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Apollo-Soyuz Test Project

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Apollo-Soyuz Test Project

Apollo–Soyuz Test Project
Mission insignia
Mission statistics
Mission name Apollo–Soyuz Test Project
Command Module CSM-111
14,768 kg (32,558 lb)
Spacecraft mass 16,780 kg or 36,990 lb total
(CSM plus 2,012 kg or 4,436 lb Docking Module)
Crew size 5
Launch vehicle Saturn IB SA-210
Launch pad LC 39B
Kennedy Space Center
Florida, USA
Launch date July 15, 1975 19:50 UTC
Landing site

21°52′N 162°45′W / 21.867°N 162.750°W / 21.867; -162.750 (Apollo–Soyuz Test Project landing)

Landing July 24, 1975 21:18 (1975-07-24UTC21:19) UTC
Mission duration 9 d 01 h 28 min
Number of orbits 148
Apogee 231 km (144 mi)
Perigee 217 km (135 mi)
Orbital period 88.91 m
Orbital inclination 51.75°
Distance traveled ~5,990,000 km (3,720,000 mi)
Crew photo
Error creating thumbnail: Invalid thumbnail parameters or image file with more than 12.5 million pixels
Left to right: Slayton, Stafford, Brand, Leonov, Kubasov
Related missions
Previous Subsequent
Skylab 4 Approach and Landing Tests
Soyuz 19
Mission statistics
Mission name Soyuz 19
Spacecraft type Soyuz 7K-TM
Spacecraft mass 6,790 kg (14,970 lb)
Crew size 2
Call sign Союз (Soyuz - "Union")
Launch vehicle Soyuz-U
Launch pad Gagarin's Start
Baikonur Cosmodrome
Kazakh SSR
Launch date July 15, 1975 12:20 (1975-07-15UTC12:20) UTC
Landing July 21, 1975 10:50 UTC
Mission duration 5 d 22 h 30 m
Number of orbits 96
Apogee 231 km (144 mi)
Perigee 218 km (135 mi)
Orbital period 88.92 min
Orbital inclination 51.76°
Distance traveled ~3,900,000 km (2,400,000 mi)
Related missions
Previous Subsequent
Soyuz 18 Soyuz 20

The Apollo–Soyuz Test Project (ASTP) (Russian: Экспериментальный полёт «Союз» — «Аполлон», Eksperimantalniy polyot Soyuz-Apollon, lit. "Experimental flight Soyuz-Apollo"), in July 1975, was the first joint U.S.–Soviet space flight, and the last flight of an Apollo spacecraft. Its primary purpose was as a symbol of the policy of détente that the two superpowers were pursuing at the time, and marked the end of the Space Race between them that began in 1957.

The mission included both joint and separate scientific experiments (including an engineered eclipse of the Sun by Apollo to allow Soyuz to take photographs of the solar corona), and provided useful engineering experience for future joint US–Russian space flights, such as the Shuttle–Mir Program and the International Space Station.

ASTP was the last manned US space mission until the first Space Shuttle flight in April 1981. It was also U.S. astronaut Donald "Deke" Slayton's only space flight. He was chosen as one of the original Mercury Seven astronauts in April 1959, but had been grounded until 1972 for medical reasons.

Apollo crew

Position Astronaut
Commander Thomas P. Stafford
Fourth and last spaceflight
Command Module Pilot Vance D. Brand
First spaceflight
Docking Module Pilot Donald K. Slayton
Only spaceflight

Backup crew

Position Astronaut
Commander Alan L. Bean
Command Module Pilot Ronald E. Evans
Docking Module Pilot Jack R. Lousma

Crew notes

Jack Swigert had originally been assigned as the command module pilot for the ASTP prime crew, but prior to the official announcement he was removed as punishment for his involvement in the Apollo 15 postage stamp scandal.[1]

Support crew

Flight directors

  • Pete Frank, Orange team
  • Neil Hutchinson, Silver team
  • Don Puddy, Crimson team
  • Frank Littleton, Amber team

Soyuz crew

Position Cosmonaut
Commander Alexey Leonov
Second and last spaceflight
Flight Engineer Valeri Kubasov
Second spaceflight

Backup crew

Position Cosmonaut
Commander Anatoly Filipchenko
Flight Engineer Nikolai Rukavishnikov

Mission parameters

  • Mass:
    • 14,768 kg (32,558 lb) (Apollo),
    • 6,790 kg (14,970 lb) (Soyuz)
  • Perigee:
    • 152 km (94 mi) (Apollo),
    • 186 km (116 mi) (Soyuz)
  • Apogee:
    • 166 km (103 mi) (Apollo),
    • 220 km (140 mi) (Soyuz)
  • Inclination:
    • 51.7° (Apollo),
    • 51.8° (Soyuz)
  • Period:
    • 87.6 minutes (Apollo),
    • 88.5 minutes (Soyuz)


  • First docking: July 17, 1975 - 16:19:09 UTC
  • Last undocking: July 19, 1975 - 15:26:12 UTC
  • Time docked: 1 day, 23 hours, 07 minutes, 03 seconds

Historical background

The purpose and catalyst of the Apollo–Soyuz Test Project was the policy of détente between the United States and the Soviet Union. Previous to this mission, tensions remained high between the two world superpowers while the United States was engaged in the Vietnam War. Meanwhile, the Soviet press was highly critical of the Apollo space missions, printing "the armed intrusion of the United States and Saigon puppets into Laos is a shameless trampling underfoot of international law" over a photograph of the Apollo 14 launch in 1971.[2] Although Soviet leader Nikita 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.

Due to tense relations, space cooperation between the United States and the Soviet Union was unlikely in the early 1970s. Each nation was making its own extravagant claims about accomplishments in space. Most recently on the seventh of June, 1971, the USSR had bragging rights over the first piloted orbital space station, Salyut. Meanwhile, the United States had just launched the Apollo 14, the third American spacecraft to land personnel on the moon. Each side gave the other close to no coverage whatsoever of their achievements.[2]

Furthermore, 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 were both unmanned 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 were designed to be operated by humans and required highly trained astronauts in order to operate. The Soviet Union accused the Apollo spacecraft of being "extremely complex and dangerous".[2]

The Americans also had their own concerns about Soviet spacecraft. Christopher Johnson, director of the Lyndon B. Johnson Space Center, critiqued the design of the Soyuz: "We in NASA 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".[3] However, American and Soviet engineers already settled their differences for a possible docking of American and Soviet spacecraft in meetings between June and December 1971 in Houston and Moscow, including Bill Creasy’s design of an androgynous docking system between the two ships that would allow either to be active or passive during docking.[4]

With the close of the Vietnam War, relations between the United States and the USSR began to improve, as did the prognosis for a potential cooperative space mission.[2] The Apollo-Soyuz Test Project was made possible by the thaw in these relations, and the project itself endeavored to amplify and solidify the improving relations between the United States and the Soviet Union. According to Soviet leader Leonid Brezhnev, "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".[2] Thus, both sides recognized ASTP as a political act of peace.[5]

In October 1970, Soviet Academy of Sciences president Mstislav Keldysh responded to NASA Administrator Thomas O. Paine’s letter proposing a project about a cooperative space mission, and there was subsequently a meeting to discuss technical details. By January 12, U.S. President Richard Nixon's Foreign Policy Adviser Henry Kissinger enthusiastically espoused plans for the mission, and expressed these views to NASA administrator George M. 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."[6] 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,[7] committing both the USSR and the United States to the launch of the Apollo–Soyuz Test Project in 1975.[8]

The 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 space mission to be televised in a live fashion during the launch, while in space, and at the landing.[2] Furthermore, the Soyuz 19 was the first spacecraft to which a foreign flight crew had access before flight. The Apollo crew were permitted to inspect the Soyuz 19 as well as the launch and crew training site, constituting an unprecedented sharing of information with Americans about any Soviet space program.

Not all reactions to the ASTP were positive, however. Many Americans feared that the 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.[2] However, soliciting appropriations from the American Congress proved to be quite difficult, which was not a problem in the Soviet Union, and the dedication to space exploration demonstrated by the Soviet Union rejected these criticisms. Some Soviet publicists called American critics of the mission "demagogues who stand against scientific cooperation with the U.S.S.R."[2] In general, however, tensions between the United States and the USSR had softened, and the project set a precedent for future cooperative projects in space.[7]

Mission summary


The Apollo–Soyuz Test Project entailed the docking of an American Apollo spacecraft with the then-Soviet Soyuz spacecraft. Although the Soyuz was given a mission designation number (Soyuz 19) as part of the ongoing Soyuz program, it was referred to simply as "Soyuz" for the duration of the joint mission. The Apollo mission was not officially numbered, though some sources refer to it as "Apollo 18".[9]

The Apollo Command/Service Module (CSM) 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 on the lunar flights, the docking module had to be retrieved from the S-IVB upper-stage of the Saturn IB rocket after launch. The docking module was designed as both an airlock — as the Apollo was pressurized at 5.0 psi using pure oxygen, while the Soyuz used a nitrogen/oxygen atmosphere at sea level pressure — 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 and the Soviet Academy of Sciences 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 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 fitting with the Soyuz 19 was releasable, allowing the two spacecraft to separate.

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 miles of the lunar surface, and was the first general officer to fly into space (he was a brigadier general in the United States Air Force at the time of the flight; he would retire with three stars in 1979). Slayton was one of the original Mercury Seven astronauts selected in 1958, 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 used for this mission during his time as a backup Apollo 15 command module pilot, and had served multiple stints as a backup Skylab commander. The closest he came 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: Alexey Leonov and Valery Kubasov. Leonov became the first man to walk in space on Voskhod 2 in 1965. Kubasov, who flew on Soyuz 6 in 1969, ran some of the earliest space manufacturing experiments. Both were slated 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 to have tuberculosis. 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 panels 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 10.2 psi, 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 unmanned as KOSMOS satellites. The third was launched as the manned 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 July 15, and docked on July 17. 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,[10] but a delay resulted in its occurrence being over the town of Metz in France.[11] During the first crew exchange, the crews were read a statement from Soviet premier Leonid Brezhnev, and received a phone call from U.S. President Gerald Ford.

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), 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.

After 44 hours together, the two ships separated, and maneuvered to use the Apollo to create an artificial solar eclipse 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 five days, and the Americans for nine, during which the Apollo crew also conducted experiments in Earth observation.

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 nitrogen tetroxide fumes, caused by the reaction control system (RCS) oxidizer venting from the spacecraft and reentering a cabin air intake. The RCS was inadvertently left on during descent, and highly toxic nitrogen tetroxide was 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.[12] 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 initiated drogue parachute deployment; these procedures were manually performed later than usual, allowing the ingestion of the propellant fumes through the ventilation system.[13]

The ASTP was the final flight of an Apollo spacecraft. Immediately after the launch of the Apollo spacecraft, preparations began to convert Launch Pad 39B and the Vehicle Assembly Building at Kennedy Space Center for use by the Space Shuttle, the United States' next manned spacecraft program. Launch Pad 39A had already been closed after the launch of Skylab.

Spacecraft locations

The Apollo command module from the mission is on display at the California Science Center in Los Angeles. The descent module of Soyuz 19 is on display at the RKK Energiya museum in Korolyov, Moscow Oblast, Russia.

A display at the National Air and Space Museum in Washington, D.C. shows the docked Apollo/Soyuz configuration with the restored Apollo Command and Service Module used for testing prior to the mission, 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.

The Apollo–Soyuz display in the National Air and Space Museum


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 Russo-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, TM-16, in 1993).

The American Space Shuttle continued to use the same APAS-89 docking hardware through the end of the Space Shuttle program to dock to Mir and then the International Space Station, 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, and so the APAS continues in use to this day.

A minor planet, 2228 Soyuz-Apollo, discovered in 1977 by Soviet astronomer Nikolai Stepanovich Chernykh, is named after the mission.[14]


The US Postal Service issued the Apollo–Soyuz commemorative stamps, honoring the United States–Soviet link up in space, on July 15, 1975, the day of the launch. The remaining crew's most recent reunion was on July 16, 2010, when Leonov, Kubasov, Stafford, and Brand met at an Omega timepiece store in New York City. All except Leonov participated in a public roundtable that evening. Omega had produced several watches to be used on the mission.[15]


In the wake of the mission, a large Soyuz–Apollo monument was constructed outside TsUP (the Soviet, later Russian space control center) in Moscow. It consisted of a metal Earth overarched by an arc terminating in a scale model of the joined Apollo–Soyuz spacecraft. It was damaged when a vehicle collided with it in the late 1990s, and was removed for repairs.

Program cost

The United States spent $245 million on Apollo-Soyuz, or $1 billion in 2010 inflation-adjusted dollars.[16]

See also

Spaceflight portal


External links

  • ASTP Chronology
  • ASTP home page
  • Apollo–Soyuz
  • The Partnership: A History of the Apollo–Soyuz Test Project – the official NASA history of the mission
  • International rendezvous and docking mission (Apollo–Soyuz/Salyut) 1971 - NASA report (PDF format)
  • Apollo/Soyuz test project operational data book. Volume 2: ASTP mass properties data book - NASA report (PDF format)
  • Apollo–Soyuz test project operation handbook command service docking modules systems operating procedures - NASA flight operations manual (PDF Format)
  • NASA History Series Publications (many of which are on-line)
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