|Mission type||Test flight|
|Operator||Soviet space program|
|Mission duration||90 days 11 hours 47 minutes|
|Spacecraft||Soyuz 7K-T No.8|
|Spacecraft type||Soyuz 7K-T/A9|
|Launch mass||6570 kg |
|Landing mass||2800 kg|
|Dimensions||7.13 m long|
2.72 m wide
|Start of mission|
|Launch date||17 November 1975,|
|Launch site||Baikonur, Site 1/5 |
|End of mission|
|Landing date||16 February 1976, 02:24 UTC|
|Landing site||56 km at the southwest of Arkalyk, Kazakhstan|
|Reference system||Geocentric orbit |
|Regime||Low Earth orbit|
|Perigee altitude||199.7 km|
|Apogee altitude||263.5 km|
|Docking with Salyut 4|
Soyuz 20 (Russian: Союз 20, Union 20) was an unmanned 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.
- 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
It was recovered on 16 February 1976 at 02:24 UTC.
- "Display: Soyuz 20 1975-106A". NASA. 14 May 2020. Retrieved 13 October 2020. This article incorporates text from this source, which is in the public domain.
- "Baikonur LC1". Encyclopedia Astronautica. Archived from the original on 15 April 2009. Retrieved 4 March 2009.
- "Trajectory: Soyuz 20 1975-106A". NASA. 14 May 2020. Retrieved 13 October 2020. This article incorporates text from this source, which is in the public domain.