The closest long-term information we have comes from Biosphere 2. They spent a lot of time managing their ecosystem, and I think that would be true of any similar attempt for the next few decades. They had about 1500m2 per person, which included "water treatment / recycling and humanure." By comparison, ISS is 837 cubic meters, so assuming 2m for z gives a bit over 400m2 total.
We have a long way to go before getting that sort of volume. (Which, yes, is precisely what you said. I just wanted to work out the details for myself, out loud. :)
BTW, there's many people who have gone their lives without animal products in their diet, so I don't know what literature and research you are talking about.
I strongly doubt it will be economically viable to think of building (near) self-sufficient colonies for many decades. Brin's essay was very influential on me; it's much easier to build a self-sufficient colony in the Gobi desert (or the Sahara) than in space, so I would expect to see those first, if there's an economic need for the space.
If asteroid mining, or He3 mining of the moon, gives the economic impetus for a long-term off-earth location, then I look to oil platforms or McMurdo base as more relevant example.
What time frame are you thinking? Might as well be planning self-sustaining orbital colonies; and afaik there's not realistic "sealed biosphere" possibilities yet, you'd need fairly large inputs of stuff thats only available on earth still.
To expand on your point, if one was to sustainably grow all vegetables required for a healthy, sustainable diet, then currently this can be achieved on around 100-200m2 per person (on earth, requiring no extra fertilisers / soil etc) based on research by John Jeavons. This hasn't taken into account external rainfall or air movement, but the basic premise is fairly well established. Throw in water treatment / recycling and humanure composting to close the circle completely, then all you need is a light source (assuming a closed atmospheric situation....)
Assuming that we can compress that down into 50m2 per person, the spatial requirements for a sustainable colony blow out quickly to large proportions, and we don't have information over the long term of just how well such a closed environment can nourish a small population - there's literature and research suggesting that we must have animal products in our diet for long term health, so that quickly adds up.
Given all these factors, supply runs from a known good source (earth / the mother country / home) are a sensible choice - but once you start roaming much further, it isn't an option any more. This is the stage we'll find ourselves at in 10-20 years time, as space travel will be economical to the point of sending out pioneer crews to space.
Until we can get close to self sustaining infrastructure sending people into space seems really pointless. If we could even get something like Biosphere 2 to actually work that seems like a solid first step.
BIOS-3 seemed to work, but Dried meat was imported into the facility, and urine and feces were generally dried and stored, rather than being recycled.
This is the technology that's absolutely needed for off-Earth agriculture.
We take so many things for granted, like air and sunlight. I think the Biosphere 2 project was the only one that tried to figure out just what we need to support life in a closed system. It was horribly expensive and it looks to be horribly inefficient - 8 people to make the food and oxygen, and 3.14 acres of land. What we do currently for the space station is to ship them 1000 pounds of stuff every month per person.
I think the main problem with space colonization is the whole nutrient cycle - using and/or recycling every part of food that is grown and consumed, including human excrements and other organic waste (skin, hair, blood, etc.). I don't think that terrestrial farming practice focus on that, no matter how technologically advanced or futursistic.
I don't think anyone would expect that - but the goal in space is not to replicate as much of the Earth biospheres variety in a closed system, but to feed a couple people for as long as possible (but not necessarily indefinitely) with the materials at hand.
I think a vat-grown culture of highly nutritious fungi (or algae or whatever, I'm no expert and I don't pretend to have even an SF writer's level of understanding of the subject) would be a much more viable solution.
> Transporting people with current human lifetimes might not be practical. But brain scans on a computer? Or people in some form of cryogenic state or with life extension tech?
Or a generation ship. The most common approach proposed is a self-contained ecosystem that can grow the food and recycle the waste necessary to keep the ecosystem going and to support a breeding population of people, plants, and animals for the hundreds of years the trip takes.
That approach seems pretty far in the future. I don't think anyone has ever built a self-contained ecosystem that comes anywhere near close to being able to be self-sustaining for any great length of time.
Another approach might be possible that doesn't require a self-sustaining ecosystem, and seems much more in reach. The idea is to send most of the people as frozen eggs and sperm. Same for the animals that will be needed to establish a colony at the destination. Send the colony plants as frozen seeds.
The only already born people you would send is a small crew to operate the ship. They operate the ship for one generation, then make the next generation crew from some of the frozen eggs and sperm, train them, and hand off the ship to them. Repeat until the ship reaches the destination, and the final crew then uses the remaining frozen eggs and sperm to make and raise the colonists. Same for the animals and plants.
Because this approach only has a small crew on the ship at any time, it should be feasible to include their food upfront when the ship leaves. If you use food that has a large calorie/volume ratio, a lifetime supply of food for a person fits in a space that is probably smaller than you would guess.
For example, a typical protein bar is about 200 calories. If you need 3000 calories a day (space crewing is hard work!) for 100 years that works out to about 547500 bars. If each bar has a volume of 10 cm^3, you could store all that in a cube 176 cm on a side. Enough for a crew averaging 10 people at a time for 400 years would fit in the volume of a small single family house.
Air, Water and Shelter are solved and field-proven. (eg. nuclear submarines can theoretically stay out for years, only limited by food)
Food is an interesting challenge, since we haven't done food production at scale beyond earth yet. Small scale experiments and applications seem promising though.
Full self-sustaining is not a requirement provided there is a supply chain. (And vice versa) . Of course: As self-self sustaining as possible as soon as possible would definitely be something to aim for.
The one company proposing to colonize mars in the near future would do so with a fleet of reusable spacecraft capable of 100-metric-tons to mars surface.
"Take three of everything" becomes a bit less of a problem in that kind of situation.
Within those constraints, the challenges are certainly still significant, but need not be insurmountable. Also said ship is -itself- not yet proven, so we'll have to wait and see.
Don't forget the 3 million acres of farmland you need to support your 1 million city folk. We might be able to breed radiation-resistant corn -- not so confident about radiation-resistant chickens. The martians will all be vegan. Good for them.
This all seems very plausible (even necessary) and I find myself inspired similarly to how I have been with SpaceX. It's super cool. Just one nitpick.
> There are also abundant opportunities to see how plants and livestock fare in low gravity, which will also be needed to ensure food security in space.
Do we really need to involve 'livestock'? I can't think of anything essential they would provide that couldn't be sourced with far less cost and nastiness in a different way.
You might be interested in Biosphere 2 [1], a 3 acre hermetically sealed dome stucture designed to house about 8 people with an ecosystem to provide them with everything they need to survive.
They didn't quite get oxygen and food production to the required level, but if you add another acre or so it should work. With renewed interest in moon and mars colonies somebody is bound to revive that line of research.
In space, any food produced would have to be grown inside, sealed away from the outside environment to protect it from the vacuum or near-vacuum of space or Mars. We will grow it in greenhouses or perhaps vats (staples like corn or wheat can be replaced by fermented foods like @solar_foods or @feedkind, using ultimately solar power, this is actually more efficient than photosynthesis and with a much smaller environmental footprint than agriculture) and certainly not have free grazing cattle (which is the biggest land use in the US). On Mars, we’re already beginning to master solar/battery-electric flight, so perhaps we may not need so many surface roads and we can place trains and such underground. Our footprint on the planet Earth could shrink by an order of magnitude even as our economy and quality of life improve (the density effect on economic productivity is well-established—and Mars will be really expensive to live on unless in large, dense cities... suburban sprawl being prohibitively expensive). These are all things that are fairly hard to prove on Earth as the whole system has an inertia due to developing with abundant fossil fuels, but on Mars we will be forced to rely entirely on renewable (mostly solar but perhaps wind and geothermal) or nuclear power, so a Martian society becomes a blueprint and a powerful proof of concept of how Earth life can be..
I think the ballpark you are looking for would be Biosphere 2 [0]. This is a 3 acre enclosed system that supports the food and oxygen needs of 8 people, although the people lost a lot of weight and oxygen levels dropped dangerously. While this (somewhat failed) experiment is in the ballpark of what long-term spacecraft will need to sustain generations of crew, it also shows how much land is needed to supply the air we breathe.
One view point: it's a waste of space and fuel to launch livestock with humans to a colony in the early days. Seeds and enough reserves to keep going would take up much less space.
Another view point: livestock isn't just useful for food, cultures and civilisations have been turning livestock into food, clothing, tools and other resources for centuries. It could be useful.
I know some people find it abhorrent we exploit animals as resources (not me personally), but Musk seems like a pragmatist. If it makes sense to send a bunch of meat loving carnivores to Mars with a ship hold full of livestock then that'll be the option.
On the upside, if they're using a liquid oxygen/methane rich mixture for the fuel they'd have a natural source of methane by having livestock.
There seems to be limited space, though, not for agriculture, but for actual living. Granted, if we could put all humans into little boxes of 2m^2 and somehow attach life support systems to them and stack those boxes, a lot of them might fit on the planet. Forgive me if I don't consider that a desirable scenario (unless virtual reality makes up for it).
Food, power, shelter and air are essentially the big issues for space colonization. With the lab protein I was speaking of the possibility of shipping a close to self sustaining bio reactor in a box to a colony to solve for the food issue. I mentioned this as it's an evolving technology that may be closer to prime time at the same time as the solar panels concept the article mentioned.
Seems a bit silly, you can buy a glass sphere with small closed ecosystem that can last years with indirect sunlight. Surely we can manage something that recycles astronaut poop/pee into something vaguely edible with the help of bacteria, fungus, plants, and algae. Sure some genetic editing (of humans, bacteria, fungus, plants, and algae) might be necessary. Even just some minor tweak like happened in the last 1000s of years to make humans more compatible with cows milk.
Indeed; even if they can make lettuce grow, it's very low in nutritional value so they'd need to sacrifice a lot of space and energy into creating something edible. Potatoes would work better. Space pigs, too, but they'd require a lot of nutrients to keep alive and grow. iirc they need ten times as much food than what their meat is worth in nutritional value.
The future is probably artificially produced food, like the porridge / sludge shown in the Matrix. Something out of a chemical process instead of a biological one.
We have a long way to go before getting that sort of volume. (Which, yes, is precisely what you said. I just wanted to work out the details for myself, out loud. :)
BTW, there's many people who have gone their lives without animal products in their diet, so I don't know what literature and research you are talking about.
I strongly doubt it will be economically viable to think of building (near) self-sufficient colonies for many decades. Brin's essay was very influential on me; it's much easier to build a self-sufficient colony in the Gobi desert (or the Sahara) than in space, so I would expect to see those first, if there's an economic need for the space.
If asteroid mining, or He3 mining of the moon, gives the economic impetus for a long-term off-earth location, then I look to oil platforms or McMurdo base as more relevant example.
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