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Mission record

Sputnik 7

Also known as Tyazheliy Sputnik 4, 1961 Beta 1, Venera-1961A, Sputnik7

U.S.S.R · Launched

Explore trajectory

Failed · Failure

The first Soviet attempt at a Venus probe. An SL-6/A-2-e (Molniya 8K78) launcher put an Earth orbiting launch platform and the attached Venera probe into orbit, but the fourth stage, a Blok L Zond rocket, failed to ignite for the Venus transfer, probably because of a fault in the power supply to the guidance system. The spacecraft and launch platform remained attached in a 212 x 318 km Earth orbit until it decayed and they reentered on 26 February 1961. NSSDCA records the flight as the first attempt to launch a spacecraft from a preliminary Earth orbit.

Destinations
Launch vehicle
Modified SS-6 (Sapwood) with 2nd Generation Upper Stage + Escape Stage
Launch site
Tyuratam (Baikonur Cosmodrome), U.S.S.R
Countries
Soviet Union
Mission types
Atmospheric probe, Lander

Chronology

Mission timeline

  1. Launch

    Launched into Earth orbit, where the escape stage failed to ignite

    NSSDCA's launch/orbital information page gives the launch date and time as 1961-02-04T01:18:04Z and an Earth orbit with a periapsis of 212.00 km, an apoapsis of 318.00 km, a period of 89.80 minutes and an inclination of 64.950°. The master catalog records that the fourth stage was supposed to launch the Venera probe towards a landing on Venus after one Earth orbit but ignition failed, and that the spacecraft and launch platform remained attached. That page disagrees with itself on the mass and the disagreement is recorded rather than resolved: its Facts in Brief gives 6843 kg while its description gives the spacecraft's large size as 6483 kg. Source review: The 6483 kg orbiting mass includes the upper stage; the approximately 645 kg probe is not a second independently tracked object.

    Earth

  2. Mission end

    Orbit decayed and the spacecraft reentered

    The master catalog records that the orbit decayed and the spacecraft reentered the Earth's atmosphere on 26 February after 22 days; the launch/orbital information page gives a decay date of 1961-02-26 and ends the Earth-orbit epoch at 1961-02-26 00:00:00. Recorded at day precision because that is the precision both pages publish.

    Earth

Mission architecture

Vehicles

  • Sputnik 7 · Spacecraft

    Destinations: Venus

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.
  • 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