STS-90 was a 1998 Space Shuttle mission flown by the Space Shuttle Columbia. The 16-day mission marked the last flight of the European Space Agency's Spacelab laboratory module, which had first flown on Columbia on STS-9, and was also the last daytime landing for Columbia.

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.