UGM-27 Polaris

UGM-27 Polaris
Polaris A-3 on launch pad before 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))
Mass	35,700 lb (16,200 kg)
Height	32 ft 4 in (9.86 m)
Diameter	4 ft 6 in (1,370 mm)
Warhead	1 x W47, 3 × W58 thermonuclear weapon
Blast yield	3 × 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)
Maximum 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). 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 missile project with the U.S. Army, and had influenced the design by making it squat so it would fit in submarines. However, they had concerns about the use of liquid fuel rockets on board ships, and some consideration was given to a solid fuel version, Jupiter S. In 1956, during an anti-submarine study known as Project Nobska, Edward Teller suggested that very small hydrogen bomb warheads were possible. A crash program to develop a missile suitable for carrying such warheads began as Polaris, launching its first shot less than four years later, in February 1960.^[1]

As the Polaris missile was fired underwater from a moving platform, it was essentially invulnerable to counterattack. This led the Navy to suggest, starting around 1959, that they be given the entire nuclear deterrent role. This led to new infighting between the Navy and the U.S. Air Force, the latter responding by developing the counterforce concept that argued for the strategic bomber and ICBM as key elements in flexible response. Polaris formed the backbone of the U.S. Navy's nuclear force aboard a number of custom-designed submarines. In 1963, the Polaris Sales Agreement led to the Royal Navy taking over the United Kingdom's nuclear role, and while some tests were carried out by the Italian Navy, this did not lead to use.

The Polaris missile was gradually replaced on 31 of the 41 original SSBNs in the U.S. Navy by the MIRV-capable Poseidon missile beginning in 1972. During the 1980s, these missiles were replaced on 12 of these submarines by the Trident I missile. The 10 George Washington- and Ethan Allen-class SSBNs retained Polaris A-3 until 1980 because their missile tubes were not large enough to accommodate Poseidon. With USS Ohio beginning sea trials in 1980, these submarines were disarmed and redesignated as attack submarines to avoid exceeding the SALT II strategic arms treaty limits.

The Polaris missile program's complexity led to the development of new project management techniques, including the Program Evaluation and Review Technique (PERT) to replace the simpler Gantt chart methodology.