Apollo-Soyuz Test Project (ASTP). Launch of the Soyuz 19 spacecraft from Baikonur Cosmodrome on 15 July 1975 at the start of the joint Soviet/US ASTP mission. Soyuz 19 and the American spacecraft Apollo 18 successfully docked in orbit on 17 July. The programme was intended to test a jointly- designed international docking mechanism. On board Soyuz 19 were cosmonaunts Aleksey A. Leonov & Valerii N. Kubasov. The US crew consisted of Thomas P. Stafford, Vance D. Brand & Donald K. Slayton.