Cosmos 27

This spacecraft mission was intended as a Venus flyby. The SL-6/A-2-e launcher successfully achieved Earth orbit, but the spacecraft failed to escape orbit for its flight to Venus, and was designated Cosmos 27.

Beginning in 1962, the name Cosmos was given to Soviet spacecraft which remained in Earth orbit, regardless of whether that was their intended final destination. The designation of this mission as an intended planetary probe is based on evidence from Soviet and non-Soviet sources and historical documents. Typically Soviet planetary missions were initially put into an Earth parking orbit as a launch platform with a rocket engine and attached probe. The probes were then launched toward their targets with an engine burn with a duration of roughly 4 minutes. If the engine misfired or the burn was not completed, the probes would be left in Earth orbit and given a Cosmos designation.