The probe was the first dedicated 3MV spacecraft that the Soviets launched (earlier missions had been of the test “Object-Probe” versions). It was designed to accomplish atmospheric entry into Venus followed by descent and impact.

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 rather than one related to quality control. The spacecraft burned up in Earth’s atmosphere the following day. If successful, this mission would probably have been given a Venera designation.


Siddiqi, Asif A. Beyond Earth: A Chronicle of Deep Space Exploration, 1958-2016. NASA History Program Office, 2018.

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