Author Topic: Scaling Agriculture on Mars  (Read 233942 times)

Offline Robotbeat

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Re: Scaling Agriculture on Mars
« Reply #1240 on: 08/05/2018 01:00 AM »
Mylar is so lightweight itís also trivial to bring from Earth. No making on Mars required.
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Offline sanman

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Re: Scaling Agriculture on Mars
« Reply #1241 on: 08/05/2018 01:01 AM »
2400kcal per day per person is based on Earthly requirements - any chance that this could be substantially lower on Mars with its ~1/3 Earth-gravity?

Offline AegeanBlue

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Re: Scaling Agriculture on Mars
« Reply #1242 on: 08/05/2018 06:41 AM »
2400kcal per day per person is based on Earthly requirements - any chance that this could be substantially lower on Mars with its ~1/3 Earth-gravity?

How many calories you need per day depends on body and kind of work you do. 2400 kcal is for a male office worker, female office workers need closer to 2,000 kcal/day. Special Forces soldiers need 5,000 kcal/day. How many sedentary office workers will the colony have? I would say more realistic is to try to plan for 3,000-4,000 per day. In any case we won't know until we get there

Offline john smith 19

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Re: Scaling Agriculture on Mars
« Reply #1243 on: 08/05/2018 09:26 AM »
2400kcal per day per person is based on Earthly requirements - any chance that this could be substantially lower on Mars with its ~1/3 Earth-gravity?

How many calories you need per day depends on body and kind of work you do. 2400 kcal is for a male office worker, female office workers need closer to 2,000 kcal/day. Special Forces soldiers need 5,000 kcal/day. How many sedentary office workers will the colony have? I would say more realistic is to try to plan for 3,000-4,000 per day. In any case we won't know until we get there
An obvious question is how much EVA is going to take place. A 30 hour week is equal to the entire exposure of a nuclear industry worker for a year. Realistically a surface habitat will offer 1/20 the rad protection of the Earths atmosphere, so unless people dig in PDQ they are going to get cooked.

Long term settlement (we are talking long term settlement, aren't we?) demands
a) Very much better radiation protection (suits or drugs, or both)
or
b) Remotely operated avatars to carry out the initial early tunneling/boring to get enough regolith over your head that you can move to either a light weight suit or pressurize the environment and work in regular(ish) clothes.

We don't really know how to do a) but we're getting a lot better at b).  A slim (lightweight) cable could supply all the power and data capacity to run an avatar with enough operating radius to do a lot of work, while trickle charging a backup battery to allow it to go off cable for limited periods, or move exceptionally heavy loads.

While operating b) should be lighter work than actually walking around inside an EVA suit I don't think it will be that less physically stressful, but I'm not sure any work has been done on the calorific needs of operators of remote manipulators, so it's difficult to say.
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Offline sghill

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Re: Scaling Agriculture on Mars
« Reply #1244 on: 08/24/2018 02:47 PM »
Mylar is so lightweight itís also trivial to bring from Earth. No making on Mars required.

And unless it's perfectly flat (difficult for the size we'd be talking about here) it is useless at a distance as a reflecting surface that can direct enough focused light to boost plant growth.  Mylar is great for reflecting light from up close (I've got a mylar covered grow tent that works great for my wintertime crops), but the light redirected goes down with the square of the distance.

If you really want to talk about the benefits of mylar, it's better by far to use large mylar blankets as an retractable awning to cover the greenhouse at night and save the energy that would have been used to heat the greenhouse at night instead to power LED's for longer growing cycles.
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Offline speedevil

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Re: Scaling Agriculture on Mars
« Reply #1245 on: 08/24/2018 03:47 PM »
Mylar is so lightweight itís also trivial to bring from Earth. No making on Mars required.

And unless it's perfectly flat (difficult for the size we'd be talking about here) it is useless at a distance as a reflecting surface that can direct enough focused light to boost plant growth.
http://www.barrisolwelch.com/products/stretch-mirror/

Simply stretching it over a frame works, pretty much to get a decent mirror.

Online KelvinZero

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Re: Scaling Agriculture on Mars
« Reply #1246 on: 09/05/2018 07:44 AM »
Simply stretching it over a frame works, pretty much to get a decent mirror.
Yep, you don't need concave, just many elements.

One configuration could be like a solar tower, but the tower is a vertical farm/garden.

IMO towers are better than domes asthetically: they give more convenient viewing area to more people AND more radiation protection, except for the very top levels that could contain other useful things than living/growing area, including water tanks.. and we could probably build some spectacular towers on Mars.

Dust storms could be a big problem for concentrators. If you have to build for the worst case maybe a 3x cost difference on average is not important. You could send thin-film roll out solar cell material almost as easily as mylar.

Another pet idea: roll out thin film solar cell material that only reflects photosynthesis wavelengths.

Offline zhangmdev

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Re: Scaling Agriculture on Mars
« Reply #1247 on: 09/05/2018 09:09 AM »
EVA is not that physically demanding, like chopping wood or walking in snow. The closest example to Mars EVA is Lunar EVA.

"Average metabolic rates ranged from 822 kJ/hr (780 Btu/hr) to 1267 kJ/hr (1200 Btu/hr), with an overall average of 979.2 kJ/hr (928.1 Btu/hr).

The highest average metabolic rate (1267 kJ/hr, 1200 Btu/hr) during an EVA was experienced by the Lunar Module Pilot (LMP) on Apollo 11 during a locomotion evaluation for which he had to be very active. The LMP encountered the highest discrete metabolic rates during transport of the Apollo Lunar Surface Experiments Package pallet, Lunar Module (LM) ingress with lunar samples, and drilling and removal of drill bits. Overhead activities such as vehicle egress, offloading and setup of equipment around the LM, vehicle ingress, and stowage of the lunar samples required the highest energy consumption.

The lowest observed metabolic rate (414 kJ/hr, 392.4 Btu/hr) occurred during LRV operations, and is lower than that of riding in an automobile on Earth (~502 kJ/hr, ~392 Btu/hr)."

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20120003917.pdf

Offline AegeanBlue

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Re: Scaling Agriculture on Mars
« Reply #1248 on: 09/10/2018 05:35 PM »
As far as Mars colonization goes, I think 1/3 of the modules will be for living areas, 1/3 will be for working, manufacturing, etc, and 1/3 for food production.  This may vary depending on what transpires.  Americans are used to large homes compared to the rest of the world, also depending on how soon industrialization can occur, some industry will need a lot of space.  For a wide variety of food, that too will require a lot of space.  It won't happen overnight.
Keeping in mind that the growing space will have to build out at the same pace as settlers arrive

I think that farm space will, at the first stages, dominate colony space on Mars. I have been on a military exercise under the Myrtoan Sea on the Hellenic Submarine Proteus, and it unbelievable how 54 people fit in the space of a double bus (as in long folding bus, not double decker). A 209 type diesel power submarine would go on 3 month trips to the Western Mediterranean for NATO exercises, with the crew getting out once in a blue moon for shore leave. On the other hand I don't think we can really feed people, even in the most intensive way, for less than 200 m2 of farm growing space per person. I would not be surprised if people choose to live inside greenhouses in Mars colonies, just for the space

Offline sanman

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Re: Scaling Agriculture on Mars
« Reply #1249 on: 09/10/2018 06:05 PM »
On the other hand I don't think we can really feed people, even in the most intensive way, for less than 200 m2 of farm growing space per person. I would not be surprised if people choose to live inside greenhouses in Mars colonies, just for the space

So should it be possible to have greenhouses on Mars which look roughly similar to those on Earth? Sure, I understand that geometry would have to be different due to the near-vacuum conditions on the surface, but would these be transparent enclosed areas where plants with foliage could grow? I remember back near the start of the thread it was asserted that hydroponics/aeroponics would be the most efficient - but if you're going to combine growing spaces with living spaces for the sake of argument, then how would these spaces be integrated to accommodate both effectively?

Offline AegeanBlue

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Re: Scaling Agriculture on Mars
« Reply #1250 on: 09/10/2018 10:48 PM »
I am not thinking something very formal. More like people taking a sleeping bag and sleeping between the rows of tomatoes. There will be space between plant rows for work, you don't want to trample one plant while harvesting the next one

Offline Lar

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Re: Scaling Agriculture on Mars
« Reply #1251 on: 09/11/2018 12:15 AM »
I roll over in my sleep, I'd be pretty bummed if I wiped out all the tomatoes that I was going to get for the next month...  but yeah
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Online KelvinZero

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Re: Scaling Agriculture on Mars
« Reply #1252 on: 09/11/2018 12:21 AM »
People often imply martians would be living in cramped tin cans.. but on mars you must be living amongst the entire volume needed to support you. If people on earth did that, we would each be standing in the middle of an empty acre of farmland.

Offline nacnud

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Re: Scaling Agriculture on Mars
« Reply #1253 on: 09/11/2018 12:27 AM »
I roll over in my sleep, I'd be pretty bummed if I wiped out all the tomatoes that I was going to get for the next month...  but yeah

You get to sleep in the hammock, if you do manage to fall out hopefully you will wake up before rolling too far.

Offline colbourne

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Re: Scaling Agriculture on Mars
« Reply #1254 on: 09/11/2018 01:30 AM »
People often imply martians would be living in cramped tin cans.. but on mars you must be living amongst the entire volume needed to support you. If people on earth did that, we would each be standing in the middle of an empty acre of farmland.
I agree. We always see in scifi films the Mars base being sterile and full of electronic equipment, but I would expect it to be more like a jungle, with plants on many levels and the humans probably sleeping on folding beds coming out of the walls (to prevent blocking sunlight in the day time).
The main problem will be the smell, as the soil is going to be human waste mixed with Martian soil, but people will get used to it over time.
Food from Earth could be something simple like dried pampadoms, including essential vitamins in their ingrediants, which are very compact and should last a long time, and can be microwaved before eating or in emergencies eaten raw. ( I would expect 100g of these would be enough to survive on per person per day in a worst case scenario). Farming can then be ramped up over time to supplement the Earth food using the poop to build up the Martian soil.

Offline sanman

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Re: Scaling Agriculture on Mars
« Reply #1255 on: 09/11/2018 03:30 AM »
People often imply martians would be living in cramped tin cans.. but on mars you must be living amongst the entire volume needed to support you. If people on earth did that, we would each be standing in the middle of an empty acre of farmland.
I agree. We always see in scifi films the Mars base being sterile and full of electronic equipment, but I would expect it to be more like a jungle, with plants on many levels and the humans probably sleeping on folding beds coming out of the walls (to prevent blocking sunlight in the day time).
The main problem will be the smell, as the soil is going to be human waste mixed with Martian soil, but people will get used to it over time.
Food from Earth could be something simple like dried pampadoms, including essential vitamins in their ingrediants, which are very compact and should last a long time, and can be microwaved before eating or in emergencies eaten raw. ( I would expect 100g of these would be enough to survive on per person per day in a worst case scenario). Farming can then be ramped up over time to supplement the Earth food using the poop to build up the Martian soil.

I've read that use of human feces in agriculture can result in the growth/proliferation of organisms that can become intestinal parasites, etc. Shouldn't we be worried about that? How do you prevent that from happening? Do you have to do some kind of reprocessing of the human waste to prevent this?

Offline guckyfan

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Re: Scaling Agriculture on Mars
« Reply #1256 on: 09/11/2018 07:02 AM »
I've read that use of human feces in agriculture can result in the growth/proliferation of organisms that can become intestinal parasites, etc. Shouldn't we be worried about that? How do you prevent that from happening? Do you have to do some kind of reprocessing of the human waste to prevent this?

Feces and other organic matter would go through a composting process in bio reactors designed to kill of parasites and harmful germs.

Offline speedevil

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Re: Scaling Agriculture on Mars
« Reply #1257 on: 09/11/2018 10:34 AM »
I've read that use of human feces in agriculture can result in the growth/proliferation of organisms that can become intestinal parasites, etc. Shouldn't we be worried about that? How do you prevent that from happening? Do you have to do some kind of reprocessing of the human waste to prevent this?
Composting is one answer, compounded with 'don't take those organisms'.
Many of the problematic organisms are not endemic in the human population, but get into it through animal contamination of human accessed spaces, either infecting people through direct or indirect contact with feces/urine, or contact with unwashed or uncooked produce.

If you ensure clean seed-stock and begin with no humans with particular pathogens (these can be screened for, and in many cases are vanishingly rare in 'the west') then the problems that can arise go down dramatically.

Simply wearing gloves and shoes and washing and/or cooking produce will eliminate nearly all risk of spread, even if these precautions are not taken.

Malaria can't occur if you don't take mosquitoes, Lassa fever if you don't take (infected) rats, and cholera which is another major issue with human waste globally isn't in the west.



Offline Paul451

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Re: Scaling Agriculture on Mars
« Reply #1258 on: 09/11/2018 02:36 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.

Offline Lar

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Re: Scaling Agriculture on Mars
« Reply #1259 on: 09/11/2018 04:44 PM »
I've read that use of human feces in agriculture can result in the growth/proliferation of organisms that can become intestinal parasites, etc. Shouldn't we be worried about that? How do you prevent that from happening? Do you have to do some kind of reprocessing of the human waste to prevent this?

Feces and other organic matter would go through a composting process in bio reactors designed to kill of parasites and harmful germs.

why would it first not heated to high enough temperatures to sterilize it?
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