Launch from Baikonur; landing 110 km northeast of Tselinograd; docking on space station Salyut 4, which had been launched 3 days earlier.

Transfer into space station and 29 days stay time there. Several astronomical experiments were performed. The crew discovered that the main mirror of the solar telescope had been ruined by direct exposure to sunlight when the pointing system failed. They resurfaced the mirror and worked out a way of pointing the telescope using a stethoscope, stopwatch, and the noises the moving mirror made in its casing.