Salyut Seven (DOS-6) was the ninth station of the Salyut programme and the sixth of the Durable Orbital Station series of civilian space stations. It was launched on 19 April 1982 on a Proton-K rocket from Site 200/40 at the Baikonur Cosmodrome in the Soviet Union. It remained in orbit until February 1991 when prematurely de-orbited and was destroyed by re-entry into the Earth's atmosphere. It was first crewed in May 1982 and last visited in June 1986. Over its lifetime it was visited by twelve crews and fifteen un-crewed craft.

Salyut Seven was a single module station but used as a testbed for docking of additional modules and expanded station operations. It was the last of the second generation of DOS-series single module space stations. It was replaced by Mir, the multi-module, expandable, third generation station.

Salyut Seven was originally built as the backup for Salyut Six and therefore had very similar equipment and capabilities. Because of delays with the Mir programme it was decided to launch Salyut Seven to test components and systems to be used in Mir.

Once in orbit Salyut Seven experience various technical failures which required its crews to improvise solutions. This was possible because of the experience of the crews and the improved payload capacity of the visiting Progress and Soyuz craft.

Soyuz Seven was in orbit for eight years and ten months (a record not broken until Mir), during which time it was visited by 10 crews constituting six main expeditions and four secondary flights. The station crews performed many experiments and observations and also tested the docking and use of large modules. The modules, called "Heavy Kosmos modules", were variants of the TKS craft intended for the Almaz military stations which were cancelled. This helped the development the technology necessary to build Mir.

Reference: Wikipedia - Salyut 7