STS-93 in 1999 marked the 95th launch of the Space Shuttle, the 26th launch of Columbia, and the 21st night launch of a Space Shuttle. Eileen Collins became the first female shuttle Commander on this flight. Its primary payload was the Chandra X-ray Observatory.

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 upper North American Pacific coast 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. As only the second full-scale orbiter to be manufactured after the Approach and Landing Test vehicle Enterprise, Columbia retained unique features indicative of its experimental design compared to later orbiters, such as test instrumentation and distinctive black chines. In addition to a heavier 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. 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.