KENNEDY SPACE CENTER, FLA. - In NASA Kennedy Space Center's Vehicle Assembly Building, a crane has been attached to the newly delivered external tank, which is resting on a transporter in the transfer aisle. Designated ET-119, the 154-foot tank will be raised to vertical and lifted into a checkout cell for further work. The tank, which will launch space shuttle Discovery on mission STS-121, will fly with many major safety changes, including the removal of the protuberance air load ramps. A large piece of foam from a ramp came off during the last shuttle launch in July 2005. The ramps were removed to eliminate a potential source of damaging debris to the space shuttle. The next launch of Discovery is scheduled for May 2006. Photo credit: NASA/Jim Grossmann KSC-06pd0418a

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.