* April 12-14, 1981. Columbia completed 36 orbits in a successful 54-hour mission.
* Nov. 12-14, 1981. Completed 36 orbits after fuel-cell problems reduced the planned 124-hour mission to 54 hours.
* March 22-30, 1982. The shuttle stretched a seven-day trip into eight days due to poor landing conditions. The extended flight demonstrated the program's flexibility.
* June 27-July 4, 1982. The mission ended the STS test phase, despite loss of the rocket boosters, which sank before recovery.
* Nov. 11-16, 1982. The first operational STS flight included mission specialists. The major objective of the flight was the launching of two commercial satellites. Pressure-suit problems scrubbed a planned spacewalk.