The Hubble Space Telescope rests in the Space Shuttle Discovery's cargo bay during the third repair mission in December 1999. Hubble must attach to the shuttle for astronauts to perform repairs. Discovery is the shuttle that originally carried Hubble into orbit in 1990. The telescope stretches five stories tall, and the tubular part of its body is 14 feet (4.2 m) across. Its school bus-size bulk completely filled Discovery’s cargo bay during the trip from Earth to space.