Apollo–Soyuz was the first crewed international
space mission, carried out jointly by the United States and the
Soviet Union
The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, ...
in July 1975. Millions of people around the world watched on television as a United States
Apollo
Apollo, grc, Ἀπόλλωνος, Apóllōnos, label=genitive , ; , grc-dor, Ἀπέλλων, Apéllōn, ; grc, Ἀπείλων, Apeílōn, label=Arcadocypriot Greek, ; grc-aeo, Ἄπλουν, Áploun, la, Apollō, la, Apollinis, label= ...
spacecraft
docked with a Soviet
Soyuz capsule. The project, and its handshake in space, was a symbol of
détente
Détente (, French: "relaxation") is the relaxation of strained relations, especially political ones, through verbal communication. The term, in diplomacy, originates from around 1912, when France and Germany tried unsuccessfully to reduce ...
between the two superpowers during the
Cold War.
The mission was officially known as the Apollo–Soyuz Test Project (ASTP; russian: Экспериментальный полёт «Союз» – «Аполлон» (ЭПАС), translit=Eksperimentalniy polyot Soyuz–Apollon (EPAS), lit=Experimental flight Soyuz-Apollo, and commonly referred to in the
Soviet Union
The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, ...
as Soyuz–Apollo; the Soviets officially designated the mission as Soyuz 19). The unnumbered American vehicle was left over from the
canceled Apollo missions
Several planned missions of the Apollo crewed Moon landing program of the 1960s and 1970s were canceled for a variety of reasons, including changes in technical direction, the Apollo 1 fire, hardware delays, and budget limitations. After the la ...
, and was the last Apollo module to fly.
The three American astronauts,
Thomas P. Stafford
Thomas Patten Stafford (born September 17, 1930) is an American former Air Force officer, test pilot, and NASA astronaut, and one of 24 people who flew to the Moon. He also served as Chief of the Astronaut Office from 1969 to 1971.
After grad ...
,
Vance D. Brand
Vance DeVoe Brand (born May 9, 1931) is an American naval officer, aviator, aeronautical engineer, test pilot, and NASA astronaut. He served as command module pilot during the first U.S.-Soviet joint spaceflight in 1975, and as commander of t ...
, and
Deke Slayton
Donald Kent "Deke" Slayton (March 1, 1924 – June 13, 1993) was a United States Air Force pilot, aeronautical engineer, and test pilot who was selected as one of the original NASA Mercury Seven astronauts. He went on to become NASA's fir ...
, and two Soviet cosmonauts,
Alexei Leonov and
Valeri Kubasov, performed both joint and separate scientific experiments, including an arranged
eclipse of the Sun by the Apollo module to allow instruments on the Soyuz to take photographs of the
solar corona. The pre-flight work provided useful engineering experience for later joint American–Russian space flights, such as the
Shuttle–''Mir'' program and the
International Space Station
The International Space Station (ISS) is the largest Modular design, modular space station currently in low Earth orbit. It is a multinational collaborative project involving five participating space agencies: NASA (United States), Roscosmos ( ...
.
Apollo–Soyuz was the last crewed United States spaceflight for nearly six years until
the first launch of the
Space Shuttle
The Space Shuttle is a retired, partially reusable low Earth orbital spacecraft system operated from 1981 to 2011 by the U.S. National Aeronautics and Space Administration (NASA) as part of the Space Shuttle program. Its official program na ...
on 12 April 1981, and the last crewed United States spaceflight in a
space capsule
A space capsule is an often-crewed spacecraft that uses a blunt-body reentry capsule to reenter the Earth's atmosphere without wings. Capsules are distinguished from other satellites primarily by the ability to survive reentry and return a paylo ...
until
Crew Dragon Demo-2
Crew Dragon Demo-2 (officially Crew Demo-2, SpaceX Demo-2, or Demonstration Mission-2) was the first crewed test flight of the Crew Dragon spacecraft. The spacecraft, named ''Endeavour'', launched on 30 May 2020 on a Falcon 9 booster, and car ...
on 30 May 2020.
Historical background
The purpose and catalyst of Apollo–Soyuz was the policy of
détente
Détente (, French: "relaxation") is the relaxation of strained relations, especially political ones, through verbal communication. The term, in diplomacy, originates from around 1912, when France and Germany tried unsuccessfully to reduce ...
between the two
Cold War superpowers: the United States and the Soviet Union. Tensions ran high between the two world superpowers while the United States was engaged in the
Vietnam War
The Vietnam War (also known by #Names, other names) was a conflict in Vietnam, Laos, and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. It was the second of the Indochina Wars and was officially fought between North Vie ...
. Meanwhile, the Soviet press was highly critical of the Apollo space missions, printing "the armed intrusion of the United States and
Saigon
, population_density_km2 = 4,292
, population_density_metro_km2 = 697.2
, population_demonym = Saigonese
, blank_name = GRP (Nominal)
, blank_info = 2019
, blank1_name = – Total
, blank1_ ...
puppets into
Laos is a shameless trampling underfoot of international law" over a photograph of the
Apollo 14
Apollo 14 (January 31, 1971February 9, 1971) was the eighth crewed mission in the United States Apollo program, the third to land on the Moon, and the first to land in the lunar highlands. It was the last of the " H missions", landings at s ...
launch in 1971.
[Committee on Aeronautical and Space Sciences, Soviet Space Programs, 1971–75. Washington: U.S. Govt. Print. Off., 1976. ] Although Soviet leader
Nikita Khrushchev
Nikita Sergeyevich Khrushchev (– 11 September 1971) was the First Secretary of the Communist Party of the Soviet Union from 1953 to 1964 and chairman of the country's Council of Ministers from 1958 to 1964. During his rule, Khrushchev ...
made the Soviet Union's policy of détente official in his 1956 doctrine of peaceful coexistence at the
20th Congress of the Communist Party of the Soviet Union, the two nations seemed to be in perpetual conflict.
After
John Glenn's 1962
orbital flight, an exchange of letters between President
John F. Kennedy and Soviet Premier
Nikita Khrushchev
Nikita Sergeyevich Khrushchev (– 11 September 1971) was the First Secretary of the Communist Party of the Soviet Union from 1953 to 1964 and chairman of the country's Council of Ministers from 1958 to 1964. During his rule, Khrushchev ...
led to a series of discussions led by NASA Deputy Administrator
Hugh Dryden and Soviet scientist
Anatoly Blagonravov
Anatoly Arkadevich Blagonravov (russian: Анатолий Аркадьевич Благонравов; – 4 February 1975) was a Soviet engineer and diplomat. He represented the Soviet Union on the United Nations Committee on the Peaceful Uses ...
. Their 1962 talks led to the
Dryden-Blagonravov agreement, which was formalized in October of that year, the same time the two countries were in the midst of the
Cuban Missile Crisis
The Cuban Missile Crisis, also known as the October Crisis (of 1962) ( es, Crisis de Octubre) in Cuba, the Caribbean Crisis () in Russia, or the Missile Scare, was a 35-day (16 October – 20 November 1962) confrontation between the Unite ...
. The agreement was formally announced at the United Nations on 5 December 1962. It called for cooperation on the exchange of data from weather satellites, a study of the
Earth's magnetic field
Earth's magnetic field, also known as the geomagnetic field, is the magnetic field that extends from Earth's interior out into space, where it interacts with the solar wind, a stream of charged particles emanating from the Sun. The magneti ...
, and joint tracking of the NASA
Echo II balloon satellite. Kennedy could even interest Khrushchev in a joint crewed
Moon landing
A Moon landing is the arrival of a spacecraft on the surface of the Moon. This includes both crewed and robotic missions. The first human-made object to touch the Moon was the Soviet Union's Luna 2, on 13 September 1959.
The United S ...
.
The assassination of Kennedy on 22 November 1963,
and the removal from office of Khrushchev on 14 October 1964, made any personal preferences of the respective leaders moot. Unfortunately, as the competition between the two nation's crewed space programs heated up, efforts to further cooperation at that point came to an end.
Due to tense relations and military implications, space cooperation between the United States and the Soviet Union was unlikely in the early 1970s. On 7 June 1971, the USSR had launched the first piloted orbital space station,
Salyut 1
Salyut 1 (DOS-1) (russian: Салют-1) was the world's first space station launched into low Earth orbit by the Soviet Union on April 19, 1971. The Salyut program followed this with five more successful launches of seven more stations. The f ...
. Meanwhile, the United States had launched the
Apollo 14
Apollo 14 (January 31, 1971February 9, 1971) was the eighth crewed mission in the United States Apollo program, the third to land on the Moon, and the first to land in the lunar highlands. It was the last of the " H missions", landings at s ...
mission several months prior, the third space mission to land humans on the Moon. Each side gave the other little coverage of their achievements.
Both sides had severe criticisms of the other side's engineering. Soviet spacecraft were designed with automation in mind; the
Lunokhod 1 and
Luna 16
''Luna 16'' was an uncrewed space mission, part of the Soviet Luna program. It was the first robotic probe to land on the Moon and return a sample of lunar soil to Earth. The 101 grams (3.56 ounces) sample was returned from Mare Fecunditati ...
were both uncrewed probes, and each
Soyuz spacecraft had been designed to minimize risk due to human error by having fewer manual controls with which human operators would have to contend during flight. By contrast, the Apollo spacecraft was designed to be operated by humans and required highly trained astronauts in order to operate. The Soviet Union criticized the Apollo spacecraft as being "extremely complex and dangerous".
The Americans also had their own concerns about Soviet spacecraft.
Christopher C. Kraft, director of the
Johnson Space Center
The Lyndon B. Johnson Space Center (JSC) is NASA's center for human spaceflight (originally named the Manned Spacecraft Center), where human spaceflight training, research, and flight control are conducted. It was renamed in honor of the late ...
, criticized the design of the Soyuz:
"We in NASA
The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research.
NASA was established in 1958, succeedi ...
rely on redundant components — if an instrument fails during flight, our crews switch to another in an attempt to continue the mission. Each Soyuz component, however, is designed for a specific function; if one fails, the cosmonauts land as soon as possible. The Apollo vehicle also relied on astronaut piloting to a much greater extent than did the Soyuz machine."[ ]
The American astronauts had a very low opinion for the Soyuz space craft as it was a craft that was designed to be controlled from the ground. This was in stark contrast with the Apollo module that was meant to be flown from the capsule. Eventually Glynn Lunney, the Manager of the Apollo–Soyuz Test Program, warned them about talking to the press about their dissatisfaction as they had offended the Soviets.
NASA was worried that any slight would cause the Soviets to pull out and the mission to be scrapped.
American and Soviet engineers settled their differences for a possible docking of American and Soviet spacecraft in meetings between June and December 1971 in
Houston
Houston (; ) is the List of cities in Texas by population, most populous city in Texas, the Southern United States#Major cities, most populous city in the Southern United States, the List of United States cities by population, fourth-most pop ...
and
Moscow
Moscow ( , US chiefly ; rus, links=no, Москва, r=Moskva, p=mɐskˈva, a=Москва.ogg) is the capital and largest city of Russia. The city stands on the Moskva River in Central Russia, with a population estimated at 13.0 million ...
, including Bill Creasy's design of the
Androgynous Peripheral Attach System (APAS) between the two ships that would allow either to be active or passive during docking.
[Debbora Battaglia, "Arresting Hospitality: the Case of the 'Handshake in Space'," Journal of the Royal Anthropological Institute vol. 18 issue 1 June 2012. pp. S76-S89]
With the close of the
Vietnam War
The Vietnam War (also known by #Names, other names) was a conflict in Vietnam, Laos, and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. It was the second of the Indochina Wars and was officially fought between North Vie ...
, relations between the United States and the USSR began to improve, as did the prognosis for a potential cooperative space mission.
Apollo–Soyuz was made possible by the thaw in these relations, and the project itself endeavoured to amplify and solidify the improving relations between the United States and the Soviet Union. According to Soviet leader
Leonid Brezhnev
Leonid Ilyich Brezhnev; uk, links= no, Леонід Ілліч Брежнєв, . (19 December 1906– 10 November 1982) was a Soviet politician who served as General Secretary of the Communist Party of the Soviet Union between 1964 and ...
, "The Soviet and American spacemen will go up into outer space for the first major joint scientific experiment in the history of mankind. They know that from outer space our planet looks even more beautiful. It is big enough for us to live peacefully on it, but it is too small to be threatened by nuclear war".
Thus, both sides recognized ASTP as a political act of peace.
In October 1970,
Soviet Academy of Sciences president
Mstislav Keldysh responded to
NASA Administrator
The Administrator of the National Aeronautics and Space Administration is the highest-ranking official of NASA, the national space agency of the United States. The administrator is NASA's chief decision maker, responsible for providing clarity to ...
Thomas O. Paine's letter proposing a cooperative space mission, and there was subsequently a meeting to discuss technical details. At a meeting in January 1971, U.S. President
Richard Nixon
Richard Milhous Nixon (January 9, 1913April 22, 1994) was the 37th president of the United States, serving from 1969 to 1974. A member of the Republican Party, he previously served as a representative and senator from California and was t ...
's Foreign Policy Adviser
Henry Kissinger
Henry Alfred Kissinger (; ; born Heinz Alfred Kissinger, May 27, 1923) is a German-born American politician, diplomat, and geopolitical consultant who served as United States Secretary of State and National Security Advisor under the preside ...
enthusiastically espoused plans for the mission, and expressed these views to NASA administrator
George Low: "As long as you stick to space, do anything you want to do. You are free to commit—in fact, I want you to tell your counterparts in Moscow that the President has sent you on this mission". By April 1972, both the United States and the USSR signed an
Agreement Concerning Cooperation in the Exploration and Use of Outer Space for Peaceful Purposes,
[Jennifer Ross-Nazzal,"Détente on Earth and in Space: The Apollo–Soyuz Test Project", ''Organization of American Historians Magazine of History'', September 2010, Volume 24, Issue 3, pp. 29–34.] committing both the USSR and the United States to the launch of the Apollo–Soyuz Test Project in 1975.
ASTP was particularly significant for the USSR's policy of keeping the details of their space program secret from the Soviet people and the world at large, especially Americans. The ASTP was the first Soviet space mission to be televised in a live fashion during the launch, while in space, and during the landing.
Soyuz 19 was also the first Soviet spacecraft to which a foreign flight crew had access before flight; the Apollo crew were permitted to inspect it and the launch and crew training site, which was an unprecedented sharing of information with Americans about any Soviet space program.
Not all reactions to ASTP were positive. Many Americans feared
that ASTP was giving the USSR too much credit in their space program, putting them on equal footing with the sophisticated space exploration efforts of NASA. More feared that the apparent peaceful cooperation between the USSR and the United States would lull people into believing there was no conflict at all between the two superpowers.
Some Soviet publicists called American critics of the mission "demagogues who stand against scientific cooperation with the
USSR
The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen nation ...
".
In general, tensions between the United States and the USSR had softened, and the project set a precedent for future cooperative projects in space.
Apollo crew
Backup crew
Crew notes
It was American astronaut
Deke Slayton
Donald Kent "Deke" Slayton (March 1, 1924 – June 13, 1993) was a United States Air Force pilot, aeronautical engineer, and test pilot who was selected as one of the original NASA Mercury Seven astronauts. He went on to become NASA's fir ...
's only space flight. He was chosen as one of the original
Mercury Seven
The Mercury Seven were the group of seven astronauts selected to fly spacecraft for Project Mercury. They are also referred to as the Original Seven and Astronaut Group 1. Their names were publicly announced by NASA on April 9, 1959; these seve ...
astronauts in April 1959, but had been grounded until 1972 for medical reasons.
Jack Swigert had originally been assigned as the command module pilot for the ASTP prime crew, but he was removed before the official announcement as punishment for his involvement in the
Apollo 15 postal covers incident.
;Support crew
:
Karol J. Bobko
Karol Joseph "Bo" Bobko (born December 23, 1937), ( Col, USAF, Ret.), is an American aerospace engineer, retired U.S. Air Force officer, test pilot, and a former USAF and NASA astronaut. Bobko was the first graduate of the US Air Force Academy ...
,
Robert Crippen,
Robert F. Overmyer,
Richard H. Truly
;Flight directors
:Pete Frank (Orange team), Neil Hutchinson (Silver team),
Don Puddy
Donald Ray Puddy (May 31, 1937November 22, 2004) was a NASA engineer and manager. He joined NASA in 1964, eventually becoming the agency's tenth flight director. His Flight Team colors were Crimson. He served as a flight director during the Apollo ...
(Crimson team), Frank Littleton (Amber team)
Soyuz crew

It was the last space mission for Soviet cosmonaut
Alexei Leonov, who had become the first person to
walk in space during the March 1965
Voskhod 2 mission.
Backup crew
Mission summary
Background

The ASTP entailed the docking of an American
Apollo command and service module
The Apollo command and service module (CSM) was one of two principal components of the United States Apollo (spacecraft), Apollo spacecraft, used for the Apollo program, which landed astronauts on the Moon between 1969 and 1972. The CSM functio ...
(CSM) with a Soviet
Soyuz 7K-TM
The 1975 Apollo–Soyuz Test Project version of the Soyuz spacecraft (Soyuz 7K-TM) served as a technological bridge to the third generation Soyuz-T (T - транспортный, ''Transportnyi'' meaning transport) spacecraft (1976–1986).
...
spacecraft. Although the Soyuz was given a mission designation number (Soyuz 19) as part of the ongoing
Soyuz programme
The Soyuz programme ( , ; russian: link=no, Союз , meaning "Union") is a human spaceflight programme initiated by the Soviet Union in the early 1960s. The Soyuz spacecraft was originally part of a Moon landing project intended to put a So ...
, its radio call sign was simply "Soyuz" for the duration of the joint mission. The Apollo mission was not a numbered mission of the
Apollo program, and similarly bore the call sign "Apollo". Despite this, the press and NASA have referred to the mission as "Apollo 18", but this should not be confused with the
canceled lunar mission.
The Apollo spacecraft was launched with a docking module specially designed to enable the two spacecraft to dock with each other, used only once for this mission. The
Saturn IB
The Saturn IB (also known as the uprated Saturn I) was an American launch vehicle commissioned by the National Aeronautics and Space Administration (NASA) for the Apollo program. It uprated the Saturn I by replacing the S-IV second stage (, 43, ...
launch vehicle and
CSM were surplus material. Like the
Apollo Lunar Module
The Apollo Lunar Module (LM ), originally designated the Lunar Excursion Module (LEM), was the lunar lander spacecraft that was flown between lunar orbit and the Moon's surface during the United States' Apollo program. It was the first crewed s ...
, the docking module
had to be retrieved from the
S-IVB
The S-IVB (pronounced "S-four-B") was the third stage on the Saturn V and second stage on the Saturn IB launch vehicles. Built by the Douglas Aircraft Company, it had one J-2 rocket engine. For lunar missions it was fired twice: first for Earth ...
upper-stage of the
Saturn IB
The Saturn IB (also known as the uprated Saturn I) was an American launch vehicle commissioned by the National Aeronautics and Space Administration (NASA) for the Apollo program. It uprated the Saturn I by replacing the S-IV second stage (, 43, ...
rocket after launch. The docking module was designed as both an airlock — as the Apollo was pressurized at about using
pure oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...
, while the Soyuz used a
nitrogen
Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at seve ...
/
oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as we ...
atmosphere at
sea level pressure (about ) — and an adapter, since the surplus Apollo hardware used for the ASTP mission was not equipped with the
APAS
The terms Androgynous Peripheral Attach System (APAS), Androgynous Peripheral Assembly System (APAS) and Androgynous Peripheral Docking System (APDS), are used interchangeably to describe a family of spacecraft docking mechanisms, and are also som ...
docking collar jointly developed by
NASA
The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research.
NASA was established in 1958, succeedi ...
and the
Academy of Sciences of the Soviet Union
The Academy of Sciences of the Soviet Union was the highest scientific institution of the Soviet Union from 1925 to 1991, uniting the country's leading scientists, subordinated directly to the Council of Ministers of the Soviet Union (until 1946 ...
for the mission. One end of the docking module was attached to the Apollo using the same "probe-and-
drogue" docking mechanism used on the Lunar Module and the
Skylab
Skylab was the first United States space station, launched by NASA, occupied for about 24 weeks between May 1973 and February 1974. It was operated by three separate three-astronaut crews: Skylab 2, Skylab 3, and Skylab 4. Major operation ...
space station, while its other end had the APAS docking collar, which Soyuz 19 carried in place of the standard Soyuz/Salyut system of the time. The APAS collar fitted onto Soyuz 19 was releasable, allowing the two spacecraft to separate in case of malfunction.
The Apollo flew with a three-man crew on board:
Tom Stafford,
Vance Brand, and
Deke Slayton
Donald Kent "Deke" Slayton (March 1, 1924 – June 13, 1993) was a United States Air Force pilot, aeronautical engineer, and test pilot who was selected as one of the original NASA Mercury Seven astronauts. He went on to become NASA's fir ...
. Stafford had already flown into space three times, including within eight
nautical mile
A nautical mile is a unit of length used in air, marine, and space navigation, and for the definition of territorial waters. Historically, it was defined as the meridian arc length corresponding to one minute ( of a degree) of latitude. Today t ...
s of the lunar surface as Commander of
Apollo 10
Apollo 10 (May 18–26, 1969) was a human spaceflight, the fourth crewed mission in the United States Apollo program, and the second (after Apollo8) to orbit the Moon. NASA described it as a "dress rehearsal" for the first Moon landing, an ...
, and was the first
general officer to fly into space. He was a
brigadier general
Brigadier general or Brigade general is a military rank used in many countries. It is the lowest ranking general officer in some countries. The rank is usually above a colonel, and below a major general or divisional general. When appointed t ...
in the
United States Air Force
The United States Air Force (USAF) is the air service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part of the United States Army S ...
at the time of the flight; he would retire with three stars in 1979. Slayton was one of the original
Mercury Seven
The Mercury Seven were the group of seven astronauts selected to fly spacecraft for Project Mercury. They are also referred to as the Original Seven and Astronaut Group 1. Their names were publicly announced by NASA on April 9, 1959; these seve ...
astronauts selected in 1959, but an irregular heartbeat grounded him until 1972. He became head of NASA's astronaut office and, after a lengthy medical program, selected himself for this mission. At the time, Slayton was the oldest person to fly in space and the one with the longest gap between selection as an astronaut and first flight into space. Brand, meanwhile, had trained with the Apollo spacecraft during his time as a backup
Apollo 15
Apollo 15 (July 26August 7, 1971) was the ninth crewed mission in the United States' Apollo program and the fourth to land on the Moon. It was the first J mission, with a longer stay on the Moon and a greater focus on science than ea ...
command module pilot, and had served two stints as a backup Skylab commander. The closest he had come to flying prior to ASTP was as commander for the
Skylab Rescue mission mustered to potentially retrieve the crew of
Skylab 3 due to a fuel leak on that mission's Apollo CSM.
The Soyuz flew with two men:
Alexei Leonov and
Valeri Kubasov. Leonov became the first man to
walk in space on
Voskhod 2 in March 1965. Kubasov, who flew on
Soyuz 6 in 1969, ran some of the earliest
space manufacturing experiments. Both were to have flown on the ill-fated
Soyuz 11 in 1971 (Leonov as commander, Kubasov as the flight engineer), but were grounded because Kubasov was suspected of having
tuberculosis
Tuberculosis (TB) is an infectious disease usually caused by ''Mycobacterium tuberculosis'' (MTB) bacteria. Tuberculosis generally affects the lungs, but it can also affect other parts of the body. Most infections show no symptoms, in w ...
. The two-man crew on the Soyuz was a result of the modifications needed to allow the cosmonauts to wear the
Sokol space suit during launch, docking, and reentry.
The ASTP-class
Soyuz 7K-TM
The 1975 Apollo–Soyuz Test Project version of the Soyuz spacecraft (Soyuz 7K-TM) served as a technological bridge to the third generation Soyuz-T (T - транспортный, ''Transportnyi'' meaning transport) spacecraft (1976–1986).
...
spacecraft used was a variation of the post-Soyuz 11 two-man design, with the batteries replaced by
solar panel
A solar cell panel, solar electric panel, photo-voltaic (PV) module, PV panel or solar panel is an assembly of photovoltaic solar cells mounted in a (usually rectangular) frame, and a neatly organised collection of PV panels is called a pho ...
s enabling "solo" flights (missions not docking to one of the
Salyut space stations). It was designed to operate, during the docking phase, at a reduced nitrogen/oxygen pressure of , allowing easier transfers between the Apollo and Soyuz. Six ASTP-class Soyuz spacecraft were built in total, including the one used. Before the actual mission, two craft were launched uncrewed as Kosmos satellites. The third was launched as the crewed
Soyuz 16 flight as a rehearsal in order to test the APAS docking mechanism. Another craft was used fully fueled as a "hot backup" at the launch site – later it was disassembled. And the sixth craft was available as a "cold" backup; it was later used on the
last "solo" Soyuz flight in 1976, but with the APAS docking adapter replaced by the
MKF-6 multispectral camera.
Launch and mission
The Soyuz and Apollo flights launched within seven-and-a-half hours of each other on 15 July 1975, and docked on 17 July 1975. Three hours later, the two mission commanders, Stafford and Leonov, exchanged the first international handshake in space through the open hatch of the Soyuz. NASA had calculated that the historic handshake would have taken place over the British seaside resort of
Bognor Regis
Bognor Regis (), sometimes simply known as Bognor (), is a town and seaside resort in West Sussex on the south coast of England, south-west of London, west of Brighton, south-east of Chichester and east of Portsmouth. Other nearby to ...
, but a delay resulted in its occurrence being over the city of
Metz
Metz ( , , lat, Divodurum Mediomatricorum, then ) is a city in northeast France located at the confluence of the Moselle and the Seille rivers. Metz is the prefecture of the Moselle department and the seat of the parliament of the Grand Est ...
in France. During the first crew exchange, the crews were read a statement from Soviet Premier
Leonid Brezhnev
Leonid Ilyich Brezhnev; uk, links= no, Леонід Ілліч Брежнєв, . (19 December 1906– 10 November 1982) was a Soviet politician who served as General Secretary of the Communist Party of the Soviet Union between 1964 and ...
, and received a phone call from
U.S. President Gerald Ford
Gerald Rudolph Ford Jr. ( ; born Leslie Lynch King Jr.; July 14, 1913December 26, 2006) was an American politician who served as the 38th president of the United States from 1974 to 1977. He was the only president never to have been elected ...
.
While the two ships were docked, the three Americans and two Soviets conducted joint scientific experiments, exchanged flags and gifts (including tree seeds which were later planted in the two countries), listened to each other's music (examples include "
Tenderness" by
Maya Kristalinskaya and "
Why Can't We Be Friends?" by
War), signed certificates, visited each other's ships, ate together, and conversed in each other's languages. (Because of Stafford's pronounced drawl when speaking Russian, Leonov later joked that there were three languages spoken on the mission: Russian, English, and "Oklahomski".) There were also docking and redocking maneuvers, during which the two spacecraft reversed roles and the Soyuz became the "active" ship.
American scientists developed four of the experiments performed during the mission. Embryologist
Jane Oppenheimer analyzed the effects of weightlessness on fish eggs at various stages of development.
After 44 hours together, the two ships separated, and maneuvered to use the Apollo to create an artificial
solar eclipse
A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby obscuring the view of the Sun from a small part of the Earth, totally or partially. Such an alignment occurs during an eclipse season, approximately every six mo ...
to allow the crew of the Soyuz to take photographs of the
solar corona. Another brief docking was made before the ships went their separate ways. The Soviets remained in space for two more days, and the Americans for five, during which the Apollo crew also conducted
Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surf ...
observation experiments.
File:Soyuz 19 (Apollo Soyuz Test Project) spacecraft.jpg, Soyuz 19 as seen from the Apollo
File:Apollo Soyuz Test Project Mission Control.jpg, Mission control center in Houston during ASTP
File:ASTP handshake - cropped.jpg, The historic handshake between Stafford and Leonov
File:President Ford talks to ASTP crew.jpg, U.S. President Gerald Ford
Gerald Rudolph Ford Jr. ( ; born Leslie Lynch King Jr.; July 14, 1913December 26, 2006) was an American politician who served as the 38th president of the United States from 1974 to 1977. He was the only president never to have been elected ...
speaks to the Soviet and American crews on 18 July 1975.
File:Astronaut Donald K. Slayton and cosmonaut Aleksey A. Leonov in the Soyuz Orbital Module.jpg, Deke Slayton (right) with Leonov in the Soyuz spacecraft
File:Apollo-Soyuz Test Project Commemorative Plaque.jpg, The astronauts and cosmonauts assembled this commemorative plaque in orbit as a symbol of the international cooperation.
Re-entry and aftermath
The mission was considered a great success, both technically and as a public-relations exercise for both nations. The only serious problem was during
reentry and
splashdown
Splashdown is the method of landing a spacecraft by parachute in a body of water. It was used by crewed American space capsules prior to the Space Shuttle program, by SpaceX Dragon and Dragon 2 capsules and by NASA's Orion Multipurpose ...
of the Apollo craft, during which the crew were accidentally exposed to toxic
hydrazine
Hydrazine is an inorganic compound with the chemical formula . It is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour. Hydrazine is highly toxic unless handled in solution as, for example, hydrazin ...
and
nitrogen tetroxide
Dinitrogen tetroxide, commonly referred to as nitrogen tetroxide (NTO), and occasionally (usually among ex-USSR/Russia rocket engineers) as amyl, is the chemical compound N2O4. It is a useful reagent in chemical synthesis. It forms an equilibrium ...
fumes, caused by unignited
reaction control system
A reaction control system (RCS) is a spacecraft system that uses thrusters to provide attitude control and translation. Alternatively, reaction wheels are used for attitude control. Use of diverted engine thrust to provide stable attitude con ...
(RCS)
hypergolic propellant
A hypergolic propellant is a rocket propellant combination used in a rocket engine, whose components spontaneously ignite when they come into contact with each other.
The two propellant components usually consist of a fuel and an oxidizer. Th ...
s venting from the spacecraft and reentering a cabin air intake. The RCS was inadvertently left on during descent, and the toxic fumes were sucked into the spacecraft as it drew in outside air. Brand briefly lost consciousness, while Stafford retrieved emergency oxygen masks, put one on Brand, and gave one to Slayton. The three astronauts were hospitalized for two weeks in
Honolulu
Honolulu (; ) is the capital and largest city of the U.S. state of Hawaii, which is in the Pacific Ocean. It is an unincorporated county seat of the consolidated City and County of Honolulu, situated along the southeast coast of the islan ...
,
Hawaii
Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only ...
. Brand took responsibility for the mishap; because of high noise levels in the cabin during reentry, he believes he was unable to hear Stafford call off one item of the reentry checklist, the closure of two switches which would have automatically shut off the RCS and begun drogue parachute deployment. These procedures were manually performed later than usual, allowing the ingestion of the propellant fumes through the ventilation system.
The ASTP was the final flight of an Apollo spacecraft. Immediately after the launch of the Apollo spacecraft, preparations began to convert
LC-39B and the
Vehicle Assembly Building
The Vehicle Assembly Building (originally the Vertical Assembly Building), or VAB, is a large building at NASA's Kennedy Space Center (KSC), designed to assemble large pre-manufactured space vehicle components, such as the massive Saturn V and th ...
at
Kennedy Space Center
The John F. Kennedy Space Center (KSC, originally known as the NASA Launch Operations Center), located on Merritt Island, Florida, is one of the National Aeronautics and Space Administration's (NASA) ten field centers. Since December 196 ...
for use by the
Space Shuttle
The Space Shuttle is a retired, partially reusable low Earth orbital spacecraft system operated from 1981 to 2011 by the U.S. National Aeronautics and Space Administration (NASA) as part of the Space Shuttle program. Its official program na ...
, the United States' next crewed spacecraft program.
LC-39A had already been closed after the launch of
Skylab
Skylab was the first United States space station, launched by NASA, occupied for about 24 weeks between May 1973 and February 1974. It was operated by three separate three-astronaut crews: Skylab 2, Skylab 3, and Skylab 4. Major operation ...
.
Legacy
Technical

A derivative (but mechanically incompatible) docking collar,
APAS-89, was launched as part of the
Kristall module of the Soviet
Mir space station. Originally intended as the docking port for the (defunct)
Buran Soviet space shuttle, the APAS-89 unit was used for the next Russian-American docking mission,
STS-71, twenty years later as part of the
Shuttle–Mir program (though not before the docking port was tested by the last APAS-equipped Soyuz,
Soyuz TM-16, in 1993).
The American
Space Shuttle
The Space Shuttle is a retired, partially reusable low Earth orbital spacecraft system operated from 1981 to 2011 by the U.S. National Aeronautics and Space Administration (NASA) as part of the Space Shuttle program. Its official program na ...
continued to use the same APAS-89 docking hardware through the end of the
Space Shuttle program
The Space Shuttle program was the fourth human spaceflight program carried out by the U.S. National Aeronautics and Space Administration (NASA), which accomplished routine transportation for Earth-to-orbit crew and cargo from 1981 to 2011. I ...
to dock to Mir and then the
International Space Station
The International Space Station (ISS) is the largest Modular design, modular space station currently in low Earth orbit. It is a multinational collaborative project involving five participating space agencies: NASA (United States), Roscosmos ( ...
, the latter through the
Pressurized Mating Adapters (PMAs).
The PMAs are equipped with the later
APAS-95 adapters, which differ from the APAS-89 adapters in that they are no longer androgynous; while compatible with the APAS-89 docking collars, they are not capable of acting as the "active" partner in docking.
The first PMA, PMA-1, remains in use as the interface connecting the Russian-built, NASA-owned
Zarya module to the
US segment of the ISS (USOS), and so the APAS continues in use to this day (2021).
Political
Apollo–Soyuz was the first joint US–Soviet space mission. At the time it was thought that space would become either more international or competitive as a result, but it became both. The mission became symbolic of each country's goals of scientific cooperation, while their news reports downplayed the technical prowess of the other. Soviet press implied that it was leading the United States in space flight, tying it to
Marxist ideology, while the United States reported that the Soyuz was technically primitive. High-profile space cooperation declined after the successful mission and became entangled in
linkage politics, but it set a precedent of cooperation that continued in the
Shuttle–Mir Program.
Cultural
The American and Soviet commanders, Stafford and Leonov, became lasting friends. Leonov was the godfather of Stafford's younger children.
Stafford gave a eulogy at Leonov's funeral in October 2019.
An asteroid
An asteroid is a minor planet of the Solar System#Inner solar system, inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic o ...
, 2228 Soyuz-Apollo
2228 Soyuz-Apollo, provisional designation , is a carbonaceous Themistian asteroid from the outer region of the asteroid belt, approximately 26 kilometers in diameter. It was discovered on 19 July 1977, by Soviet–Russian astronomer Nikolai Chern ...
, discovered in 1977 by Soviet astronomer Nikolai Chernykh, is named after the mission.
Spacecraft locations
The Apollo Command Module
The Apollo command and service module (CSM) was one of two principal components of the United States Apollo spacecraft, used for the Apollo program, which landed astronauts on the Moon between 1969 and 1972. The CSM functioned as a mother shi ...
from the mission is on display at the California Science Center in Los Angeles
Los Angeles ( ; es, Los Ángeles, link=no , ), often referred to by its initials L.A., is the largest city in the state of California and the second most populous city in the United States after New York City, as well as one of the wor ...
. The descent module of Soyuz 19 is on display at the RKK Energiya museum in Korolyov, Moscow Oblast, Russia.
upright=1.4, left, The Apollo–Soyuz display in the National Air and Space Museum
A display at the National Air and Space Museum in Washington, D.C. shows the docked Apollo/Soyuz configuration. The display is made up of Apollo Command and Service Module 105 (used for vibration testing for the Skylab
Skylab was the first United States space station, launched by NASA, occupied for about 24 weeks between May 1973 and February 1974. It was operated by three separate three-astronaut crews: Skylab 2, Skylab 3, and Skylab 4. Major operation ...
program), the back-up Docking Module, and a model of the Soyuz spacecraft. An identical Soyuz model is exhibited at the Kennedy Space Center Visitor Complex. A full-size mockup of the two docked spacecraft is at the Cosmosphere in Hutchinson, Kansas
Hutchinson is the largest city and county seat in Reno County, Kansas, United States, and located on the Arkansas River. It has been home to salt mines since 1887, thus its nickname of "Salt City", but locals call it "Hutch". As of the 2020 ce ...
.
Commemorations
The United States Postal Service
The United States Postal Service (USPS), also known as the Post Office, U.S. Mail, or Postal Service, is an Independent agencies of the United States government, independent agency of the executive branch of the Federal government of the Uni ...
issued the Apollo–Soyuz commemorative stamps, honoring the United States–Soviet link up in space, on 15 July 1975, the day of the launch.
The remaining crew's most recent reunion was on 16 July 2010, when Leonov, Kubasov, Stafford, and Brand met at an Omega
Omega (; capital: Ω, lowercase: ω; Ancient Greek ὦ, later ὦ μέγα, Modern Greek ωμέγα) is the twenty-fourth and final letter in the Greek alphabet. In the Greek numeric system/ isopsephy ( gematria), it has a value of 800. Th ...
timepiece store in New York City
New York, often called New York City or NYC, is the most populous city in the United States. With a 2020 population of 8,804,190 distributed over , New York City is also the most densely populated major city in the U ...
. All except Leonov participated in a public roundtable that evening. Omega had produced several watches to be used on the mission.First International Space Crew Reunites for Mission's 35th Anniversary
Space.com. Retrieved on 4 August 2012
Monument
A large Soyuz–Apollo monument was constructed outside
TsUP (the Soviet, later Russian space control center) in
Moscow
Moscow ( , US chiefly ; rus, links=no, Москва, r=Moskva, p=mɐskˈva, a=Москва.ogg) is the capital and largest city of Russia. The city stands on the Moskva River in Central Russia, with a population estimated at 13.0 million ...
. It consisted of a metal scale model of
Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surf ...
overarched by an arc terminating in the joined Soyuz–Apollo spacecraft. It was damaged when a vehicle collided with it in the late 1990s, and was removed for repairs.
Mission Control Center
The mission control room that hosted the Americans in
Korolyov, Russia, was preserved as a memorial to the Soyuz–Apollo mission.
[
]
Program cost
The United States spent US$245 million ($ today) on Apollo–Soyuz.
See also
* Interkosmos, a Soviet
The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen national ...
space program from 1967 to 1994, designed to give foreign nations access to space missions.
References
External links
ASTP Chronology
Apollo-Soyuz Test Project Overview
– official NASA history of the mission
International rendezvous and docking mission (Apollo–Soyuz/Salyut) 1971
– NASA report (PDF)
Apollo/Soyuz test project operational data book. Volume 2: ASTP mass properties data book
– NASA report (PDF)
Apollo–Soyuz test project operation handbook command service docking modules systems operating procedures
– NASA flight operations manual (PDF)
(many of which are on-line)
– tell Soviet scientists, engineers and astronauts – participants of the joint work of American specialists, Politizdat 1976, with a circulation of 100,000 copies.
Apollo Soyuz Collection, The University of Alabama in Huntsville Archives and Special Collections
; Media
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* (several types of media formats are available)
* (several types of media formats are available)
Apollo-Soyuz Test Project (1973) Film
Texas Archive of the Moving Image
The Texas Archive of the Moving Image (TAMI) is an independent 501(c)(3) organization founded in 2002 by film archivist and University of Texas at Austin professor Caroline Frick, PhD. TAMI's mission is to preserve, study, and exhibit Texas film ...
{{DEFAULTSORT:Apollo-Soyuz
1975 in international relations
1975 in the Soviet Union
Crewed Soyuz missions
Soviet Union–United States relations
Spacecraft launched in 1975
Spacecraft which reentered in 1975
July 1975 events
Spacecraft launched by Soyuz-U rockets
Spacecraft launched by Saturn rockets
Alexei Leonov
Thomas P. Stafford
Deke Slayton