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 to 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.

STS-55, or Deutschland 2 (D-2), was the 55th overall flight of the NASA Space Shuttle and the 14th flight of Shuttle Columbia. This flight was a multinational Spacelab flight involving 88 experiments from eleven different nations. The experiments ranged from biology sciences to simple Earth observations.

Spacelab was a reusable laboratory developed by European Space Agency (ESA) and used on certain spaceflights flown by the Space Shuttle. The laboratory comprised multiple components, including a pressurized module, an unpressurized carrier, and other related hardware housed in the Shuttle's cargo bay. The components were arranged in various configurations to meet the needs of each spaceflight.

April 26 is the 116th day of the year in the Gregorian calendar; 249 days remain until the end of the year.