Mars 7
Failed Soviet flyby/lander mission to Mars (1973–1974)
title: "Mars 7" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["spacecraft-launched-in-1973", "1973-in-spaceflight", "1973-in-the-soviet-union", "mars-program", "derelict-satellites-in-heliocentric-orbit", "4mv"] description: "Failed Soviet flyby/lander mission to Mars (1973–1974)" topic_path: "general/spacecraft-launched-in-1973" source: "https://en.wikipedia.org/wiki/Mars_7" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0
::summary Failed Soviet flyby/lander mission to Mars (1973–1974) ::
::data[format=table title="Infobox spaceflight"]
| Field | Value |
|---|---|
| name | Mars 7 |
| image | Mars 6.jpg |
| image_size | 300px |
| mission_type | Mars flyby/lander |
| operator | Soviet space program |
| COSPAR_ID |
| | SATCAT | 6776 7224 | | mission_duration | | | spacecraft | 3MP No.51P | | manufacturer | NPO Lavochkin | | launch_mass | 3260 kg | | landing_mass | 635 kg | | launch_date | UTC | | launch_rocket | Proton-K/D | | launch_site | Baikonur 81/24 | | launch_contractor | Khrunichev | | last_contact | 25 March 1974 | | orbit_reference | Heliocentric | | apsis | helion | | type | flyby | | object | Mars | | component | Bus | | arrival_date | 9 March 1974 | | type | lander_flyby | | object | Mars | | component | Lander | | arrival_date | 9 March 1974 | | distance | 1300 km | | programme | Mars program | | previous_mission | Mars 6 | ::
| name = Mars 7 | image = Mars 6.jpg | image_size = 300px
| mission_type = Mars flyby/lander | operator = Soviet space program | COSPAR_ID =
| SATCAT = 6776 7224 | mission_duration =
| spacecraft = 3MP No.51P | manufacturer = NPO Lavochkin | launch_mass = 3260 kg | landing_mass = 635 kg
| launch_date = UTC | launch_rocket = Proton-K/D | launch_site = Baikonur 81/24 | launch_contractor = Khrunichev | last_contact = 25 March 1974
| orbit_reference = Heliocentric | apsis = helion
|interplanetary = |type = flyby |object = Mars |component = Bus |arrival_date = 9 March 1974 |type = lander_flyby |object = Mars |component = Lander |arrival_date = 9 March 1974 |distance = 1300 km
| programme = Mars program | previous_mission = Mars 6
Mars 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.
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. 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.
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. 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.
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 1300 km. Known faults with the spacecraft's transistors were blamed for the failure, along with that of Mars 4.
References
| url= https://science.nasa.gov/wp-content/uploads/2023/09/DSC_monograph24.pdf | author1= Asif A. Siddiqi | title= Deep Space Chronicle: A Chronology of Deep Space and Planetary Probes 1958-2000 | year= 2002 | publisher= NASA | pages= 101–106 | id= NASA-SP-2002-4524 | isbn= 978-1-780-39324-7 }}
| url= https://planet4589.org/space/gcat/data/derived/launchlog.html | title= Launch Log | author1= Jonathan McDowell | work= Jonathan's Space Page | access-date= 12 April 2013 }}
| url= https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1973-053A | title= Mars 7 | website= nssdc.gsfc.nasa.gov | publisher= NASA | access-date= 12 April 2013 | archive-date= 24 March 2017 | archive-url= https://web.archive.org/web/20170324131810/https://nssdc.gsfc.nasa.gov/nmc/spacecraftDisplay.do?id=1973-053A | url-status= dead
| author1= Gunter D. Krebs | url= https://space.skyrocket.de/doc_sdat/mars-73-lander.htm | title= Mars 6, 7 (Mars M73 Lander #1, #2) | work= Gunter's Space Page | access-date= 13 April 2013 }}
::callout[type=info title="Wikipedia Source"] This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page. ::