429
xkcd #2978: Stranded
(xkcd.com)
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
this post was submitted on 28 Aug 2024
429 points (99.1% liked)
xkcd
8822 readers
108 users here now
A community for a webcomic of romance, sarcasm, math, and language.
founded 1 year ago
MODERATORS
Humans are very picky. Must have certain amount of gravity, need to see green stuff, can’t handle radiation etc. it’s is as if they were built to be on a specific planet and nowhere else.
You're totally right, but that gravity, that green stuff, neither of those are on Mars. In orbit at least you get the gravity, rotating habitats aren't that much more complicated than static ones.
I'm not sure if Mars' poison and irradiated soil will ever be useful for growing plants. I'm telling you while it is a similarly sized planet, it's still barely useful.
The presence of water is nice
That's true. Local water, even as trace ice crystals, would be easier to harvest than chipping apart a comet in deep zero g. But ultimately, your materials for both construction and life support are going to have to start coming from space, and asteroids and comets are the obvious choice.
The best strategy would probably be to send a relatively small vehicle to the comet (small relative to the comet), something like the power and propulsion core for the new lunar gateway, essentially just a big ion thruster with a bunch of solar panels. This can push the comet into an orbit that swings it by the moon to capture it into an earth orbit. You may need to do some earth flybys to lower the comet's orbit first, so the mission could take years. But to make up for that, comets are huge, and after it's done you have a source of many different materials to work with right here in earth orbit, enough material to last decades or more.
But not all water is useful.
We have a lot of non useful water on Earth in the oceans that has too much salt.
Water from non-Earth sources might contain dissolved minerals at poisonous levels for agriculture, much less human consumption.
And if there's liquid water from a non-Earth setting, there might be some kind of unknown exo-organisms living in it.
Oh yeah, it's practically guaranteed to contain nasty stuff! We're gonna drink it anyway though.
Most of that water on earth that we'd consider "not useful" would fall into the "100% useful" category if found in space. As long as the contaminants have a different boiling temperature from water, you can always boil the water into steam in order to separate it. Or you could also use electrolysis to separate out the hydrogen and oxygen and then recombine then in clean tanks.
These are expensive methods of purification, energy intensive, but solar panels really well with no atmosphere and 24/7 sun exposure, so this is all feasible.
I think we could send robot farmers there to grow some food for the people living in orbit. Maybe low-G carrots could be nicer than the ones grown on earth.
Entirely possible. But hey, in a space station you could have a separate agriculture ring, it may turn out that plants grow most efficiently at some particular amount of gravity, having its own ring would let you experiment, to maximize yield. Also you can use shades and mirrors to precisely control the amount of sun the plants get, even provide them constant sun if that speeds up growth.