Model of docked Apollo and Soyuz spacecraft in the foreground and skylight in the Vehicle Assembly Building high bay frame.

Model of docked Apollo and Soyuz spacecraft in the foreground and skylight in the Vehicle Assembly Building high bay frame the second stage of the Saturn 1B booster that will launch the United States ASTP mission as a crane raises it prior to its mating with the Saturn 1B first stage. Mating of the Saturn 1B first and second stages was completed this morning. The U. S. ASTP launch with mission commander Thomas Stafford, command module pilot Vance Brand and docking module pilot Donald Slayton is scheduled at 3:50 p.m. EDT July 15.

The first international crewed spaceflight was a joint U.S.-U.S.S.R. rendezvous and docking mission. The Apollo-Soyuz Test Project, or ASTP, took its name from the spacecraft employed: the American Apollo and the Soviet Soyuz. The three-man Apollo crew lifted off from Kennedy Space Center aboard a Saturn IB rocket on July 15, 1975, to link up with the Soyuz that had launched a few hours earlier. A cylindrical docking module served as an airlock between the two spacecraft for transfer of the crew members.
Photo credit: NASA