ApolloSoyuz

The Apollo–Soyuz Test Project (ASTP) was a joint spaceflight conducted by the United States and the Soviet Union in July 1975. It was the first crewed international spaceflight and the first docking of U.S. and Soviet spacecraft in orbit, using the Apollo Command/Service Module and a Soviet Soyuz spacecraft.

Mission profile and objectives: ASTP aimed to test rendezvous and docking procedures in low Earth orbit, conduct limited joint operations, and perform coordinated experiments. The Apollo and Soyuz crews conducted a series of shared activities, including a handshake through the docking hatch and the exchange of commemorative items, as well as a post-docking exchange of data and materials. The mission showcased interoperability between the two programs and provided engineering and operational experience for future international collaboration. The docking used the Androgynous Peripheral Attach System (APAS-75) to connect the two spacecraft.

Crew and hardware: The American crew consisted of Thomas P. Stafford (Commander) and Vance D. Brand (Command Module Pilot). The Soviet crew consisted of Alexei Leonov (Commander/Flight Engineer) and Valeri Kubasov (Flight Engineer). The two spacecraft remained docked for a period in orbit before undocking and returning separately to Earth.

Significance and legacy: ASTP demonstrated the practicality of international cooperation in human spaceflight during the Cold War era. It yielded technical lessons on docking, life-support interoperability, and joint mission planning that influenced subsequent collaborations, including Shuttle–Mir and the development of international cooperation on the International Space Station.