ASTP patch

American crew insignia for the Apollo/Soyuz mission

The Apollo–Soyuz Test Project (ASTP) (Template:Lang-ru, Eksperimentalniy polyot Apollon-Soyuz, lit. "Experimental flight Apollo-Soyuz", commonly referred to by the Soviets as "Soyuz-Apollo"), conducted in July 1975, was the first joint U.S.–Soviet space flight, as a symbol of the policy of détente that the two superpowers were pursuing at the time. It involved the docking of an Apollo Command/Service Module with the Soviet Soyuz 19. The unnumbered Apollo vehicle was a surplus from the terminated Apollo program and the last one to fly. This mission ceremoniously marked the end of the Space Race that had begun in 1957 with the Sputnik launch.[1]

ASTP commemorative flag

ASTP commemorative flag autographed by Alexei Leonov

The mission included both joint and separate scientific experiments (including an engineered eclipse of the Sun by Apollo to allow Soyuz to take photographs of the solar corona), and provided useful engineering experience for future joint US–Russian space flights, such as the Shuttle–Mir Program and the International Space Station.

ASTP was U.S. astronaut Donald "Deke" Slayton's only space flight. He was chosen as one of the original Mercury Seven astronauts in April 1959, but had been grounded until 1972 for medical reasons.


  1. Samuels, Richard J., ed (December 21, 2005). Encyclopedia of United States National Security (1st ed.). SAGE Publications. p. 669. Template:Citation/identifier. Retrieved May 25, 2016. "Most observers felt that the U.S. moon landing ended the space race with a decisive American victory. […] The formal end of the space race occurred with the 1975 joint Apollo-Soyuz mission, in which U.S. and Soviet spacecraft docked, or joined, in orbit while their crews visited one another's craft and performed joint scientific experiments."