Soyuz 18

Soyuz 18 was the second successful crewed expedition to Salyut 4. Pyotr Klimuk and Vitaly Sevastyanov launched from Baikonur Site 31/6 on May 24, 1975, docked with Salyut 4 the next day, and spent nearly 63 days aboard the station before landing east of Arkalyk on July 26. The crew had originally backed up the failed Soyuz 18a launch and then carried the next Salyut 4 expedition. Their work emphasized biomedical studies of long-duration spaceflight, plant-growth investigations, Earth photography, solar observations, and maintenance of station systems. Spacefacts notes that the crew remained aboard Salyut 4 during the Apollo-Soyuz Test Project period, requiring Soviet controllers to support two unrelated crewed missions at the same time. The flight gave Klimuk his second spaceflight and Sevastyanov his second and final spaceflight.