The Space Shuttle Columbia is launched on mission STS-55 to conduct experiments aboard the Spacelab module

Space Shuttle Columbia (OV-102) was a Space Shuttle orbiter manufactured by Rockwell International and operated by NASA. Named after the first American ship to circumnavigate the globe, and the female personification of the United States, Columbia was the first of five Space Shuttle orbiters to fly in space, debuting the Space Shuttle launch vehicle on its maiden flight on April 12, 1981 and becoming the first spacecraft to be re-used after its first flight when it launched on STS-2 on November 12, 1981. As only the second full-scale orbiter to be manufactured after the Approach and Landing Test vehicle Enterprise, Columbia retained unique external and internal features compared with later orbiters, such as test instrumentation and distinctive black chines. In addition to a heavier aft fuselage and the retention of an internal airlock throughout its lifetime, these made Columbia the heaviest of the five spacefaring orbiters: around 1,000 kilograms heavier than Challenger and 3,600 kilograms heavier than Endeavour when originally constructed. Columbia also carried ejection seats based on those from the SR-71 during its first six flights until 1983, and from 1986 onwards carried an imaging pod on its vertical stabilizer.