Kosmos 839 (Russian: Космос 839 meaning Cosmos 839) was a satellite which was used as a target for tests of anti-satellite weapons.

It was launched by the Soviet Union in 1976 as part of the Dnepropetrovsk Sputnik programme,[1] and used as a target for Kosmos 843 as part of the Istrebitel Sputnikov programme.

[2] It was launched aboard a Kosmos-3M carrier rocket,[3] from Site 132/1 at the Plesetsk Cosmodrome.

[4] Kosmos 839 was placed into a low Earth orbit with a perigee of 915 kilometres (569 mi), an apogee of 2,053 kilometres (1,276 mi), 65.9 degrees of inclination, and an orbital period of 115.6 minutes.

[2][5] Kosmos 839 was the third of ten Lira satellites to be launched,[1] of which all but the first were successful.