KENNEDY SPACE CENTER, FLA. -- At NASA's Kennedy Space Center, the STS-120 crew don their launch and entry suits before heading to Launch Pad 39A for launch aboard space shuttle Discovery to the International Space Station. Seen here is Commander Pamela Melroy, who is making her third shuttle flight. She is only the second woman to command a shuttle mission. Discovery is scheduled for liftoff at 11:38 a.m. EDT. The mission will be the 23rd assembly flight to the space station and the 34th flight for Discovery. Payload on the mission is the Italian-built U.S. Node 2, called Harmony. During the 14-day 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/Kim Shiflett KSC-07pd2936

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.