It sounds like a riddle: How do astronauts do their laundry in outer space? The answer: They don't. There's no room up at the International Space Station for a washer-dryer set, and even if there were, using such appliances in an environment of weightlessness would be difficult, to say the least. Sadly, though, zero gravity does not mean zero dirt, and one can easily imagine that without clean clothes, things might get pretty gamy up there at a certain point. So the astronauts and cosmonauts who staff the ISS do what many of us do: they send their laundry out.
In their case, "out" means way, way out—hundreds of miles, to Earth's surface, where it can be washed the old-fashioned way. Since old-fashioned pickup and delivery are out of the question, though, this task is accomplished by the Space Shuttle, which on a few trips a year to the ISS carries a multi-purpose logistics module (MPLM) full of supplies (food, toiletries, clean clothes) and then returns with a payload of dirty laundry and other things that aren't wanted—or, more likely, can't be kept (not much closet space in the ISS either). "When you have humans living in space," says Sharon Castle, an ISS launch-package manager at NASA, "you have to look out for their needs—not only their glamorous needs but their necessary needs as well."
After one recent mission the shuttle Endeavour's MPLM, "Leonardo," came back carrying 2,500 pounds of stuff—reusable food containers, hardware, space-suit components, IMAX film equipment, and a Russian air-conditioner that wasn't working properly, along with 400 pounds of clothing. Although this kind of payload is occasionally characterized by civilians as "space trash," Castle is careful to point out that everything that comes back to Earth in an MPLM is recycled and reused, one way or another. "Things that we no longer have a need for—that are really garbage—go in the 'Progress,'" she explains. The "Progress" is an unmanned cargo vehicle attached to the ISS—a space Dumpster, if you will, which is cut loose when full and ultimately burns up in Earth's atmosphere. Perhaps you spotted it one night and made a wish.