The LGM-30 Minuteman is a U.S. nuclear missile, a land-based intercontinental ballistic missile (ICBM). As of 2009, 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 ground targets; the “M” indicates that it is a guided missile.
The name “Minuteman” comes from the Revolutionary War’s Minutemen. It also refers to its quick reaction time; the missile can be launched in about 1 minute. The Air Force planned to keep the missile in service until 2020, but it may be upgraded to stay in service until 2030.
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.
GCRM - Replace the log as needed or container if the cache container is broken or missing. Before you replace a missing container, you must spend a reasonable amount of time searching - at least 5 minutes per difficulty rating. The cache owner accepts that there is a chance that multiple containers could be at the site. Please remove duplicate containers if you find multiple caches at the site. Broken containers and full logs may be disposed of at will.