Kosmos 1686 (top) docked to Salyut 7, imaged by Range-Doppler radar.
Salyut program insignia
|Call sign||Salyut 7|
Docked to Salyut 7 on 1985-10-02.
|Launch pad||Baikonur Cosmodrome, USSR|
|Reentry||February 7, 1991|
|Periapsis altitude||219 km (118.25 nmi)|
|Apoapsis altitude||278 km (150.1 nmi)|
|Orbital inclination||51.6 degrees|
|Orbital period||89.2 minutes|
|Orbits per day||16.14|
|Days in orbit||1959 days|
|Statistics as of deorbit & reentry|
Combined Kosmos 1686-Salyut 7 space station complex
Kosmos 1686 (Russian: Космос 1686 meaning Cosmos 1686), also known as TKS-4, was a heavily modified TKS spacecraft which docked unmanned to the Soviet space station Salyut 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 the Mir 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 on Soyuz T-14. It was the last flown TKS spacecraft.