The International Space Station is a vast outpost, its scale inspiring awe even in the astronauts who have constructed it. From the edge of one solar panel to the edge of the opposite one, the station stretches the length of a football field, including the end zones. The station weighs nearly 1 million pounds, and its solar arrays cover more than an acre. It’s as big inside as a six-bedroom house, more than 10 times the size of a space shuttle’s interior. Astronauts regularly volunteer how spacious it feels. It’s so big that during the early years of three-person crews, the astronauts would often go whole workdays without bumping into one another, except at mealtimes.

On the station, the ordinary becomes peculiar. The exercise bike for the American astronauts has no handlebars. It also has no seat. With no gravity, it’s just as easy to pedal furiously, feet strapped in, without either. You can watch a movie while you pedal by floating a laptop anywhere you want. But station residents have to be careful about staying in one place too long. Without gravity to help circulate air, the carbon dioxide you exhale has a tendency to form an invisible cloud around your head. You can end up with what astronauts call a carbon-dioxide headache.

Even by the low estimates, it costs $350,000 an hour to keep the station flying, which makes astronauts’ time an exceptionally expensive resource—and explains their relentless scheduling: Today’s astronauts typically start work by 7:30 in the morning, Greenwich Mean Time, and stop at 7 o’clock in the evening. They are supposed to have the weekends off, but Saturday is devoted to cleaning the station—vital, but no more fun in orbit than housecleaning down here—and some work inevitably sneaks into Sunday.

Life in space is so complicated that a lot of logistics have to be off-loaded to the ground if astronauts are to actually do anything substantive. Just building the schedule for the astronauts in orbit on the U.S. side of the station requires a full-time team of 50 staffers.

Almost anyone you talk with about the value of the Space Station eventually starts talking about Mars. When they do, it’s clear that we don’t yet have a very grown-up space program. The folks we send to space still don’t have any real autonomy, because no one was imagining having to “practice” autonomy when the station was designed and built. On a trip to Mars, the distances are so great that a single voice or email exchange would involve a 30-minute round-trip. That one change, among the thousand others that going to Mars would require, would alter the whole dynamic of life in space. The astronauts would have to handle things themselves.

That could be the real value of the Space Station—to shift NASA’s human exploration program from entirely Earth-controlled to more astronaut-directed, more autonomous. This is not a high priority now; it would be inconvenient, inefficient. But the station’s value could be magnified greatly were NASA to develop a real ethic, and a real plan, for letting the people on the mission assume more responsibility for shaping and controlling it. If we have any greater ambitions for human exploration in space, that’s as important as the technical challenges. Problems of fitness and food supply are solvable. The real question is what autonomy for space travelers would look like—and how Houston can best support it. Autonomy will not only shape the psychology and planning of the mission; it will shape the design of the spacecraft itself.