Many were canceled as a result of the Challenger and the Columbia disasters or due to delays in the development of the shuttle.
[2] The details of the first 23 projected missions, listed in the third edition of Manned Spaceflight (Reginald Turnill, 1978) and the first edition of the STS Flight Assignment Baseline, an internal NASA document published in October 1977,[3] are presented below.
Later in the development process, NASA suggested using the first crewed Space Shuttle mission, STS-1, as a sub-orbital test of the Return to Launch Site (RTLS) flight profile devised for emergency abort scenarios.
[11] Columbia would have launched from Kennedy Space Center, then executed a 180-degree turn at a speed of 8,400 kilometres per hour (5,200 mph), or 6.7 times the speed of sound, in order to land at the Kennedy Space Center runway.
Lampton was originally assigned to STS-45, but was replaced by his back-up Dirk Frimout owing to medical issues.