Trident (missile)

Trident
Production history
Manufacturer	Lockheed Martin Space Systems
Unit cost	$30.9 million
Specifications
Mass	58,500 kg (130,000 lb)
Length	44 ft (13.41 m)
Diameter	83 in (2.11 m)

The Trident missile, named after the trident, is a submarine-launched ballistic missile or SLBM which is armed with nuclear warheads and is launched from SSBNs, nuclear-powered ballistic missile submarines.

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.

The Trident is carried by fourteen active US navy Ohio class submarines and, with British warheads, four Royal Navy Vanguard class submarines.

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 its fuselage. Within about two minutes, after the third stage motor fires, the missile is traveling faster than 20,000 ft/s (6,000 m/s).

Trident I (C4) was deployed in 1979 and phased out in the 1990s and early 2000s. Trident II (D5) was deployed in 1990, and was planned to be in service for the thirty year life of the submarines, until 2027. However, a decision was taken in 2002 to extend the life of the submarines and the D5 missiles to forty-five years. This requires a D5 Life Extension (D5LE) Program, which is currently ongoing. The main aim is to replace obsolete components at minimal cost, while maintaining the demonstrated performance of the existing missiles. In 2006, The UK Government said that it would maintain the UK's independent nuclear deterrent, although it still had to decide exactly how. It is expected to join in fully with the D5LE program for the missiles and have its own program (posslibly US-aided) for replacing the Vanguard class submarines and the UK's own warheads.

Trident I (C4) UGM-96A

Trident I first launch on 18 January 1977 at Cape Canaveral

A montage of the launch of a Trident I (C4) missile and its reentry vehicles.

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

• Purpose: strategic nuclear deterrence
• Contractor: Lockheed Martin Space Systems, Sunnyvale, California
• Propulsion: three stage solid propellant
• Length: 34 ft (10.2 m)
• Weight: 73,000 lb (33,142 kg)
• Diameter: 74 in (1.8 m)
• Range: 7400 km (4,600 statute miles)
• Guidance system: inertial, with stellar sensor update
• CEP: 1250 ft (380 m)
• Warhead: nuclear multiple independently targetable reentry vehicles (MIRV). Eight W76 (100 kt) warheads (Mark 4).
• Date deployed: 1979

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 later Ohio SSBNs.

Characteristics

• Purpose: strategic nuclear deterrence
• Contractor: Lockheed Martin Space Systems Co., Sunnyvale, Calif.
• Unit Cost: $30.9 million
• Propulsion: three stage solid propellant
• Length: 44 ft (13.41 m)
• Weight: 130,000 lb (58,500 kg)
• Diameter: 83 in (2.11 m)
• Range: 12000 km (7,500 statute miles)
• Maximum speed: 29,030 km/h (18,000 mph)
• Guidance system: inertial, with stellar sensor update
• CEP: 300 ft (90 m)
• Warhead (in USA usage only): nuclear MIRV. Up to eight W88 (475 kt) warheads (Mark 5) or eight W76 (100 kt) warheads (Mark 4).
• Date deployed: 1990

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 vehicles equipped with GPS for navigation update and a reentry guidance and control (trajectory correction) segment to perform 10m 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.

The primary drawback would have been establishing sufficient warning systems so that other nuclear countries would not mistake it for a nuclear launch. For that reason among others, this project raised a substantial debate before US Congress for the FY07 Defense budget, but also internationally. Russian President Vladimir Putin, among others, warned that the project would increase the danger of accidental nuclear war. "The launch of such a missile could ... provoke a full-scale counterattack using strategic nuclear forces," Putin said in May 2006.

See also

• Nuclear weapons and the United States
• Nuclear weapons and the United Kingdom

External links

• Trident I and II, at navysite.de
• Trident II D-5, at Federation of American Scientists website
• Picture of the Trident missile compartment on a British Vanguard class submarine
• Basic characteristics of Trident II D5
• Current British Nuclear Weapons at nuclearweapons.org
• Ballistic Missile Submarines
• Trident Ploughshares Campaign website
• Time for a nuclear entente cordiale, Bulletin of Atomic Scientists, September/October 2005
• UK's Parliamentary Defence Select Committee: Session 2001/02 Update on weapons programmes.
• UK to Upgrade Its Nukes, Spinwatch, Tuesday, 03 May 2005
• US-UK Mutual Defence Agreement (MDA) 1958
• Trident II Missile Launch - YouTube video