KENNEDY SPACE CENTER, FLA. -- During a crew equipment interface test in the Orbiter Processing Facility bay 3 at NASA's Kennedy Space Center, STS-124 Commander Mark Kelly closely examines a window in the cockpit of space shuttle Discovery. The shuttle will transport the Kibo Japanese Experiment Module - Pressurized Module (JEM-PM) and the Japanese Remote Manipulator System (JEM-RMS) to the International Space Station to complete the Kibo laboratory. The launch of Discovery is targeted for April 24. Photo credit: NASA/Kim Shiflett KSC-08pd0312

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.