CAPE CANAVERAL, Fla. – At NASA's Kennedy Space Center in Florida, workers prepare to store External Tank-135, newly delivered to the transfer aisle of the Vehicle Assembly Building. The tank arrived in Florida on Dec. 26 aboard the Pegasus barge, towed by a solid rocket booster retrieval ship from NASA's Michoud Assembly Facility near New Orleans. ET-135 will be used to launch space shuttle Discovery on the STS-131 mission to the International Space Station. Launch is targeted for March 18. For information on the components of the space shuttle and the STS-131 mission, visit http://www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts131/index.html. Photo credit: NASA/Jack Pfaller KSC-2010-1008

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.