Mars 7
Mission typeMars flyby/lander[1]
COSPAR IDBus: 1973-053A
Lander: 1973-053D[2]
SATCAT no.Bus: 6776
Lander: 7224[2]
Mission duration7 months (launch to nearest approach)
Spacecraft properties
Spacecraft3MP No.51P
Launch mass3,260 kg (fueled lander and bus)[2]
Start of mission
Launch date9 August 1973, 17:00:17 (1973-08-09UTC17:00:17Z) UTC[3]
Launch siteBaikonur 81/24
End of mission
Last contact25 March 1974[4]
Orbital parameters
Reference systemHeliocentric
Flyby of Mars
Spacecraft componentBus
Closest approach9 March 1974
Mars flyby (failed landing)
Spacecraft componentLander
Closest approach9 March 1974
Distance1,300 km (810 mi)

Mars 7 (Russian: Марс-7), also known as 3MP No.51P was a Soviet spacecraft launched in 1973 to explore Mars. A 3MP bus spacecraft which comprised the final mission of the Mars programme, it consisted of a lander and a coast stage with instruments to study Mars as it flew past. Due to a malfunction, the lander failed to perform a maneuver necessary to enter the Martian atmosphere, missing the planet and remaining in heliocentric orbit along with the coast stage.


Mars 7 spacecraft carried an array of instruments to study Mars. The lander was equipped with a thermometer and barometer to determine the surface conditions, an accelerometer and radio altimeter for descent, and instruments to analyse the surface material including a mass spectrometer.[5] The coast stage, or bus, carried a magnetometer, plasma traps, cosmic ray and micrometeoroid detectors, stereo antennae, and an instrument to study proton and electron fluxes from the Sun.[5]

Built by Lavochkin, Mars 7 was the second of two 3MP spacecraft launched to Mars in 1973, having been preceded by Mars 6. Two orbiters, Mars 4 and Mars 5, were launched earlier in the 1973 Mars launch window and were expected to relay data for the two landers. However, Mars 4 failed to enter orbit, and Mars 5 failed after a few days in orbit.


Mars 7 was launched by a Proton-K carrier rocket with a Blok D upper stage, flying from Baikonur Cosmodrome Site 81/24.[3] The launch occurred at 17:00:17 UTC on 9 August 1973, with the first three stages placing the spacecraft and upper stage into a low Earth parking orbit before the Blok D fired to propel Mars 7 into heliocentric orbit bound for Mars. The spacecraft performed a course correction on 16 August 1973.[5]

Mars 7's lander separated from the flyby bus on 9 March 1974. Initially, it failed to separate. However, it was eventually released to begin its descent. Due to a retrorocket failure, the probe missed the atmosphere of Mars, and, instead of landing, flew past along with the coast stage, with a closest approach of 1,300 km (810 mi).[5] Known faults with the spacecraft's transistors were blamed for the failure, along with that of Mars 4.[5]

See also


  1. ^ Krebs, Gunter. "Interplanetary Probes". Gunter's Space Page. Retrieved 13 April 2013.
  2. ^ a b c "Mars 7". US National Space Science Data Centre. Retrieved 12 April 2013.
  3. ^ a b McDowell, Jonathan. "Launch Log". Jonathan's Space Page. Retrieved 12 April 2013.
  4. ^ Asif A. Siddiqi. "Beyond Earth : A CHRONICLE OF DEEP SPACE EXPLORATION, 1958–2016" (PDF). Retrieved 25 January 2022.
  5. ^ a b c d e Siddiqi, Asif A. (2002). "1973". Deep Space Chronicle: A Chronology of Deep Space and Planetary Probes 1958-2000 (PDF). Monographs in Aerospace History, No. 24. NASA History Office. pp. 101–106. Archived (PDF) from the original on 25 September 2004.