Author Topic: Mars ISRU for food crops and consumables.  (Read 96501 times)

Offline Kaputnik

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Re: Mars ISRU for food crops and consumables.
« Reply #40 on: 09/05/2012 02:34 pm »
Fascinating topic.
Genetic Modification would seem to be very useful here. You could produce plants engineered for the artificial environment. Perhaps you could get around the need for pollination and have clones of the same plant.
One massive benefit that I don't think has been mentioned is that the Martian environment could be kept completely free of pests and diseases.
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Offline Robotbeat

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Re: Mars ISRU for food crops and consumables.
« Reply #41 on: 09/05/2012 05:44 pm »
Plant cultivation is one area where genetic modification is not at all science fiction.

But anyway, if you go the multi-layered approach, remember that you lose light due to reflection at every interface. 9 layers is 18 interfaces... Since the index of refraction of mylar is 1.74 (and vacuum or air is ~1), Reflectivity at each interface is:

((1-1.74)/(1+1.74))^2=(-.74/2.74)^2 = ~7.3% at each interface... so... 92.7% transmittance at each interface... (.927)^18 gives you just 25% transmittance*!

Thus, go for fewer layers. You can also apply non-reflective coatings, but that is expensive and difficult for an early Mars settlement to do.


*(Of course, some of that "lost" to reflection would be reflected back /into/ the greenhouse so not actually lost... but I was just trying to illustrate a point... the answer would still be roughly the same, i.e. significant amounts of light lost to reflection)

You could possibly operate the greenhouse at very low pressures, as long as you had a pressure above the Armstrong Limit (possibly even less than that, though it wouldn't be as safe). This would mean an order of magnitude less mass. Of course, that may affect plant yield, but I am not an expert in that.

Another possibility that would reduce the mass is to use a net of much higher strength/mass ratio material, like Kevlar or Spectra. The mylar could be much thinner in that case (or the volume much larger for the same thickness), since it'd only be holding back the pressure over a tiny area instead of the whole circumference.

Both those techniques taken together would give you a theoretical mass of just one hundredth what we started out with... Or, a greenhouse one hundred times bigger for the same mass (i.e. a hundred times longer). It may be hard to manufacture it on Mars, but if you got the mass low enough, it could still be feasible to transport it from Earth.

And, since we are primarily concerned with ground area covered and not volume, at the greatest limit, you want your greenhouse as low of a height as feasible... At the extreme limit, you could imagine just thin-walled tubes of algae. These could be manufactured (and "seeded"?) in a continuous process... as the biomass got to a certain level, you could just process the whole entire tube in bulk, plastic and all.
« Last Edit: 09/05/2012 05:50 pm by Robotbeat »
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Re: Mars ISRU for food crops and consumables.
« Reply #42 on: 09/05/2012 07:11 pm »
I like the kevlar net method. There are a couple of problems with the multiple layer method, not the least of which is the maintainability problem. That is, with nine layers, there are seven layers for which there is no maintenance access to repair leaks. I guess that leaves two layers maximum to enable maintenance (patching of leaks), but with the kevlar net approach, two layers might be enough. For a greenhouse at full Earth atmospheric pressure, just control the air pressure in the gap so that if the outer layer leaks, the inner pressure drops to a level maintainable by a single layer, and if the gap pressure rises, lower the inner pressure, same as above. Then find and patch the leak. That way, the greenhouse would probably survive even operating at half pressure for a time.

There is another consideration to allow wider greenhouses. Set two greenhouses side by side, then instead of anchoring the adjacent edges to the ground, anchor and seal them to a beam that is tethered 6 - 8 foot above the ground. Now your open space would be 32 feet wide instead of 16.

edit: Oops. Kevlar is susceptable to UV degradation. Need another material, maybe steel wire or cable?

I would like to see someone's design of a "walk about" dome. That is, a large enclosure for the habitat area with enough pressure to allow colonists to walk over to the neighbor's house using at most a breathing mask. The habitats would be inside this area, accessable via airlocks. The greenhouses would not be inside this enclosure (due to sunlight attenuation and space) but would also be accessable from it via airlocks. What would the "walk about" air pressure be?

« Last Edit: 09/05/2012 08:01 pm by aero »
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Offline mrmandias

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Re: Mars ISRU for food crops and consumables.
« Reply #43 on: 09/05/2012 07:56 pm »
Also, the SkyLab experiments seemed to confirm for me that plants in lower gees would be taller and more spindly than here on Earth.  My corn is maybe 6'-7' hi; lower than the 8'+ I've had in previous gardens.  I'm thinking that the corn plants on Mars will be 12'-16' high.  The appearance of the garden will be quite different from earthly ones.

We like to wave our hands and say ‘genetic engineering,’ but that is easier said than done.  However, you have just suggested one possibly practical way to genetically engineer food plants for higher efficiency.  Possibly practical, because it has been done.

A big part of the ‘green revolution’ that dramatically increased crop yields was simply breeding the plants to be shorter.  Wheat nowadays is shorter than it used to be.  (Which means it doesn’t choke out the weeds as well, so you have to use herbicides).  The plant put less energy into stalk thickness and a lot less energy into stalk height,  and more energy into food.
On Mars you could sacrifice a lot of  height and stalk thickness.

Offline mrmandias

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Re: Mars ISRU for food crops and consumables.
« Reply #44 on: 09/05/2012 08:12 pm »
Some will say that we should use lower pressure allowing wider and shorter greenhouses per acre. Until we can calculate the crop production with justification, assuming lower pressure is inherently to risky for me. If lower pressure greenhouses produced a lower crop yield, then more greenhouse space would be needed to produce the same amount of food. Study is needed, unless we design for near earth normal atmosphere and augmented sunlight to near earth normal. If we design to reproduce earth normal conditions we don't need to study, we can just build them and put in enough earth soil to know they will work.

Earth agriculture takes place at altitudes up to around 10,000 feet.  There is plenty of data on the effects of air pressure on crop yields.

But even if there isn’t, build a greenhouse, reduce the pressure, reduce the sunlight, and study the issue.  Studying this stuff earthside is WAY cheaper than sub-optimal systems on Mars.

Also, upthread you mentioned that greenhouses need to be flat to avoid water ponding at one end.  This is a concern only if you use flood irrigation or row irrigation, which would be nuts.  Using sprinklers and drip systems, as in earthside greenhouses, means that some slope on the greenhouse isn’t much of a problem.

edit: pinto beans are grown in the four corners area at around 700 ft.  Yields are not optimal but are within comparable normal ranges for lowland agriculture.  That's about a 30% reduction in air pressure, which is pretty significant for Mars greenhouses purposes.  Also, most of the reduction in yeild is probably because of a shorter growing season. 
« Last Edit: 09/05/2012 08:23 pm by mrmandias »

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Re: Mars ISRU for food crops and consumables.
« Reply #45 on: 09/05/2012 08:29 pm »

You could possibly operate the greenhouse at very low pressures, as long as you had a pressure above the Armstrong Limit (possibly even less than that, though it wouldn't be as safe). This would mean an order of magnitude less mass. Of course, that may affect plant yield, but I am not an expert in that.

You can go much lower than that. The Armstrong limit applies to humans. As plants will not have human bodytemperature, lower pressure becomes feasible. With humans working in pressures suits only. Feasible pressure will need to be tested, plants possibly adapted. But for the biochemistry there should be no problem. Partial presure is the issue. Partial pressure of CO2 is very low, a small fraction of even mars level pressure. Some oxygen partial pressure too, but not too much as the metabolism of plants is much slower than that of a human.

Everything should be tested on earth first, to avoid nasty surprises though. But the benefits of low pressure are so big that everything should be tried.

Another possibility that would reduce the mass is to use a net of much higher strength/mass ratio material, like Kevlar or Spectra. The mylar could be much thinner in that case (or the volume much larger for the same thickness), since it'd only be holding back the pressure over a tiny area instead of the whole circumference.
The outer coating would need to be UV reflecting to protect the materials below. Such coatings are used widely on earth already, for example on the transparent roof of my garden terrace.


And, since we are primarily concerned with ground area covered and not volume, at the greatest limit, you want your greenhouse as low of a height as feasible... At the extreme limit, you could imagine just thin-walled tubes of algae. These could be manufactured (and "seeded"?) in a continuous process... as the biomass got to a certain level, you could just process the whole entire tube in bulk, plastic and all.

Algae, my favorite. Yes definitely they would eliminate most of the problems associated with producing biomass on mars. Very nutricious too. Very healthy proteins and essential fatty acids. Just not very good tasting. But recipes for processsing can be developed. And settlers will have to adjust and develop a new taste. Taste is largely acquired.

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Re: Mars ISRU for food crops and consumables.
« Reply #46 on: 09/05/2012 08:50 pm »
Second Add - Just to add another fly to the ointment, consider this:

http://en.wikipedia.org/wiki/List_of_crop_plants_pollinated_by_bees

What is the ideal range (size of greenhouse) for bees to thrive?

A very important remark. Many plants need to be pollinated by bees for good yield. Those are the ones which would need a higher air pressure level for bees to fly and have enough oxygen. As their weight is less than on earth the pressure should not need to be too high. This is something that cannot be tested on earth. How do bees fly on mars? Do they need as much oxygen as humans?

Wheat and its family don't need bees. Their pollen is propagated by wind. Some means of airflow is needed anyway and maybe ventilators during pollination time.

Potatoes don't need pollination. Their seeds are not needed.

It was mentioned that bees would need a big space. But that is not a problem as long as the total area is available. The hive can be transfered from greenhouse to greenhouse. You can also feed them, if the area is too small.

Online A_M_Swallow

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Re: Mars ISRU for food crops and consumables.
« Reply #47 on: 09/06/2012 12:31 am »
A very important remark. Many plants need to be pollinated by bees for good yield. Those are the ones which would need a higher air pressure level for bees to fly and have enough oxygen. As their weight is less than on earth the pressure should not need to be too high. This is something that cannot be tested on earth. How do bees fly on mars? Do they need as much oxygen as humans?
{snip}

The breathing of insects will need a through investigation.  They do not have lungs but some sort of air tubes.

Low air pressure can be tested on Earth.

Insects are small so a centrifuge can be used to test their flying.  This could be on the ISS or say a Dragonlab.

Online aero

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Re: Mars ISRU for food crops and consumables.
« Reply #48 on: 09/06/2012 05:08 am »
Two things: plus edits

1. Is it going to be a problem for the use of Mylar that Mylar pretty effectively blocks UV radiation?

2. What is the Mars One schedule. We've identified a lot of studies that should be done and some of them will take a long time to complete. How much time remains before the study results are needed and firm planning could begin?

Regarding pressure needed for a walk about area, would it need to be nearly the same pressure as the habitat to avoid the bends or pre-breathing waste of time. Or could such problems be overcame with the air mix in the respirator? I also imagine people working on large projects "outside" where a full Mars suit might slow the work progress.
« Last Edit: 09/06/2012 05:19 am by aero »
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Re: Mars ISRU for food crops and consumables.
« Reply #49 on: 09/06/2012 05:47 am »
We will need meat and dairy products to establish the colony in a self sustainable way.

I am sure beef and milk is a nice to have. But we don't really need it. Milk is a relatively recent addition to our diet, many people are lactose intolerant as it is not in our genes to drink milk after infancy.

If we want beef and milk we would feed the cattle algae. To get them to Mars we would probably send dwarf varieties and implant fertilized eggs of larger breeds to get the breeds we want.

Initially I believe we would go for fish, shrimp and chicken if we want animal protein. Again the feedstock would be algae.
Especially fish and shrimps would not require large structures. Pipes or inflatable plastics of maybe 1m diameter would require much less resistant materials.

Edit: If we chose to ignore cultural preferences, insects would be a perfect addition to our diets. Meal worms are easy to raise and a good addition to the diet.

Regarding pressure needed for a walk about area, would it need to be nearly the same pressure as the habitat to avoid the bends or pre-breathing waste of time. Or could such problems be overcame with the air mix in the respirator? I also imagine people working on large projects "outside" where a full Mars suit might slow the work progress.

The problem comes with the Nitrogen partial pressure in the breathing air. If we breathe an atmosphere with nitrogen we need an adaption time to get rid of the nitrogen. That makes space walks on the ISS difficult. The night before going out is used to get rid of the nitrogen in an all oxygen atmosphere or else there are health risks similar to that of divers coming up from deep dives.

Unfortunately the problem cannot be addressed with the air mixture breathed. We need the partial pressure of oxygen to work and additional nitrogen will increase the total pressure.

According to a german blog I read NASA was actually considering a low pressure all oxygen atmosphere on Mars stations for that reason. But I don't like the idea because of fire hazard.

For working larger aeras probably some kind of acricultural machines would be used. Either remotely controlled or with a pressurized cabin. Large agricultural machines on earth are allready using climatized cabins.

For outside work a new type of pressure suits is in development. Bio-Suits will not use internal air pressure but provide mechanical pressure directly to the skin. They are lighter, less bulky and will make it much easier to work with. They are also much less critical for small ruptures as internal pressure will not be affected or only locally. But they do not eliminate the nitrogen problem unfortunately unless they are so efficient you can increase the total pressure.

http://www.astronautix.com/craft/biosuit.htm

I have read about a recent developement for fish farming. As the water becomes an evironmental problem a new system was developed. The water from the fishtanks goes through biological filters and is then fed to aqua culture tomatoes for fertilizer. A closed circuit of water can be established that way. The method is economically viable and the beauty of it is, that you cannot use antibiotics on the fish because it would destroy the filters.
« Last Edit: 09/06/2012 05:53 am by guckyfan »

Offline QuantumG

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Re: Mars ISRU for food crops and consumables.
« Reply #50 on: 09/06/2012 06:15 am »
We will need meat and dairy products to establish the colony in a self sustainable way.

I am sure beef and milk is a nice to have. But we don't really need it. Milk is a relatively recent addition to our diet, many people are lactose intolerant as it is not in our genes to drink milk after infancy.

Do you have any idea what life was like before the safe availability of dairy products?
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Re: Mars ISRU for food crops and consumables.
« Reply #51 on: 09/06/2012 06:30 am »
Do you have any idea what life was like before the safe availability of dairy products?

Lots of things have changed since that time. For example our knowledge about dietary needs. A perfectly healthy diet is possible without any animal products. Not that I am a Vegetarian or even Vegan. I like my beef, pork, milk, and cheese  too.


Offline JohnFornaro

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Re: Mars ISRU for food crops and consumables.
« Reply #52 on: 09/06/2012 02:25 pm »
We will need meat and dairy products to establish the colony in a self sustainable way.

I am sure beef and milk is a nice to have. But we don't really need it. Milk is a relatively recent addition to our diet, many people are lactose intolerant as it is not in our genes to drink milk after infancy.

Do you have any idea what life was like before the safe availability of dairy products?

Well, at least the human species was never in danger of extinction, even without homogenization.

The main problem with milk, is that you need some kind of meat, which means you'd have to launch and land some dairy animals.  I won't grant the handwave of launching the DNA sequence of a cow or goat, and then growing it on site. 

Why not bring some baby goats, pigs, and chickens?  Yes, it would be added launch and travel and landing complexity.  But those food products provide a lot of benefits.  All three of those animals are also great recyclers of organic waste, and producers of organic fertilizer.  If it would be objected that the nascent colony might be overrun with pig poop, then it would be proof that the colonists aren't cleaning up very well, and that the nascent eco system is doing pretty well.
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Offline mrmandias

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Re: Mars ISRU for food crops and consumables.
« Reply #53 on: 09/06/2012 02:52 pm »
Most people of Northern European descent do have it in their genes to continue drinking milk after infancy.  It really helps in childhood growth, though careful nutrition can probably compensate.

Cattle are an inefficient source of meat.  You are better off with seafood or chicken or rabbits.  I also believe that goats give more milk per pound of feed than cattle do, though the flavor is a little strong and goats can be pretty destructive.

We will need meat and dairy products to establish the colony in a self sustainable way.

I am sure beef and milk is a nice to have. But we don't really need it. Milk is a relatively recent addition to our diet, many people are lactose intolerant as it is not in our genes to drink milk after infancy.

If we want beef and milk we would feed the cattle algae. To get them to Mars we would probably send dwarf varieties and implant fertilized eggs of larger breeds to get the breeds we want.

Initially I believe we would go for fish, shrimp and chicken if we want animal protein. Again the feedstock would be algae.
Especially fish and shrimps would not require large structures. Pipes or inflatable plastics of maybe 1m diameter would require much less resistant materials.

Edit: If we chose to ignore cultural preferences, insects would be a perfect addition to our diets. Meal worms are easy to raise and a good addition to the diet.

Regarding pressure needed for a walk about area, would it need to be nearly the same pressure as the habitat to avoid the bends or pre-breathing waste of time. Or could such problems be overcame with the air mix in the respirator? I also imagine people working on large projects "outside" where a full Mars suit might slow the work progress.

The problem comes with the Nitrogen partial pressure in the breathing air. If we breathe an atmosphere with nitrogen we need an adaption time to get rid of the nitrogen. That makes space walks on the ISS difficult. The night before going out is used to get rid of the nitrogen in an all oxygen atmosphere or else there are health risks similar to that of divers coming up from deep dives.

Unfortunately the problem cannot be addressed with the air mixture breathed. We need the partial pressure of oxygen to work and additional nitrogen will increase the total pressure.

According to a german blog I read NASA was actually considering a low pressure all oxygen atmosphere on Mars stations for that reason. But I don't like the idea because of fire hazard.

For working larger aeras probably some kind of acricultural machines would be used. Either remotely controlled or with a pressurized cabin. Large agricultural machines on earth are allready using climatized cabins.

For outside work a new type of pressure suits is in development. Bio-Suits will not use internal air pressure but provide mechanical pressure directly to the skin. They are lighter, less bulky and will make it much easier to work with. They are also much less critical for small ruptures as internal pressure will not be affected or only locally. But they do not eliminate the nitrogen problem unfortunately unless they are so efficient you can increase the total pressure.

http://www.astronautix.com/craft/biosuit.htm

I have read about a recent developement for fish farming. As the water becomes an evironmental problem a new system was developed. The water from the fishtanks goes through biological filters and is then fed to aqua culture tomatoes for fertilizer. A closed circuit of water can be established that way. The method is economically viable and the beauty of it is, that you cannot use antibiotics on the fish because it would destroy the filters.

« Last Edit: 09/06/2012 02:53 pm by mrmandias »

Online guckyfan

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Re: Mars ISRU for food crops and consumables.
« Reply #54 on: 09/06/2012 03:55 pm »
I won't grant the handwave of launching the DNA sequence of a cow or goat, and then growing it on site. 

 :)

Actually I believe they would do exactly this. Just launch the DNA - in form of a fertilized egg. Plus a female of some dwarf cattle variety.

Implant the egg and you have the desired breed without the launch cost. Continue to use imported fertilized eggs for genetic variety.


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Re: Mars ISRU for food crops and consumables.
« Reply #55 on: 09/06/2012 04:59 pm »
I won't grant the handwave of launching the DNA sequence of a cow or goat, and then growing it on site. 

 :)

Actually I believe they would do exactly this. Just launch the DNA - in form of a fertilized egg. Plus a female of some dwarf cattle variety.

Implant the egg and you have the desired breed without the launch cost. Continue to use imported fertilized eggs for genetic variety.


I'm more with John on this. Artificial insemination is well established in animal husbandry, but implanting a fertilized egg is more difficult as is giving birth to a larger variety of offspring. Risky techniques should be reserved for later. Risking one or two of a small herd of Mars bred dwarf cattle is one thing, risking the first cow that came from Earth is quite another.

Anyway, it will take time to establish the crop lands to feed the cattle.
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Online guckyfan

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Re: Mars ISRU for food crops and consumables.
« Reply #56 on: 09/06/2012 05:15 pm »
I'm more with John on this. Artificial insemination is well established in animal husbandry, but implanting a fertilized egg is more difficult as is giving birth to a larger variety of offspring. Risky techniques should be reserved for later. Risking one or two of a small herd of Mars bred dwarf cattle is one thing, risking the first cow that came from Earth is quite another.

I agree. Don't risk the one or two specimens shipped in fom earth. Start with raising a small herd of dwarf cattle and then go for implanting fertilized eggs of larger breeds. If necessary use incremental steps with the size of the offspring.

Anyway, it will take time to establish the crop lands to feed the cattle.

Again, algae are the magic wand, no corn or soy for the cattle. Unless we really succed in growing at least grass under unpressurized domes. But yes, it will take time. And I doubt they would go for cattle before a sizeable colony of humans has been established, if at all. A nutricious substitute for milk can be formulated for the children. They won't know the difference, because they have never had milk. And research is ongoing to produce beef without cattle. No idea how good the chances for success are, though.

Offline Patchouli

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Re: Mars ISRU for food crops and consumables.
« Reply #57 on: 09/06/2012 08:46 pm »
A very important remark. Many plants need to be pollinated by bees for good yield. Those are the ones which would need a higher air pressure level for bees to fly and have enough oxygen. As their weight is less than on earth the pressure should not need to be too high. This is something that cannot be tested on earth. How do bees fly on mars? Do they need as much oxygen as humans?
{snip}

The breathing of insects will need a through investigation.  They do not have lungs but some sort of air tubes.

Low air pressure can be tested on Earth.

Insects are small so a centrifuge can be used to test their flying.  This could be on the ISS or say a Dragonlab.

There has been some work on seeing if they'd survive at different pressures insects and spiders have been brought on Apollo and Skylab missions.
http://history.nasa.gov/SP-401/ch17.htm
http://heroicrelics.org/uhc/skylab-spider/index.html
More work needs to be done a dragon lab would be perfect since they don't need much room.
In fact the Mars gravity satellite experiment could be flown on the same vehicle.
http://en.wikipedia.org/wiki/Mars_Gravity_Biosatellite
« Last Edit: 09/06/2012 08:47 pm by Patchouli »

Offline zodiacchris

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Re: Mars ISRU for food crops and consumables.
« Reply #58 on: 09/06/2012 09:20 pm »
Realistically, given that you have to feed an animal 10 calories for every calorie in meat produced, meat is a luxury we will not be able to afford for a long, long time on a colony! You can have a human live on the caloric intake of a pig!
Face it guys, a mostly vegetarian diet with aquaculture will be the most manageable approach, you just have to accept that a different planet wll have a different menu...

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Re: Mars ISRU for food crops and consumables.
« Reply #59 on: 09/06/2012 11:38 pm »
Realistically, given that you have to feed an animal 10 calories for every calorie in meat produced, meat is a luxury we will not be able to afford for a long, long time on a colony! You can have a human live on the caloric intake of a pig!

A human can't eat meat on the caloric intake of a pig, but 20 humans and a pig can eat meat on the caloric intake of 21 humans while saying thanks for the pig. But pigs are distructive and dangerous animals, take sheep instead.
 
Quote
Face it guys, a mostly vegetarian diet with aquaculture will be the most manageable approach,

I agree that the first colonists will by necessity be limited in food variety, but the first colonists are not the end of it...
Quote

you just have to accept that a different planet wll have a different menu...


Why? If we have 100 colonists and are producing crops giving a reasonable safety margin of calories to consume, why not feed those excess calories to sheep rather than let last year's crops spoil in the granaries. If we start running low on grain reserves we will do what family farmers have always done, eat more meat.
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