In 1972, NASA's planners had projected 570 Space Shuttle missions between 1980 and 1991. Later, this estimate was lowered to 487 launches between 1980 and 1992. 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, are: 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 an emergency abort.
Columbia would have launched from Kennedy Space Center, then executed a 180-degree turn at a speed of , or 6.7 times the
speed of sound, in order to land at the Kennedy Space Center runway. The mission was canceled when astronauts refused to fly it, having deemed the plan to be too dangerous. STS-1 commander
John W. Young recalled that "I said no. I said let's not practice
Russian roulette, because you may have a loaded gun there. So we didn't." == Canceled between the first flight of the Space Shuttle (1981) and the
Challenger disaster (1986) ==