CAPE CANAVERAL, Fla. - The STS-125 crew heads for the Astrovan after suiting up in the Operations and Checkout Building at NASA's Kennedy Space Center in Florida. From left are Mission Specialists Michael Good, John Grunsfeld, Mike Massimino, Andrew Feustel and Megan McArthur, Pilot Gregory C. Johnson and Commander Scott Altman. The crew is heading for Launch Pad 39A where they will take part in a simulated launch countdown aboard space shuttle Atlantis. The countdown is the culmination of terminal countdown demonstration test, or TCDT, activities as preparation before launch. TCDT provides astronauts and ground crews with an opportunity to participate in various simulated countdown activities, including equipment familiarization, emergency training and the countdown. Atlantis’ STS-125 mission to service NASA’s Hubble Space Telescope is targeted for launch Oct. 14. Photo credit: NASA/Kim Shiflett KSC-08pd2884

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.

Space Shuttle Atlantis was a space shuttle that was operated by NASA as part of the Space Shuttle program. It was the fourth operational shuttle built, and the last one to be built before the program was retired in 2011. Atlantis was named after the first research vessel operated by the Woods Hole Oceanographic Institution, and it made its first flight in October 1985. Over the course of its career, Atlantis completed 33 missions and spent a total of 307 days in space. Its last mission was STS-135, which was the final mission of the Space Shuttle program. Atlantis is now on display at the Kennedy Space Center Visitor Complex in Florida. Space Shuttle Atlantis (Orbiter Vehicle Designation: OV-104) was one of the four first operational orbiters in the Space Shuttle fleet of NASA, the space agency of the United States. (The other two are Discovery and Endeavour.) Atlantis was the fourth operational shuttle built. Atlantis is named after a two-masted sailing ship that operated from 1930 to 1966 for the Woods Hole Oceanographic Institute. Atlantis performed well in 25 years of service, flying 33 missions.