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This article contains technical information about the Trident ballistic missile. For a discussion of the British Trident weapons program, see UK Trident Programme The Trident missile, named after the Trident , is a Submarine-launched Ballistic Missile (SLBM) which is armed with Nuclear Warhead s and is launched from SSBN s, nuclear-powered ballistic missile submarines. Trident missiles are carried by fourteen active US Navy ''Ohio ''class Submarine s and, with British warheads, four Royal Navy ''Vanguard'' Class Submarine s. DEVELOPMENT Trident I (C4) was deployed in 1979 and phased out in the 1990s and early 2000s. Trident II (D5) was first deployed in 1990, and was planned to be in service for the thirty year life of the submarines, until 2027. Trident missiles are provided to the United Kingdom under the terms of the 1963 Polaris Sales Agreement which was modified in 1982 for Trident. British Prime Minister Margaret Thatcher had written to President Carter on July 10 1980 to request that he approve supply of Trident I missiles. However in 1982 Thatcher wrote to President Reagan to request the United Kingdom be allowed to procure the Trident II (Trident D5) system, the procurement of which had been accelerated by the US Navy. This was agreed in March 1982. Reagan letter to Thatcher Under the agreement, the United Kingdom made a 5% research and development contribution. D5 life extension A decision was taken in 2002 to extend the life of the submarines and the D5 missiles to the year 2042. This requires a D5 Life Extension (D5LE) Program, which is currently underway. The main aim is to replace obsolete components at minimal cost by leveraging 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 $789.9 million in contracts to perform this work, which also includes upgrading the missiles' guidance and reentry systems.Lockheed press release April 9, 2007 The 2006 , Tony Blair Outlined Plans in Parliament to build a New Generation Of Submarines to carry existing Trident missiles, and join the D5LE project to refurbish them.BBC News UK nuclear weapons plan unveiled DESCRIPTION The launch from the submarine occurs below the ocean surface. The missiles are ejected from their tubes by gas pressure created by a "gas generator", a solid-fuel rocket motor attached to the bottom of the missile tube which heats a pool of water creating steam. After the missile leaves the tube and rises through the water over the submarine, the first stage motor ignites, the aerospike extends, and the boost phase begins. Ideally, the missile is "sheathed" in gas bubbles for its entire time in the water, so liquid never touches the missile. When the third stage motor fires, within two minutes of launch, the missile is traveling faster than 20,000 ft/s (6,000 m/s), or 12,000 mph. The Trident was built in two variants: the I (C4) UGM-96A and II (D5) UGM-133A. The C4 and D5 designations put the missiles within the "family" that started in 1960 with Polaris (A1, A2 and A3) and continued with the 1971 Poseidon (C3). Both Trident versions are three-stage, solid-propellant, inertially guided missiles whose range is increased by an Aerospike , a telescoping outward extension that halves aerodynamic drag. In the post-boost phase, the Trident missile uses stellar sighting to update its position and reduce the Drift error inherent in all Inertial Reference Systems . Trident I (C4) UGM-96A 1977 at Cape Canaveral]] The first eight Ohio-class subs were built with the Trident I missiles. Trident Is were also retrofitted onto 12 SSBNs of the James Madison and Benjamin Franklin classes, replacing Poseidon missiles. Characteristics
Trident II (D5) UGM-133A The second variant of the Trident is more sophisticated and can carry a heavier payload. It is accurate enough to be a First Strike weapon. All three stages of the Trident II are made of Graphite Epoxy , making the missile much lighter. The Trident II was the original missile on the British Vanguard and ''Ohio'' SSBNs since USS ''Tennessee'' (SSBN-734) . The D5 missile is currently carried by twelve Ohio class SSBNs.Lockheed press release April 9, 2007 Lockheed has carried out 119 consecutive successful test launches of the D5 missile since 1989, according to a company press release.Lockheed Press Release May 16, 2007 Characteristics
CONVENTIONAL TRIDENT The Pentagon proposed the Conventional Trident Modification program in 2006 to diversify its strategic options, as part of a broader long-term strategy to develop worldwide rapid strike capabilities, dubbed "Prompt Global Strike". The US $503 million program would have converted existing Trident II missiles (presumably two missiles per submarine) into conventional weapons, by fitting them with modified Mk4 Reentry Vehicle s equipped with GPS for navigation update and a reentry guidance and control (trajectory correction) segment to perform 10 m class impact accuracy. No explosive is said to be used since the reentry vehicle's mass and hypersonic impact velocity provide sufficient mechanical energy and "effect". It offered the promise of accurate conventional strikes with little warning and flight time. |
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