CAPE CANAVERAL, Fla. – Ground support equipment technicians monitor the progress as one of the jacking, equalizing and leveling, or JEL, hydraulic cylinders is lifted from crawler-transporter 1 at the crawler transporter maintenance facility at NASA’s Kennedy Space Center in Florida. Sixteen new JEL hydraulic cylinders will be installed on CT-1 to increase load carrying capacity and reliability. The Ground Systems Development and Operations Program at Kennedy continues to upgrade CT-1 as part of its general maintenance. CT-1 could be available to carry commercial launch vehicles to the launch pad. The crawler-transporters were used to carry the mobile launcher platform and space shuttle to Launch Complex 39 for space shuttle launches for 30 years. Photo credit: NASA/Tim Jacobs KSC-2013-3711

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.