The mission followed an aborted Soyuz 18-1 launch three months earlier that nearly killed its crew, and its success helped restore confidence in the Soviet space program ahead of the joint Apollo-Soyuz Test Project later that month. Klimuk and Sevastyanov conducted solar and astrophysical observations aboard Salyut 4.
Soviet human spaceflight had suffered a harrowing scare in April 1975 when Soyuz 18-1's launch failed mid-ascent, forcing cosmonauts Vasily Lazarev and Oleg Makarov into a ballistic abort that subjected them to forces of over 20g before they landed in a remote, snow-covered stretch of the Altai mountains, narrowly avoiding tumbling down a cliff. The near-disaster forced a pause and review before the program continued.
Soyuz 18's successful docking with Salyut 4 that July was therefore a relief as much as a triumph, arriving just weeks before the historic Apollo-Soyuz handshake in orbit was due to mark the symbolic thaw of the Space Race. Klimuk and Sevastyanov spent 63 days aboard the station, running solar telescope observations and medical experiments on long-duration spaceflight.
The mission's quiet competence, rarely remembered next to Apollo-Soyuz's headlines, nonetheless mattered enormously to Soviet engineers rebuilding confidence in their hardware, and it demonstrated the kind of extended-duration orbital science that would define the Salyut and later Mir programs for the next two decades.
Key people: Pyotr Klimuk, Vitaly Sevastyanov