Soyuz 25

Soyuz 25 was the first crewed attempt to visit Salyut 6 after the station reached orbit. Vladimir Kovalyonok commanded the mission with Valeri Ryumin as flight engineer, launching from Baikonur Site 1/5 on October 9, 1977. The spacecraft reached Salyut 6 and made repeated soft-docking attempts, but the docking mechanism did not achieve a firm connection. With limited battery life and not enough propellant margin to try the opposite station port, mission control brought the crew home after about two days in orbit. The safe return preserved the crew but changed later Soviet crew-assignment practice, because future long-duration station crews were required to include at least one spaceflight veteran.