KENNEDY SPACE CENTER, FLA. - In high bay 3 of the Vehicle Assembly Building, Atlantis' external tank and solid rocket boosters are ready on the mobile launcher platform for mating with the orbiter Atlantis, being lowered by a crane. After the stacking, Atlantis will undergo a shuttle interface test and other prelaunch processing. Atlantis' launch window begins Aug. 28. During its 11-day mission to the International Space Station, the STS-115 crew of six astronauts will continue construction of the station and install their cargo, the Port 3/4 truss segment with its two large solar arrays. Photo credit: NASA/Troy Cryder KSC-06pd1664

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.