|Mission type||ABM radar target|
|Launch mass||300 kilograms (660 lb)|
|Start of mission|
|Launch date||14 January 1971, 12:00:00UTC|
|Launch site||Plesetsk 133/1|
|End of mission|
|Decay date||21 February 1971|
|Perigee altitude||267 kilometres (166 mi)|
|Apogee altitude||803 kilometres (499 mi)|
Kosmos 391 (Russian: Космос 391 meaning Cosmos 391), also known as DS-P1-I No.11 was a satellite which was used as a radar target for anti-ballistic missile tests. It was launched by the Soviet Union in 1971 as part of the Dnepropetrovsk Sputnik programme.
Kosmos 391 was placed into a low Earth orbit with a perigee of 267 kilometres (166 mi), an apogee of 803 kilometres (499 mi), 70.9 degrees of inclination, and an orbital period of 95.3 minutes. It decayed from orbit on 21 February 1971.