UGM-27 Polaris

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Image:Polaris-a1.jpg Image:Polaris-a3.jpg The Polaris missile was a submarine-launched, nuclear-tipped ballistic missile (SLBM) built during the Cold War by the United States Navy. It was designed to be used as part of the US Navy's contribution to the United States' nuclear deterrent, replacing the Regulus cruise missile.

Lockheed developed the solid-fuel Fleet Ballistic Missile (FBM), which first flew from Cape Canaveral on January 7, 1960.

The Polaris's first version, the A-1, weighed 28,800 lb (13.1 t), stood 28.5 ft (8.7 m) tall, had a diameter of 54 in (1.4 m), and had a range of 1,000 nautical miles (1850 km). A test launch from a submarine on July 20, 1960, was the first underwater guided-missile launch. The USS George Washington was the first fleet ballistic missile submarine (SSBN in US naval terminology) and carried 16 missiles. Forty more SSBNs were launched in 1960-66.

Work on its nuclear warhead began in 1957 at the facility now called the Lawrence Livermore National Laboratory by a team headed by Harold Brown. The Navy accepted delivery of the first 16 warheads in July 1960, and first launched one from a submarine on November 15.

On May 6, 1962, a Polaris missile with a live W47 warhead was tested in Operation Dominic I, in the Pacific Ocean the only U.S. test of a live offensive nuclear missile. (Surface-to-air and air-to-air missiles with nuclear warheads were also tested in the atmosphere, such as over Nevada.)

The later versions (the A-2, A-3, and B-3) were larger, weighed more, and had longer ranges. The range increase was most important: The A-2 could fly 1,500 nautical miles (2300 km), the A-3 2,500 nautical miles (4600 km), and the B-3 2,000 nautical miles (3700 km). The A-3 featured multiple independently-targeted reentry vehicles (MIRVs) and the B-3 was to have penetration aids to counter Soviet Anti-Ballistic Missile defenses. The B-3 evolved into the C-3 Poseidon missile.

Polaris missiles had two stages, both steered by thrust vectoring. An inertial navigation system could guide the missile to about a 900 meter (3000 feet) circular error probability. This made them unsuitable for use against hardened targets, which means they were mostly useful for retaliation.

The missile began to be replaced by Poseidon beginning in 1972. In the 1980s both were replaced by the Trident I.

The UGM-27A Polaris A-1 missile was a medium-range, submarine-launched, solid propellant ballistic missile. It was originally developed from a plan to create a submarine-based Jupiter missile, which eventually evolved into the far smaller, solid-propellant Polaris. The Polaris program resulted in a series of three missiles, the A-1, A-2 and A-3. The Polaris A-1 was the first missile launched from a submerged submarine, the USS George Washington, as well as the first US missile to use a cold launch system.

Originally, the Navy favored cruise missile systems in a strategic role as deployed on the earlier USS Greyback, but it quickly became apparent that ballistic missile systems had advantages over cruise missiles in range and accuracy. The prime contractor for all three versions was Lockheed, now Lockheed-Martin.

The Polaris A-1 missile served as a strategic asset. The missile was developed to complement the limited number of medium-range systems deployed throughout Europe. As those systems lacked the range to attack major Russian targets, the Polaris was developed to increase the level of nuclear deterrence and calm concerned allies. During this time period, there was little threat of counterforce strikes, as few systems had the accuracy to destroy missile systems. Due to this, the primary advantage of missile submarines was the ability to move shorter ranged systems to within range. However, as the technology developed, the submarine-launched Polaris gained increased survivability over fixed systems. It had no capability to destroy hardened targets but would have been effective against population centers.

The Polaris A-1 had a range of 2200 km (1,367 miles) on its single Mk 1 reentry vehicle. It carried a W-47-Y1 600 kT nuclear warhead, which was guided by an inertial guidance system which provided an accuracy of 1800 m. The missile had a length of 8.53 m, a body diameter of 1.37 m and a launch weight of 12 700 kg. It used a two-stage solid propellant design.

The Polaris program started development in 1956, with its first flight test in 1959. In 1962, the USS Ethan Allen successfully fired a Polaris A-1 missile equipped with a W-47 nuclear warhead against a test target. The missile entered service onboard the USS George Washington, the first US missile submarine, in 1960. The Polaris A-2 was essentially an upgraded A-1 and entered service in late 1961. The A-2 was fitted on a total of 13 submarines and served until June 1974.(1)

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British Polaris

The British became interested in Polaris after the cancellations of the Blue Streak and Skybolt missiles in the 1950s. Under the Nassau agreement that emerged from the 1962 Nassau Conference between Harold Macmillan and John F. Kennedy, the United States would supply Britain with Polaris missiles, launch tubes, and the fire control system. Britain would make the warheads and submarines. In return, America was given certain assurances by Britain regarding the use of the missile. The Polaris Sales Agreement was signed on April 6, 1963.

The British Polaris submarines were the Resolution-class ballistic missile submarines. The Polaris system underwent a British-designed life extension programme called Chevaline that reduced the number of warheads and added defensive countermeasures.

The British eventually upgraded to the Trident missile after much political wrangling over the cost and necessity, but waited for the Trident II (D5) variant.

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