A fter weeks or months in Earth orbit, it is finally time for the space station inhabitants to make their way home. Scientific equipment and other gear must be packed up and either stowed on the station for the next crew or brought aboard the spacecraft that will take the astronauts home. The astronauts also review the procedures they will use to get home since it has been a long time since they trained for this mission. If the station will not be inhabited for a while after they leave, the astronauts shut down the station's major systems and prepare it for the absence of a crew.

In most cases the next space station crew comes aboard before the previous crew departs. In these cases a spacecraft comes from Earth carrying the new station crew—and the departing astronauts' ride home. Watching the...