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The UGM-27 Polaris missile was a two-stage solid-fuel rocket 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 . Despite the successful launching tests, the US never provided the missiles, due to political convenience. Instead 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. The Polaris missile was gradually replaced on 31 of the 41 original SSBNs in the US Navy by the MIRV-capable Poseidon missile beginning in 1972. During the 1980s, these missiles were replaced on twelve of these submarines by the Trident I missile. The ten - and SSBNs retained Polaris A-3 until 1980 because their missile tubes were not large enough to accommodate Poseidon. With commencing sea trials in 1980, these submarines were disarmed and redesignated as attack submarines to avoid exceeding the SALT II strategic arms treaty limits. Many new project management techniques were introduced during the development of the Polaris missile program, to deal with the inherent system complexity. This includes the use of the Program Evaluation and Review Technique (PERT). This technique replaced the simpler Gantt chart methodology which was largely employed prior to this program. ==History and development== The Polaris missile replaced an earlier plan to create a submarine-based missile force based on a derivative of the U.S. Army Jupiter Intermediate-range ballistic missile. Chief of Naval Operations Admiral Arleigh Burke appointed Rear Admiral W. F. "Red" Raborn as head of a Special Project Office to develop Jupiter for the Navy in late 1955. The Jupiter missile's large diameter was a product of the need to keep the length short enough to fit in a reasonably-sized submarine. At the seminal Project Nobska conference in 1956, with Admiral Burke present, nuclear physicist Edward Teller stated that a physically small one-megaton warhead could be produced for Polaris within a few years, and this prompted Burke to leave the Jupiter program and concentrate on Polaris in December of that year.〔Friedman, pp. 109-114〕 Polaris was spearheaded by the Special Project Office's Missile Branch under Rear Admiral Roderick Osgood Middleton,〔(Navy Office of Information biography on Roderick Osgood Middleton )〕 and is still under the Special Project Office.〔(History of the Jupiter Missile, pp. 23-35 )〕 Admiral Burke later was instrumental in determining the size of the Polaris submarine force, suggesting that 40-45 submarines with 16 missiles each would be sufficient.〔("How Much is Enough?": The U.S. Navy and "Finite Deterrence" ), National Security Archive Electronic Briefing Book No. 275〕 Eventually, the number of Polaris submarines was fixed at 41.〔Friedman, pp. 196-197〕 There is a contention that the Navy's "Jupiter" missile program was unrelated to the Army program. A huge surfaced submarine would carry four "Jupiter" missiles, which would be carried and launched horizontally.〔(1946:1 )〕 This was probably the never-built SSM-N-2 Triton program.〔Friedman, p. 183〕 However, a history of the Army's Jupiter program states that the Navy was involved in the Army program, but withdrew at an early stage.〔 Originally, the Navy favored cruise missile systems in a strategic role, such as the Regulus missile deployed on the earlier and a few other submarines, but a major drawback of these early cruise missile launch systems (and the Jupiter proposals) was the need to surface, and remain surfaced for some time, to launch. Submarines were very vulnerable to attack during launch, and a fully or partially fueled missile on deck was a serious hazard. Rough weather was another major drawback for these designs, but rough sea conditions did not unduly affect Polaris' submerged launches. It quickly became apparent solid-fueled ballistic missiles had advantages over cruise missiles in range and accuracy, and unlike both Jupiter and cruise, were able to be launched from a submerged submarine, improving submarine survivability. The prime contractor for all three versions of Polaris was Lockheed Missiles and Space Company, now Lockheed Martin. The Polaris program started development in 1956. , the first US missile submarine, successfully launched the first Polaris missile from a submerged submarine on July 20, 1960. The A-2 version of the Polaris missile was essentially an upgraded A-1, and it entered service in late 1961. It was fitted on a total of 13 submarines and served until June 1974.(1). Ongoing problems with the W-47 warhead, especially with its mechanical arming and safing equipment, led to large numbers of the missiles being recalled for modifications, and the U.S. Navy sought a replacement with either a larger yield or equivalent destructive power. The result was the W-58 warhead used in a "cluster" of three warheads for the Polaris A-3, the final model of the Polaris missile. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「UGM-27 Polaris」の詳細全文を読む スポンサード リンク
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