Space Shuttle orbiter

The Space Shuttle orbiter was the spaceplane component of the Space Shuttle, a partially reusableorbitalspacecraft system that was part of the discontinued Space Shuttle program. Operated from 1981 to 2011 by NASA, the U.S. space agency, this vehicle could carry astronauts and payloads into low Earth orbit, perform in-space operations, then re-enter the atmosphere and land as a glider, returning its crew and any on-board payload to the Earth.

Six orbiters were built for flight: Enterprise, Columbia, Challenger, Discovery, Atlantis, and Endeavour. All were built in Palmdale, California, by the Pittsburgh, Pennsylvania-based Rockwell International company's North American Aircraft Operations branch. The first orbiter, Enterprise, made its maiden flight in 1977. An unpowered glider, it was carried by a modified Boeing 747 airliner called the Shuttle Carrier Aircraft and released for a series of atmospheric test flights and landings. Enterprise was partially disassembled and retired after completion of critical testing. The remaining orbiters were fully operational spacecraft, and were launched vertically as part of the Space Shuttle stack.

Columbia was the first space-worthy orbiter; it made its inaugural flight in 1981. Challenger, Discovery, and Atlantis followed in 1983, 1984, and 1985, respectively. In 1986, Challenger was destroyed in a disaster shortly after its 10th launch, killing all seven crew members. Endeavour was built as Challenger's successor, 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 final Shuttle flight, STS-135, on July 21, 2011.

In addition to their crews and payloads, the reusable orbiter carried most of the Space Shuttle's liquid-propellant rocket system, but both the liquid hydrogenfuel and the liquid oxygenoxidizer for its three main rocket engines were fed from an external cryogenic propellant tank. Two reusable solid rocket boosters (SRBs) provided additional thrust for approximately the first two minutes of launch. The orbiters themselves also carried hypergolic propellant for the onboard Reaction Control System (RCS) thrusters and Orbital Maneuvering System (OMS) engines.