The
Space Shuttle Orbiter was the orbital
spacecraft of the
Space Shuttle program operated by
NASA, the space agency of the United States.
[1] The orbiter was a reusable winged "
space-plane", a mixture of
rockets,
spacecraft, and aircraft. This space-plane could carry crews and payloads into
low Earth orbit, perform on-orbit operations, then
re-enter the atmosphere and land as a
glider, returning its crew and any on-board payload to the Earth.
A total of six Orbiters were built for flight:
Columbia,
Challenger,
Discovery,
Atlantis,
Endeavour and
Enterprise. All were built by the
Pittsburgh,
PA based
Rockwell International company. The first Orbiter to fly,
Enterprise, took its maiden flight in 1977. Built solely for unpowered atmospheric test flights and landings, its take-off was from the back of a modified Boeing-747 cargo plane, the
Shuttle Carrier Aircraft, while the remaining Orbiters were built for orbital space flights, launched vertically as part of the full
Space Shuttle package.
Enterprise was partially disassembled and retired after completion of critical testing.
Columbia was the first Orbiter to launch into space as a Space Shuttle, in 1981. The first launches of
Challenger,
Discovery, and finally
Atlantis, followed in 1983, 1984 and 1985 respectively. In 1986,
Challenger was
destroyed in an accident after launch.
Endeavour was built as
Challenger's replacement, and was first launched in 1992. In 2003,
Columbia was
destroyed during re-entry, leaving just three remaining Orbiters.
Discovery completed its final flight on March 9, 2011, and
Endeavour completed its final flight on June 1, 2011.
Atlantis completed the last ever Shuttle flight,
STS-135, on July 21, 2011.
In addition to their crews and payloads, the reusable Orbiter carried most of the
Space Shuttle System's
liquid-fueled rocket propulsion system, but both the
liquid hydrogen fuel and the
liquid oxygen oxidizer for its three
main rocket engines were fed from an
external cryogenic propellant tank, and there were also two reusable
large solid-fueled rocket boosters that helped to lift both the Orbiter and its external
propellant tanks during approximately the first two minutes of its ascent into outer space. The orbiters also carried hypergolic fuels for use in their RCS systems and in the Orbital Manoeuvring System.
http://en.wikipedia.org/wiki/Space_Shuttle_orbiter