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Mission record

Sputnik 20

Also known as 1962 Alpha Tau 1, Sputnik 24 (USNSC), Sputnik20

U.S.S.R · Launched

Explore trajectory

Failed · Failure

A Venera-type spacecraft intended to be a Venus landing mission. The SL-6/A-2-e launcher inserted it into geocentric orbit on 1 September 1962, but ignition of the Block L engine failed when a fuel valve did not open, and the spacecraft was stranded in Earth orbit until it reentered the atmosphere five days later.

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
Lander

Chronology

Mission timeline

  1. Launch

    Launched into Earth orbit, where the Block L engine failed to ignite

    NSSDCA's launch/orbital information page gives the launch date and time as 1962-09-01T02:24:00Z, recorded at minute precision because the page prints a whole minute with zero seconds, and an Earth orbit with a periapsis of 180.00 km, an apoapsis of 310.00 km, a period of 89.40 minutes and an inclination of 64.900°. The master catalog records that ignition of the Block L engine to achieve Venus orbit failed when a fuel valve did not open. Source review: NSSDCA gives September 1 launch at 02:24 UTC; NASA history gives 02:12:33 UT. The conflict remains explicit; neither a midpoint nor a more precise combined epoch is justified.

    Earth

  2. Mission end

    Orbit decayed five days after launch

    The master catalog records that the spacecraft was stranded in Earth orbit until it reentered the Earth's atmosphere five days later; the launch/orbital information page gives a decay date of 1962-09-06 and ends the Earth-orbit epoch at 1962-09-06 00:00:00.

    Earth

Mission architecture

Vehicles

  • Sputnik 20 · Spacecraft

    Destinations: Venus

    • 2MV-1 No. 2 SA · Other

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