So somebody asked Popular Science: “What would people eat in a permanent space colony?” If you’re thinking astronaut food, yeah, there’d be some of that—but think of the expense involved in shipping food supplies from Earth to, say, Mars, and the idea of a space colony of indefinite size subsisting entirely off of vacuum-sealed peanut-butter-and-honey tortillas for all eternity starts looking less and less plausible. It works great for a space station, where there are just a few people to feed (and where there’s no room to drive a tractor anyway)—but the bigger the colony, the more important it becomes that it can produce at least most of its own food.
And that’s where subsistence farming comes in, as Cornell’s Jean Hunter explains in Popular Science‘s answer:
“Small-scale agriculture is notoriously inefficient … I worry about the colonists underestimating the amount of human capital needed to grow and process their own food, to the point where everybody becomes a subsistence farmer and they’re toiling all day just to get enough to eat—kind of like our ancestors in America.”
The good news is that space agriculture is already a reality. Thanks to the SpaceX module that docked with the International Space Station last month, astronauts are already beginning to grow their own vegetables (starting with red romaine lettuce). Additional seed packets will allow the astronauts to continue to test the Veg-01 module on more substantial produce in the coming years, bringing astronauts closer to the subsistence farming that will make space colonization possible.