Apollo-Soyuz

Apollo-Soyuz (officially called the Apollo-Soyuz Test Project, or ASTP) grew from a series of cooperative agreements between the United States and the Soviet Union in the 1960s. In March 1970, U.S. President Richard Nixon declared international cooperation a prime objective of the National Aeronautics and Space Administration (NASA). The U.S. space agency and Soviet space officials agreed in October 1970 to study a common docking system that would allow each country to rescue the other's space travelers. Nixon and Soviet Premier Alexei Kosygin, taking advantage of a spirit of reconciliation (detente) between the United States and the Soviet Union, signed the Space Cooperation Agreement in Moscow on May 24, 1972, formally creating the ASTP.

On January 30, 1973, NASA introduced astronauts Thomas Stafford, Donald Slayton, and Vance Brand as its prime ASTP crew. In May, the Soviets tapped Alexei Leonov and Valeri Kubasov as its ASTP prime cosmonauts. The crews trained together in Houston, Texas, and in Moscow and learned each other's language. The Moscow and Houston mission control centers also learned to work together. Meanwhile, Soviet and American engineers worked to make the ASTP spacecraft compatible.

Docking System and Spacecraft Modifications

The common docking unit, the Androgynous Peripheral Docking System (APDS), was based on a U.S. design. Unlike previous docking units, the APDS could play both passive and active roles in docking. To play the active role, motors extended the APDS unit. Spade-shaped guides aligned the APDS units so latches could hook them together. In the U.S. APDS, shock absorbers absorbed impact; the Soviet unit used a gear system. The active APDS then retracted to lock the ships together and create an airtight tunnel for crew transfers.

ASTP Apollo (unofficially designated "Apollo 18") was a stripped-down Apollo lunar spacecraft. In keeping with its short-duration Earth-orbital mission, it carried few supplies and little propellant, making it the lightest Apollo ever flown (12,731 kilograms [28,008 pounds]). A two-stage Saturn IB rocket launched ASTP Apollo into Earth orbit. A second Apollo was prepared as a backup.

The Docking Module (DM), built by the United States, allowed movement between the incompatible Apollo and Soyuz atmospheres by acting as a medical hyperbaric chamber where astronauts and cosmonauts could adjust their bodies. Apollo had a low-pressure pure oxygen atmosphere, whereas Soyuz replicated Earth's atmosphere (an oxygen-nitrogen mixture at three times Apollo pressure). The 2,012-kilogram (4,426-pound) DM included an Apollo-type docking unit at one end and the U.S. APDS docking system at the other. The DM reached orbit under the Apollo spacecraft, on top of the Saturn IB second stage.

The Soviets committed five Soyuz to ASTP. Two unpiloted Soyuz, Cosmos 638 (April 3-13, 1974) and Cosmos 672 (August 12-18, 1974), as well as the piloted Soyuz 16 (December 2-8, 1974), tested Soyuz modifications for ASTP. Modifications included replacing the standard Soyuz docking system (designed for docking with Salyut space stations) with the Soviet APDS; adding electricity-generating solar arrays ; and making life support upgrades so Soyuz cosmonauts could host two visiting Apollo astronauts.

The Mission

The Soviet ASTP spacecraft, Soyuz 19, lifted off from Soviet Kazakhstan on July 15, 1975. A backup Soyuz stood by on a launch pad in case the first Soyuz could not launch on time. Seven hours later, ASTP Apollo lifted off from Florida. After separating from the Saturn IB second stage, Apollo turned around and docked with the DM. Stafford, Slayton, and Brand then set out in pursuit of Soyuz 19. Docking occurred on July 17 with Apollo maneuvering and its APDS docking unit playing the active role.

The crews conducted four transfers between their spacecraft over the next two days. During these, much attention was given to television coverage and symbolism. They shared a meal, heard from U.S. and Soviet leaders Gerald Ford and Leonid Brezhnev, and exchanged plaques, flags, and certificates. Leonov and Kubasov gave the American public a television tour of Soyuz 19, and the Americans reciprocated. Though science was of secondary importance, the crews performed twenty-seven experiments, some using a furnace in the DM.

Apollo and Soyuz 19 undocked on July 19 and redocked with Soyuz maneuvering and its APDS docking unit playing the active role. They undocked again, then Apollo maneuvered to block the Sun, creating an artificial solar eclipse, which Soyuz 19 photographed. Soyuz 19 landed on July 21, and ASTP Apollo landed on July 24.

After ASTP

NASA considered a second ASTP mission in 1977, but worried that it would interfere with space shuttle development. The Space Cooperation Agreement was renewed in 1977, calling for a shuttle-Salyut docking in 1981, but the spirit of detente that made ASTP possible evaporated following the 1979 Soviet invasion of Afghanistan. The United States dropped APDS development, but the Soviet Union continued; in the 1990s, NASA equipped the space shuttle with Russian-built APDS units for the shuttle-Mir and International Space Station program dockings.

see also Apollo (volume 3); Astronauts, Types of (volume 3); Cosmonauts (volume 3); History of Humans in Space (volume 3); International Cooperation (volume 3); International Space Station (volumes 1 and 3); Nasa (volume 3); Zero Gravity (volume 3).

David S. F. Portree

Bibliography

Baker, David. "ASTP Mission Report-1." Spaceflight (1975):356-358.

——. "ASTP Mission Report-2." Spaceflight (1975):384-391.

——. "ASTP Mission Report-3." Spaceflight (1975):427-434, 448.

Ezell, Edward Clinton, and Linda Neuman Ezell. The Partnership: A History of the Apollo-Soyuz Test Project. Washington, DC: NASA Scientific and Technical Information Office, 1978.

Portree, David S. F. Mir Hardware Heritage. Houston, TX: NASA Lyndon B. Johnson Space Center, Information Services Division, 1995.

Internet Resources

Ezell, Edward Clinton, and Linda Neuman Ezell. The Partnership: A History of the Apollo-Soyuz Test Project. 1978. National Aeronautics and Space Administration. <http://www.hq.nasa.gov/office/pao/History/SP-4209/cover.htm>.

Portree, David S. F. Mir Hardware Heritage. 1995. National Aeronautics and Space Administration. <http://spaceflight.nasa.gov/history/shuttle-mir/ops/mir/mirheritage.pdf>.