Soyuz 20

Soyuz 20 (Союз 20, Union 20) was an uncrewed spacecraft launched by the Soviet Union. It was a long-duration test of the Soyuz spacecraft that docked with the Salyut 4 space station. Soyuz 20 performed comprehensive checking of improved on-board systems of the spacecraft under various flight conditions. It also carried a biological payload. Living organisms were exposed to three months in space.

Mission parameters

 * Mass: 6570 kg
 * Perigee: 199.7 km
 * Apogee: 263.5 km
 * Inclination: 51.6°
 * Period: 88.8 minutes

Return
It was recovered on 16 February 1976 at 02:24 UTC.