Tags: Artificialsatellite, Satellite.
Kosmos 521 (Russian: Космос 521 meaning Cosmos 521) also known as DS-P1-M No.4 is a satellite which was intended for use as a target for tests of anti-satellite weapons. It was launched by the Soviet Union in 1972 as part of the Dnepropetrovsk Sputnik programme and was to have been used as a target for an IS-A interceptor as part of the Istrebitel Sputnik programme.