HILL AIR FORCE BASE, Utah – Lockheed Martin Corp. received a nearly half-billion-dollar contract on Thursday to provide the reentry vehicle for the next-generation U.S. nuclear intercontinental ballistic missile (ICBM) to replace the Minuteman III.
Officials of the The Air Force Nuclear Weapons Center at Hill Air Force Base, Utah, announced a $454 million order to the Lockheed Martin Space segment in King of Prussia, Pa., for the MK21A Reentry Vehicle for the future LGM-35A Sentinel nuclear missile.
Lockheed Martin Space will handle MK21A Reentry Vehicle engineering, manufacturing, and design to provide a low-technical-risk and affordable reentry vehicle for Sentinel. The MK21A will be fitted with the future Sentinel's nuclear warhead. This order brings Lockheed Martin's MK21A contract to $1.5 billion.
The Sentinel, formerly known as the Ground Based Strategic Deterrent, is being designed by Northrop Grumman Corp. in Roy, Utah. The Air Force wants the new missile to be operational by 2029.
Inertial and celestial guidance
ICBM warheads typically use inertial and celestial guidance, which rely on precision gyros to measure movement, speed, and acceleration, as well as electro-optical sensors that determine the warhead's position relative to the stars.
The Mk21A Reentry Vehicle will deploy the W87-1 nuclear warhead as part of the Sentinel future ICBM. It serves as Sentinel's critical front-end, and is in full-scale development.
The vehicle was flight-tested in June 2024 from a Minotaur I rocket from Vandenberg Space Force Base, Calif., into the Pacific Ocean to validate technologies and designs. The Mk21A will offer aeroshell, arming and fuzing subsystems, radio-frequency subsystem, and spin subsystem, and is planned for production and deployment between 2027 through 2032.
The LGM-35A Sentinel ICBM is the follow-on to the aging LGM-30G Minuteman III ICBM, which first became operational in 1970. The LGM-35A Sentinel ICBM will have increased accuracy, enhanced security, and improved reliability.
300-kiloton warhead
The LGM-35A Sentinel will have a 300-kiloton W87 Mod 0 thermonuclear warhead of unknown yield, capable of air- or ground-burst detonation. The silo-launched missile will have three-stage solid-fuel rocket propulsion with inertial and celestial guidance.
The LGM-35A Sentinel will replace the U.S. Minuteman III fleet, which constitutes one-third of the nation's nuclear weapons deterrent. Other U.S nuclear warheads are on submarine-launched ballistic missiles and on manned jet bombers.
Each Minuteman III missile is 60 feet tall, 5.5 feet in diameter, and powered by three solid rocket motors that can launch the 80,000-pound missile to altitudes of 700 miles to deliver nuclear warheads as far away as 6,500 miles. Each missile contains as many as three independently targeted warheads in separate reentry vehicles.
Replacing Minuteman III
The U.S. maintains Minuteman III missiles at 450 missile sites in Colorado, Montana, Nebraska, North Dakota, and Wyoming. The missiles themselves are in underground silos and are ready for launch on very short notice.
The Minuteman III originally was equipped with a Rockwell Autonetics D37D flight computer, but as of 2008 had been upgraded as part of the Minuteman-III Guidance Replacement Program (GRP).
On the MK21A Reentry Vehicle contract, Lockheed Martin will do the work in King of Prussia, Pa., and should be finished by September 2032. For more information contact Lockheed Martin Space online at www.lockheedmartin.com/en-us/products/icbm.html, Northrop Grumman at www.northropgrumman.com/what-we-do/advanced-weapons/sentinel, or the Air Force Nuclear Weapons Center at www.afnwc.af.mil.
