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Cosmos 27



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

Spacecraft and Subsystems

The spacecraft was a Venera type (3MV) flyby bus and a hard-lander probe. The bus was equipped with an STS-5 gas discharge counter, an LA-2 atomic hydrogen spectrometer, a scintillation counter, magnetometer, ion traps, and micrometeoroid detector. The probe carried an RMV barometer, TIPG thermometer, L-1A radiation detector, atmospheric composition experiment, DAS-2 luminosity experiment, K-2 electro-conductivity experiment, R-3 acidity measurement experiment, and a microorganism detection experiment.

Mission Profile

The spacecraft launched on 27 March 1964 at 03:24:43 UT, but could not leave Earth orbit due to a failure of the Blok I upper stage. The circuit that poweredd the valves for the attitude control system malfunctioned and the spacecraft could not maintain a stable attitude for the burn to head for Venus. The spacecraft was left in Earth orbit ad designated Cosmos 27. It reentered and burned up in the atmosphere the next day.

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designation of this mission as an intended planetary probe is based on evidence from Soviet and non-Soviet sources and historical documents.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.

Alternate Names

  • 00770
  • Cosmos27
  • Kosmos 27

Facts in Brief

Launch Date: 1964-03-27
Launch Vehicle: Molniya-M
Launch Site: Tyuratam (Baikonur Cosmodrome), U.S.S.R
Mass: 6520 kg

Funding Agency

  • Unknown (U.S.S.R)


  • Planetary Science
  • Engineering

Additional Information

Questions and comments about this spacecraft can be directed to: Dr. David R. Williams



NameRoleOriginal AffiliationE-mail

Selected References

  • Shelton, W., Soviet space exploration - the first decade, Arthur Barker Ltd., Unnumbered, London, England, 1969.
  • Harvey, B., The new Russian space programme from competition to collaboration, John Wiley and Sons, Chichester, England, 1996.
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