The program began with the various designs and estimates that were
given to Nixon and his Budget Office, and in 1972, they gave a go ahead
for a specific development plan. After the system was developed, the
first prototype, Enterprise was used in drop tests that validated the
last portion of the return to Earth phase. As well, Enterprise was used
for pad fit tests before an operational shuttle was available.
Columbia flew the first Shuttle orbital flight April 12-14 1981.
Challenger was destroyed on Jan 28, 1986.
The Gemini program ended on Nov 15, 1966, with the landing of the last
Gemini mission, Gemini 12, so the Gemini program was long before the
Shuttle, and had nothing to do with the Shuttle program. Apollo came
after Gemini and before the Shuttle.
