Kosmos 1686

Kosmos 1686(top) docked toSalyut 7, imaged by Range-Doppler radar.
Salyut program insignia
Station statistics
COSPAR ID	1985-086A
SATCATno.	16095
Call sign	Salyut 7
Launch	1985-09-27 02:01:00UTC Docked toSalyut 7 on 1985-10-02.
Launch pad	Baikonur200/39
Reentry	February 7, 1991
Mass	20,000 kg
Length	15 m
Width	16 m
Diameter	4.15 m
Periapsis altitude	219 km (118.25nmi)
Apoapsis altitude	278 km (150.1 nmi)
Orbital inclination	51.6degrees
Orbital period	89.2minutes
Orbits per day	16.14
Days in orbit	1959 days
Statistics as of deorbit & reentry References:[1][2]
Configuration
Combined Kosmos 1686-Salyut 7 space station complex

Kosmos 1686 (Russian:Космос 1686 meaningCosmos 1686), also known asTKS-4, was a heavily modifiedTKS spacecraft which docked unmanned to theSovietspace stationSalyut 7 as part of tests to attach scientific expansion modules to stations in Earth orbit. The module which docked to the station was the FGB component of a TKS vehicle launched on September 27, 1985, and was designed to test systems planned for use on theMir Core Module. The spacecraft docked with Salyut 7 on October 2, 1985, during the long-duration stay of the cosmonauts of its fifth principal expedition, which arrived onSoyuz T-14.^[2] It was the last flown TKS spacecraft.

• The spacecraft'sVA capsule was greatly modified to carry instruments – the retrorocket and parachute packages were replaced by scientific equipment, including an infrared telescope and the Ozon spectrometer.^[2]
• The combined Salyut 7-Kosmos 1686 complex massed 43 tons, with Kosmos 1686 delivering 4500 kg of cargo to Salyut 7 and nearly doubling the amount of habitable volume available to the station's crew.^[2]
• On August 19–22, 1986, ground controllers boosted the vacant Salyut 7-Kosmos 1686 complex to a 474 km by 492 km orbit using engines on Kosmos 1686. This reduced the propellant supply of the complex to 70 kg (about 500 kg were required for controlled deorbit). In addition, Kosmos 1686 and Salyut 7 each suffered major systems breakdowns soon after they were abandoned, making the complex impossible to control.^[2]
• All previous space stations over which the Soviets maintained control were intentionally deorbited after their last cosmonaut crew departed. The Soviets estimated that the reboost gave the complex an 8-yr lifetime in orbit. They considered recovering the station using theBuran shuttle. However, following delays to and the eventual cancellation of theBuran program, Kosmos 1686 underwent uncontrolled reentry with Salyut 7 on February 7, 1991, reentering over Argentina, scattering much of its debris over the town ofCapitan Bermudez.^[3][4][5]

• Salyut program
• Kosmos satellites
• 1985 in the Soviet Union
• Spacecraft launched in 1985

• Articles with short description
• Short description matches Wikidata
• Use mdy dates from February 2013
• Articles containing Russian-language text