Apollo–Soyuz Test Project
The Apollo–Soyuz Test Project (ASTP) was the last flight of a Saturn IB. On 15 July 1975, a three-person crew was launched on a six-day mission to dock with a Soviet Soyuz spacecraft. The primary purpose was to provide engineering experience for future joint space flights, but both spacecraft also had scientific experiments. This was the last crewed U.S. space mission until April 1981.