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The LGM-30 Minuteman is a United States nuclear missile, a land-based intercontinental ballistic missile (ICBM). As of 2006, it is the only land-based ICBM in service in the United States. It is complemented by the sea-launched Trident missile SLBM and by nuclear weapons carried by long-range strategic bombers; see current status of United States nuclear weapons. The “L” indicates that the missile is silo-launched; the “G” indicates that it is designed to attack surface targets; the “M” indicates that it is a guided missile. The name “Minuteman” comes from the Revolutionary War’s Minutemen.
Current model The current Minuteman force consists of 500 Minuteman-III missiles in missile silos around F.E. Warren Air Force Base, Wyoming, Malmstrom Air Force Base, Montana, and Minot Air Force Base, North Dakota. It is a guided missile, with three solid-fuel stages, and in addition, in the post-boost stage (“bus”), a liquid-fuel propulsion system rocket engine used to fine-tune the trajectory of the reentry vehicle and/or dispense individual warheads to separate targets across a broad area. The missile has a gimballed inertial guidance system. The third stage has precision shutdown ports which, when opened, reduce the chamber pressure so abruptly that the interior flame is blown out. This allows a more precise trajectory which improves targeting accuracy. The post-boost stage carries, in addition to the warheads, penetration aids such as chaff and decoys. With START II’s ban on multiple independently targetable reentry vehicles (MIRVs) now a dead letter, earlier plans to reduce the number of warheads per missile to one have been revised: the United States is now considering keeping 800 warheads on the Minuteman force. The Minuteman-III missile entered service in 1970, with weapon systems upgrades included during the production run from 1970 to 1978 to increase accuracy and payload capacity. 1998 USAF plans are to operate it until 2025. The LGM-118A Peacekeeper MX ICBM, which was to have replaced the Minuteman, was retired by 2005. The Peacekeeper suffered from controversy over various mobile basing schemes, but the original Peacekeeper basing plan included being deployed on railroad cars. Guidance Replacement Program (GRP) The Guidance Replacement Program (GRP) replaces the NS20A Missile Guidance Set with the NS50A Missile Guidance Set. The newer system extends the service life of the Minuteman missile beyond the year 2020 by replacing aging parts and assemblies with current, high reliability technology while maintaining the current accuracy performance. Propulsion Replacement Program (PRP) The Propulsion Replacement Program extends the life, maintains the performance, and improves the reliability of the operational ICBM force by replacing the old solid propellant boosters (downstages) with new “environmentally friendly” booster. Single Reentry Vehicle (SRV) The Single Reentry Vehicle (SRV) modification allows the United States ICBM force to abide by START treaty requirements by reconfiguring Minuteman-III missiles from three reentry vehicles down to one. Safety Enhanced Reentry Vehicle (SERV) Beginning in 2006, Mk-21/W87 RVs from the deactivated LGM-118A Peacekeeper missile will be placed on the Minuteman-III force under the Safety Enhanced Reentry Vehicle (SERV) program. The older W78 currently used is not equipped with important safety features. In addition to adding additional safety features into at least a portion of the future Minuteman-III force, the decision to transfer W87s onto the missile is based on two features that will improve the targeting capabilities of the weapon: more fusing options which will allow for greater targeting flexibility and the most accurate reentry vehicle available which provide a greater probability of damage. Organization The basic tactical unit of a Minuteman wing is the squadron, consisting of five flights. Each flight consists of ten unmanned launch facilities (LFs) which are remotely controlled by a manned launch control center (LCC). The five flights are interconnected and status from any LF may be monitored by any of the five LCCs. Each LF is located at least three nautical miles (5.6 km) from any LCC. Control does not extend outside the squadron (i.e. The 319th Missile Squadron’s five LCCs cannot control the 320th Missile Squadron’s 50 LFs). Each Minuteman wing is assisted logistically by a nearby Missile Support Base (MSB). Operator : The United States Air Force is the only operator of the Minuteman-III, with three operational wings and one test squadron operating the LGM-30G: History The Minuteman-I and Minuteman-II were in service from 1960 until 1997. The Minuteman-III was first deployed in 1969 and with the latest upgrades is expected to remain in service through the year 2025. The Minuteman had two innovations that gave it a long practical service life: a solid rocket booster, and a digital flight computer. This computer was one of the very first recognizably modern embedded systems. The solid rocket booster made the Minuteman faster to launch than other ICBMs, which used liquid fuels. A crucial innovation in this area was to include a valve to release the booster pressure, and permit effective throttling of the booster. A reprogrammable inertial guidance system was a major risk in the original program. When first proposed, no one had built a digital computer that would fit in a missile. One program, the SM-64 Navaho, had already failed to produce such a system. A digital computer was essential to obtain the accuracy gains that kept this weapon effective throughout the Cold War. As the Defense Mapping Agency (now part of National Geospatial-Intelligence Agency) more accurately mapped mass concentrations in the Earth, the inertial guidance software could be updated and loaded into the missiles to make them ever more accurate by having them compensate for these sources of gravity. Another gain that persuaded program managers to accept the risk of the computer was that the computer could also be used to test the missile. This saved a large amount of weight in cables and connectors. Minuteman I (LGM-30A/B or SM-80/HSM-80A) The LGM-30A Minuteman-I entered into the Strategic Air Command’s arsenal in 1962, at Malmstrom Air Force Base, Montana; the “improved” LGM-30B became operational at Ellsworth Air Force Base, South Dakota, Minot Air Force Base, North Dakota, F.E. Warren Air Force Base, Wyoming, Grand Forks Air Force Base, North Dakota, and Whiteman Air Force Base, Missouri in 1963. All 800 Minuteman-I missiles were delivered by June 1965. Each of the bases had 150 missiles emplaced, except for F.E. Warren Air Force Base, which had 200 missiles. The Minuteman-I Autonetics D-17 flight computer used a rotating air bearing magnetic disk holding 2,560 “cold-stored” words in 20 tracks (write heads disabled after program fill) of 24 bits each and one alterable track of 128 words. The time for a D-17 disk revolution was 10 ms. The D-17 also used a number of short loops for faster access of intermediate results storage. The D-17 computational minor cycle was three disk revolutions or 30 ms. During that time all recurring computations were performed. For ground operations the inertial platform was aligned and gyro correction rates updated. During flight, filtered command outputs were sent each minor cycle to the engine nozzles. Unlike modern computers, which use descendants of that technology for secondary storage on hard disk, the disk was the active computer memory. The disk storage was considered hard to radiation from nearby nuclear explosions, making it an ideal storage medium. To improve computational speed, the D-17 borrowed an instruction look-ahead feature from the Autonetics-built Field Artillery Data Computer (FADAC) that permitted simple instruction execution every word time. Minuteman-II (LGM-30F)
Minuteman-III (LGM-30G)
Weapon system programs Influences The author Thomas Pynchon worked as a technical writer for the field support unit for the Minuteman missile, something that is probably reflected in the narrative of his novels The Crying of Lot 49 and ''Gravity’s Rainbow''. The Minuteman Missile National Historic Site in South Dakota has recently been created. It preserves a Launch Control Facility and a missile silo complex under the control of the National Park Service. Mobile Minuteman program While the silo-based Minuteman was in development, the United States Air Force released details about a rail-based counterpart. On October 12 1959, details on the system, called the “Mobile Minuteman,” were released to the public. The system used the United States railroad network to help increase the system's survivability during nuclear attack. A performance test, code named Operation Big Star, was conducted from June 20 to August 27 1960 at Hill Air Force Base, Utah. The United States Air Force then activated the 4062nd Mobile Missile Wing on December 1 1960. The wing was to have three missile train squadrons, each with ten trains and each train carrying three missiles (30 missiles per squadron). Lack of support by the Kennedy Administration killed the Mobile Minuteman Program; on December 1 1961, the Department of Defense deleted the three mobile missile squadrons from its budget. The USAF officially deactivated the 4062nd Mobile Missile Wing on February 20 1962. The idea for a rail-based missile system was kept alive through the LGM-118A Peacekeeper Rail Garrison and the Soviet Union’s SS-24 Scalpel rail-based ICBM. Emergency Rocket Communications System (ERCS) An additional part of the National Command Authority communication relay system was called the emergency rocket communication system (ERCS). Specially designed rockets called BLUE SCOUT carried radio-transmitting payloads high above the continental United States, to relay messages to units within line-of-sight. In the event of a nuclear attack, ERCS payloads would relay preprogrammed messages giving the “go-order” to SAC units. BLUE SCOUT launch sites were located at Wisner, West Point and Tekamah, Nebraska. These locations were vital for ERCS effectiveness due to their centralized position in the US, within range of all missile complexes. Later ERCS configurations were placed on the tops of modified Minuteman-II ICBMs (LGM-30Fs) under the control of the 510th Strategic Missile Squadron located at Whiteman Air Force Base, Missouri. Satellite launching role The U.S. Air Force has considered using some decommissioned Minuteman missiles in a satellite launching role. These missiles would be stored in silos, for launch upon short notice. The payload would be variable, and would have the ability to be replaced quickly. This would allow a surge capability in times of emergency. See also Minotaur (rocket). Missile Defense Minutemen modifications are being produced at Prime Machine in Salt Lake City, Utah as part of the Alliant Kinetic Energy Interceptor (KEI, a guided “space bullet”) portion of the USA’s missile defense program. Minuteman chronology
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