View source for Proton (rocket family)

{{short description|Soviet designed rocket family}}
{{Use dmy dates|date=October 2019}}
{{Infobox rocket
|image = Proton Zvezda crop.jpg
|caption = Launch of a Proton-K rocket carrying the ''[[Zvezda (ISS module)|Zvezda]]'' module to the [[International Space Station|ISS]].
|name = Proton 8K82K
|function = [[Heavy-lift launch vehicle]]
|manufacturer = {{Indented plainlist|
* [[Khrunichev State Research and Production Space Center]]
* [[Chemical Automatics Design Bureau]]
}}
|country-origin = [[Soviet Union]]{{,}}[[Russia]]
|height = {{cvt|53|m}}
|diameter = {{cvt|7.4|m}}
|mass = {{cvt|693810|kg}}, 3&nbsp;stage
|stages = {{plainlist|
* '''Proton-K''': 3
* '''Proton-M''': 4
}}
|capacities = 
  {{Infobox rocket/payload
  |location = [[low Earth orbit|LEO]]
  |kilos    = {{cvt|23700|kg}}<ref name="ReferenceA">[http://www.khrunichev.ru/main.php?id=42 Khrunichev State Research and Production Space Center - Proton-M rocket] // russianforces.org</ref>
  }}
  {{Infobox rocket/payload
  |location = [[geostationary transfer orbit|GTO]]
  |kilos    = {{cvt|6300|kg}}<ref name="ReferenceA" />
  }}
|status = Active
|sites = [[Baikonur Cosmodrome|Baikonur]], [[Baikonur Cosmodrome Site 200|LC-200]] & [[Baikonur Cosmodrome Site 81|LC-81]]<!--
The following launch numbers below: Total launches (430), M (115), K (311), Proton (4); Success M (104), Proton (3); Fail M (9), Proton (1); Partial fail M (2) are compatible with the Wikipedia article: List of Proton launches (12 March 2023 version). The following launch numbers below: Success (382), K (275); Fail (34), K (24); Partial fail (13), K (11) are NOT compatible with the List of Proton launches (9 October 2019 18:00 UTC version). This is because the Wikipedia article: Proton-K and the Wikipedia article: List of Proton launches list differently the successes, failures and partial failures of the Proton-K rocket. This discrepancy should be rectified at some future time.
--><!--
DO NOT CHANGE THE LAUNCH NUMBERS THAT ARE TAGGED "UPDATE after each flight" UNLESS YOU MAKE THE CHANGES ALSO TO THE ARTICLE: LIST OF PROTON LAUNCHES
-->
|launches = 430<!-- As of 12 March 2023--><!-- UPDATE after each flight-->{{plainlist|
* '''Proton''': 4
* '''Proton-K''': 311
* '''Proton-M''': 115<!-- UPDATE after each flight-->
}}
|success = 382<!-- As of 12 March 2023--><!-- UPDATE after each flight-->{{plainlist|
* '''Proton''': 3
* '''Proton-K''': 275<!-- Suspicious number; not necessarily correct -->
* '''Proton-M''': 104<!-- UPDATE after each flight-->
}}
|fail = 44<!-- As of 12 March 2023--><!-- UPDATE after each flight-->{{plainlist|
* '''Proton''': 1
* '''Proton-K''': 34<!-- Suspicious number; not necessarily correct -->
* '''Proton-M''': 9<!-- UPDATE after each flight-->
}}
|partial = 4<!-- As of 12 March 2023--><!-- UPDATE after each flight-->{{plainlist|
* '''Proton-K''': 2<!-- Suspicious number; not necessarily correct -->
* '''Proton-M''': 2<!-- UPDATE after each flight-->
}}
|first='''Proton:''' 16 July 1965<br />'''[[Proton-K]]:''' 10 March 1967<br />'''[[Proton-M]]:''' 7 April 2001
|last='''Proton:''' 6 July 1966<br />'''Proton-K:''' 30 March 2012<br/>'''Proton-M:''' 12 March 2023<!-- UPDATE after each flight-->
|payloads = {{flatlist|
* [[Salyut 6]]
* [[Salyut 7]]
* ''[[Mir]]'' (all components except [[Mir Docking Module|Docking Module]])
* [[International Space Station|ISS components]] ([[Zarya (ISS module)|''Zarya'']], [[Zvezda (ISS module)|''Zvezda'']], [[Nauka (ISS module)|''Nauka'']])
* [[ViaSat-1]]
* [[GLONASS]]
* [[ExoMars]]
* {{nobr|[[Spektr-RG]]}}
* [[Eutelsat 5 West B]]
}}
|stagedata    =
  {{Infobox rocket/stage
  |type       = stage
  |stageno    = First
  |engines    = 6 × [[RD-275]]
  |thrust     = {{cvt|10470|kN}}
  |burntime   = 126 seconds
  |fuel       = [[Dinitrogen tetroxide|N<sub>2</sub>O<sub>4</sub>]]/[[UDMH]]
  }}
  {{Infobox rocket/stage
  |type       = stage
  |stageno    = Second
  |engines    = 3 × [[RD-0210]] & 1 × [[RD-0211]]
  |thrust     = {{cvt|2399|kN}}<ref>{{Cite web|url=http://www.friends-partners.org/partners/mwade/lvs/pro8k82k.htm|title=Proton 8K82K|website=www.friends-partners.org|archive-url=https://web.archive.org/web/20211116232347/http://www.friends-partners.org/partners/mwade/lvs/pro8k82k.htm |access-date=2021-11-16|archive-date=16 November 2021 }}</ref>
  |SI         = {{cvt|327|isp}}
  |burntime   = 208 seconds
  |fuel       = [[Dinitrogen tetroxide|N<sub>2</sub>O<sub>4</sub>]]/[[UDMH]]
  }}
  {{Infobox rocket/stage
  |type       = stage
  |stageno    = Third
  |engines    = 1 × [[RD-0212]]
  |thrust     = {{cvt|630|kN}}
  |SI         = {{cvt|325|isp}}
  |burntime   = 238 seconds
  |fuel       = [[Dinitrogen tetroxide|N<sub>2</sub>O<sub>4</sub>]]/[[UDMH]]
  }}
  {{Infobox rocket/stage
  |type       = stage
  |stageno    = Fourth
  |name       = Blok-D/DM
  |engines    = 1 × [[RD-58M]]
  |thrust     = {{cvt|83.4|kN}}
  |SI         = {{cvt|349|isp}}
  |burntime   = 770 seconds 
  |fuel       = [[LOX]]/[[RP-1]]
  }}
}}

'''Proton''' ({{langx|ru|Протон}}, formal designation: '''[[Universal Rocket|UR-500]]''') is an [[expendable launch system]] used for both commercial and Russian government space launches. The first Proton [[rocket]] was launched in 1965. Modern versions of the launch system are still in use {{as of|2025|lc=y}}, making it one of the most successful heavy boosters in the history of spaceflight. The components of all Protons are manufactured in the [[Khrunichev State Research and Production Space Center]] factory in Moscow and [[Chemical Automatics Design Bureau]]<ref>{{Cite web|url=http://www.kbkha.ru|script-title=ru:АО "Конструкторское Бюро Химавтоматики"|trans-title=JSC "Chemical Automation Design Bureau" ''(Khrunichev State Research and Production Space Center Homepage)''}}</ref> in [[Voronezh]], then transported to the [[Baikonur Cosmodrome]], where they are assembled at Site 91 to form the launch vehicle.<ref>{{cite web |url=http://www.russianspaceweb.com/baikonur_proton_92.html |title=Site 92 in Baikonur Cosmodrome |website=russianspaceweb.com |access-date=26 September 2022}}</ref> Following payload integration, the rocket is then brought to the launch pad horizontally by rail and raised into vertical position for launch.<ref>{{cite web |url=http://www.ilslaunch.com/launch-services/proton-mission-planners-guide |title=Proton Mission Planner's Guide |publisher=International Launch Services}}</ref><ref>{{cite web |url=https://www.flickr.com/photos/alexpgp/40437004/ |date=5 September 2005|title=Proton Verticalization, Pad 39, Baikonur |publisher=flickr}}</ref>

As with many Soviet rockets, the names of recurring payloads became associated with the launch vehicle itself. The moniker "Proton" originates from a series of [[Proton satellite|similarly named scientific satellite]]s, which were among the rocket's first payloads. During the Cold War, it was designated the '''D-1'''/'''D-1e''' or '''SL-12'''/'''SL-13''' by Western intelligence agencies.

Launch capacity to [[low Earth orbit]] is about {{convert|22.8|t|lb|lk=in}}.<ref name="khrunichevZvezda">{{cite web |url=http://www.khrunichev.ru/main.php?id=54 |script-title=ru:Служебный модуль «Звезда» |trans-title='Zvezda' Service Module |publisher=Khrunichev State Research and Production Space Center |archive-url=https://web.archive.org/web/20110416083215/http://www.khrunichev.ru/main.php?id=54 |archive-date=16 April 2011 |url-status=dead}}</ref> Geostationary transfer capacity is about {{convert|6.3|tonnes|lb}}.<ref>{{cite web|date=9 June 2016|publisher=Spaceflightnow.com|url=http://spaceflightnow.com/2016/06/09/upgraded-proton-booster-adds-satellite-to-intelsats-fleet/ |last=Clark|first=Stephen|title=Upgraded Proton booster adds satellite to Intelsat's fleet}}</ref> [[Private spaceflight|Commercial launches]] are marketed by [[International Launch Services]] (ILS).<ref>{{cite web|url=http://www.ilslaunch.com/launch-services/ils-proton-breeze-m-launch-vehicle/proton-heritage |title=Commercial Launch Heritage |publisher=International Launch Services}}</ref>

In 2013, the rocket was intended to be retired before 2030.<ref>{{cite web |url=http://www.russianspaceweb.com/rockets_launchers_2010s.html |title=Russian rocket development in the 2010s|publisher=Anatoly Zak}}</ref> {{asof|2018|06}}, production on the Proton rocket is ceasing as the new [[Angara (rocket family)|Angara]] launch vehicle comes on line and becomes operational. No new launch service contracts for Proton are likely to be signed.<ref name="asr20100625" />

==History==
Proton<ref>{{cite web |url=http://www.ilslaunch.com/launch-services/ils-proton-breeze-m-launch-vehicle/proton-heritage |title=Proton Heritage |publisher=International Launch Services}}</ref> started its life as a "super [[heavy ICBM]]". It was designed to launch a 100-[[TNT equivalent|megaton]] (or larger) [[thermonuclear weapon]] over a distance of 13,000&nbsp;km. It was hugely oversized for an ICBM and was never deployed in such a capacity. It was eventually used as a space [[launch vehicle]]. It was the brainchild of [[Vladimir Chelomei]]'s design bureau as a foil to [[Sergei Korolev]]'s [[N1 (rocket)|N1]] rocket, whose purpose was to send a two-man [[Zond program|Zond]] spacecraft around the Moon; Korolev openly opposed Proton and Chelomei's other designs for their use of toxic propellants. 

The unusual appearance of the first stage results from the need to transport components by rail. The central oxidizer tank is the maximum width for the [[loading gauge]] of the track. The six tanks surrounding it carry fuel and serve as the attachment points for the engines. Despite resembling [[booster (rocketry)|strap-on booster]]s, they are not designed to separate from the central oxidizer tank. The first and second stages are connected by a lattice structure. The second stage engine ignites shortly before separation of the first stage and the lattice allows the exhaust to escape.<ref>[http://www.russianspaceweb.com/proton_stage1.html The first stage of the Proton rocket] at Russian Space Web</ref> This is called "hot staging" and it eliminates the need for [[ullage motor]]s on the second stage.

A rushed development program led to dozens of failures between 1965 and 1972. Proton did not complete its State Trials until 1977, at which point it was judged to have a higher than 90% reliability.

Proton's design was kept secret until 1986, with the public being only shown the upper stages in film clips and photographs, and the first time the complete vehicle was shown to the outside world happened during the televised launch of [[Mir]].

Mass-production of [[guidance, navigation and control]] system for Proton has begun in 1964 on "Communard" Industrial Association ([[Kharkov, Ukraine]]).<ref name="History">{{cite web |title=History of SSIA "Communard" |url=http://www.tvset.com.ua/en/about/ |access-date=5 May 2019 |archive-date=27 January 2021 |archive-url=https://web.archive.org/web/20210127171628/https://www.tvset.com.ua/en/about/ |url-status=dead }}</ref>

Proton launched the uncrewed Soviet circumlunar flights and was intended to have launched the first crewed Soviet [[circumlunar]] spaceflights, before the United States flew the [[Apollo 8]] mission. Proton launched the [[Salyut]] space stations, the [[Mir]] core segment and expansion modules, and both the [[Zarya (ISS module)|Zarya]] and [[Zvezda (ISS module)|Zvezda]] modules of the [[International Space Station|ISS]].

Proton also launches commercial [[satellite]]s, most of them being managed by [[International Launch Services]]. The first ILS Proton launch was on 9 April 1996 with the launch of the [[SES (company)|SES]] [[Astra 1F]] [[communications satellite]].<ref name="ilslaunch">{{cite web|url=http://www.ilslaunch.com/mission-control/proton-launch-archives|title=Proton Launch Archives &#124; International Launch Services|publisher=ilslaunch.com|access-date=13 September 2014}}</ref>

Between 1994 and mid-2010, Proton revenues were $4.3&nbsp;billion, and were projected to grow to $6&nbsp;billion by 2011.<ref name="nesterov">{{cite web |url=http://www.khrunichev.ru/main.php?id=1&nid=1735 |title=Statement by Vladimir Ye. Nesterov, Khrunichev Director-General, at Press Conference on 15 July 2010
|archive-url=https://web.archive.org/web/20190924112805/http://www.khrunichev.ru/main.php?id=1&nid=1735 |archive-date=24 September 2019 |url-status=dead}}</ref>

In January 2017, the Proton was temporarily grounded due to the manufacturer, [[Voronezh Mechanical Plant]], having substituted a heat-resistant alloy in the engines with a cheaper metal.<ref>{{Cite web|url=http://www.planetary.org/blogs/guest-blogs/2017/20170125-proton-rocket-grounded.html|title=Russia's Proton rocket grounded by poor quality control|website=www.planetary.org|language=en|access-date=2017-01-26}}</ref><ref>{{Cite web|url=http://spaceflight101.com/proton-rocket-faces-extended-grounding/|title=Russia's Proton Rocket faces extended Grounding due to systemic Engine Problems|website=spaceflight101.com|date=25 January 2017 |language=en|access-date=2017-02-24}}</ref>

In June 2018, the [[state corporation]] [[Roscosmos]] announced that the Proton rocket would cease production as the new [[Angara (rocket family)|Angara]] launch vehicle comes on line and becomes operational. No new launch service contracts for Proton are likely to be signed.<ref name=asr20100625>
{{cite news |last=Berger|first=Eric |url=https://arstechnica.com/science/2018/06/russias-proton-rocket-which-predates-apollo-will-finally-stop-flying/ |title=Russia's Proton rocket, which predates Apollo, will finally stop flying Technical problems, rise of SpaceX are contributing factors. |work=arsTechica |date=25 June 2018 |access-date=26 June 2018 |quote="...failures have followed in recent years. These problems, combined with the rapid rise of low-cost alternatives such as SpaceX's Falcon 9 rocket, have caused the number of Proton launches in a given year to dwindle from eight or so to just one or two."}}</ref>

Proton flew its last scheduled commercial mission on 9 October 2019, delivering [[Eutelsat 5 West B]] and [[Mission Extension Vehicle]]-1 to geostationary orbit.<ref>{{Cite web|url=http://russianspaceweb.com/eutelsat5wb-mev1.html|title=Proton flies its last scheduled commercial mission|website=russianspaceweb.com}}</ref> A number of Roscosmos and other Russian government missions remain on Proton launch manifest.

==Proton K==
{{Main|Proton-K}}
Proton K is fueled by very toxic [[UDMH|unsymmetrical dimethyl hydrazine]] and [[nitrogen tetroxide]].<ref name="ilslaunch2">{{cite web|url=http://www.ilslaunch.com/launch-services/ils-proton-breeze-m-launch-vehicle|title=Commercial Launch Vehicle &#124; ILS Proton Breeze M &#124; International Launch Services|publisher=ilslaunch.com|access-date=13 September 2014}}</ref> These are [[hypergolic]] fuels which ignite on contact, avoiding the need for an ignition system, and can be stored at ambient temperatures. This avoids the need for components that are tolerant of low temperatures, and allows the rocket to remain on the pad indefinitely (other launchers with such capability include the U.S. [[Titan II GLV]], [[Titan III]], and [[Titan IV]], the Chinese [[Long March 2]] and [[Long March 4]], the Soviet/Ukrainian [[Tsyklon]] launchers, the Soviet/Russian [[Kosmos-3]] and [[Kosmos-3M]] launchers and the European Ariane 1 to [[Ariane 4]] launchers). In contrast, [[cryogenic fuel]]s need periodic replenishment as they boil off.

The fourth stage has multiple variants, depending on the mission. The simplest, [[Blok D]], was used for interplanetary missions. Blok D had no guidance module, depending on the probe to control flight. Three different Blok DM versions (DM, DM2, and DM-2M) were for high Earth orbits. The Blok D/DM were unusual in that the fuel was stored in a toroidal tank, around the engine and behind the oxidizer tank.

The initial Proton tests in 1965–66 only used the first two stages of the booster, the complete four-stage vehicle being flown for the first time in 1967. When the Soviet space station program began in 1971, Protons began being flown with the Blok D removed for use as a heavy-lift LEO launcher.

Proton-K payloads included all of the Soviet Union's [[Salyut program|''Salyut'']] [[space stations]], almost all [[Mir]] modules (with the exception of the [[Mir Docking Module|Docking Module]], which was launched on the United States [[Space Shuttle]]), and the [[Zarya (ISS module)|Zarya]] and [[Zvezda (ISS module)|Zvezda]] modules of the [[International Space Station]]. It was intended to launch the crewed [[TKS spacecraft]], prior to the cancellation of that programme, although a few robotic flights of spacecraft were fulfilled. In addition it was intended to launch the 1970s [[LKS (spacecraft)|LKS]] spaceplane that was never realised.<ref>{{Cite book |last1=Hendrickx |first1=Bart |url=https://link.springer.com/book/10.1007/978-0-387-73984-7 |title=Energiya-Buran: The Soviet Space Shuttle |last2=Vis |first2=Bert |publisher=Springer-Praxis |year=2007 |isbn=978-0-387-69848-9 |series=Space Exploration |pages=431–433 |chapter=Beyond Buran - Chelomey's LKS |doi=10.1007/978-0-387-73984-7}}</ref>

The final launch of Proton-K was on 30 March 2012.

==Proton-M==
{{Main|Proton-M}}
{{stack
 | float=left
 | [[File:Launch Vehicle "Verticalization", Proton-M.jpg|left|thumb|Proton-M, part being rotated to vertical. In the background, the mobile service tower can be observed.]]
}}
The initial version of Proton M, could launch {{convert|3|-|3.2|t|lb}} into [[geostationary orbit]] or {{convert|5.5|t|lb}} into a [[geostationary transfer orbit]]. It could place up to {{convert|22|t|lb}} in low Earth orbit with a 51.6-degree inclination, the orbit of the International Space Station (ISS).

The Proton M's improvements included lower stage modifications to reduce structural mass, increase thrust, and fully use propellants. Generally a [[Briz-M]] ({{langx|ru|Бриз}} meaning ''Breeze'') storable propellant upper stage is used instead of the [[Blok D]] or [[Blok DM]] stage, removing the need for multiple fuel supplies and oxygen top-off due to boiling; the Proton-M also flew with a Blok-DM upper stage. Efforts were also made to reduce dependency on foreign (usually Ukrainian) component suppliers. With the Briz-M upper stage, the payload fairing diameter is 4.1&nbsp;m (13.45&nbsp;ft).<ref>{{Cite web|url=https://www.ilslaunch.com/launch-vehicle/proton-breeze-m/|title=Proton Breeze M – ILS|website=www.ilslaunch.com|language=en-US|access-date=2019-11-09}}</ref>

Proton launch vehicles and Briz-M upper stages are designed and built by Khrunichev State Research and Production Space Center (Khrunichev) in Moscow, the majority owner of International Launch Services (ILS). The center is home to all engineering, assembly and test functions of Proton production. With the recent consolidation of the Russian space enterprises, Khrunichev has direct oversight and control of up to 70% of all Proton manufacturing from suppliers to manufacturers. The consolidation directly supports Khrunichev's ongoing efforts for vertical integration of Proton production.<ref name="ilslaunch3">{{cite web|url=http://www.ilslaunch.com/sites/default/files/pdf/ILS%20Proton%20Brochure.pdf|date=4 March 2011|title=Experience ILS: Achieve Your Mission|archive-url=https://web.archive.org/web/20120117041434/http://www.ilslaunch.com/sites/default/files/pdf/ILS%20Proton%20Brochure.pdf |archive-date=17 January 2012 |url-status=dead}}</ref>

=== Phase III ===
An enhanced variant, the Phase III Proton-M/Briz-M launch vehicle, was flight proven on the Russian Federal dual mission of Express AM-44 and Express MD-1 in February 2009 and performed its first commercial launch in March 2010 with the Echostar XIV satellite. The Proton-M/Briz-M phase III configuration provides 6150&nbsp;kg of GTO performance, an increase of 1150&nbsp;kg over the original Proton-M Briz-M, while maintaining the fundamental design configuration.

On 6 August 2012, the Russian Federal Space Agency lost a Russian and an Indonesian communications satellite in an attempt to launch them into orbit on a Proton-M due to technical difficulties with the last stage.<ref name="latimes">{{cite web|url=http://latimesblogs.latimes.com/world_now/2012/08/russia-suffers-another-embarrassing-failure-in-space-.html|title=News from around the world|date=7 August 2012|publisher=latimesblogs.latimes.com|access-date=13 September 2014}}</ref>

On 2 July 2013, a Proton-M launching three [[GLONASS]] navigation satellites experienced a failure reminiscent of the 1960s disasters shortly after liftoff when the booster crashed near LC-39 at Baikonour, ending a 30-year unbroken stretch without a first stage failure; all future Proton flights were suspended pending investigation.<ref name="rswproton">{{cite web |url=http://russianspaceweb.com/proton_glonass49.html |title=Russia's Proton crashes with a trio of navigation satellites |date=2 July 2013 |publisher=Russian Space Web}}</ref> The accident was eventually determined to be caused by the rate gyro package having been installed upside-down. Due to the difficulty of installing the package incorrectly, it was widely suspected that it had been done deliberately by a disgruntled or drunk worker at the Khrunichev plant.{{citation needed|date=February 2022}}

On 15 May 2014, a Proton-M/Briz-M carrying an Ekspress satellite suffered a third stage failure from a bad turbopump bearing. Debris fell in Manchuria. On 21 October, another Ekspress satellite was left in a useless orbit when the Briz stage cut off 24 seconds too early.

On 16 May 2015, a [[Mexican Satellite System|MEXSAT]] communications satellite failed to orbit due to another third stage malfunction, the eighth Proton failure since 2010.

=== Phase IV ===
Khrunichev has initiated development of a set of phase IV enhancements in order to keep pace with market demands and the mass growth trends of commercial satellites. The implementation of Phase IV Proton Briz-M enhancements were completed in 2016. The payload mass performance for phase IV has been increased to 6320&nbsp;kg to a reference GTO orbit with 1500&nbsp;m/s of residual [[delta V]] to GSO.<ref name="ilslaunch4">{{cite web|url=http://www.ilslaunch.com/launch-services/ils-proton-breeze-m-launch-vehicle/proton-heritage|title=Commercial Launch Heritage &#124; Proton Rocket &#124; International Launch Services|publisher=ilslaunch.com|access-date=13 September 2014}}</ref>

==Future developments==
Significant upgrades were temporarily put on hold following announcement (in 1992) of the new [[Angara (rocket family)|Angara]] launch vehicle. The single largest upgrade {{when|date=July 2020}} was the KVRB stage. This [[cryogenic fuel|cryogenic]] stage would have greatly increased capacity. The engine{{which|date=July 2024}} was developed successfully,{{when|date=July 2024}} and the stage as a whole had progressed to hardware. However, as KVRB is noticeably larger than Block D, the vehicle's aerodynamics, flight control, software, and possibly electronics would have to be reevaluated. In addition, the launch pad can supply existing Protons with common hypergolic fuels from single sources. The upper stages, in particular, are fed by common loading pipes running along the rocket. Switching to a stage with different fuels requires the addition of extra support articles; switching to cryogens requires that such support articles top off the stage periodically.{{Citation needed|date=September 2014}}

Heavy variants of Angara will be simpler and cheaper than Proton (and like the [[Atlas V]] rocket, will not use hypergolic fuels; instead, it will be a [[Kerolox]] rocket, like the [[Soyuz (rocket family)|Soyuz rocket]]). They will also be designed from the start to accept a [[KVTK (rocket stage)|KVTK]] stage and will already have a liquid oxygen supply at the pad; only a hydrogen supply will be called upon.{{Citation needed|date=September 2014}}

==See also==
* [[List of Proton launches]]
* [[Comparison of orbital launchers families]]
* [[Comparison of orbital launch systems]]

===Similar launch systems===
{{colbegin}}
* {{annotated link| Delta IV|Delta IV Heavy}}
* {{annotated link| Atlas V|Atlas V Heavy}}
* {{annotated link| Ariane 5}}
* {{annotated link| Long March 5}}
* {{annotated link| Angara (rocket)|Angara A5}}
* {{annotated link| Falcon 9}}
* {{annotated link| H-IIB}}
* {{annotated link| Saturn I}}
* {{annotated link| Saturn IB|Saturn IB}}
* {{annotated link| Heavy-lift launch vehicle}}
{{colend}}

==References==
{{reflist|30em}}

==External links==
{{Commons and category|Proton (Rocket)|Proton (rocket)}}
*[http://www.lyngsat.com/launches/Baikonur.html Proton launches page on LyngSat]
*[http://www.russianspaceweb.com/proton.html Proton rocket specifications sheet]
*{{usurped|1=[https://web.archive.org/web/20051201160120/http://www.spaceandtech.com/digest/sd2001-14/sd2001-14-001.shtml Proton M Debuts With Successful Ekran Launch on April 7, 2001]}}
*[https://web.archive.org/web/20080913224630/http://www.astronautix.com/lvs/proton.htm Proton 8K82K / Briz-M]. Astronautix.
*[https://fas.org/spp/guide/russia/launch/proton.htm FAS – Proton Launch Vehicle] {{Webarchive|url=https://web.archive.org/web/20160602185546/http://fas.org/spp/guide/russia/launch/proton.htm |date=2 June 2016 }}
*[http://www.ilslaunch.com/launch-services/ils-proton-breeze-m-launch-vehicle ILS Proton]
*[http://www.satlaunch.net/p/launch-schedule-2011.html Proton launch schedules on Satlaunch] {{Webarchive|url=https://web.archive.org/web/20210208021030/http://www.satlaunch.net/p/launch-schedule-2011.html |date=8 February 2021 }}
*[http://masterok.livejournal.com/141745.html#cutid1 Слабое звено – "Бриз-М"]

{{Universal Rocket}}
{{Russian launch vehicles}}
{{Expendable launch systems}}
{{N1-L3}}

[[Category:1967 in spaceflight]]
[[Category:1971 in spaceflight]]
[[Category:1972 in spaceflight]]
[[Category:1973 in spaceflight]]
[[Category:Space launch vehicles of Russia]]
[[Category:Soviet inventions]]
[[Category:Universal Rocket (rocket family)]]
[[Category:Space launch vehicles of the Soviet Union]]
[[Category:Rocket families]]