Editing Proton (satellite program)

{{Short description|Series of Soviet satellites}}
{{good article}}
{{Infobox spaceflight
| name                  = {{nowrap|'' Proton 1'', ''2'', ''3'', and ''4''}}
| image                 = File:Proton1-2.gif
| image_caption         = A Proton satellite
| mission_type          = [[Astronomy]]
| operator              = [[Soviet Union]]
| COSPAR_ID             = {{plainlist|
*1965-054A  (Proton 1)
*1965-087A  (Proton 2)
*1966-060A  (Proton 3)
*1968-103A  (Proton 4)}}
| SATCAT                = 
| mission_duration      =

| spacecraft_type       = 
| manufacturer          = [[OKB-52]]
| dry_mass              = 
| launch_mass           = {{plainlist|
*{{convert|12200|kg|lb|abbr=on}} (Proton 1)
*{{convert|12200|kg|lb|abbr=on}} (Proton 2)
*{{convert|12200|kg|lb|abbr=on}} (Proton 3)
*{{convert|17000|kg|lb|abbr=on}} (Proton 4)}}
| power                 = 
| launch_date           = {{plainlist|
*'''Proton 1''': {{start-date|16 July 1965 11:16|timezone=yes}}&nbsp;UTC
*'''Proton 2''': {{start-date|2 November 1965 12:28|timezone=yes}}&nbsp;UTC
*'''Proton 3''': {{start-date|6 July 1966 12:57|timezone=yes}}&nbsp;UTC
*'''Proton 4''': {{start-date|16 November 1968 11:40|timezone=yes}}&nbsp;UTC}}
| launch_rocket         = [[UR-500]] (1–3), [[Proton-K]] (4)
| launch_site           = [[Baikonur Cosmodrome Site 81/23]] (1–3), [[Baikonur Cosmodrome Site 81/24]] (4)
| launch_contractor     = 
| last_contact          =
| disposal_type         = De-orbited
| decay_date            = {{plainlist|
*'''Proton 1''': {{end-date|11 October 1965|timezone=yes}}
*'''Proton 2''': {{end-date|6 February 1966|timezone=yes}}
*'''Proton 3''': {{end-date|16 September 1966|timezone=yes}}
*'''Proton 4''': {{end-date|24 July 1969|timezone=yes}}}}
| orbit_epoch           = 
| orbit_reference       = [[Geocentric orbit|Geocentric]]
| orbit_periapsis       = {{plainlist|
*'''Proton 1''': {{convert|183|km}} 
*'''Proton 2''': {{convert|189|km}} 
*'''Proton 3''': {{convert|185|km}} 
*'''Proton 4''': {{convert|248|km}}}} 
| orbit_apoapsis        = {{plainlist|
*'''Proton 1''': {{convert|589|km}}<ref name=nssdc1>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1965-054A|title=Proton 1| publisher=NASA Space Science Data Coordinated Archive|access-date=23 October 2020}}</ref>
*'''Proton 2''': {{convert|608|km}}<ref name=nssdc2>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1965-087A|title=Proton 2| publisher=NASA Space Science Data Coordinated Archive|access-date=23 October 2020}}</ref>
*'''Proton 3''': {{convert|585|km}}<ref name=nssdc3>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1966-060A|title=Proton 3| publisher=NASA Space Science Data Coordinated Archive|access-date=23 October 2020}}</ref> 
*'''Proton 4''': {{convert|477|km}}}}<ref name=nssdc4>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1968-103A|title=Proton 4| publisher=NASA Space Science Data Coordinated Archive|access-date=23 October 2020}}</ref>
| orbit_inclination     =  63.5° (1–3), 31.5° (4)
| orbit_period          =  ~92 minutes (1–4)
| orbit_eccentricity    =  .030 (1–3), .017 (4)
| apsis                 = gee

| programme             = 
| previous_mission      = 
| next_mission          = 
}}

{{Use dmy dates|date=January 2021}}
'''Proton''' ({{langx|ru|протон}}) ('[[proton]]') was a Soviet series of four cosmic ray and elementary particle detecting satellites. Orbited 1965–68, three on test flights of the [[UR-500]] [[ICBM]] and one on a [[Proton-K]] rocket, all four satellites completed their missions successfully, the last reentering the Earth's atmosphere in 1969.

==Background==

The Proton satellites were heavy automated laboratories launched 1965–68 to study high energy particles and cosmic rays.<ref name=astro>{{cite web|url=http://www.astronautix.com/u/ur-500.html|title=UR-500|last=Wade|first=Mark|access-date=23 October 2020|url-status=dead|archive-url=https://web.archive.org/web/20201026155026/http://www.astronautix.com/u/ur-500.html|archive-date=26 October 2020}}</ref> These satellites were built to utilize the test launches of the [[UR-500]], a heavy two-stage [[ICBM]] designed by [[Vladimir Chelomey|Vladimir Chelomey's]] [[OKB-52]] to carry a 100-megaton nuclear payload. Each Proton was housed in a purpose-built third stage added to the UR-500 stack.<ref name=rop>{{cite book|title=Rockets and People. Volume IV, The Moon Race| last = Chertok |  first = Boris | publisher = NASA | location = Washington D.C. | oclc= 775599532 | date = 2011 | page = 21}}</ref>

==Spacecraft design==

[[File:Proton satellite schematic (from SP-133).jpg|thumb|150px|Schematic of the Proton satellite|left]]

Protons 1–3 were largely identical craft massing {{convert|12200|kg|lb|abbr=on}}, with scientific packages developed under the supervision of Academician Sergey Nikolayevich Vernov of [[Moscow State University]]'s Scientific-Research Institute of Nuclear Physics.<ref name=rop/> Experiments included a [[gamma-ray]] telescope, a [[Scintillation counter|scintillator telescope]], and [[proportional counter]]s.<ref name="SP-133">{{cite book|url=https://archive.org/details/scientificsatell00corl/page/778/mode/2up|author=William R. Corliss|title=Scientific Satellites|publisher=Science and Technical Information Division, Office of Technology Utilization, National Aeronautics and Space Administration|date=1967|location=Washington D.C.|pages=779–780}}</ref> The counters were able to determine the total energy of each super-high energy cosmic particle individually, a capability no prior satellite had possessed. Though the equipment had been developed eight years earlier (by Professor N. L. Grigorov), the UR-500 was the first booster powerful enough to orbit a satellite carrying the sensitive particle counter.<ref name="aa1965">{{cite web|url=https://history.nasa.gov/AAchronologies/1965.pdf|title=Aeronautics and Astronautics, 1965|publisher=NASA|page=342|access-date=24 April 2020}}</ref> The counters could measure cosmic rays with energy levels up to 100 million [[Electronvolt|eV]].<ref name=sov>{{cite book|title=The Encyclopedia of Soviet Spacecraft|oclc=17249881|first=Douglas M.|last=Hart|date=1987|location=New York|publisher=Exeter Books|pages=82–83}}</ref> 

Proton 3 also was equipped with a [[Cherenkov radiation|gas-Cerenkov-scintillator]] telescope<ref name=meas>{{Cite journal |last=Akimov |first=V. V. |last2=Grigorov |first2=N. L. |last3=Nesterov |first3=V. E. |last4=Rapoport |first4=I. D. |last5=Savenko |first5=I. A. |last6=Skuridin |first6=G. A. |last7=Titenkov |first7=A. F. |date=1970 |title=Measurements of the primary cosmic ray spectra in the 1011-1014 eV energy range from Proton-1, 2, 3 satellites |url=https://ui.adsabs.harvard.edu/abs/1970ICRC....1..517A |journal=Proceedings of the 11th International Conference on Cosmic Rays, held in Budapest, 25 August – 4 September 1969 |volume=1 |pages=517-520 |bibcode=1970ICRC....1..517A|bibcode-access=free}}</ref> to attempt to detect the newly postulated fundamental particle, the [[quark]]. The entire experiment package massed {{convert|4000|kg|lb|abbr=on}} and was composed of metal, plastic, and paraffin blocks.<ref name=sov/>

[[Telemetry]] was relayed via a 19.910 [[Hertz|MHz]] beacon. Four solar panels powered the crafts, which were cooled by heat exchangers. The Protons were spin-stabilized, their [[Spacecraft attitude control|attitude]] controlled by jet and an on-board dampener. Satellite systems were controlled by an internal computer.<ref name="SP-133"/>

Proton 4 was considerably more massive at {{convert|17000|kg|lb|abbr=on}}. Its primary instrument was an ionization calorimeter composed of steel bars and plastic scintillators. A measuring device comprising one lump of carbon and another of polyethylene<ref name=sov/> provided data on cosmic rays and the energy spectrum in orbit, the possible collisions of cosmic ray particles with atmospheric nuclei of hydrogen, carbon, and iron, and continued the search for the quark.<ref name=nssdc4/>

==Missions==

===Proton 1===

Proton 1 was launched into Earth orbit 16 July 1965 11:16&nbsp;UTC from [[Baikonur Cosmodrome Site 81/23]],<ref name=log>{{Cite web|url=http://planet4589.org/space/log/launchlog.txt|title=Launch Log|last=McDowell|first=Jonathan|publisher=Jonathon's Space Report|access-date=30 December 2018}}</ref> though the launch was threatened by a leak in the oxidizer pipeline resulting in [[nitrogen tetroxide]] spilling on electrical wires. Early in the flight, launch specialists only received signals indicating that the satellite was functioning. Eventually, however, Proton 1 performed normally, returning physics data on ultra-high-energy cosmic particles. Its mission lasted 45 days,<ref name=astro/> and the satellite reentered Earth's atmosphere 11 October 1965.<ref name=cat>{{Cite web|url=https://www.planet4589.org/space/log/satcat.txt|title=Satellite Catalog|last=McDowell|first=Jonathan|publisher=Jonathon's Space Report|access-date=23 October 2020}}</ref> 

===Proton 2===

The virtually identical Proton 2 was launched 2 November 1965 12:28&nbsp;UTC, also from Baikonur Cosmodrome Site 81/23.<ref name=log/> It reentered Earth's atmosphere on 6 February 1966.<ref name=cat/> At the time of their launch, American experts believed the first Protons were experimental space station components due to their weight and the Soviet use of the word "station" in describing the observatory satellites.<ref name=avweek1965d>{{cite magazine| date = 8 November 1965| title = News Digest (Soviets launched)| url = http://archive.aviationweek.com/issue/19651108#!&pid=24| magazine = Aviation Week and Space Technology| location = New York| publisher = McGraw Hill Publishing Company| access-date = 23 October 2020}}</ref><ref name="aa1965a">{{cite web|url=https://history.nasa.gov/AAchronologies/1965.pdf|title=Aeronautics and Astronautics, 1965|publisher=NASA|page=333|access-date=24 April 2020}}</ref>

===Proton 3===

[[File:Gt11fig3a.gif|thumb|150px|alt=Proton 3 as seen from [[Gemini 11]], 13 September 1966|Proton 3 as seen from Gemini 11, 13 September 1966<ref name=macc>{{cite web|url=http://www.brumac.mysite.com/Gemini_11/GEMINI_11.html|title=Gemini 11 UFO|author=Bruce S. Maccabee|date=August 2000}}</ref>]]

After an unsuccessful launch of the third test UR-500 on 24 March 1966 14:39&nbsp;UTC, Proton 3 was successfully launched into Earth orbit from Baikonur Cosmodrome Site 81/23 on 6 July 1966 12:57&nbsp;UTC<ref name=log/> on the fourth and final UR-500 test flight<ref name=astro/> and began searching for quarks and other elementary particles of fractional electron charge.<ref name=sov/> The satellite returned data for most, if not all, of its short time in orbit,<ref name="aa1966">{{cite web|url=https://history.nasa.gov/AAchronologies/1966.pdf|title=Aeronautics and Astronautics, 1966|publisher=NASA|page=285|access-date=26 August 2021}}</ref> reentering Earth's atmosphere on 16 September 1966.<ref name=cat/> Shortly before reentry, Proton 3 was observed tumbling once per second over the [[Indian Ocean]] by the crew of [[Gemini 11]].<ref name=avweek1966>{{cite magazine| date = 19 September 1966| title = Gemini 11 Demonstrates Pilot Capabilities| url = http://archive.aviationweek.com/issue/19660919#!&pid=26| magazine = Aviation Week and Space Technology| location = New York| publisher = McGraw Hill Publishing Company|page=27|access-date = 25 August 2021|url-access=subscription}}</ref>

===Proton 4===

After the end of the run of UR-500 test launches, the rocket (now designated Proton) and its successors were largely employed in the launch of the [[Zond program|Zond]] lunar spacecraft. However, on 16 November 1968 11:40&nbsp;UTC, the final and much larger Proton 4 was launched into orbit via [[Proton-K]] rocket from [[Baikonur Cosmodrome Site 81/24]] to continue the search for the quark and supplement the earlier Proton satellites' cosmic ray measurements.<ref name=sov/> This final Proton reentered Earth's atmosphere on 24 July 1969.<ref name=cat/>

==Legacy==

The Proton satellites were heralded by Soviet media as the start of a new stage in Soviet space exploration.<ref name=challenge>{{cite book|url=https://history.nasa.gov/SP-4408pt1.pdf|title=Challenge to Apollo: The Soviet Union and the Space Race, 1945–1974|author=Asif A. Siddiqi|publisher=NASA|location=Washington D.C.|oclc=1001823253|page=339-440, 967, 971}}</ref> The success of Proton afforded Chelomey a status in the Soviet rocket industry equal to that of [[Sergei Korolev]] of [[OKB-1]] (developer of [[Sputnik]], [[Vostok (spacecraft)|Vostok]], and [[Voskhod (spacecraft)|Voskhod]]) and [[Mikhail Yangel]] of [[OKB-456]] (an important designer of military missiles). The UR-500, originally named "Gerkules" ({{langx|ru|Геркулес}}) ('[[Hercules]]'), was renamed "Proton" when news reports conflated the launcher and its payload. Though the Proton was never used in the ICBM role it had been built for, the rocket became an extraordinarily successful booster for commercial satellites, serving well into the 1990s.<ref name=challenge/>

==See also==
{{Portal|Spaceflight}}
* [[Soviet space program]]

==References==
{{reflist}}

== External links ==
* [http://www.npomash.ru/society/en/about.htm The history of "NPO Mashinostroyenia"]
* [http://www.inr.ac.ru/~muhamed/INCA_project_eng.htm The INCA Project], Ionization-Neutron CAlorimeter – a modern continuation of Proton experiment project at [[Institute for Nuclear Research]] of [[Russian Academy of Sciences]] website {{Dead link|date=September 2010}}
{{Orbital launches in 1965}}
{{Orbital launches in 1966}}
{{Orbital launches in 1968}}

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{{DEFAULTSORT:Proton Satellite}}
[[Category:Satellites of the Soviet Union]]
[[Category:Spacecraft launched in 1965]]
[[Category:Spacecraft launched in 1966]]
[[Category:Spacecraft launched in 1968]]
[[Category:Satellite series]]