The UGM-73 Poseidon missile was the second

US Navy The United States Navy (USN) is the naval warfare, maritime military branch, service branch of the United States Department of Defense. It is the world's most powerful navy with the largest Displacement (ship), displacement, at 4.5 millio ...

submarine-launched ballistic missile A submarine-launched ballistic missile (SLBM) is a ballistic missile capable of being launched from Ballistic missile submarine, submarines. Modern variants usually deliver multiple independently targetable reentry vehicles (MIRVs), each of which ...

(SLBM) system, powered by a

two-stage A multistage rocket or step rocket is a launch vehicle that uses two or more rocket ''stages'', each of which contains its own engines and propellant. A ''tandem'' or ''serial'' stage is mounted on top of another stage; a ''parallel'' stage is ...

solid-fuel rocket A solid-propellant rocket or solid rocket is a rocket with a rocket engine that uses Rocket propellant#Solid chemical propellants, solid propellants (fuel/oxidizer). The earliest rockets were solid-fuel rockets powered by gunpowder. The incepti ...

. It succeeded the

UGM-27 Polaris The UGM-27 Polaris missile was a two-stage solid-fueled nuclear-armed submarine-launched ballistic missile (SLBM). As the United States Navy's first SLBM, it served from 1961 to 1980. In the mid-1950s the Navy was involved in the Jupiter missi ...

beginning in 1972, bringing major advances in warheads and accuracy. It was followed by Trident I in 1979, and Trident II in 1990.

Development

A development study for a longer range version of the Polaris missile—achieved by enlarging it to the maximum possible size allowed by existing launch tubes—started in 1963. Tests had already shown that Polaris missiles could be operated without problems in launch tubes that had their

fiberglass Fiberglass (American English) or fibreglass (English in the Commonwealth of Nations, Commonwealth English) is a common type of fibre-reinforced plastic, fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened i ...

liners and locating rings removed. The project was given the title Polaris B3 in November, but the missile was eventually named Poseidon C3 to emphasize the technical advances over its predecessor. The C3 was the only version of the missile produced, and it was also given the designation UGM-73A. Slightly longer and considerably wider and heavier than Polaris A3, Poseidon had the same range, greater payload capacity, improved accuracy, and

multiple independently targetable reentry vehicle A multiple independently targetable reentry vehicle (MIRV) is an exoatmospheric ballistic missile payload containing several warheads, each capable of being aimed to hit a different target. The concept is almost invariably associated with i ...

(MIRV) capability. MIRV capacity has been given as up to either ten or fourteen W68 thermonuclear warheadsPoseidon C3 at MissileThreat.com
contained in Mark 3 reentry vehicles to multiple targets. As with Polaris, starting a rocket motor when the missile was still in the submarine was considered very dangerous. Therefore, the missile was ejected from its launch tube using high pressure steam produced by a solid-fueled boiler. The main rocket motor ignited automatically when the missile had risen approximately above the submarine. The first test launch took place on 16 August 1968, the first successful at-sea launch was from a surface ship, the (from July 1 to December 16, 1969), earning the ship the

Meritorious Unit Commendation The Meritorious Unit Commendation (MUC; pronounced ''muck'') is a mid-level unit award of the United States Armed Forces. The U.S. Army awards units the Army MUC for exceptionally meritorious conduct in performance of outstanding achievement or ...

, and the first test launch from a submarine took place on the on 3 August 1970. The weapon officially entered service on 31 March 1971. It eventually equipped 31 -, -, and -class submarines. The Royal Navy also considered adopting Poseidon in the 1970s as an upgrade to its Polaris A3T boats, and like the US this would have kept the existing hulls. Although the Navy's favoured option, the British government instead adopted

Chevaline Chevaline () was a system to improve the penetrability of the warheads used by the UK Polaris programme, British Polaris nuclear weapons system. Devised as an answer to the improved Soviet Union, Soviet A-35 anti-ballistic missile system, anti-b ...

, a two warhead MRV system with decoys, on the existing Polaris airframes and later moved to the Trident D5 in new boats. Beginning in 1979, 12 Poseidon-equipped

SSBN A ballistic missile submarine is a submarine capable of deploying submarine-launched ballistic missiles (SLBMs) with nuclear warheads. These submarines became a major weapon system in the Cold War because of their nuclear deterrence capabil ...

s were refitted with Trident I. By 1992, the

Soviet Union The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...

had collapsed, 12 Ohio-class submarines had been commissioned, and the

START I START I (Strategic Arms Reduction Treaty) was a bilateral treaty between the United States and the Soviet Union on the reduction and the limitation of strategic offensive arms. The treaty was signed on 31 July 1991 and entered into force on 5 De ...

treaty had gone into effect, so the 31 older Poseidon- and Trident I-armed SSBNs were disarmed, withdrawing Poseidon from service.

Operators

* **

United States Navy The United States Navy (USN) is the naval warfare, maritime military branch, service branch of the United States Department of Defense. It is the world's most powerful navy with the largest Displacement (ship), displacement, at 4.5 millio ...

Gallery

References

{{Authority control Cold War missiles of the United States Nuclear missiles of the United States Cold War submarine-launched ballistic missiles of the United States Lockheed Corporation UGM-073 Military equipment introduced in the 1970s

Development

Operators

Gallery

See also

References