Editing Mariner 5

{{Short description|NASA flyby mission to Venus (1967–1968)}}
{{Use mdy dates|date=March 2020}}
{{Infobox spaceflight
| name              = Mariner 5
| image             = Mariner 5.jpg
| image_size        = 300
| image_caption     = 
| mission_type      = [[Venus]] flyby
| operator          = [[NASA]] / [[Jet Propulsion Laboratory|JPL]]
| mission_duration  = {{time interval|14 Jun 1967|5 Nov 1968}}
| COSPAR_ID         = 1967-060A
| SATCAT            = 2845
| spacecraft_type   = 
| manufacturer      = [[Jet Propulsion Laboratory]]
| dry_mass          = 
| launch_mass       = {{convert|244.9|kg}}<ref name=beyond/>
| power             = 170 W
| launch_date       = {{start-date|June 14, 1967, 06:01:00|timezone=yes}} UTC
| launch_rocket     = [[Atlas-Agena|Atlas-SLV3 Agena-D]]
| launch_site       = [[Cape Canaveral Air Force Station|Cape Canaveral]] [[Cape Canaveral Air Force Station Launch Complex 12|LC-12]]
| launch_contractor = 
| last_contact      = December 4, 1967<br><small>Loss of contact</small><br>October 14, 1968<br><small>Briefly regained</small>{{r|quickfacts|dem1}}
| instruments        = Ultraviolet Photometer <br /> Two-Frequency Beacon Receiver <br /> S-Band Occultation <br /> Helium-Vector Magnetometer  <br /> Solar-Plasma Probe <br /> Trapped Radiation Detector
| programme         = '''[[Mariner program]]'''
| previous_mission  = [[Mariner 4]]
| next_mission      = [[Mariner 6]]
| interplanetary    = {{Infobox spaceflight/IP
  |type         = flyby
  |object       = [[Venus]]
  |distance     = {{convert|3990|km|mi|abbr=off|sp=us}}
  |arrival_date = October 19, 1967
 }}
}}

[[Image:KSC-67PC-0184.jpg|thumb|Launch of Mariner 5]]

'''Mariner 5''' ('''Mariner V''' or '''Mariner Venus 1967''') was a spacecraft of the [[Mariner program]] that carried a complement of experiments to probe [[Venus]]' atmosphere by [[radio occultation]], measure the hydrogen Lyman-alpha (hard ultraviolet) spectrum, and sample the solar particles and [[magnetic field]] fluctuations above the [[planet]]. Its goals were to measure interplanetary and Venusian magnetic fields, charged particles, plasma, radio refractivity and UV emissions of the Venusian atmosphere.

==History==
Mariner 5 was built as a backup to [[Mariner 4]], but after the success of the Mariner 4 mission, it was modified to be used for a Venus flyby mission  to take place during the 1967 Venus launch window. Mariner 5 omitted several experiments from Mariner 4, including the TV camera, the ionization chamber/geiger counter, the cosmic ray detector, and the cosmic dust detector. It retained the helium-vector magnetometer, solar plasma probe, and trapped radiation detector from Mariner 4. Unlike Mariner 4, Mariner 5 needed to face away from the Sun to keep its high-gain antenna pointed at Earth because of its trajectory. As a result, the solar panels were reversed to be aft facing so they could remain pointed at the Sun. Additionally, since its mission to Venus brought it in closer proximity to the Sun, fewer solar cells were needed to achieve the necessary power generation, and as a result the solar panels were reduced in size to save mass as well as to make room for two 50&nbsp;MHz dual-frequency receiver (DFR) antennas that were mounted on the frame of two of the solar panels. Since the aft side of the spacecraft faced the Sun, the solar plasma probe was relocated to the aft-facing side of Mariner 5.<ref name=Layman/>

[[File:Mariner 5 diagram.png|thumb|Mariner 5 diagram]]

The mounting for the high-gain antenna also needed modification. Unlike Mariner 4, where the geometry of the transfer orbit allowed for the high-gain antenna to be inclined at a relatively simple 38 degrees from the bottom plane, Mariner 5's trajectory required the high-gain antenna to be skewed at a more awkward angle. The high-gain antenna also included a single-use mechanism that allowed the high-gain antenna to make a shift in its angle as part of the radio occultation experiment.<ref name=Layman/> Mariner 5 also included some additional equipment that was not flown on Mariner 4, such as its Ultraviolet Photometer, two 50&nbsp;MHz DFR antennas, a 423&nbsp;MHz DFR antenna mounted on the end of one of the solar panels, and a deployable Sun-shade on the aft of the spacecraft for thermal control. The UV Photometer was originally supposed to fly on Mariner 4 and would have been mounted to its TV Camera scan platform. However, it was removed (allowing it to be flown on Mariner 5) and swapped out for a thermal/inertial mass simulator late in the assembly of Mariner 4 as it was discovered to create electrical arcing problems that would have jeopardized the TV Camera.<ref name=Layman/>

Prior to the choice of Venus as the target, proposals had been made to send it to either the comet [[7P/Pons–Winnecke]] or [[10P/Tempel]].<ref name=Ulivi57/>

==Launch==
Liftoff took place on June 14, 1967, from [[Cape Canaveral Air Force Station]] Launch Complex 12 on Atlas vehicle 5401. Booster performance was normal through the Atlas portion of the launch and the first Agena burn, with all systems operating at the proper level. During the second Agena burn, abnormal fluctuations in the engine chamber pressure occurred, however they did not preclude successful interplanetary injection. There had been several occurrences of this behavior on previous NASA and Air Force launches and a program was initiated to correct it which led to a redesign of the Agena turbopump gearbox.

==Venus flyby==
Mariner 5 flew by Venus on  October 19, 1967,  at an altitude of {{convert|3990|km|mi|sp=us}}. With more sensitive instruments than its predecessor [[Mariner 2]], Mariner 5 was able to shed new light on the hot, [[cloud]]-covered planet and on conditions in interplanetary space.

Radio occultation data from Mariner 5 helped to understand the temperature and pressure data returned by the [[Venera 4]] lander, which arrived at Venus shortly before it. The ''Venera 4'' and ''Mariner 5'' data was subsequently analysed together under a combined Soviet–American working group of [[COSPAR]] in 1969,{{r|sagan-1969|conf1}} an organization of early space cooperation.<ref name=nasa1/> With the data of these missions, it was clear that Venus had a very hot surface and an atmosphere even denser than expected.

The operations of Mariner 5 ended in November 1967 and it is now defunct in a [[heliocentric orbit]].

==Further communication attempts==
Further communication attempts were tried, in a joint spacecraft solar wind / solar magnetic fields investigation with [[Mariner 4]], back in communication with Earth after being out of telemetry for about a year or more around superior conjunction. During the experiment, both spacecraft were going to be on the same idealized magnetic field spiral carried out from the sun by the solar wind.

Between April and November 1968 NASA tried to reacquire Mariner 5 to continue probing interplanetary conditions.
Attempts to reacquire Mariner 5 during June, July, and early August 1968 yielded no spacecraft signal.

On October 14, the receiver operator at DSS 14 obtained a lock on the Mariner 5 signal. A carrier wave was detected, but outside expected frequency limits and varying in wavelength. Signal strength changes indicated the spacecraft was in a slow roll. Nevertheless, it was possible to lock the spacecraft to an uplink signal, but no response was observed to any commands sent to it. Without telemetry and without any signal change in response to commands, there was no possibility to repair or continue to use the spacecraft. Operations were terminated at the end of the track from DSS 61 at 07:46 GMT on November 5, 1968.

==Experiments==
Mariner 5 returned data from seven experiments:<ref>{{Cite web |title=Mariner 5 Experiment Search Results |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/displayExperiment.action?spacecraftId=1967-060A |website=NSSDCA Master Catalog}}</ref>

=== Celestial Mechanics ===
Tracking data from Mariner 5, combined with [[NASA Deep Space Network|Deep Space Network]] equipment, were used to refine the masses of Venus and the Moon, improve the [[astronomical unit]], and update Earth-Venus [[Ephemeris|ephemerides]]. [[Doppler effect|Doppler]] measurements worked effectively up to 48 million km. Principal investigator was [[John D. Anderson]] from the [[Jet Propulsion Laboratory]].<ref>{{Cite web |title=Celestial Mechanics |url=https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1967-060A-07 |website=NSSDCA Master Catalog}}</ref>

=== Interplanetary Ion Plasma Probe for E/Q of 40 to 9400 Volts ===
This three-part [[Faraday cup]] measured positive ions from 40 to 9400 eV/Q in eight energy ranges. Always facing the Sun, it gathered directional data by comparing signals from its three 120° collectors. It cycled through voltage settings in two modes—total and individual plate currents—producing 64 measurements every 5 minutes. The instrument functioned normally throughout the mission. Principal investigator was Herbert S. Bridge from the [[Massachusetts Institute of Technology]].<ref>{{Cite web |title=Interplanetary Ion Plasma Probe for E/Q of 40 to 9400 Volts |url=https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1967-060A-03 |website=NSSDCA Master Catalog}}</ref>

=== S-Band Occultation ===
This experiment aimed to study Venus's atmosphere and [[ionosphere]] by analyzing changes in the [[S band|S-band]] signal, including phase shift, Doppler shift, and signal weakening. Principal investigator was Arvydas J. Kliore from the Jet Propulsion Laboratory.<ref>{{Cite web |title=S-Band Occultation |url=https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1967-060A-01 |website=NSSDCA Master Catalog}}</ref>

=== Trapped Radiation Detector ===
This experiment aimed to measure energetic particles in interplanetary space and investigate potential radiation belts or particle effects near Venus. It used specialized detectors to capture electrons and protons at various [[Energy level|energy levels]] and angles relative to the probe-Sun line. Principal investigator was [[James Van Allen|James A. Van Allen]] from the [[University of Iowa]].<ref>{{Cite web |title=Trapped Radiation Detector |url=https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1967-060A-04 |website=NSSDCA Master Catalog}}</ref>

=== Triaxial Low Field Helium Magnetometer ===
This experiment used a helium [[magnetometer]] mounted on a 1.5-meter boom to measure interplanetary and Venusian magnetic fields in three directions. It operated in both high and low bit-rate modes, collecting precise data with a dynamic range of ±204 nT and accuracy up to ±0.2 nT. High-quality data were gathered from June to October 1967, except for a brief period in late September. Principal investigator was Edward J. Smith from the Jet Propulsion Laboratory.<ref>{{Cite web |title=Triaxial Low Field Helium Magnetometer |url=https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1967-060A-05 |website=NSSDCA Master Catalog}}</ref>

=== Two-Frequency Beacon Receiver ===
A steerable antenna at Stanford transmitted two radio signals (423.3 MHz and 49.8 MHz) to the spacecraft’s two-frequency receiver. The high-frequency signal acted as a reference, while delays in the low-frequency signal revealed total electron content along the path. Phase and group velocity differences were measured onboard and sent back to Earth, helping to determine interplanetary electron content and [[solar wind]] variations. The experiment ran successfully from launch through November 1967. Principal investigator was Von R. Eshleman from [[Stanford University]].<ref>{{Cite web |title=Two-Frequency Beacon Receiver |url=https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1967-060A-02 |website=NSSDCA Master Catalog}}</ref>

=== Ultraviolet Photometer ===
This experiment used a [[Ultraviolet|UV]] [[photometer]] to study Venus' upper atmosphere by measuring ultraviolet emissions caused by solar radiation scattering off atmospheric atoms. By analyzing these emissions, especially hydrogen [[Lyman-alpha]] and [[atomic oxygen]] lines, scientists could determine the composition and temperature at various altitudes. The instrument had three [[Photomultiplier tube|photomultiplier tubes]] with specific filters to isolate key wavelengths. Principal investigator was Charles A. Barth from the [[University of Colorado]].<ref>{{Cite web |title=Ultraviolet Photometer |url=https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1967-060A-06 |website=NSSDCA Master Catalog}}</ref>

==See also==
{{Portal|Spaceflight}}
* [[List of missions to Venus]]

==References==
{{reflist|refs=

<ref name="beyond">{{Cite book
| author1= Asif A. Siddiqi
| url= https://www.nasa.gov/connect/ebooks/beyond_earth_detail.html
| title= Beyond Earth: A Chronicle of Deep Space Exploration, 1958–2016
| date= 20 September 2018
| edition= 2nd
| isbn= 978-1-626-83042-4
| lccn= 2017059404
| publisher= [[NASA]]
| id= SP2018-4041
| series= The NASA History series
| location= Washington, DC }}
</ref>

<ref name="conf1">{{cite conference
| title= Report on the Activities of the COSPAR Working Group VII
| page= 94
| date= 11–24 May 1969
| location= Prague, Czechoslovakia
| book-title= Preliminary Report, COSPAR Twelfth Plenary Meeting and Tenth International Space Science Symposium
| publisher= [[National Academy of Sciences]] }}
</ref>

<ref name="dem1">{{Cite web
| author1= Andrew LePage
| url= https://www.drewexmachina.com/2017/06/15/the-return-to-venus-the-mission-of-mariner-5/
| title= The Return to Venus: The Mission of Mariner 5
| website= Drew Ex Machina
| date= 15 June 2017 }}
</ref>

<ref name="Layman">{{cite book
| title= Mariner-Venus 1967
| id= SP-190
| publisher= [[NASA]]
| date= 1971
| url= https://ntrs.nasa.gov/citations/19720013159 
| access-date= 29 July 2022 }}
</ref>

<ref name="nasa1">{{cite web
| author1= Roald Sagdeev
| author2= Susan Eisenhower
| date= 28 May 2008
| title= United States-Soviet Space Cooperation during the Cold War 
| url= http://www.nasa.gov/50th/50th_magazine/coldWarCoOp.html
| access-date= 19 July 2009
| archive-date= 25 January 2015
| archive-url= https://web.archive.org/web/20150125082836/http://www.nasa.gov/50th/50th_magazine/coldWarCoOp.html
| url-status= dead }}
</ref>

<ref name="quickfacts">{{Cite web
| url= http://lasp.colorado.edu/home/missions-projects/quick-facts-mariner-5/
| title= Quick Facts: Mariner 5
| access-date= 28 September 2018
| archive-date= 23 September 2020
| archive-url= https://web.archive.org/web/20200923232101/https://lasp.colorado.edu/home/missions-projects/quick-facts-mariner-5/
| url-status= dead }}
</ref>

<ref name="sagan-1969">{{cite journal
| doi= 10.1016/0019-1035(69)90052-9
| author1= Carl Sagan
| date= September 1969
| title= The COSPAR Meetings in Prague
| journal= [[Icarus (journal)|Icarus]]
| volume= 11
| issue= 2
| pages= 268–272
| bibcode= 1969Icar...11..268S }}
</ref>

<ref name=Ulivi57>{{cite book
| author1= Paolo Ulivi
| author2= David M. Harland
| date= 2007
| title= Robotic Exploration of the Solar System Part I: The Golden Age 1957–1982
| publisher= Springer
| pages= 57–58
| isbn= 978-0-387-49326-8 }}
</ref>

}}

==External links==
{{commons|Mariner 5}}
*[https://web.archive.org/web/20110614112433/http://solarsystem.nasa.gov/missions/profile.cfm?MCode=Mariner_05 Mariner 5 Mission Profile] by [https://web.archive.org/web/20010202092700/http://solarsystem.nasa.gov/ NASA's Solar System Exploration]
* [https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19720013159_1972013159.pdf Mariner Venus 1967 Final Project Report]
* [https://web.archive.org/web/20100521093325/https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19690023898_1969023898.pdf The Mariner 5 flight path and its determination from tracking data (now from archive.org)]

{{Mariner program}}
{{Orbital launches in 1967}}
{{Venus spacecraft}}
{{Satellite and spacecraft instruments}}

[[Category:Derelict satellites in heliocentric orbit]]
[[Category:Mariner program]]
[[Category:Missions to Venus]]
[[Category:Spacecraft launched in 1967]]
[[Category:Derelict space probes]]
[[Category:Spacecraft launched by Atlas-Agena rockets]]

[[de:Mariner#Mariner 5]]