Modern Farmer magazine has an article about NASA's efforts into growing food in space, a slow, difficult process that's nonetheless necessary if humanity is to have any significant presence away from Earth's surface. Quoting: "This December, NASA plans to launch a set of Kevlar pillow-packs, filled with a material akin to kitty litter, functioning as planters for six romaine lettuce plants. The burgundy-hued lettuce (NASA favors the 'Outredgeous' strain) will be grown under bright-pink LED lights, ready to harvest after just 28 days. NASA has a long history of testing plant growth in space, but the goals have been largely academic. Experiments have included figuring out the effects of zero-gravity on plant growth, testing quick-grow sprouts on shuttle missions and assessing the viability of different kinds of artificial light. But [the Vegetable Production System] is NASA's first attempt to grow produce that could actually sustain space travelers. Naturally, the dream is to create a regenerative growth system, so food could be continually grown on the space station — or, potentially, on moon colonies or Mars. ... Plant size is a vital calculation in determining what to grow on the space station, where every square foot is carefully allotted. Harvest time is also of extreme importance; the program wants to maximize growth cycles within each crew’s (on average) six-month stay."