Editing Trident (missile) (section)

==Description==
[[File:Trident I C-4 missiles.jpg|thumb|300px|The launching of a Trident I C-4 missile from the submerged [[USS Francis Scott Key (SSBN-657)|USS ''Francis Scott Key'']] and the re-entry vehicles plunging into the Atlantic Ocean, 1981]]
The launch from the submarine occurs below the sea surface. The missiles are ejected from their tubes by igniting an explosive charge in a separate container. The energy from the blast is directed to a water tank, where the water is flash-vaporized to steam. The subsequent pressure spike is strong enough to eject the missile out of the tube and give it enough momentum to reach and clear the surface of the water. The missile is pressurized with [[nitrogen]] to prevent the intrusion of water into any internal spaces, which could damage the missile or add weight, destabilizing the missile. Should the missile fail to breach the surface of the water, there are several safety mechanisms that can either deactivate the missile before launch or guide the missile through an additional phase of launch. Inertial motion sensors are activated upon launch, and when the sensors detect downward acceleration after being blown out of the water, the first-stage motor ignites. The [[Drag-reducing aerospike|aerospike]], a telescoping outward extension that halves aerodynamic drag, is then deployed, and the boost phase begins. When the third-stage motor fires, within two minutes of launch, the missile is traveling faster than 20,000&nbsp;ft/s (6,000&nbsp;m/s), or 13,600&nbsp;mph (21,600&nbsp;km/h) Mach 18. Minutes after launch, the missile is outside the atmosphere and on a [[Sub-orbital spaceflight|sub-orbital trajectory]]. 

The guidance system for the missile was developed by the [[Charles Stark Draper Laboratory]] and is maintained by a joint Draper/General Dynamics Mission Systems facility. It is an [[inertial navigation system]] with an additional [[star-sighting]] system (this combination is known as [[astro-inertial guidance]]), which is used to correct small position and velocity errors that result from launch condition uncertainties due to errors in the submarine navigation system and errors that may have accumulated in the guidance system during the flight due to imperfect instrument calibration.  GPS has been used on some test flights but is assumed not to be available for a real mission. The fire control system was designed and continues to be maintained by General Dynamics Mission Systems. Once the star-sighting has been completed, the "bus" section of the missile maneuvers to achieve the various velocity vectors that will send the deployed multiple independent reentry vehicles to their individual targets. The downrange and crossrange dispersion of the targets remains classified.

The Trident was built in two variants: the I (C4) UGM-96A and II (D5) UGM-133A; however, these two missiles have little in common. While the C4, formerly known as EXPO (Extended Range Poseidon), is just an improved version of the Poseidon C-3 missile, the Trident II D-5 has a completely new design (although with some technologies adopted from the C-4). The C4 and D5 designations put the missiles within the "family" that started in 1960 with [[Polaris missile|Polaris]] (A1, A2 and A3) and continued with the 1971 [[Poseidon missile|Poseidon]] (C3). Both Trident versions are three-stage, solid-propellant, inertially guided missiles, and both guidance systems use a star sighting to improve overall weapons system accuracy.

===Trident I (C4) UGM-96A===
{{main|UGM-96 Trident I}}
[[File:Protest against Trident II Missile, Cape Canaveral Florida, 1987 04.jpg|right|thumb|"Stop Trident I Testing Now" sign in 1987 protest at [[Cape Canaveral Space Launch Complex 40|Cape Canaveral]], Florida]]
The first eight ''Ohio''-class submarines were built with the Trident I missiles.

===Trident II (D5) UGM-133A===
[[File:Trident II missile image.jpg|upright|thumb|A Trident II missile fires its first stage after an underwater launch from a [[Royal Navy]] {{sclass|Vanguard|submarine|0}} [[ballistic missile submarine]].]]
{{main|UGM-133 Trident II}}
The second variant of the Trident is more sophisticated and can carry a heavier payload. It is accurate enough to be a [[Pre-emptive nuclear strike|first strike]], [[counterforce]], or [[second strike]] weapon.  All three stages of the Trident II are made of [[Carbon fiber reinforced polymer|graphite epoxy]], making the missile much lighter. The Trident II was the original missile on the British ''Vanguard''-class and American ''Ohio''-class SSBNs from ''Tennessee'' on. The D5 missile is currently carried by fourteen ''Ohio''-class and four ''Vanguard''-class SSBNs. There have been 191 successful test flights of the D5 missile since design completion in 1989, the most recent being from {{USS| Louisiana |SSBN-743|6}} in September 2023. <ref>{{cite web |url= https://www.cpf.navy.mil/Newsroom/News/Article/3542092/uss-louisiana-proves-readiness-of-unmatched-strategic-weapons-system/ |title= USS Louisiana Proves Readiness of Unmatched Strategic Weapons System |publisher=U.S. Navy Strategic Systems Programs Public Affairs |date=28 September 2023|access-date=7 October 2024}}</ref> There have been fewer than 10 test flights that were failures,<ref>{{cite news |url=https://www.telegraph.co.uk/news/2017/01/23/theresa-may-briefed-trident-missile-test-allegedly-misfired2/ |title=US Trident failure claims contradict Michael Fallon |first1=Kate |last1=McCann |first2=Peter |last2=Dominiczak |first3=Steven |last3=Swinford |newspaper=The Daily Telegraph |date=23 January 2017 |access-date=26 January 2017 |url-status=live |archive-url=https://web.archive.org/web/20170125175326/http://www.telegraph.co.uk/news/2017/01/23/theresa-may-briefed-trident-missile-test-allegedly-misfired2/ |archive-date=25 January 2017}}</ref> the most recent being from {{HMS|Vanguard|S28|6}} in January 2024. This is the second failure in a row for the Royal Navy after a launch from {{HMS|Vengeance|S31|6}}, one of Britain's four nuclear-armed submarines, off the coast of Florida in June 2016.<ref name="UKDJ2017">{{cite web|title=How serious was the Trident missile test failure?|url=https://ukdefencejournal.org.uk/serious-trident-missile-test-failure/|publisher=UK Defence Journal|access-date=24 January 2017|date=22 January 2017|url-status=live|archive-url=https://web.archive.org/web/20170202015319/https://ukdefencejournal.org.uk/serious-trident-missile-test-failure/|archive-date=2 February 2017}}</ref>

The [[Royal Navy]] operates their missiles from a shared pool, together with the Atlantic squadron of the [[U.S. Navy]] ''Ohio''-class SSBNs at [[Naval Submarine Base Kings Bay|King's Bay, Georgia]]. The pool is 'co-mingled' and missiles are selected at random for loading on to either nation's submarines.<ref>{{cite web|url=https://ukdjcdn-b4d.kxcdn.com/uploads/2014/07/UK-Nuclear-Deterrent-FOI-Response.pdf|title=Freedon of information request about the UK nuclear deterrent|date=19 July 2005|access-date=25 January 2017|publisher=Ministry of Defence|url-status=dead|archive-url=https://web.archive.org/web/20161030002309/https://ukdjcdn-b4d.kxcdn.com/uploads/2014/07/UK-Nuclear-Deterrent-FOI-Response.pdf|archive-date=30 October 2016}}</ref>

===D5LE (D5 Life Extension Program)===
In 2002, the United States Navy announced plans to extend the life of the submarines and the D5 missiles to the year 2040.<ref>{{cite press release|title=Navy Awards Lockheed Martin $248 Million Contract for Trident II D5 Missile Production and D5 Service Life Extension |publisher=Lockheed Martin Space Systems Company |date=29 January 2002 |url=http://www.lockheedmartin.com/news/press_releases/2002/NavyAwardsLockheedMartin248MillionC.html |access-date=2009-01-28 |url-status=dead |archive-url=https://web.archive.org/web/20090227182711/http://www.lockheedmartin.com/news/press_releases/2002/NavyAwardsLockheedMartin248MillionC.html |archive-date=27 February 2009 }}</ref> This requires a D5 Life Extension Program (D5LEP), which is currently underway. The main aim is to replace obsolete components at minimal cost{{citation needed|date=June 2018}} by using commercial off the shelf (COTS) hardware; all the while maintaining the demonstrated performance of the existing Trident II missiles. In 2007, [[Lockheed Martin]] was awarded a total of $848 million in contracts to perform this and related work, which also includes upgrading the missiles' reentry systems.<ref name="ReferenceA">{{cite press release |title=Defence.gov: Contracts for Monday 26th November 2007 |publisher=US DoD |date=26 November 2007 |url=http://www.defense.gov/Contracts/Contract.aspx?ContractID=3654 |access-date=2010-07-30 |url-status=dead |archive-url=https://web.archive.org/web/20100829064918/http://www.defense.gov/contracts/contract.aspx?contractid=3654 |archive-date=29 August 2010}}</ref> On the same day, Draper Labs was awarded $318 million for upgrade of the guidance system.<ref name="ReferenceA" /> Then-British Prime Minister [[Tony Blair]] outlined plans in Parliament on 4 December 2006 to build a new generation of submarines ([[Dreadnought-class submarine|Dreadnought-class]]) to carry existing Trident missiles, and join the D5LE project to refurbish them.<ref>{{cite news |work = [[BBC News]] |url = http://news.bbc.co.uk/2/hi/uk_news/politics/6205174.stm |title = UK nuclear weapons plan unveiled |date= 4 December 2006|access-date  = 2012-11-23|url-status= live|archive-url  = https://web.archive.org/web/20121108031010/http://news.bbc.co.uk/2/hi/uk_news/politics/6205174.stm|archive-date = 8 November 2012}}</ref>

The first flight test of a D-5 LE subsystem, the MK 6 Mod 1 guidance system, in [[Demonstration and Shakedown Operation (DASO)|Demonstration and Shakedown Operation]] (DASO)-23,<ref>{{cite web |url= https://www.youtube.com/watch?v=V1eFhUMSJ9s |title= DASO 23 Video |publisher   = US Navy |date= 22 February 2012 |access-date  = 2012-12-14 |url-status= live |archive-url  = https://web.archive.org/web/20121012182154/http://www.youtube.com/watch?v=V1eFhUMSJ9s |archive-date = 12 October 2012}}</ref> took place on {{USS|Tennessee|SSBN-734|6}} on 22 February 2012.<ref>{{cite journal |url= http://www.public.navy.mil/subfor/underseawarfaremagazine/Issues/Archives/issue_48/USW_SPRING%2012_FINAL.pdf |journal= Undersea Warfare Magazine |title= Back to the Future with Trident Life Extension|publisher  = US Navy |date       = Spring 2012 |access-date = 2012-12-14}}{{dead link|date=April 2025|bot=medic}}{{cbignore|bot=medic}}</ref> This was almost exactly 22 years after the first Trident II missile was launched from ''Tennessee'' in February 1990.{{fact|date=April 2025}}

===D5LE2 (D5 Life Extension Program 2)===
US Navy Vice Admiral Johnny Wolfe, in charge of overall submarine weapons systems procurement, indicated in 2020 that he had initiated trade studies to apply lessons from the D5LE program to extend the Trident II's lifespan to 2084. Wolfe said he expected the first D5LE2 missiles to be deployed aboard the ninth [[Columbia-class submarine|''Columbia''-class submarine]] by FY 2039.<ref name="NextSub">{{Cite web |last1=Burgess |first1=Richard R. |date=2018-11-08 |title=Next Sub-Launched Ballistic Missile 'Won't Be Completely New' |url=https://seapowermagazine.org/next-sub-launched-ballistic-missile-wont-be-completely-new/ |access-date=2020-05-22 |website=Seapower |language=en-US}}</ref><ref name="Burgess 2021">{{cite web | last=Burgess | first=Richard R. | title=Navy's SSP Admiral: New Missile Planned for Introduction on 9th Columbia SSBN | website=Seapower | date=10 June 2021 | url=https://seapowermagazine.org/navys-ssp-admiral-new-missile-planned-for-introduction-on-9th-columbia-ssbn/ | access-date=9 November 2022}}</ref>