The Peacekeeper missile
is America's newest intercontinental ballistic missile. Its deployment fulfilled
a key goal of the strategic modernization program and increased strength and
credibility to the ground-based leg of the U.S. strategic triad. With the end of
the Cold War, the U.S. has begun to revise its strategic policy and has agreed
to eliminate the multiple re-entry vehicle Peacekeeper ICBMs by the year 2003 as
part of the Strategic Arms Reduction Treaty II. The Peacekeeper is capable of
delivering 10 independently targeted warheads with greater accuracy than any
other ballistic missile. It is a three-stage rocket ICBM system consisting of
three major sections: the boost system, the post-boost vehicle system and the
re-entry system.

Peacekeeper
missile
also called MX, U.S.
intercontinental ballistic missile (ICBM) that entered service in
1986.Under development from 1971, the MX (for "missile
experimental") evolved into a 71-foot (22-metre) ICBM with a "bus,"
or fourth stage, located in its front end that carried 10 or 12
independently targetable thermonuclear warheads. This endowed each
missile with several times the firepower of the two- or
three-warhead Minuteman III, which it was designed to replace. In
addition, the MX's extremely accurate guidance--an inertial system
capable of being updated in flight by signals from navigation
satellites--gave its 300-kiloton warheads greater potential to
destroy reinforced missile silos and command bunkers in the Soviet
Union. The MX had a range of approximately 7,000 miles (11,000
km).In order to be able to evade attack by Soviet ICBMs, which
lagged behind U.S. ICBMs in accuracy but were far more powerful,
several types of bases for the MX were proposed. These included
launching by air from huge transport jets, "deep basing" in silos
located more than 1,000 feet (305 m) underground, shuttling the
missiles continuously on trucks or rail cars among "multiple
protective shelters," and grouping silos close together in a "dense
pack," so that incoming nuclear warheads would destroy or deflect
one another. All of these modes proved to be prohibitively
expensive, and none was politically popular; in 1983 it was decided
to place the missiles in Minuteman III silos. Although plans called
for 100 Peacekeepers, only 50 were authorized for deployment at
Warren Air Force Base, Wyoming.

LGM-118A Peacekeeper The Peacekeeper missile is America's
newest intercontinental ballistic missile. With the end of the Cold War, the US
has begun to revise its strategic policy, and has agreed to eliminate the
multiple re-entry vehicle Peacekeeper ICBMs by the year 2003 as part of the
Strategic Arms Reduction Treaty II. The Peacekeeper (designated LGM-118A) is a
four-stage intercontinental ballistic missile capable of carrying up to ten
independently-targetable reentry vehicles with greater accuracy than any other
ballistic missile. Its design combines advanced technology in fuels, guidance,
nozzle design, and motor construction with protection against the hostile
nuclear environment associated with land-based systems. The Peacekeeper is much
larger than Minuteman, over 70 feet long and weighing 198,000 pounds. It is a
four stage missile like the Minuteman III, with the first three stages being
solid propellant and the fourth stage bu hypergolicly fueled with hydrazine and
nitrogen tetroxide. Although capable of carrying eleven Mark 21 RVs, treaty
limits mandated deploying the Peacekeeper with only ten RVs. The entire missile
is encased in a canister in the silo to protect it against damage and to permit
"cold launch". The Minuteman II and III ignite their first stage engines while
in the LF, but the Peacekeeper is ejected by pressurized gas some fifty feet
into the air before first stage ignition.
The Peacekeeper is a three-stage rocket ICBM system consisting of three major
sections: the boost system, the post-boost vehicle system and the re-entry
system.
The boost system consists of three rocket stages that launch the missile into
space. These rocket stages are mounted atop one another and fire successively.
Three of the four stages exhausted their solid propellants through a single
adjustable nozzle which guided the missile along its flight path. Motorcases
made of kevlar epoxy material held the solid propellants. The fourth stage
post-boost vehicle employed a liquid bi- propellant rocket propulsion system to
provide velocity and attitude correction for missile guidance. The post-boost
vehicle also employed a self-contained inertial navigation system that allowed
the missile to operate independent of ground reference or commands during
flight.
The 28-foot first-stage solid-fuel rocket motor weighed approximately 108,000
pounds and is capable of boosting the missile to about 75,000 feet. The 18-foot
long second-stage motor propelled the missile to an altitude of about 190,000
feet and weighed 60,000 pounds. The rocket motor in the eight-foot third stage
weighed 17,000 pounds and supplied the thrust to boost the missile to about
700,000 feet. The 2,300 pound post-boost fourth stage vehicle was designed to
maneuver the missile into position for the multiple reentry vehicles to deploy
in their respective ballistic trajectories.
Following the burnout and separation of the boost system's third rocket
stage, the post-boost vehicle system, in space, maneuvers the missile as its
re-entry vehicles are deployed in sequence. The post-boost vehicle system is made up of a maneuvering rocket, and a
guidance and control system. The vehicle rides atop the boost system, weighs
about 3,000 pounds (1,363 kilograms) and is 4 feet (1.21 meters) long. The top section of the Peacekeeper is the re-entry system. It consists of the
deployment module, up to 10 cone-shaped re-entry vehicles and a protective
shroud. The shroud protects the re-entry vehicles during ascent. It is topped
with a nose cap, containing a rocket motor to separate it from the deployment
module.
The deployment module provides structural support for the re-entry vehicles
and carries the electronics needed to activate and deploy them. The vehicles are
covered with material to protect them during re-entry through the atmosphere to
their targets and are mechanically attached to the deployment module. The
attachments are unlatched by gas pressure from an explosive cartridge broken by
small, exploding bolts, which free the re-entry vehicles, allowing them to
separate from the deployment module with minimum disturbance. Each deployed
re-entry vehicle follows a ballistic path to its target.
The Peacekeeper was the first U.S. ICBM to use cold launch technology. The
missile was placed inside a canister and loaded into the launch facility. When
launched, high-pressure steam ejected the canister from the launch silo to an
altitude of 150 to 300 feet, and once the missile has cleared the silo, the
first stage ignited and sent the missile on its course. This technique allowed
SAC to launch the Peacekeeper from Minuteman silos despite the fact that the
Peacekeeper was three times larger than the Minuteman III.