Timeline of Space Shuttle Orbiters

Timeline Of Space Shuttle Orbiters

The Space Shuttle Orbiter was the orbital spacecraft of the Space Shuttle program operated by NASA, the space agency of the United States. 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.