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Mission record

Mars 7

Also known as M-73 No.51P, Mars7

U.S.S.R · Launched

Explore trajectory

Failed · Failure

The last of the four Soviet spacecraft launched towards Mars in July and August of 1973. The Mars 7 interplanetary station was intended to be a Mars lander, consisting of a flyby bus and a descent module designed to enter the martian atmosphere and make in-situ studies of the atmosphere and surface, but a malfunction on board caused the lander to miss the planet. Due to a problem in the operation of one of the onboard systems the landing probe separated prematurely, four hours before encounter, and missed the planet by 1300 km; the lander and bus continued on into heliocentric orbits.

Destinations
Launch vehicle
Proton Booster Plus Upper Stage and Escape Stages
Launch site
Tyuratam (Baikonur Cosmodrome), U.S.S.R
Countries
Soviet Union
Mission types
Lander, Flyby

Chronology

Mission timeline

  1. Launch

    Launched into an intermediate Earth orbit

    NSSDCA's launch/orbital information page gives the launch date and time as 1973-08-09T17:00:17Z and an Earth orbit with a periapsis of 154.00 km, an apoapsis of 193.00 km, a period of 87.90 minutes and an inclination of 51.500°. Mars 7 successfully lifted off into an intermediate Earth orbit on a Proton SL-12/D-1-e booster and then launched into a Mars transfer trajectory. Total fueled launch mass of the lander and bus was 3260 kg.

    Earth

  2. Milestone

    Course correction burn

    After one course correction burn on 16 August 1973, it reached Mars on 9 March 1974.

  3. Deployment

    The landing probe separated 4 hours before encounter

    Due to a problem in the operation of one of the onboard systems (attitude control or retro-rockets) the landing probe separated prematurely (4 hours before encounter) and missed the planet by 1300 km. The early separation was probably due to the computer chip error which resulted in degradation of the systems during the trip to Mars. The intended landing site was 50 S, 28 W and landed mass would have been 635 kg.

    Mars

  4. Flyby

    The lander and bus continued on into heliocentric orbits

    The lander and bus continued on into heliocentric orbits. NSSDCA's launch/orbital information page records a Mars flyby with a closest approach time of 1974-03-09 00:00:00 and a periapsis of 1300.00 km, which is the same figure the master catalog gives as the distance by which the probe missed the planet. That page also prints a Decay Date of 1974-03-09, which the master catalog's heliocentric orbits contradict; the disagreement is recorded rather than resolved. Recorded at day precision because the trajectory page's time is midnight rather than an observed one.

    Mars

  5. Mission end

    Last reported contact with the flyby carrier

    NASA reports carrier contact through March 25, after its Mars encounter. The separately released capsule missed Mars; neither vehicle performed surface operations. Loss of contact does not establish a physical end of either heliocentric orbit.

    Mars

Mission architecture

Vehicles

  • Mars 7 flyby bus · Spacecraft

    Destinations: Mars

    • Mars 7 descent module · Lander

      Destinations: Mars

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.
  • Approach/departure directions and burn vectors between the reported encounters; body names and encounter distances alone are insufficient.
  • 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