In May 1972, an agreement was reached between the United States and the Soviet Union that would set the stage for an historic meeting in space. At the height of the cold war, President Richard M. Nixon and Chairman of the Council of Ministers of the USSR Aleksey N. Kosygin signed an Agreement on Cooperation in the Exploration and the Use of Outer Space for Peaceful Purposes. This would lead to the first ever joint space mission between the two countries. Up until this point, the U.S. and the Soviet Union had been rivals in the space race. For the first time, they would now collaborate rather than compete.
The joint mission was designated the Apollo-Soyuz Test Project or ASTP for short. The main goals of the ASTP were to test the compatibility of rendezvous and docking systems and the possibility of an international space rescue. The United States would use its Apollo Spacecraft that had been designed for the Apollo lunar missions. The Soviet Union would use its Soyuz spacecraft that was used to ferry cosmonauts to its Salyut Space Stations. These two vehicles used very different and incompatible docking hatches. To overcome this problem, NASA designed and constructed a special docking module to serve as an airlock and transfer corridor between the two craft. It would also compensate for the differing atmospheric pressures between the two vehicles.
On July 15, 1975, at 8:20 a.m. EDT Soyuz 19 launched from the Baikonur Cosmodrome in Kazakhstan carrying cosmonauts Alexey Leonov and Valery Kubasov. Leonov was notable for being the first human to ever perform a spacewalk in March 1965. Soyuz 19 also marked the first time a Soviet launch had been televised live. The Apollo spacecraft lifted off from NASA’s Kennedy Space Center at 3:50 p.m. with astronauts Thomas Stafford, Vance Brand and Donald Slayton on board. Donald Slayton, known as “Deke”,was one of the original seven Mercury astronauts. He did not get a chance to fly in the Mercury Program because of a heart irregularity. He became director of flight crew operations and the person responsible for astronaut flight assignments. In 1972 he regained his flight status and was finally able to fly in space on the ASTP mission as the docking module pilot.
Apollo and Soyuz linked up in Earth orbit on July 17 at 12:12 p.m. and the hatches between the two vehicles were opened about three hours after docking. Commanders Leonov and Stafford greeted each other in the docking module. The astronauts and cosmonauts took congratulatory calls from Soviet General Secretary Leonid Brezhnev and U.S. President Gerald Ford. They also exchanged commemorative gifts and shared a meal before closing the hatch for the day. The next day, Brand joined Kubasov in the Soyuz, while Leonov joined Stafford and Slayton in the Apollo. After giving TV viewers a tour of each vehicle, the crew members conducted science experiments and had lunch. Later, Kubasov and Brand left the Soyuz to join Slayton in the Apollo while Leonov and Stafford were in the Soyuz.
The two spacecraft undocked on July 19 at 8:02 a.m. marking the end of the first joint docking in space. Soyuz 19 returned to Earth on July 21, landing less than seven miles from its target near The Baikonur Cosmodrome. Apollo splashed down in the Pacific Ocean west of Hawaii on July 24. This was the last splashdown landing for U.S. human spaceflight until 2020. When astronauts Bob Behnken and Doug Hurley return to Earth in the Dragon Crew Capsule, they will make the first ocean splashdown of U.S. astronauts since Stafford, Brand, and Slayton 45 years ago.
The Apollo-Soyuz Test Project was a great success. It proved that two countries that had been rivals could work together in space and also develop compatible space hardware. This mission helped pave the way for later missions of Space Shuttles visiting the MIR Space Station. Cosmonauts would fly on shuttles, and astronauts would stay for months on the MIR Station. Later, the International Space Station would be built fulfilling the promise of international cooperation first begun in July 1975.