View source for Mars 4

{{Short description|Failed Soviet orbiter mission to Mars (1973–1974)}}
{{Infobox spaceflight
| name                  = Mars 4
| image                 = Mars 4-5.jpg
| image_size            = 300px

| mission_type          = [[Mars]] orbiter<ref>{{cite web|url=http://space.skyrocket.de/doc_sat/ip_probe.htm|title=Interplanetary Probes|work=Gunter's Space Page|first=Gunter|last=Krebs|access-date=12 April 2013}}</ref>
| operator              = Soviet space program
| COSPAR_ID             = 1973-047A
| SATCAT                = 6742
| mission_duration      = {{time interval|21 Jul 1973 19:31|10 Feb 1974 15:38|show=dhm}}

| spacecraft            = [[3MS]] No.52S
| manufacturer          = [[NPO Lavochkin]]
| launch_mass           = {{cvt|3440|kg|lb}}<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1973-047A|title=Mars 4|publisher=NASA|access-date=6 December 2018}}</ref>

| launch_date           = {{start-date|21 July 1973, 19:30:59|timezone=yes}}&nbsp;UTC<ref name="LL">{{cite web|url=http://planet4589.org/space/log/launchlog.txt|title=Launch Log|first=Jonathan|last=McDowell|work=Jonathan's Space Page|access-date=12 April 2013}}</ref>
| launch_rocket         = [[Proton-K]]/[[Blok D|D]]  
| launch_site           = [[Baikonur Cosmodrome|Baikonur]] [[Baikonur Cosmodrome Site 81|81/23]]
| last_contact          = 10 February 1974, 15:38 UTC
| launch_contractor     = [[Khrunichev State Research and Production Space Center|Khrunichev]]

| orbit_reference       = [[Heliocentric orbit|Heliocentric]]<ref name="EA">{{cite web |url=http://www.astronautix.com/m/marsm-73.html|title=Mars M-73|author1=Mark Wade|publisher=Encyclopedia Astronautica|access-date=26 May 2024}}</ref>
| orbit_periapsis       = 1.02 AU
| orbit_apoapsis        = 1.63 AU
| orbit_inclination     = 2.2°
| orbit_period          = 556 days
| apsis                 = helion

|interplanetary         = 
 {{Infobox spaceflight/IP
   |type                = flyby
   |note                = failed orbiter
   |object              = [[Mars]]
   |arrival_date        = 10 February 1974, 15:34&nbsp;UTC
   |distance            = {{cvt|1844|km|mi}}
 }}

| programme             = '''[[Mars program]]'''
| previous_mission      = [[Mars 3]]
| next_mission          = [[Mars 5]]
}}

'''Mars 4''' ({{Langx|ru|Марс-4}}), also known as '''3MS No.52S''' was a [[Soviet Union|Soviet]] spacecraft intended to explore Mars. A 3MS spacecraft launched as part of the [[Mars program]]me, it was intended to enter orbit around Mars in 1974. However, computer problems prevented orbital insertion from occurring.<ref name="NSSDC">{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1973-047A|title=Mars 4|publisher=US National Space Science Data Centre|access-date=12 April 2013}}</ref>

== Spacecraft ==
The Mars 4 spacecraft carried an array of instruments to study Mars. In addition to cameras, it was equipped with a radio telescope, an IR [[radiometer]], multiple [[photometer]]s, [[polarimeter]]s, a [[magnetometer]], [[plasma trap]]s, an [[electrostatic analyzer]], a [[gamma-ray spectrometer]], and a radio probe.<ref name="DSC73">{{cite book |url=https://history.nasa.gov/monograph24/1973.pdf |archive-url=https://web.archive.org/web/20040925103513/http://history.nasa.gov/monograph24/1973.pdf |archive-date=2004-09-25 |url-status=live |last=Siddiqi |first=Asif A. |title=Deep Space Chronicle: A Chronology of Deep Space and Planetary Probes 1958-2000 |series=Monographs in Aerospace History, No. 24 |year=2002 |publisher=NASA History Office |chapter=1973 |pages=101–106}}</ref>

Built by Lavochkin, Mars 4 was the first of two 3MS spacecraft launched to Mars in 1973, being followed by [[Mars 5]]. A 3MS was also launched during the 1971 launch window as [[Kosmos 419]]. However, due to a launch failure, it failed to depart Earth orbit. In addition to the orbiters, two 3MP lander missions, [[Mars 6]] and [[Mars 7]], were launched during the 1973 window.

== Launch ==
Mars 4 was launched by a Proton-K carrier rocket, a Blok D upper stage, flying from Baikonur Cosmodrome Site 81/23.<ref name="LL"/> The launch occurred at 19:30:59 UTC on 21 July 1973, with the first three stages placing the spacecraft and upper stage into a [[low Earth orbit|low Earth]] [[parking orbit]] before the Blok D fired to propel Mars 4 into heliocentric orbit bound for Mars.

Shortly after performing a course correction on 30 July 1973, two onboard computers failed, leaving Mars 4 unable to perform maneuvers. As a result of this, it was unable to enter orbit around Mars. Twelve photographs were taken on 10 February 1974 from 15:32 UTC to 15:38 UTC as the probe flew past Mars with a closest approach of {{convert|1844|km}} at 15:34 UTC.<ref>Siddiqi, Asif A. (2016). Beyond Earth: A Chronicle of Deep Space Exploration 1958-2016, NASA History Program Office, http://www.nasa.gov/ebooks.</ref>

== Scientific Instruments ==
Mars 4 orbiter carried 15 scientific instruments on board to study Mars from orbital trajectory<ref name="DSC73" />

* Atmospheric Radio-probing Instrument
* [[Radio telescope|Radio Telescope]]
* [[Infrared]] Radiometer
* [[Spectrophotometry|Spectrophotometer]]
* Narrow-band [[Photometer]]
* Narrow-band Interference-[[Polarization (waves)|Polarization]] Photometer
* [[Imaging system|Imaging System]]
* [[Photometer]]s
* Two [[Polarimeter]]s
* [[Ultraviolet|Ultraviolet Photometer]]
* Scattered [[Solar Radiation]] Photometer
* [[Gamma spectrometry|Gamma Spectrometer]]
* [[Magnetometer]]
* [[Plasma trap|Plasma Traps]]
* Multichannel [[Electrostatic analyzer|Electrostatic Analyzer]]
 {{Clear}}

==See also==
* [[List of missions to Mars]]
* [[Timeline of artificial satellites and space probes]]

== References ==
{{reflist|2}}

{{Portal bar|Spaceflight|Solar System}}
{{Mars programme}}
{{Orbital launches in 1973}}
{{Mars spacecraft}}

{{Use British English|date=January 2014}}
{{Use dmy dates|date=May 2020}}

[[Category:1973 in the Soviet Union]]
[[Category:Spacecraft launched in 1973]]
[[Category:1973 in spaceflight]]
[[Category:Mars program]]
[[Category:Derelict satellites in heliocentric orbit]]
[[Category:4MV]]
[[Category:Non Earth orbiting satellites of the Soviet Union]]