![1370793.TIF American astronaut Deke Slayton and Russian cosmonaut Alexei Leonov during the US-Soviet Apollo-Soyuz linkup.](https://api.time.com/wp-content/uploads/2015/07/apollo-soyuz-anniversary-0006.jpg?quality=85&w=2400)
![This artist's concept illustrates the Apollo-type spacecraft about to dock with a Soviet Soyuz-type spacecraft (right).](https://api.time.com/wp-content/uploads/2015/07/apollo-soyuz-test-program-artist-rendering.jpg?quality=75&w=2400)
![President Richard Nixon and Soviet Premier Alexei Kosygin sign an agreement in May of 1972 that paved the way for the Apollo–Soyuz mission.](https://api.time.com/wp-content/uploads/2015/07/nixon_kosygin_may_1972.jpg?quality=75&w=2400)
![The U.S.-USSR crew for the 1975 Apollo Soyuz Test Project mission: astronaut Tom Stafford (standing on left), commander of the American crew; cosmonaut Alexei Leonov (standing on right), commander of the Soviet crew; astronaut Donald Slayton (seated on left), docking module pilot of the American crew; astronaut Vance Brand (seated in center), command module pilot of the American crew; and cosmonaut Valeriy Kubasov (seated on right), engineer on the Soviet crew.](https://api.time.com/wp-content/uploads/2015/07/apollo-soyuz-anniversary-0001.jpg?quality=75&w=2400)
![The Soviet Soyuz launch vehicle leaves from the Baikonur Cosmodrome in Kazakhstan.](https://api.time.com/wp-content/uploads/2015/07/soyuz_astp_rocket_launch.jpg?quality=75&w=2400)
![launch of apollo-soyuz test project (MIX FILE) The Saturn IB launch vehicle lifts the American crew into orbit on July 15, 1975.](https://api.time.com/wp-content/uploads/2015/07/apollo-soyuz_test_project_saturn_ib_launch.jpg?quality=75&w=2400)
![Activity inside Mission Control in Houston during the Apollo Soyuz Test Project docking mission.](https://api.time.com/wp-content/uploads/2015/07/apollo_soyuz_test_project_mission_control.jpg?quality=75&w=2400)
![1370817.jpg American astronauts Tom Stafford and Deke Slayton hold tubes of vodka given to them by Russian cosmonauts during their historic rendezvous and linkup of Apollo and Soyuz spacecraft.](https://api.time.com/wp-content/uploads/2015/07/apollo-soyuz-anniversary-0003.jpg?quality=75&w=2400)
![The American Apollo spacecraft as seen in Earth orbit from the Soviet Soyuz 19 spacecraft during the joint U.S.-USSR Apollo Soyuz Test Project (ASTP) mission.](https://api.time.com/wp-content/uploads/2015/07/apollo-soyuz_imagery.jpg?quality=75&w=2400)
![1370805.TIF The Soviet Soyuz spacecraft approaches the Apollo for linkup in space, the first rendezvous and docking of vessels from different nations.](https://api.time.com/wp-content/uploads/2015/07/apollo-soyuz-anniversary-0005.jpg?quality=75&w=2400)
![Astronaut Tom Stafford (in foreground) and cosmonaut Alexei Leonov make their historic handshake in space on July 17, 1975.](https://api.time.com/wp-content/uploads/2015/07/astp_handshake_-_cropped.jpg?quality=75&w=2400)
![President Gerald R. Ford watches crewmen Tom Stafford, Donald Slayton and Valeriy Kubasov on a television as he talks to them by phone while they orbited the Earth on July 18, 1975. The American Apollo spacecraft and Soviet Soyuz spacecraft were docked.](https://api.time.com/wp-content/uploads/2015/07/president_ford_talks_to_astp_crew.jpg?quality=75&w=2400)
![1370793.TIF American astronaut Deke Slayton and Russian cosmonaut Alexei Leonov during the US-Soviet Apollo-Soyuz linkup.](https://api.time.com/wp-content/uploads/2015/07/apollo-soyuz-anniversary-0006.jpg?quality=75&w=2400)
More Must-Reads from TIME
- Biden Drops Out of Presidential Race , Endorses Harris to Replace Him
- Why Biden Dropped Out
- The Chaos and Commotion of the RNC in Photos
- Why We All Have a Stake in Twisters’ Success
- 8 Eating Habits That Actually Improve Your Sleep
- Stop Feeling Bad About Sweating
- Welcome to the Noah Lyles Olympics
- Get Our Paris Olympics Newsletter in Your Inbox
Write to Jonathan D. Woods at jonathan.woods@time.com