Extravehicular activity (
EVA) is any activity done by an
astronaut or cosmonaut outside a
spacecraft beyond the
Earth's appreciable atmosphere. The term most commonly applies to a
spacewalk made outside a craft orbiting Earth (such as the
International Space Station), but also has applied to
lunar surface exploration (commonly known as
moonwalks) performed by six pairs of American astronauts in the
Apollo program from 1969 to 1972. On each of the last three of these missions, astronauts also performed deep-space EVAs on the return to Earth, to retrieve film canisters from the outside of the spacecraft. Astronauts also used EVA in 1973 to repair launch damage to
Skylab, the United States' first space station.