Peacekeeper (MX) Missile System Development
Soon after the first Minuteman IIIs were deployed, SAC planners began their search for a third-generation ICBM that would carry the nation's strategic nuclear deterrent into the next century. In April 1972 the Air Force designated its new advanced ICBM program "Missile-X," or MX, and over the next 8 years it struggled to determine what capabilities the MX should have and how it should be based.
Basing was a critical consideration. In the early 1970s SAC became increasingly concerned that the next generation of Soviet ICBMs would carry multi-megaton warheads and guidance systems accurate enough to destroy U.S. ICBMs within their hardened silos. To protect the MX from a Soviet first strike, SAC planners considered two alternatives: a mobile launch platform or a super-hardened launch facility. They concentrated on the former. Between 1972 and 1979 the Air Force evaluated almost 40 different basing schemes that included trains, transport aircraft, and shuttling the missiles between hundreds of above-ground launch sites scattered over the deserts of the southwest. After 7 years of study, the basing mode issue remained unresolved. In June 1979 President Carter could wait no longer; he threw his support behind the Multiple Launch Shelter scheme and authorized the Air Force to proceed with full-scale engineering development.
The Air Force, however, never found a mobile basing mode that Congress liked. As an interim measure in 1983 the Department of Defense authorized the Air Force to install 100 of the newly designated Peacekeeper (LGM-18A) missiles in reconfigured Minuteman III silos at F.E. Warren AFB, Wyoming. Congress objected to the plan and in 1985 voted to limit the deployment to 50 missiles until the Reagan administration could produce a more survivable basing plan. In 1986 the Air Force proposed basing the remaining 50 missiles on 25 specially configured trains, an approach it called the Peacekeeper Rail Garrison. The collapse of the Soviet Union, coupled with a shrinking defense budget, prompted President Bush to cancel the program in 1991.
The 50 Peacekeepers at FE. Warren AFB were placed on operational alert between 1986 and 1988. This third-generation ICBM is a four-stage solid-fuel missile that can carry up to ten 500kiloton warheads. The Peacekeeper is 70 feet tall and weighs 195,000 pounds-2 l/2 times the weight of the Minuteman III. Fitting these larger missiles into the existing Minuteman silos was a challenge. It was possible because during the mid-1970s the Air Force envisioned that Peacekeeper would be a mobile missile, and it designed the ICBM to be "cold launched" from a sealed canister. By making certain modifications to the Minuteman silo, the Air Force was able to load the sealed Peacekeeper canister into the existing structure.
To launch the missile, high-pressure steam blows the canister out of the silo and up to an altitude of 150 to 300 feet, where-upon the first-stage engine ignites and the missile streaks off toward its target. Among the many advanced features incorporated in the Peacekeeper is an advanced inertial reference system (AIRS) that can reportedly guide the Peacekeeper's warheads to within 400 feet of their targets.
Today, nearly 40 years after deploying its first Atlas missile, the United States continues to rely on ICBMs to provide a vital component of its strategic nuclear deterrent. But just as the Cold War gave the ICBM program life, that conflict's much-heralded passing has had sweeping repercussions on the missile program. With a single stroke of his pen, President Bush in 1991 ordered the deactivation and eventual destruction of 450 Minuteman II missiles. Over the past 25 years the nation's ICBM force has been cut almost in half, shrinking from a peak of 1,054 launchers in the mid-1970s to 580 in 1995. Further reductions are pending. Under the provisions of the START I Agreement, almost all of the now-abandoned missile silos, with the exception of the Atlas and Titan I facilities, are being systematically destroyed.