Apollo-Soyuz Test Project (ASTP)

(Top Row, L to R: American Thomas P. Stafford, Russian Alexei Leonov. Bottom Row, L to R: Americans Deke Slayton and Vance Brand, Russian Valeri Kubasov).  Prior to the conduct of ASTP, the astronauts and cosmonauts visited each other's space centers and became familiar with the spacecraft of the other country. The first visit was by the Russians to Johnson Space Center in July 1973, followed by a U.S. visit to Moscow in November 1973. In late April and early May 1974, the Russian flight crews returned to Johnson Space Center, and the U.S. crews went to Moscow in June and July 1974. The Russian crew made a third trip to the United States in September 1973 and came for the fourth and last time in February 1975. The U.S. crew visited the Soviet Union in late April and early May 1975 and became the first Americans to see the Russian launch facilities at Tyuratam on April 28, 1975. One of the most difficult problems to overcome was that of language differences. To alleviate this problem as much as possible, the Americans learned Russian and the Russians learned English. It was found that the best scenario was for the Russians to speak English and for the Americans to speak Russian.  

A Docking Module was designed jointly by the United States and Soviet Union, and built in the United States. Its purpose was to enable a docking between the dissimilar Soyuz spacecraft and the U.S. Apollo. It was a three meter long cylinder 1.5 meters in diameter, and in addition to serving as a docking device, also served as an airlock module between the different atmospheres of the two ships (the U.S. ship with 100% oxygen at 260 millimeters of mercury; the Soyuz with a mixed oxygen-nitrogen atmosphere at 520 mm HG--lowered from its usual 760 mm Hg for this mission). (Credit: history.nasa.gov) 

American Commander Thomas P. Stafford and Russian Commander Alexei Leonov conducted the famous "handshake in space" after successfully docking their Apollo and Soyuz Spacecraft on July 17, 1975. The historic greeting was televised live to the world. During four hours of joint activities, the crews received congratulations from Soviet General Secretary Leonid Brezhnev and U.S. President Gerald Ford. The crews signed international certificates and exchanged commemorative items such as flags and plaques.

A second period of joint activities followed when astronaut Brand entered the Soyuz and Leonov joined Stafford and Slayton in Apollo. The crews provided televised tours of each other's spacecraft and ate lunch together. After a third transfer between spacecrafts, and a joint press conference, the crews returned to their respective spacecraft. 

Amidst the iciness of the Cold War, an unlikely friendship began to thaw the tension between the U.S and Soviet Union. Alexei Leonov (left) and Thomas Stafford (right) formed a strong bond during their Apollo-Soyuz training, and the two have remained close friends through the years following their historic joint mission.