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Apollo-Soyuz

Across five qualification and operational flights—two uncrewed Soviet tests, the crewed Soyuz 16 rehearsal, Soyuz 19, and Apollo—the Apollo-Soyuz Test Project developed and proved the first compatible international crewed docking system.

Missions: 5
People: 7
Vehicles: 13

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A handshake across the Cold War

Program details1974–1975NASA · Soviet space program · 1972–1975

Flight record5 flights3 crewed · 2 uncrewed

First flown missionCosmos 638April 3, 1974

Latest flown missionSoyuz 19July 15, 1975

Core capabilities

International docking

Proved independently launched spacecraft from two nations could and dock safely.

Joint operations

Coordinated bilingual crews, flight-control teams, timelines, procedures, and communications.

Docking compatibility

Tested the purpose-built docking module and compatible docking hardware in orbit.

Crew exchange

Enabled astronauts and cosmonauts to move between spacecraft and work together in orbit.

Program story

The Apollo-Soyuz Test Project grew from a 1972 space-cooperation agreement between the United States and Soviet Union. Engineers had to reconcile different spacecraft atmospheres, docking systems, languages, measurements, procedures, and mission-control practices.

The Soviet Union qualified its modified Soyuz 7K-TM with the uncrewed Cosmos 638 and Cosmos 672 flights in 1974. Soyuz 16 then flew a six-day crewed dress rehearsal, testing the cabin-pressure changes, compatible communications, NASA tracking support, and APAS-75 docking hardware planned for the joint mission.

Soyuz 19 and Apollo launched separately on July 15, 1975. After two days of orbital maneuvering they docked, and the five crew members opened the hatches, exchanged greetings, conducted demonstrations and experiments, and moved between the two spacecraft.

The mission’s technical value centered on compatible rendezvous and docking, but its larger legacy was operational trust. The experience anticipated later Shuttle-Mir missions and the multinational work that became routine aboard the International Space Station.

Names, numbers, and patches

Official names, common names, and crew call signs

Apollo-Soyuz sources use several overlapping labels. This archive separates individual launches while preserving the names used in NASA histories, Soviet flight records, and later reference works.

FlightOfficial NASA nameCrew and patch name

First uncrewed testOfficial NASA name · Cosmos 638Crew and patch name · Kosmos 638 transliteration

Second uncrewed testOfficial NASA name · Cosmos 672Crew and patch name · Kosmos 672 transliteration

Crewed rehearsalOfficial NASA name · Soyuz 16Crew and patch name · Buran crew call sign

Soviet joint flightOfficial NASA name · SoyuzCrew and patch name · Commonly Soyuz 19

American joint flightOfficial NASA name · Apollo / ASTPCrew and patch name · Apollo 18 was unofficial

NASA historical material notes that the final spacecraft were officially referred to simply as Soyuz and Apollo. Soyuz 19 became the standard identifying name for the Soviet flight, while Apollo 18 is a later unofficial label and is retained only as an alias. Cosmos and Kosmos are alternative English transliterations of the same Russian program name.

NASA Apollo-Soyuz mission and spacecraft history →