KENNEDY SPACE CENTER, FLA. -- During crew equipment interface test activities at KSC, STS-118 Mission Specialist Dr. Dafydd Williams (right) maneuvers the latch on the crew airlock module. The airlock is located in the middeck. The airlock and airlock hatches permit flight crew members to transfer from the middeck crew compartment into the payload bay for extravehicular activities in their space suits without depressurizing the orbiter crew cabin. The airlock is sized to accommodate two fully suited flight crew members simultaneously. The STS-118 mission will be delivering the third starboard truss segment, the ITS S5, to the International Space Station, as well as the SPACEHAB single cargo module filled with supplies and equipment. Launch aboard Space Shuttle Endeavour is targeted for Aug. 9. Photo credit: NASA/Kim Shiflett KSC-07pd1151

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.