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Apollo–Soyuz was the first crewed international space mission, carried out jointly by the
United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...
and the
Soviet Union The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...
in July 1975. Millions of people around the world watched on television as an American
Apollo Apollo is one of the Twelve Olympians, Olympian deities in Ancient Greek religion, ancient Greek and Ancient Roman religion, Roman religion and Greek mythology, Greek and Roman mythology. Apollo has been recognized as a god of archery, mu ...
spacecraft docked with a Soviet
Soyuz Soyuz is a transliteration of the Cyrillic text Союз (Russian language, Russian and Ukrainian language, Ukrainian, 'Union'). It can refer to any union, such as a trade union (''profsoyuz'') or the Soviet Union, Union of Soviet Socialist Republi ...
capsule. The project, and its "handshake" in space, was a symbol of détente between the two superpowers amid the
Cold War The Cold War was a period of global Geopolitics, geopolitical rivalry between the United States (US) and the Soviet Union (USSR) and their respective allies, the capitalist Western Bloc and communist Eastern Bloc, which lasted from 1947 unt ...
. The Americans officially called the mission the Apollo–Soyuz Test Project (ASTP) while the Soviets called it Experimental flight "Soyuz"–"Apollo" () and Soyuz 19. The unnumbered American spacecraft was left over from canceled Apollo missions and was the last Apollo module to fly. The mission consisted of three American astronauts ( Thomas P. Stafford, Vance D. Brand, and Deke Slayton) and two Soviet cosmonauts ( Alexei Leonov and Valery Kubasov) who 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 In astronomy, a corona (: coronas or coronae) is the outermost layer of a star's Stellar atmosphere, atmosphere. It is a hot but relatively luminosity, dim region of Plasma (physics), plasma populated by intermittent coronal structures such as so ...
. The pre-flight work provided useful 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 a large space station that was Assembly of the International Space Station, assembled and is maintained in low Earth orbit by a collaboration of five space agencies and their contractors: NASA (United ...
. 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 launch system, 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. ...
on 12 April 1981, and the last crewed United States spaceflight in a
space capsule A space capsule is a spacecraft designed to transport cargo, scientific experiments, and/or astronauts to and from space. Capsules are distinguished from other spacecraft by the ability to survive reentry and return a payload to the Earth's surfa ...
until Crew Dragon Demo-2 on 30 May 2020.


Historical background

The purpose and catalyst of Apollo–Soyuz was the policy of détente between the two
Cold War The Cold War was a period of global Geopolitics, geopolitical rivalry between the United States (US) and the Soviet Union (USSR) and their respective allies, the capitalist Western Bloc and communist Eastern Bloc, which lasted from 1947 unt ...
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 (1 November 1955 – 30 April 1975) was an armed conflict in Vietnam, Laos, and Cambodia fought between North Vietnam (Democratic Republic of Vietnam) and South Vietnam (Republic of Vietnam) and their allies. North Vietnam w ...
. Meanwhile, the Soviet press was highly critical of the Apollo space missions, printing "the armed intrusion of the United States and
Saigon Ho Chi Minh City (HCMC) ('','' TP.HCM; ), commonly known as Saigon (; ), is the most populous city in Vietnam with a population of around 14 million in 2025. The city's geography is defined by rivers and canals, of which the largest is Saigo ...
puppets into
Laos Laos, officially the Lao People's Democratic Republic (LPDR), is the only landlocked country in Southeast Asia. It is bordered by Myanmar and China to the northwest, Vietnam to the east, Cambodia to the southeast, and Thailand to the west and ...
is a shameless trampling underfoot of international law" over a photograph of the
Apollo 14 Apollo 14 (January 31February 9, 1971) was the eighth crewed mission in the United States Apollo program, the third to Moon landing, land on the Moon, and the first to land in the Geology of the Moon#Highlands, lunar highlands. It was the las ...
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 General Secretary of the Communist Party of the Soviet Union, First Secretary of the Communist Party of the Soviet Union from 1953 to 1964 and the Premier of the Soviet Union, Chai ...
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 John Herschel Glenn Jr. (July 18, 1921 – December 8, 2016) was an American Marine Corps aviator, astronaut, businessman, and politician. He was the third American in space and the first to orbit the Earth, circling it three times in 1 ...
's 1962
orbital flight An orbital spaceflight (or orbital flight) is a spaceflight in which a spacecraft is placed on a trajectory where it could remain in space for at least one orbit. To do this around the Earth, it must be on a free trajectory which has an altitud ...
, an exchange of letters between President John F. Kennedy and Soviet Premier
Nikita Khrushchev Nikita Sergeyevich Khrushchev (– 11 September 1971) was the General Secretary of the Communist Party of the Soviet Union, First Secretary of the Communist Party of the Soviet Union from 1953 to 1964 and the Premier of the Soviet Union, Chai ...
led to a series of discussions led by NASA Deputy Administrator Hugh Dryden and Soviet scientist Anatoly Blagonravov. 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 () in Cuba, or the Caribbean Crisis (), was a 13-day confrontation between the governments of the United States and the Soviet Union, when American deployments of Nuclear weapons d ...
. 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 structure of Earth, Earth's interior out into space, where it interacts with the solar wind, a stream of charged particles emanating from ...
, and joint tracking of the NASA Echo II balloon satellite. Kennedy interested Khrushchev in a joint crewed
Moon landing A Moon landing or lunar landing is the arrival of a spacecraft on the surface of the Moon, including both crewed and robotic missions. The first human-made object to touch the Moon was Luna 2 in 1959. In 1969 Apollo 11 was the first cr ...
, but after the assassination of Kennedy in November 1963 and Khrushchev's removal from office in October 1964, the competition between the two nations' crewed space programs heated up, and talk of cooperation became less common, due to tense relations and military implications. On 19 April, 1971, the USSR launched the first piloted orbital space station,
Salyut 1 Salyut 1 (), also known as DOS-1 (Durable Orbital Station 1), was the world's first space station. It was launched into low Earth orbit by the Soviet Union on April 19, 1971. The Salyut programme, ''Salyut'' program subsequently achieved five m ...
. Meanwhile, the United States had launched the
Apollo 14 Apollo 14 (January 31February 9, 1971) was the eighth crewed mission in the United States Apollo program, the third to Moon landing, land on the Moon, and the first to land in the Geology of the Moon#Highlands, lunar highlands. It was the las ...
mission several months prior, the third mission to land on the Moon. Each side gave the other little coverage of their achievements. With the close of the
Vietnam War The Vietnam War (1 November 1955 – 30 April 1975) was an armed conflict in Vietnam, Laos, and Cambodia fought between North Vietnam (Democratic Republic of Vietnam) and South Vietnam (Republic of Vietnam) and their allies. North Vietnam w ...
, 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 (19 December 190610 November 1982) was a Soviet politician who served as the General Secretary of the Communist Party of the Soviet Union from 1964 until Death and state funeral of Leonid Brezhnev, his death in 1982 as w ...
:
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 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 until Resignation of Richard Nixon, his resignation in 1974. A member of the Republican Party (United States), Republican ...
's Foreign Policy Adviser
Henry Kissinger Henry Alfred Kissinger (May 27, 1923 – November 29, 2023) was an American diplomat and political scientist who served as the 56th United States secretary of state from 1973 to 1977 and the 7th National Security Advisor (United States), natio ...
enthusiastically espoused plans for the mission, and expressed these views to NASA administrator
George Low George Michael Low (born Georg Michael Löw; June 10, 1926 – July 17, 1984) was an administrator at NASA and the 14th president of the Rensselaer Polytechnic Institute. Low was one of the senior NASA officials who made decisions as manager ...
: "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". Both sides had severe criticisms of the other side's engineering. Soviet spacecraft were designed with automation in mind; the
Lunokhod 1 ''Lunokhod 1'' (Russian language, Russian: Луноход-1 "Moonwalker 1"), also known as Аппарат 8ЕЛ № 203 ("Device 8EL No. 203") was the first rover (space exploration), robotic rover lunar rover, on the Moon and the first to freel ...
and Luna 16 were both uncrewed probes, and each
Soyuz spacecraft Soyuz () is a series of spacecraft which has been in service since the 1960s, having made more than 140 flights. It was designed for the Soviet space program by the Korolev Design Bureau (now Energia). The Soyuz succeeded the Voskhod spacecraf ...
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 to operate. The Soviet Union criticized the Apollo spacecraft as being "extremely complex and dangerous". The Americans also had 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 in Houston, Texas (originally named the Manned Spacecraft Center), where human spaceflight training, research, and flight controller, flight control are conducted. ...
, criticized the design of the Soyuz:
"We in
NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...
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 spacecraft as it was a craft that was designed to be controlled from the ground. This was in contrast with the Apollo module that was meant to be flown from the capsule. Eventually
Glynn Lunney Glynn Stephen Lunney (November 27, 1936 – March 19, 2021) was an American NASA engineer. An employee of NASA since its creation in 1958, Lunney was a flight controller, flight director during the Project Gemini, Gemini and Project Apollo, Apo ...
, 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 the U.S. state of Texas and in the Southern United States. Located in Southeast Texas near Galveston Bay and the Gulf of Mexico, it is the county seat, seat of ...
and
Moscow Moscow is the Capital city, capital and List of cities and towns in Russia by population, largest city of Russia, standing on the Moskva (river), Moskva River in Central Russia. It has a population estimated at over 13 million residents with ...
, 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 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 live 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 Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...
". 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'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: Scott ...
astronauts in April 1959, but had been grounded until 1972 for medical reasons.
Jack Swigert John Leonard Swigert Jr. (August 30, 1931 – December 27, 1982) was an American NASA astronaut, test pilot, mechanical engineer, aerospace engineer, United States Air Force pilot, and politician. In April 1970, as command module pilot of A ...
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, Robert Crippen, Robert F. Overmyer, Richard H. Truly ;Flight directors :Pete Frank (Orange team), Neil Hutchinson (Silver team), Don Puddy (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 functi ...
(CSM) with a Soviet Soyuz 7K-TM spacecraft. Although the Soyuz was given a mission designation number (Soyuz 19) as part of the ongoing
Soyuz programme The Soyuz programme ( , ; , 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 Soviet cosmonaut on the Moon ...
, 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 The Apollo program, also known as Project Apollo, was the United States human spaceflight program led by NASA, which Moon landing, landed the first humans on the Moon in 1969. Apollo followed Project Mercury that put the first Americans in sp ...
, 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 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 sp ...
, 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 rocket after launch. The docking module was designed as both an airlock — as the Apollo was pressurized at about using pure oxygen, while the Soyuz used a
nitrogen Nitrogen is a chemical element; it has Symbol (chemistry), symbol N and atomic number 7. Nitrogen is a Nonmetal (chemistry), nonmetal and the lightest member of pnictogen, group 15 of the periodic table, often called the Pnictogen, pnictogens. ...
/
oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...
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 docking collar jointly developed by
NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...
and the Academy of Sciences of the Soviet Union for the mission. One end of the docking module was attached to the Apollo using the same "probe-and-
drogue A drogue or storm drogue is a device trailed behind a boat on a long line attached to the stern. A drogue is used to slow the boat down in a storm and to prevent the hull (watercraft), hull from becoming side-on to the water waves, waves. A boa ...
" docking mechanism used on the Lunar Module and the
Skylab Skylab was the United States' first space station, launched by NASA, occupied for about 24 weeks between May 1973 and February 1974. It was operated by three trios of astronaut crews: Skylab 2, Skylab 3, and Skylab 4. Skylab was constructe ...
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. 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 at t ...
s of the lunar surface as Commander of
Apollo 10 Apollo 10 (May 18–26, 1969) was the fourth human spaceflight in the United States' Apollo program and the second to orbit the Moon. NASA, the mission's operator, described it as a "dress rehearsal" for the first Moon landing (Apollo 11, two ...
, and was the first
general officer A general officer is an Officer (armed forces), officer of high rank in the army, armies, and in some nations' air force, air and space forces, marines or naval infantry. In some usages, the term "general officer" refers to a rank above colone ...
to fly into space. He was a brigadier general in the
United States Air Force The United States Air Force (USAF) is the Air force, air service branch of the United States Department of Defense. It is one of the six United States Armed Forces and one of the eight uniformed services of the United States. Tracing its ori ...
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: Scott ...
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 Apollo program and the fourth Moon landing. It was the first List of Apollo missions#Alphabetical mission types, J mission, with a longer stay on the Moon and a greate ...
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 The Skylab Rescue Mission (also SL-R)Mission Requirements, Skylab Rescue Mission, SL-R NASA, 24 August 1973. was an unflown rescue mission, planned as a contingency plan, contingency in the event of astronauts being stranded aboard the American S ...
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 Valery 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), also known colloquially as the "white death", or historically as consumption, is a contagious disease usually caused by ''Mycobacterium tuberculosis'' (MTB) bacteria. Tuberculosis generally affects the lungs, but it can al ...
. 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 spacecraft used was a variation of the post-Soyuz 11 two-man design, with the batteries replaced by
solar panel A solar panel is a device that converts sunlight into electricity by using photovoltaic (PV) cells. PV cells are made of materials that produce excited electrons when exposed to light. These electrons flow through a circuit and produce direct ...
s enabling "solo" flights (missions not docking to one of the
Salyut The ''Salyut'' programme (, , meaning "salute" or "fireworks") was the first space station programme, undertaken by the Soviet Union. It involved a series of four crewed scientific research space stations and two crewed military reconnaissa ...
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 (), also 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 towns include Littleham ...
, but a delay resulted in its occurrence being over the city of
Metz Metz ( , , , then ) is a city in northeast France located at the confluence of the Moselle (river), Moselle and the Seille (Moselle), Seille rivers. Metz is the Prefectures in France, prefecture of the Moselle (department), Moselle Departments ...
in France. During the first crew exchange, the crews were read a statement from Soviet
General Secretary Secretary is a title often used in organizations to indicate a person having a certain amount of authority, Power (social and political), power, or importance in the organization. Secretaries announce important events and communicate to the org ...
Leonid Brezhnev Leonid Ilyich Brezhnev (19 December 190610 November 1982) was a Soviet politician who served as the General Secretary of the Communist Party of the Soviet Union from 1964 until Death and state funeral of Leonid Brezhnev, his death in 1982 as w ...
, and received a phone call from
U.S. President The president of the United States (POTUS) is the head of state and head of government of the United States. The president directs the Federal government of the United States#Executive branch, executive branch of the Federal government of t ...
Gerald Ford Gerald Rudolph Ford Jr. (born Leslie Lynch King Jr.; July 14, 1913December 26, 2006) was the 38th president of the United States, serving from 1974 to 1977. A member of the Republican Party (United States), Republican Party, Ford assumed the p ...
. 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 Maya Vladimirovna Kristalinskaya (; 24 February 1932, Moscow – 19 June 1985, Moscow) was a Soviet-Russian singer. In 1957 she performed at the 6th World Festival of Youth and Students in Moscow with an amateur ensemble under the direction of Y ...
and " Why Can't We Be Friends?" by
War War is an armed conflict between the armed forces of states, or between governmental forces and armed groups that are organized under a certain command structure and have the capacity to sustain military operations, or between such organi ...
), 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 Earth, totally or partially. Such an alignment occurs approximately every six months, during the eclipse season i ...
to allow the crew of the Soyuz to take photographs of the
solar corona In astronomy, a corona (: coronas or coronae) is the outermost layer of a star's Stellar atmosphere, atmosphere. It is a hot but relatively luminosity, dim region of Plasma (physics), plasma populated by intermittent coronal structures such as so ...
. 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 Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...
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 the 38th president of the United States, serving from 1974 to 1977. A member of the Republican Party (United States), Republican Party, Ford assumed the p ...
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 of the Apollo craft, during which the crew were accidentally exposed to toxic monomethylhydrazine and nitrogen tetroxide fumes, caused by unignited
reaction control system A reaction control system (RCS) is a spacecraft system that uses Thrusters (spacecraft), thrusters to provide Spacecraft attitude control, attitude control and translation (physics), translation. Alternatively, reaction wheels can be used for at ...
(RCS) hypergolic propellants 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 List of capitals in the United States, capital and most populous city of the U.S. state of Hawaii, located in the Pacific Ocean. It is the county seat of the Consolidated city-county, consolidated City and County of Honol ...
,
Hawaii Hawaii ( ; ) is an island U.S. state, state of the United States, in the Pacific Ocean about southwest of the U.S. mainland. One of the two Non-contiguous United States, non-contiguous U.S. states (along with Alaska), it is the only sta ...
. Brand took responsibility for the mishap; because of high noise levels in the cabin during reentry, he believed 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) in Florida, designed to assemble large pre-manufactured space vehicle components, such as the massive Satu ...
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 NASA, National Aeronautics and Space Administration's (NASA) ten NASA facilities#List of field c ...
for use by the
Space Shuttle The Space Shuttle is a retired, partially reusable launch system, 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. ...
, the United States' next crewed spacecraft program. LC-39A had already been closed after the launch of
Skylab Skylab was the United States' first space station, launched by NASA, occupied for about 24 weeks between May 1973 and February 1974. It was operated by three trios of astronaut crews: Skylab 2, Skylab 3, and Skylab 4. Skylab was constructe ...
.


Legacy


Technical

A derivative (but mechanically incompatible) docking collar, APAS-89, was launched as part of the Kristall module of the Soviet
Mir ''Mir'' (, ; ) was a space station operated in low Earth orbit from 1986 to 2001, first by the Soviet Union and later by the Russia, Russian Federation. ''Mir'' was the first modular space station and was assembled in orbit from 1986 to ...
space station. Originally intended as the docking port for the 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 The Shuttle–''Mir'' program () was a collaborative space program between Russia and the United States that involved American Space Shuttles visiting the Russian space station ''Mir'', Russian cosmonauts flying on the Shuttle, and an American ...
(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 launch system, 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. ...
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. Its ...
to dock to Mir and then the
International Space Station The International Space Station (ISS) is a large space station that was Assembly of the International Space Station, assembled and is maintained in low Earth orbit by a collaboration of five space agencies and their contractors: NASA (United ...
, 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 (2024).


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 the Marxist–Leninist 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 The Shuttle–''Mir'' program () was a collaborative space program between Russia and the United States that involved American Space Shuttles visiting the Russian space station ''Mir'', Russian cosmonauts flying on the Shuttle, and an American ...
.


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—an object larger than a meteoroid that is neither a planet nor an identified comet—that orbits within the Solar System#Inner Solar System, inner Solar System or is co-orbital with Jupiter (Trojan asteroids). As ...
, 2228 Soyuz-Apollo, discovered in 1977 by Soviet astronomer
Nikolai Chernykh Nikolai Stepanovich Chernykh ( rus, Никола́й Степа́нович Черны́х, , nʲɪkɐˈlaj sʲtʲɪˈpanəvʲɪtɕ tɕɪrˈnɨx, links=yes; 6 October 1931 – 25 May 2004Казакова, Р.К. Памяти Николая Сте ...
, is named after the mission. To commemorate Apollo–Soyuz, renowned British/Irish bartender Joe Gilmore of The Savoy Hotel's American Bar created the ' Link-Up' cocktail. When the astronauts were told the cocktail was being flown out from London to be enjoyed on their return, they said, "Tell Joe we want it up here".


Scientific

The Apollo craft carried the SAG telescope designed to observe in the
extreme ultraviolet Extreme ultraviolet radiation (EUV or XUV) or high-energy ultraviolet radiation is electromagnetic radiation in the part of the electromagnetic spectrum spanning wavelengths shorter than the hydrogen Lyman-alpha line from 121  nm down to ...
. Across several orbits of observing the instrument discovered two ultraviolet sources; HZ 43 and FEIGE 24, both of which were
White dwarf A white dwarf is a Compact star, stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very density, dense: in an Earth sized volume, it packs a mass that is comparable to the Sun. No nuclear fusion takes place i ...
s. Other stars observed included,
Proxima Centauri Proxima Centauri is the nearest star to Earth after the Sun, located 4.25 light-years away in the southern constellation of Centaurus. This object was discovered in 1915 by Robert T. A. Innes, Robert Innes. It is a small, low-mass st ...
(a
Red Dwarf A red dwarf is the smallest kind of star on the main sequence. Red dwarfs are by far the most common type of fusing star in the Milky Way, at least in the neighborhood of the Sun. However, due to their low luminosity, individual red dwarfs are ...
),
SS Cygni SS Cygni is a variable star in the northern constellation Cygnus (constellation), Cygnus (the Swan). It was discovered in 1896 by Louisa D. Wells, a computer working under Edward Charles Pickering, Edward Pickering at Harvard College Ob ...
(a
Binary star A binary star or binary star system is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved as separate stars us ...
), and
Sirius Sirius is the brightest star in the night sky. Its name is derived from the Greek word (Latin script: ), meaning 'glowing' or 'scorching'. The star is designated  Canis Majoris, Latinized to Alpha Canis Majoris, and abbr ...
(also a Binary star). A third possible discovery was an unknown object in the Pavo constellation. The star HD 192273 was later suggested as a candidate for the Pavo observation but further study concluded that the star’s distance and spectral class made this unlikely.


Spacecraft locations

Model of joined Apollo and Soyuz at the National Air and Space Museum in Washington, DC, using the backup Docking Module The
Apollo command 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 functi ...
from the mission is on display at the California Science Center in
Los Angeles Los Angeles, often referred to by its initials L.A., is the List of municipalities in California, most populous city in the U.S. state of California, and the commercial, Financial District, Los Angeles, financial, and Culture of Los Angeles, ...
. The descent module of Soyuz 19 is on display at the RKK Energiya museum in Korolyov, Russia. A display at the
National Air and Space Museum The National Air and Space Museum (NASM) of the Smithsonian Institution is a museum in Washington, D.C., in the United States, dedicated to history of aviation, human flight and space exploration. Established in 1946 as the National Air Museum, ...
in
Washington, D.C. Washington, D.C., formally the District of Columbia and commonly known as Washington or D.C., is the capital city and federal district of the United States. The city is on the Potomac River, across from Virginia, and shares land borders with ...
shows the docked Apollo/Soyuz configuration. The display is made up of the unflown Apollo Command and Service Module 105 (used for vibration testing for the
Skylab Skylab was the United States' first space station, launched by NASA, occupied for about 24 weeks between May 1973 and February 1974. It was operated by three trios of astronaut crews: Skylab 2, Skylab 3, and Skylab 4. Skylab was constructe ...
program), the back-up Docking Module, and an unflown Soyuz spacecraft, on loan from the Russian government.


Commemorations

The
United States Postal Service The United States Postal Service (USPS), also known as the Post Office, U.S. Mail, or simply the Postal Service, is an independent agencies of the United States government, independent agency of the executive branch of the federal governmen ...
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 (, ; uppercase Ω, lowercase ω; Ancient Greek ὦ, later ὦ μέγα, Modern Greek ωμέγα) is the twenty-fourth and last letter in the Greek alphabet. In the Greek numerals, Greek numeric system/isopsephy (gematria), it has a value ...
timepiece store in
New York City New York, often called New York City (NYC), is the most populous city in the United States, located at the southern tip of New York State on one of the world's largest natural harbors. The city comprises five boroughs, each coextensive w ...
. All except Leonov participated in a public roundtable that evening. Omega had produced several watches to be used on the mission.


Monument

A large Soyuz–Apollo monument was constructed outside the Soviet (now Russian) space control center
RKA Mission Control Center The RKA Mission Control CenterRKA (): Russian space agency (, ). (), also known by its acronym TsUP () or by its radio callsign Mission Control Moscow, is the mission control center of Roscosmos. It is located in Korolyov, Moscow Oblast, on ...
(Russian acronym: TsUP) in
Moscow Moscow is the Capital city, capital and List of cities and towns in Russia by population, largest city of Russia, standing on the Moskva (river), Moskva River in Central Russia. It has a population estimated at over 13 million residents with ...
. It consisted of a metal scale model of
Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...
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 (equal to $ today) on the Apollo–Soyuz project and spacecraft. The amount of money the Soviet Union spent on the ASTP is unknown but reportedly constituted a "significant portion."NATIONAL AERONAUTICS AND SPACE ADMINISTRATION APOLLO SOYUZ TEST PROJECT
p. 8.


See also

*
Interkosmos Interkosmos () was a Soviet space program, designed to help the Soviet Union's allies with Human spaceflight, crewed and Uncrewed spacecraft, uncrewed space missions. The program was formed in April 1967 in Moscow. All members of the program fr ...
, a
Soviet The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...
space program from 1967 to 1994, designed to give foreign nations access to space missions. * '' For All Mankind'', an alternate history streaming series that depicts a fictionalized Apollo–Soyuz mission in its second season


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 * * * * * * * * * * (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 Spacecraft launched by Soyuz-U rockets Spacecraft launched by Saturn rockets Alexei Leonov Thomas P. Stafford Deke Slayton Saturn IB