CAPE CANAVERAL, Fla. – Inside Orbiter Processing Facility-1 at NASA’s Kennedy Space Center in Florida, technicians prepare to re-install the three fuel cells in space shuttle Discovery’s mid-body. The fuel cells were removed and drained of all fluids. The hydrogen and oxygen dewars which feed reactants to the fuel cells remain in Discovery’s mid-body and have been purged with inert gases and vented down. The work is part of the Space Shuttle Program’s transition and retirement processing of shuttle Discovery. Discovery is being prepared for display at the Smithsonian’s National Air and Space Museum, Steven F. Udvar-Hazy Center in Chantilly, Va. For more information, visit http://www.nasa.gov/shuttle. Photo credit: NASA/Dimitri Gerondidakis KSC-2011-8199

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.