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Cosmos 305



This flight was an attempted lunar sample return mission. After successful insertion into Earth orbit, the block D rockets of the SL-12/D-1-e Proton launcher failed, leaving the spacecraft in geocentric orbit. The design was similar to the other Luna sample return, or "Moonscooper" missions. The craft consisted of four spherical fuel tanks and nozzles, thrusters, and landing legs set in a 4 meter wide base. A spherical sample return capsule and ascent stage sat atop the structure. A robot arm to collect samples (perhaps with a drill) and then place them in a hatch in the return capsule was attached to the base. After failing to leave Earth orbit, the mission was designated Cosmos 305.

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designation of this mission as an intended planetary probe is based on evidence from Soviet and non-Soviet sources and historical documents.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

  • 04150
  • Cosmos305
  • Kosmos 305

Facts in Brief

Launch Date: 1969-10-22
Launch Vehicle: Proton
Launch Site: Tyuratam (Baikonur Cosmodrome), U.S.S.R
Mass: 5600 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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