A booster failure caused this early Soviet Mars mission to burn up in Earth's atmosphere.

  • This was the Soviet Union's second attempt to reach Mars in less than a week.
  • Unsuccessful Soviet missions often did not get names.


Besides a slightly uprated S5.9A main engine, this vehicle was identical to its predecessor, launched four days before. And like its predecessor, it never reached Earth orbit.

During the launch trajectory, there was a failure in the third stage (Blok I) engine at T+290 seconds due to frozen kerosene in the pipeline feeding its turbopump (which prevented a valve from opening). The third and fourth stages, along with the payload, burned up in Earth’s upper atmosphere over eastern Siberia.

The Mars flyby had been planned for May 15, 1961.


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

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