UGM-27 Polaris

UGM-27 Polaris
Polaris A-3 on launch pad prior to a test firing at Cape Canaveral
Type	Submarine-launched ballistic missile
Place of origin	United States
Service history
In service	1961–1996
Used by	United States Navy, Royal Navy
Production history
Designed	1956–1960
Manufacturer	Lockheed Corporation
Variants	A-1, A-2, A-3, Chevaline
Specifications (Polaris A-3 (UGM-27C))
Weight	35,700 lb (16,200 kg)
Height	32 ft 4 in (9.86 m)
Diameter	4 ft 6 in (1,370 mm)
Warhead	3 x W58 thermonuclear weapon
Blast yield	3 x 200 kT
Engine	First stage, Aerojet General Solid-fuel rocket Second stage, Hercules rocket
Propellant	Solid propellant
Operational range	2,500 nautical miles (4,600 km)
Speed	8,000 mph (13,000 km/h)
Guidance system	Inertial
Steering system	Thrust vectoring
Accuracy	CEP 3,000 feet (910 m)
Launch platform	Ballistic missile submarines

The UGM-27 Polaris missile was a two-stage solid-fueled nuclear-armed submarine-launched ballistic missile (SLBM) built during the Cold War by Lockheed Corporation for the United States Navy.

It was designed to be used for second strike countervalue (CEP not good enough for first strike counterforce) as part of the Navy's contribution to the United States arsenal of nuclear weapons, replacing the Regulus cruise missile. Known as a Fleet Ballistic Missile (FBM), the Polaris was first launched from the Cape Canaveral, Florida, missile test base on January 7, 1960.

Following the Polaris Sales Agreement in 1963, Polaris missiles were also carried on British Royal Navy submarines between 1968 and the mid-1990s.

Plans to equip the Italian Navy with the missile ended in the mid-60s, after several successful test launches carried out on board the Italian cruiser Giuseppe Garibaldi. Despite the successful launching tests, the plan was abandoned due to the completion of initial SSBN vessels. Nonetheless, the Italian Government set to develop an indigenous missile, called Alfa, with a successful program, officially halted by Italian Nuclear Non-Proliferation Treaty ratification and failure of the NATO Multilateral Force.