Soyuz 20 (, Union 20) was an uncrewed spacecraft launched by the

Soviet Union The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...

. It was a long-duration test of the

Soyuz spacecraft Soyuz () is a series of spacecraft which has been in service since the 1960s, having made more than 140 flights. It was designed for the Soviet space program by the Korolev Design Bureau (now Energia). The Soyuz succeeded the Voskhod spacecraf ...

that docked with the Salyut 4

space station A space station (or orbital station) is a spacecraft which remains orbital spaceflight, in orbit and human spaceflight, hosts humans for extended periods of time. It therefore is an artificial satellite featuring space habitat (facility), habitat ...

. 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. The primary goal of the mission was to test hardware modifications to the Soyuz 7K-T spacecraft that would extend its operating life from two to three months in preparation for long-duration Salyut crew residencies.

Mission parameters

*Mass: *Perigee: *Apogee: *Inclination: 51.6° *Period: 88.8 minutes

Return

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

References

{{Orbital launches in 1975 Soyuz uncrewed test flights Spacecraft launched in 1975 Spacecraft which reentered in 1976 Spacecraft launched by Soyuz-U rockets