seriously though, any serious attempt to live on mars would obviously use electrolysis of water to produce oxygen on mars, because to do so you only need electricity and water.
you need about 1 kg of water and 1 kWh of electricity per person per day to produce enough oxygen.
source: my own math
you can calculate this if you consider that people need about 8 MJ of energy a day, and bread has around 15 MJ of energy per kg, so people need around 0.5 kg of bread a day, that’s approx. 0.5 kg of carbon atoms. since each carbon atom combines with 2 oxygen atoms, that makes twice as many oxygen atoms as carbon atoms. assuming they are the same mass (which they almost are), that’s about 1 kg of oxygen a day. 1 kg of water contains about 1 kg of oxygen atoms.
about how much energy you need: you can calculate this with Standard enthalpy of formation of water. (given in the sidebar here)
I’m just too lazy to do this rn, so you’re gonna have to believe me.
and about how to get electricity, see my post here
and about how to get water, see my post here and this article.
and then you could produce O2, which you’re gonna breathe in, and you’re gonna exhale CO2, which you then need to remove from the atmosphere, which you can do with a CO2 scrubber
plants also need water, nutrients, some mycorizzhae depenending on the species. mars is pretty barren, and low atmosphere.
It’s amazing how complicated just the O2 cycle is. Basically, we don’t yet how to do it without a whole planet being involved.
Like, plants do release O2 sometimes, but they also use O2 as fuel when they grow. Growing a plant requires light. On the earth that’s easy, just put it in the sun. On Mars there’s no atmosphere and no magnetic field, so if you just put a plant on the surface they’ll die. So, you need to grow them underground in a mostly earth-like atmosphere at mostly earth-like pressure lit by artificial lights.
So, you plant a lot of plants deep underground lit by bright artificial lights. Then you need to supply the plants with a lot of water. Some of that water will be released into the air, but some of it will be incorporated into the plant’s body. There’s a whole water cycle that isn’t yet fully understood.
What about the soil? On earth worms and other bugs break down leaf litter and other things into usable soil and bees pollinate many of the plants. So, do you ship up a bunch of bugs? You’d have to supply a whole ecosystem of them so they live in balance. You could go with hydroponics instead, but then you’d need a constant supply of nutrients for the plants, and given the amount of plant matter needed for just one human, that would be a huge supply of nutrients.
I’d love to see another honest, scientifically rigorous attempt at a biosphere project. Building a closed ecosystem on Earth is easy-mode compared to doing it anywhere else, but so far all the Biospheres have been failures. IMO until we can easily do it on Earth, we’re nowhere near ready to do it in space, on the moon, or on another planet.
On Mars there’s no atmosphere and no magnetic field, so if you just put a plant on the surface they’ll die. So, you need to grow them underground in a mostly earth-like atmosphere at mostly earth-like pressure lit by artificial lights.
you can put algae in a plastic bag and grow them in there, so they’re in a pressurized container so there’s enough air pressure in there for them.
sth like this: link to post
i’ve actually been thinking about this exact problem, and you don’t actually need to grow wheat on mars. you only need calories, protein, fats, vitamins, fiber. you can get calories and protein from algae (which you can grow in small plastic tubes/boxes). Spirulina (bacteria type) is a typical candidate for that.
It’s especially protein-rich. Growing it would require less than 1000 m² per person, i think, though i’m not sure.
growing salad for vitamins and fiber takes significantly less area (maximum 50 m² per person) and can be done indoors, wherever you live.
asking with no experience in this field, what about those 50+ year old glass jars with worms and plants and stuff in them? Do those not count for some reason?
They work, but there are no humans inside them.
biologically, humans aren’t that special. if you can reliably sustain insects in an ecosystem, it’s not that big of a jump to feed humans as well.
Earth is pretty much just a big one. Jury is still out on our ability to maintain it.
TLDW: a fuckload of plants
Guess I should pack two fuckloads just in case
What about the tertiary backup fuckload?
The third fuckload has to be stored off-site. Also, make sure to use at least two different kinds of plants.
also bring seeds, lots of seeds, in case something goes wrong and you need to re-plant everything.
And his algae one too
That was the biosphere 2 experiment. Turns out it’s very difficult to sustain the plants without the rest of the planet.
Biosphere 2 didn’t fail at sustaining plants.
It failed because they didn’t account for the concrete structure sucking out oxygen.
Remember how Biosphere 2 went so badly that the crew nearly starved to death, but no one bothered doing a Biosphere 3? That might be a good step before attempting long-term Moon or Mars missions.
Yeah, I think of that every time somebody starts talking about fallout shelters, space stations or bases on the moon or Mars. It’s definitely not a solved problem.
No, we just need more money and it’ll be fine.
That’s the thing about centralized planning-you think everything’s possible if you just throw more slaves at the problem. And modern autocrats (musk, bezos, bin-salman) don’t seem to understand that this just isn’t true.
Edita;: they’re trying to do new kinds of things, rather than ‘big building’, and it just doesn’t work for that. You need thought for that.
Keep trying until it works?
What are you, a mockery of real humans?
Also, have you seen how HUGE the thing was?
3.14 acres of enclosed space, and still barely enough to support a crew of eight people. I think OP is going to need a bigger bag of plants.
Entropy is a bitch
An unforgiving bitch.
Yeah it turns out nobody has enough money to get around thermodynamics. The only solution is to make linegoup even more.
Plants actually use O2 themselves a lot of the time, so we would still need to truck in a whole bunch of that stuff in. Also the amount of plants needed for just a single human is huge. Most plants are rather bad at producing O2. Most of it actually comes from algae living in water, not potted plants. The YouTube channel Joel Creates did an experiment with how much algae you would actually need to breathe. It’s like a lot, a lot a lot really. Building some place on Mars or even in orbit that such a large amount of algae could happily live is pretty hard. Hell it’s pretty hard on Earth, where you don’t need to worry about temperature and pressure going out of spec or stuff like radiation. These days we do have pretty effective LED grow lights that prevent the whole thing from becoming too hot. From movies people think space is cold, but getting rid of heat is a big problem. With that much light blasting into the water, the temperature rises and the algae will die from that at some point. So radiating away all that heat is a must. On Mars or the Moon this is easier as the surrounding rocks could be used as a heat sink. The actual real hard part is not just building this, but building it in a way that can support human life for a long time. Systems such as these are chaotic in nature and often suffer from cascade failure modes. If a little thing goes wrong and some of the algae dies, it often cascades into a full failure where all of it dies off. So there would need to be many smaller systems, isolated as much as possible to prevent cascading failures. The system would also need to be modular enough so it would be easy to disconnect a module, completely clean and sterilize it and put it back into use. With staggered phases applied as to not have large swings in output. As these systems would be rather large in scale and have many different complex parts, a high level of automation is required. And we haven’t even touched on getting all of this constructed somewhere and have it bootstrapped with enough water, with the right stuff in it and none of the wrong stuff. Enough reliable energy and nutrients to feed it all and transport living algae there to kick it all off. As far as I know nobody has ever gotten close to anything like this on Earth, let alone in space or on a place like the Moon or Mars. It would be a project that rivals the original Moon landings.
It might sound like a simple enough concept and it is how we are currently living on this planet, so it should be possible. However keep in mind our planet has had huge swings in temperatures and atmospheric composition. There were many many times in Earth’s past where humans could not survive the conditions and we evolved here.
There’s a great book called “A City on Mars” and it’s mostly about stuff like this. Why colonizing mars is absolutely stupid
Difficult and stupid aren’t the same thing. There aren’t many goals on the same scale of human progress.
The attempt would likely teach us lessons about our own atmosphere and maintaining it. Learning the failure conditions of a biosphere and how to avert disaster seems extremely relevant for the upcoming decades.
OK, let me rephrase, because i’m misrepresenting the book.
Colonizing Mars is extremely, insanely complex and we have no idea how to even start, and there are SO many better places that we need to try first unless we’re just willing to throw away lives (and trillions of dollars). It goes pretty deeply into all the stuff we either don’t know but need to know, or know but can’t fix, and of course there’s all the stuff we don’t know we don’t know. It discusses the insane logistical effort you need just get the bare minimum going, and how it’s not remotely like living there for a year, or colonizing a new country.
Yup. Trees are basically carbon neutral.
NASA should let me put a plastic Koi pond on Mars and dump in a ton of algae killer, it’ll cover a hemisphere in a week.
I drew a factory with the smoke stacks making a u-turn and stuck into the ground. Seemed like a good way to keep pollution from going into the air.
You illustrated ‘clean coal’.
MARK WATNEY, SPACE PIRATE
Soon the movie of project hail mary releases.
There isn’t enough CO2 for that either. Mars’s total atmospheric pressure is way less than 1% of Earth’s. Mars is closer to the Moon in terms of atmosphere than it is to Earth!
Did you not see the plastic bag keeping the air inside? This is a flawless design.
Ahhh. I thought that was just the haze of the red planet!
a place for our grocery plastic bags to have a new life a good life
The pressure is an issue, but the CO2 levels on Mars are insane. Forget the cold and near-vacuum, we’d be choking out on a single breath of that poison.
I’m guessing CO2 uptake would be nada while the plant boils out it’s H2O?
so we need moon plants to colonize mars then
You need to keep it down because CO2 is heavier than O2
Gonna need a lot more plants
…and atmosphere!
The atmosphere is in the plastic shopping bag.
Oh, I thought it was just a yellow background!
My guess is dollar general is the source.
Congratulations, you’re thinking like a billionaire!
Or were at 12.
