Salyut 7 (Russian: Салют-7, lit. 'Salute 7'), also known as DOS-6, was a space station in low Earth orbit from April 1982 to February 1991. It was first crewed in May 1982 with two crew via Soyuz T-5, and last visited in June 1986, by Soyuz T-15. Various crew and modules were used over its lifetime, including 12 crewed and 15 uncrewed launches in total. Supporting spacecraft included the Soyuz T, Progress, and TKS spacecraft.
It was part of the Soviet Salyut programme, and launched on 19 April 1982 on a Proton-K rocket from Site 200/40 at the Baikonur Cosmodrome in the Soviet Union. Salyut 7 was part of the transition from monolithic to modular space stations, acting as a testbed for docking of additional modules and expanded station operations. It was the eighth space station of any kind launched. Salyut 7 was the last of both the second generation of DOS-series space stations and of the monolithic Salyut Program overall, to be replaced by Mir, the modular, expandable, third generation.
Salyut 7 was the backup vehicle for Salyut 6 and was very similar in equipment and capabilities. With delays to the Mir programme it was decided to launch the back-up vehicle as Salyut 7. In orbit the station suffered technical failures though it benefited from the improved payload capacity of the visiting Progress and Soyuz craft and the experience of its crews who improvised many solutions (such as a fuel line rupture in September 1983 requiring EVAs by the Soyuz T-10 crew to repair). It was aloft 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 (including French and Indian cosmonauts). The station also saw two flights of Svetlana Savitskaya making her the second woman in space since Valentina Tereshkova first flew in June 1963 and the first woman to perform an EVA during which she conducted metal cutting and welding alongside her colleague Vladimir Dzhanibekov. Aside from the many experiments and observations made on Salyut 7, the station also tested the docking and use of large modules with an orbiting space station. The modules were called "Heavy Kosmos modules" though in reality were variants of the TKS intended for the cancelled Almaz military space station. They helped engineers develop the technology necessary to build Mir.
It had two docking ports, one on either end of the station, to allow docking with the Progress uncrewed resupply craft, and a wider front docking port to allow safer docking with a Heavy Kosmos module. It carried three solar panels, two in lateral and one in dorsal longitudinal positions, but they now had the ability to mount secondary panels on their sides. Internally, the Salyut 7 carried electric stoves, a refrigerator, constant hot water and redesigned seats at the command console (more like bicycle seats). Two portholes were designed to allow ultraviolet light in, to help kill infections. The medical, biological and exercise sections were improved, to allow long stays in the station. The BST-1M telescope used in Salyut 6 was replaced by an X-ray detection system.
To support experiments in cultivating plants in space, several different plant life support systems were installed: Oasis 1A, Vazon, Svetoblok, Magnetogravistat, Biogravistat and Fiton(Phyton)-3. It was in Fiton-3 that Arabidopsis became the first plants to flower and produce seeds in the zero gravity of space.
Salyut 7 was the most advanced and comfortable space station of the Salyut series. A set of modifications to the interior made it more liveable. There were approximately 20 windows with shades on the Salyut 7. To protect the inside of the windows, they were covered with removable glass panels. The colour scheme was improved and a refrigerator was installed. The ceiling on the Salyut 7 was white; the left wall was apple green and the right one beige, a signature design by interior design architect, Galina Balashova, who carried on the concept through Soyuz to Mir and Buran, in an effort to replace 'survive' with 'comfort', working with seasoned cosmonauts to make living conditions better and 'closer to home' Externally, in a departure from previous first generation stations, the large diameter operations section which housed the large scientific apparatus, was colored in a distinctive brown-red and white stripe pattern. This was done to differentiate between it and the outwardly similar Salyut 6 that, for several months of its life, was in orbit at the same time.
The experience of long-term space missions has provided valuable information about the effects of zero gravity for space medicine, leading to the development of new medications and new medical equipment (for example, the "Biogravistat" medical device was created based on the experience of Salyut 7).
Following up the use of Kosmos 1267 on Salyut 6, the Soviets launched Kosmos 1443 on 2 March 1983 from a Proton SL-13. It docked with the station on 10 March, and was used by the crew of Soyuz T-9. It jettisoned its recovery module on 23 August, and re-entered the atmosphere on 19 September. Kosmos 1686 was launched on 27 September 1985, docking with the station on 2 October. It did not carry a recovery vehicle, and remained connected to the station for use by the crew of Soyuz T-14. Ten Soyuz T crews operated in Salyut 7. Only two Interkosmos "guest cosmonauts" worked in Salyut 7. The first attempt to launch Soyuz T-10 was aborted on the launch pad when a fire broke out at the base of the vehicle. The payload was ejected, and the crew was recovered safely.
Salyut 7 was the first crewed space vehicle to launch a satellite, when it fired the small experimental Iskra 2 satellite out of its waste airlock.
Salyut 7 had six resident crews.
The first crew, Anatoli Berezovoy and Valentin Lebedev, arrived on 13 May 1982 on Soyuz T-5 and remained for 211 days until 10 December 1982.
On 27 June 1983, the crew of Vladimir Lyakhov and Alexander Alexandrov arrived on Soyuz T-9 and remained for 150 days, until 23 November 1983.
On 8 February 1984, Leonid Kizim, Vladimir Solovyov and Oleg Atkov began a 237-day stay, the longest on Salyut 7, which ended on 2 October 1984.
Vladimir Dzhanibekov and Viktor Savinykh (Soyuz T-13) arrived at the space station on 6 June 1985 to repair its malfunctions.
On 17 September 1985, Soyuz T-14 docked with the station carrying Vladimir Vasyutin, Alexander Volkov and Georgi Grechko. Eight days later Dzhanibekov and Grechko left the station and returned to Earth after 103 days, while Savinyikh, Vasyutin and Volkov remained on Salyut 7 and returned to Earth on 21 November 1985 after 65 days.
On 6 May 1986, Soyuz T-15 carrying Leonid Kizim and Vladimir Solovyov docked with the space station and undocked, after a 50-day stay, on 25 June 1986. The Soyuz had come from the Mir space station and returned to Mir on 26 June 1986 in a flight lasting 29 hours.
There were also four visiting missions, crews which came to bring supplies and make shorter duration visits with the resident crews.
The station suffered from two major problems, the first of which required extensive repair work to be performed on a number of EVAs.