Editing Kosmos 27 (section)

== Mission ==

The probe was the first dedicated 3MV spacecraft that the Soviets launched (earlier missions had been of the test "Object-Probe" versions as Kosmos 21). It was designed to accomplish atmospheric entry into Venus followed by descent and impact. On 27 March 1964, it had a perigee of {{convert|167|km|mi}} and an apogee of {{convert|198|km|mi}}, with an inclination of 64.8° and an orbital period of 88.7 minutes.  The spacecraft successfully reached Earth orbit but failed to leave for Venus when the Blok L upper stage malfunctioned. The upper stage lost stable attitude due to a failure in the circuit of the power supply circuit that powered the valves for the attitude control system; hence, the stage remained uncontrollable and not ready to initiate a burn to leave Earth orbit. The problem was traced to a design error, the examination of [[telemetry]] data found that the failure was due to a design flaw in the circuitry of the BOZ unit, which resulted in power not being transferred to the attitude control jets on the Blok L stage, rather than one related to quality control. The spacecraft burned up in Earth's atmosphere the following day, on 28 March 1964. If successful, this mission would have been given a "Venera" designation.<ref name=siddiqi/>