CAPE CANAVERAL, Fla. -- In Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida, technicians prepare to move an aft access platform into place behind shuttle Atlantis, following the installation of the spacecraft's three main engines. Shown is the right-hand orbital maneuvering system (OMS) pod and engine taken from the right-hand access arm. Atlantis is being prepared for the "launch on need," or potential rescue mission, for the final planned shuttle flight, Endeavour's STS-134 mission. For more information, visit www.nasa.gov/shuttle. Photo credit: NASA/Kim Shiflett KSC-2010-5830

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.