The Space Shuttle was a crewed, partially reusable low Earth orbital spacecraft operated by the U.S. National Aeronautics and Space Administration. Its official program name was Space Transportation System, taken from a 1969 plan for a system of reusable spacecraft of which it was the only item funded for development. The first of four orbital test flights occurred in 1981, leading to operational flights beginning in 1982. They were used on a total of 135 missions from 1981 to 2011, launched from the Kennedy Space Center in Florida. Operational missions launched numerous satellites, interplanetary probes, and the Hubble Space Telescope; conducted science experiments in orbit; and participated in construction and servicing of the International Space Station. The Shuttle fleet had combined mission duration of 1322 days, 19 hours, 21 minutes and 23 seconds.
Shuttle components included the Orbiter Vehicle, a pair of recoverable solid rocket boosters, and the expendable external tank containing liquid hydrogen and liquid oxygen.