The Apollo program, which started during a time of intense competition between the United States and the USSR, ended in a demonstration of dŽtente in space: a joint orbital flight of the Apollo and Soyuz spaceships, known as the Apollo-Soyuz Test Project (ASTP). Technically, the joint mission in low Earth orbit demonstrated intership crew transfer and space rescue. The project had been initiated by the United States in 1969 but did not gain Soviet approval until the Nixon-Kosygin summit conference in Moscow in 1972.The docking of two space vessels of different design and manufacture required the construction of a universal docking module. This hardware was fabricated by Rockwell International, and compatible systems were installed in both Apollo and Soyuz spacecraft. For the first time Americans were allowed to tour a portion of the Soviet Baikonur Cosmodrome, and Western news correspondents were permitted inside the flight-control center at Kaliningrad.The total cost to NASA of the Apollo-Soyuz Test Project (ASTP) was $250 million. The Apollo crew consisted of Air Force Brig. Gen. Thomas P. Stafford; Vance D. Brand, a civilian; and D. K. Slayton, a civilian and one of the original seven Project Mercury astronauts.
Aboard the smaller, two-man Soyuz 19 were the pilot, Col. Aleksei Leonov, and the engineer, Valery N. Kubasov.Soyuz 19 was launched from Baikonur at 8:20 am Eastern Daylight Time, on July 15, 1975, and Apollo was launched 71/2 hours later from Florida. Because Apollo had the more powerful propulsion system, it carried the docking module to orbit. The vessels docked over a spot in the Atlantic Ocean some 1,030 km (640 mi) west of Portugal on July 17 at 12:09 pm Eastern Daylight Time. During the next two days the crews made four transfers between the two ships and completed five planned experiments.The vessels separated July 19. Soyuz landed in Kazakhstan on July 21, and Apollo in the Pacific Ocean on July 24. During their descent the Apollo crew suffered discomfort from inhaling nitrogen tetroxide fumes, which entered the cabin as the result of a landing-procedure error. The nine-day mission was the last one of the Apollo program.