Apollo-Soyuz Test Project Summary

  • Last updated on November 10, 2022

The Apollo-Soyuz Test Project was the first manned spaceflight that was conducted jointly by two nations. The mission was designed to test the capabilities of the U.S. Apollo and the Soviet Soyuz spacecraft to rendezvous and dock in earth orbit. The mission succeeded as both a technical achievement and a test of international cooperation.

Summary of Event

The flight of Apollo-Soyuz marked both the end of a highly competitive era of space exploration and the beginning of international cooperation in space. The mission took place in July, 1975, and joined an American Apollo command module with a Soviet Soyuz spacecraft. Three American astronauts and two Soviet cosmonauts proved to the world that international cooperation was possible, even between two fierce rivals. The two spacecraft remained in orbit as a single vehicle for more than forty-four hours. During that time, the two mission commanders, Thomas P. Stafford and Aleksei A. Leonov, first shook hands as they passed over the town of Metz, France. Later, the crews exchanged flags and other gifts, ate meals together, and, after separation, practiced docking maneuvers. The Soyuz capsule returned to Earth on July 21, and the Apollo capsule landed three days later. The mission was deemed a complete success in spite of the fact that the American crew members needed to be hospitalized for two weeks after breathing noxious fumes during reentry. Apollo-Soyuz Test Project[Apollo Soyuz Test Project] National Aeronautics and Space Administration;Apollo-Soyuz Test Project[Apollo Soyuz Test Project] Soyuz program Astronauts and cosmonauts [kw]Apollo-Soyuz Test Project (July 15-24, 1975) [kw]Soyuz Test Project, Apollo- (July 15-24, 1975) Apollo-Soyuz Test Project[Apollo Soyuz Test Project] National Aeronautics and Space Administration;Apollo-Soyuz Test Project[Apollo Soyuz Test Project] Soyuz program Astronauts and cosmonauts [g]North America;July 15-24, 1975: Apollo-Soyuz Test Project[02000] [g]Soviet Union;July 15-24, 1975: Apollo-Soyuz Test Project[02000] [g]Central Asia;July 15-24, 1975: Apollo-Soyuz Test Project[02000] [g]United States;July 15-24, 1975: Apollo-Soyuz Test Project[02000] [g]Kazakhstan;July 15-24, 1975: Apollo-Soyuz Test Project[02000] [c]Spaceflight and aviation;July 15-24, 1975: Apollo-Soyuz Test Project[02000] [c]Science and technology;July 15-24, 1975: Apollo-Soyuz Test Project[02000] Brand, Vance D. Kubasov, Valeri N. Leonov, Aleksei A. Slayton, Deke Stafford, Thomas P.

The idea for a joint U.S.-Soviet space mission actually came in part from the 1969 film Marooned, in which a stranded Apollo crew is rescued by a Soviet spacecraft. A similar, real-life situation later developed in 1970 during the flight of Apollo 13. That spacecraft suffered an explosion on its way to the Moon, and its astronauts were placed in a life-threatening situation. The Soviets immediately offered their assistance to help the astronauts safely return to Earth. The Apollo 13 emergency clearly demonstrated the need for international cooperation in space. Later that year, American and Soviet delegates met in Moscow to begin discussion for a joint U.S.-Soviet space mission. In early 1971, the preliminary talks evolved into a planning session, and on May 24, 1972, a formal agreement was signed and given the name the Apollo-Soyuz Test Project. A target date of July 15, 1975, was set for launch.

Astronaut Thomas P. Stafford and cosmonaut Aleksei A. Leonov meet in the hatchway connecting the Apollo Docking Module to the Soyuz Orbital Module. Leonov holds the camera.


On February 1, 1973, National Aeronautics and Space Administration (NASA) technical director Glynn Lunney announced that astronauts Thomas P. Stafford, Deke Slayton, and Vance D. Brand would be the primary crew for the Apollo command module, with astronauts Alan L. Bean, Ronald Evans, and Jack R. Lousma as the backup crew. Stafford, the mission commander, was a veteran of three previous flights, with Slayton (one of the original seven Mercury astronauts) and Brand making their first flights. On May 24, 1973, the Soviets announced their crew selections. The mission commander was Aleksei A. Leonov, the first person to walk in space, and Valeri N. Kubasov as Soyuz flight engineer, with cosmonauts Anatoli Filipchenko and Nikolai Rukavishnikov as backup crew. The astronauts and cosmonauts began their extensive training at facilities in the United States and the Soviet Union.

The Apollo-Soyuz Test Project began on July 15, 1975, with the launch of the Soyuz 19 spacecraft from the Baykonur Cosmodrome in Kazakhstan. Approximately seven hours later, the Apollo spacecraft lifted off from Cape Canaveral, Florida. One of the most important technological achievements of the mission was the development of a docking module that would permit the joining of the two distinctly different spacecraft. This module was designed and constructed by NASA engineers and served as an airlock and transfer passageway between the two space vehicles. That link-up occurred on July 17 at 2:17 p.m. U.S. central time. Greetings were exchanged, and messages from U.S. president Gerald R. Ford and Soviet leader Leonid Brezhnev were relayed to the crews. The two spacecraft would remain docked for almost two days while the astronauts and cosmonauts conducted various experiments, sharing meals and moving about between spacecraft.

The two spacecraft undocked on July 19 and conducted a second docking exercise for practice purposes. The final separation occurred at 10:27 a.m. central time, and the Soyuz 19 spacecraft would remain in orbit for another two days before landing in Kazakhstan on July 21. The Apollo spacecraft would remain in orbit for another three days, conducting various experiments. Splashdown occurred near Hawaii on July 24.

Although the Apollo-Soyuz mission was considered a complete success, there was a tense moment during the Apollo landing that threatened the lives of the crew. During preparations for landing, the reaction control system was left open when it should have been closed. This open switch allowed uncombusted thruster propellant to be sucked into the capsule as the inside pressure equalized with the outside pressure. Quick thinking by the astronauts allowed them to put on their oxygen masks, an act that most likely saved their lives. The noxious gas caused Brand to momentarily lose consciousness and Slayton to experience nausea. It was fortunate for the Apollo astronauts that their emergency training paid off. No one was seriously injured, but they were hospitalized for two weeks as a precaution.

For the United States, the Apollo-Soyuz Test Project marked a temporary end to its manned spaceflight program. Apollo had taken the United States to the Moon and contributed four flights to its Skylab program. The Saturn launch vehicle and the Apollo command and service modules were some of the best space vehicles ever flown. The United States chose to continue its manned space program with the space shuttle starting in 1981. Several Apollo astronauts would eventually fly on shuttle missions. The Soviets never made it to the Moon, but its space program continued with its Soyuz flights and later with the Salyut and Mir space stations.


The Apollo-Soyuz Test Project marked a turning point in U.S.-Soviet relations. Prior to the flight, the two superpowers were locked in a political and ideological conflict. Because of the massive buildup of nuclear weapons, neither country held a military advantage, so other means had to be found to influence world politics. Technology became the arena where each country could demonstrate its superiority over the other. On October 4, 1957, the Soviet Union took an early lead with the launch of its Sputnik satellite. From that date onward, the United States placed second to the Soviet Union in almost every aspect of space exploration. In 1961, in an effort to counter the Soviet successes, President John F. Kennedy Kennedy, John F. announced that the United States would land a man on the Moon before the end of that decade. After more than eight years of competitive spaceflights, the United States won the race to the Moon.

The monetary cost of landing a man on the Moon was enormous, and both countries could no longer afford duplicate competitive missions. International cooperation seemed to be the logical answer. Politics aside, this would not be easy since the two countries employed different designs in their spacecraft. Also, the language barrier presented a problem. All this was eventually overcome, and the 1975 flight of Apollo-Soyuz was a complete success. It not only demonstrated to the world that superpowers could peacefully cooperate in space but also opened the door for the development of the International Space Station. Apollo-Soyuz Test Project[Apollo Soyuz Test Project] National Aeronautics and Space Administration;Apollo-Soyuz Test Project[Apollo Soyuz Test Project] Soyuz program Astronauts and cosmonauts

Further Reading
  • citation-type="booksimple"

    xlink:type="simple">Cunningham, Walter. The All-American Boys. New York: Ibooks, 2003. One of the best accounts of the space race. Apollo 7 astronaut Cunningham takes readers behind-the-scenes of Project Apollo and ends his book with frank comments on U.S.-Soviet cooperation.
  • citation-type="booksimple"

    xlink:type="simple">National Aeronautics and Space Administration. Apollo-Soyuz Test Project: First International Manned Space Flight, July 15-24, 1975. Washington, D.C.: National Aeronautics and Space Administration, 1975. Comprehensive technical publication on the project.
  • citation-type="booksimple"

    xlink:type="simple">Scott, David, and Alexei Leonov. Two Sides of the Moon: Our Story of the Cold War Space Race. New York: Dunne Books, 2004. Astronaut Scott and cosmonaut Leonov discuss the motives behind the “race for the Moon” and how each country’s program strived to achieve that goal.
  • citation-type="booksimple"

    xlink:type="simple">Shepard, Alan, and Deke Slayton. Moonshot: The Inside Story of America’s Race to the Moon. New York: Turner Books, 1994. Written by two veteran astronauts, this book offers an insider’s view of the race to the Moon.
  • citation-type="booksimple"

    xlink:type="simple">Stafford, Thomas P. We Have Capture: Tom Stafford and the Space Race. Washington, D.C.: Smithsonian Press, 2002. Stafford shares his personal view of the space race that eventually put an American on the Moon and ended with his participation in the Apollo-Soyuz mission that initiated U.S.-Soviet cooperation in space.

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