Kosmos 686 (Russian: Космос 686 meaning Cosmos 686), also known as DS-P1-Yu No.72, was a Soviet satellite which was launched in 1974 as part of the Dnepropetrovsk Sputnik programme. It was a 400-kilogram (880 lb) spacecraft, which was built by the Yuzhnoye Design Bureau, and was used as a radar calibration target for anti-ballistic missile tests.^[1]

A Kosmos-2I 63SM carrier rocket was used to launch Kosmos 686 from Site 133/1 of the Plesetsk Cosmodrome.^[2] The launch occurred at 16:34:56 UTC on 26 September 1974, and resulted in the satellite successfully reaching low Earth orbit.^[3] Upon reaching orbit, the satellite was assigned its Kosmos designation, and received the International Designator 1974-074A.^[4] The North American Aerospace Defense Command assigned it the catalogue number 07447.

Kosmos 686 was the seventy-second of seventy nine DS-P1-Yu satellites to be launched,^[1] and the sixty-fifth of seventy two to successfully reach orbit.^[5] It was operated in an orbit with a perigee of 266 kilometres (165 mi), an apogee of 461 kilometres (286 mi), 70.9 degrees of inclination, and an orbital period of 91.8 minutes.^[6] It remained in orbit until it decayed and reentered the atmosphere on 1 May 1975.^[6]

• 1974 in spaceflight