KENNEDY SPACE CENTER, FLA. -- Viewed from the Shuttle Landing Facility at NASA's Kennedy Space Center, space shuttle Discovery has cleared the clouds over the seaside launch pad and hurtles toward space. Liftoff was on time at 11:38:19 a.m. EDT. Discovery carries the Italian-built U.S. Node 2, called Harmony. During the 14-day STS-120 mission, the crew will install Harmony and move the P6 solar arrays to their permanent position and deploy them. Discovery is expected to complete its mission and return home at 4:47 a.m. EST on Nov. 6. Photo credit: NASA/Chuck Tintera KSC-07pd2956

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.