Tags: Artificialsatellite, Satellite.
Kosmos 21 (Russian: Космос 21 meaning Cosmos 21) was a Soviet spacecraft with an unknown mission.[citation needed] This mission has been tentatively identified by NASA as a technology test of the Venera series space probes. It may have been an attempted Venus flyby presumably similar to the later Kosmos 27 mission or it may have been intended from the beginning to remain in geocentric orbit. In any case the spacecraft never left Earth orbit after insertion by the SL-6/A-2-e launcher.