agriculture on Mars
« Reply #1276 on: 09/27/2018 03:23 PM »
Are algae or similar foodstuffs practical for Mars?  I would think the nutrition per unit volume of cultivation for algae would be far higher than plants where only a limited part is edible, and it would be far easier to engineer algae to have whatever nutritional profile one wanted, compared to modifying traditional food crops.

I know, spirulina tastes like a swamp, and having familiar and tasty food is important for morale.  But could algae (or related foods) serve as an efficient bulk of a human diet?

There are several varieties of algae as well as other single-celled organisms that are practical, extremely low volume... and contain 0% taste or cheer.
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Online Tulse

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Re: Scaling Agriculture on Mars
« Reply #1277 on: 09/27/2018 03:35 PM »
But how easy would it be to modify those single-celled organisms to be more tasty, as opposed to growing plants that are mostly inedible leaves, stalks, and roots?  And of course it's not an either/or situation -- one could use algae for the bulk of nutrition, but also grow some regular plants to add variety and flavour.

Offline Lar

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Re: Scaling Agriculture on Mars
« Reply #1278 on: 09/27/2018 08:25 PM »
... And of course it's not an either/or situation -- one could use algae for the bulk of nutrition, but also grow some regular plants to add variety and flavour.
You've just recapitulated one of the dominant themes of this 26 page thread. You DID read the thread before posting right?
« Last Edit: 09/27/2018 08:27 PM by Lar »
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Re: Scaling Agriculture on Mars
« Reply #1279 on: 10/01/2018 03:40 PM »
Consider me chastened  :)

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