Skylab was a manned space station launched into Earth orbit by the United States in May 1973. Skylab had four major units: the orbital workshop where the crew lived and primarily worked, an airlock module used to exit Skylab for outside activities, the multiple docking adapter with docking ports for the crews' spacecraft, and the Apollo telescope mount observatory for solar research. A crew of three astronauts occupied Skylab during each of three missions. Abandoned in 1974, Skylab was destroyed during reentry through Earth's atmosphere in July 1979. This is one of various display models produced by NASA to depict the complete Skylab configuration.