Minuteman Missile Reentry System
The Minuteman III reentry system was originally designed and produced by General Electric to deploy two or three MK 12 reentry vehicles. In the late 1970s the MK 12 reentry system was modified to accommodate a new reentry vehicle, designated the MK 12A. Three hundred of the original 550 MK 12 systems were converted to the MK 12A configuration. In the 1990s the capability to deploy a single reentry vehicle was added to the existing multiple interdependently target reentry vehicle (MIRV) capability to allow strategic planners greater flexibility in meeting warhead reductions mandated by arms limitation treaties. A future modification is being planned to deploy either one or two MK 21 reentry vehicles on Minuteman III when the Peacekeeper system is deactivated (Peacekeeper was deactivated in 2005).
During a typical flight mission, the reentry system Shroud is removed from the reentry system near the end of Stage 2 burn. Following Stage 3 thrust termination, the reentry system is maneuvered by the post-boast vehicle (PBV) to an independently-targeted reentry vehicle deployment station for each reentry vehicle. Following transmission of required signals for timing and warhead arming from the computer in the missile guidance system, the reentry vehicle is separated electrically and mechanically from the post-boast vehicle. The deployed reentry vehicle is "spun up" by gas generators in the reentry vehicle aft section as the post-boast vehicle completes a maneuver to back away from the deployed reentry vehicle en route to the deployment station for the next reentry vehicle.Mark 12/12A Reentry Systems
The MK 12 and MK 12A RSs consist of a shroud assembly, deployment module, RVs, penetration aids, and ordnance devices.
The shroud assembly consists of a forward and aft shroud which provides environmental protection for the reentry vehicles, penetration aids, electronic components, electrical harness, and ordnance during powered flight. A rocket motor, located in the forward shroud, provides sufficient impulse to separate the shroud assembly from the deployment module during second stage burn at a predetermined altitude. The shroud assembly is attached to the deployment module by a V-band clamp, which is separated just prior to rocket-motor ignition.
The reentry vehicle is a high-performance ballistic envelope secured to the support payload bulkhead. The reentry system installation kit provides the mounting and support fittings for mounting up to three reentry vehicles to the bulkhead and the electrical interconnection between the reentry vehicles and electronic components mounted in the deployment module.
The reentry vehicle consists of forward, aft, and mid-sections joined together by breech lock threads. The external surfaces of the reentry vehicle are composed of ablative carbon-phenolic heat shield material, with the exception of the central portion of the aftsection cover which is protected with elastromeric shield material, and the nose tip which is carbon-carbon. Surface contours and composition of the shield are designed to achieve minimum radar cross section and to protect internal assemblies from reentry heat. A hot gas spin system, located in the aft section, stabilizes the reentry vehicle in its correct reentry orientation after deployment. The reentry vehicle contains the arming and fuzing assembly which provides various height-of detonation targeting options. The mid-section contains the warhead. Minuteman III employs two different reentry vehicless, the MK 12 deployed at Malmstrom AFB, MT and F.E. Warren AFB, WY, and the MK 12A deployed at Minot AFB, ND, and Malmstrom AFB, MT (Squadron 20).
The penetration aids consist of two chaff dispensers and the chaff attachment kit. Each dispenser is an electromechanical device which stores the chaff and dispenses it in the required pattern (cloud geometry). The chaff consists of numerous dipoles of varying lengths which are released in groups in response to discrete signals from the missile guidance system. The discretes and electronic controls govern the ejection velocity and feed rate. The chaff attachment kit consists of the mechanical attachment fixtures, electrical harnesses, and electronic control and power distribution components.
The W62 warhead has a yield of 170 kilotons. It was first deployed in 1970 and remains atop 200 Minuteman III missiles (3 reentry vehicles per missile). The MK 12 reentry vehicle is 5.9 feet (1.8 meters) long.
Weapons designers examine a W62/MK 12 reentry vehicle