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Mission record

Cosmos 27

Also known as Cosmos27, Kosmos 27

U.S.S.R · Launched

Explore trajectory

Failed · Failure

A mission NSSDCA describes as intended for a Venus flyby and probe. The SL-6/A-2-e (Molniya + Blok I) launcher successfully achieved Earth orbit on 27 March 1964, but the circuit for the valves of the attitude control system malfunctioned, the spacecraft could not maintain a stable attitude for the burn to head for Venus, and it was left in Earth orbit and designated Cosmos 27. It reentered and burned up in the atmosphere the next day.

Destinations
Launch vehicle
Molniya-M
Launch site
Tyuratam (Baikonur Cosmodrome), U.S.S.R
Countries
Soviet Union
Mission types
Flyby, Atmospheric probe

Chronology

Mission timeline

  1. Launch

    Reached Earth orbit; Blok L escape ignition failed

    Both NSSDCA pages give the launch as 27 March 1964 at 03:24:43 UT. The launch/orbital information page disagrees with itself and the disagreement is recorded rather than resolved: its Earth-orbit row gives an epoch start of 1964-03-27 03:21:00, three minutes and forty-three seconds before the launch date and time printed at the head of the same page. The two catalogues also disagree on which object carries the satellite number: the master catalog lists 00770 among this spacecraft's alternate names, while GCAT gives 00770 to the Molniya 8K78(M) Blok-I stage as S00770, piece 1964-014B, and gives the spacecraft S00772. Source review: NSSDCA calls the failed escape stage Blok I; the NASA history identifies Blok L, the fourth stage. The reviewed event uses the latter identification with the disagreement disclosed. The orbit page's 03:21 UTC start precedes its 03:24:43 launch; it cannot serve as an osculating state epoch.

    Earth

  2. Mission end

    Reentered the day after launch

    The master catalog records that the spacecraft reentered and burned up in the atmosphere the next day, and the launch/orbital information page gives a decay date of 1964-03-28.

    Earth

Mission architecture

Vehicles

  • Cosmos 27 · Spacecraft

    Destinations: Venus

    • 3MV-1 No. 3 SA · Probe

Trajectory record

Trajectory dataset not yet available

Known dates and encounters do not uniquely determine a flight path. This mission’s sourced timeline is available above; no verified trajectory is currently published here.

What is needed to reconstruct this path?
  • A frame-qualified position and vector velocity at an epoch, or equivalent complete orbital elements.
  • Separate state histories and release epochs for the listed vehicles; a parent mission trajectory cannot be assigned to every component.
  • Finer event-time constraints where required by an orbital reconstruction; the stored day/month/year precision is retained.
  • The actual failed-flight state history. Intended destinations are not evidence that the spacecraft reached them.

Provenance

Sources

Each source is listed once and labeled with the mission, event, trajectory, or destination/body context it supports.

Data verified through September 14, 2026