CAPE CANAVERAL, Fla. – In the White Room on Launch Pad 39A at NASA's Kennedy Space Center in Florida, STS-119 Mission Specialist Steve Swanson is helped by the Closeout Crew to put on his harness. The White Room provides access into space shuttle Discovery. Swanson and other crew members will conduct a simulated launch countdown as part of the prelaunch preparation known as Terminal Countdown Demonstration Test. The TCDT also includes equipment familiarization and emergency egress training. Discovery is targeted to launch on the STS-119 mission Feb. 12. During the 14-day mission, the crew will install the S6 truss segment and solar arrays to the starboard side of the International Space Station, completing the station's truss, or backbone. Photo credit: NASA/Jim Grossmann KSC-2009-1270

The Space Shuttle program was the United States government's manned launch vehicle program from 1981 to 2011, administered by NASA and officially beginning in 1972. The Space Shuttle system—composed of an orbiter launched with two reusable solid rocket boosters and a disposable external fuel tank— carried up to eight astronauts and up to 50,000 lb (23,000 kg) of payload into low Earth orbit (LEO). When its mission was complete, the orbiter would re-enter the Earth's atmosphere and lands as a glider. Although the concept had been explored since the late 1960s, the program formally commenced in 1972 and was the focus of NASA's manned operations after the final Apollo and Skylab flights in the mid-1970s. It started with the launch of the first shuttle Columbia on April 12, 1981, on STS-1. and finished with its last mission, STS-135 flown by Atlantis, in July 2011.