Mars 7

Mars 7 (Russian: Марс-7), also known as 3MP No.51P was a Soviet spacecraft launched 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
Mission typeMars flyby/lander[1]
OperatorLavochkin
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
ManufacturerLavochkin
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]
RocketProton-K/D
Launch siteBaikonur 81/24
End of mission
Last contact"contact was maintained until 25 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)
 

Spacecraft

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.

Launch

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

References
  1. Krebs, Gunter. "Interplanetary Probes". Gunter's Space Page. Retrieved 13 April 2013.
  2. "Mars 7". US National Space Science Data Centre. Retrieved 12 April 2013.
  3. McDowell, Jonathan. "Launch Log". Jonathan's Space Page. Retrieved 12 April 2013.
  4. https://www.nasa.gov/sites/default/files/atoms/files/beyond-earth-tagged.pdf
  5. 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.

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