title: Soyuz 20
text: # Soyuz 20
  
  Soyuz 20 (Russian: 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: 6,570 kg (14,480 lb)
  * Perigee: 199.7 km (124.1 mi)
  * Apogee: 263.5 km (163.7 mi)
  * Inclination: 51.6°
  * Period: 88.8 minutes
  
  ## Return
  
  It was recovered on 16 February 1976 at 02:24 UTC.
  
  