Lockheed Martin Lands Contract for Mk21A Reentry Vehicle of Sentinel ICBM.

On October 30, 2023, Lockheed Martin secured a one billion dollar contract to develop the Mk21A reentry vehicle for the Sentinel intercontinental ballistic missile, bolstering the strategic deterrence capabilities of the US Air Force. This vehicle will be equipped with the modernized W87-1 nuclear warhead and is expected to be operational by 2030. The contract was awarded following a period in which Lockheed was the sole company involved in the technology maturation and risk reduction phase.
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Logo of the Sentinel Project (Picture source: US DoD )

Jay Watson of Lockheed underscored the significance of this partnership with the Air Force, highlighting their fully digital and model-based engineering methods and their expertise in reentry and strategic missions. This development is part of the Air Force's extensive nuclear modernization program, which includes the overhaul of the B-52 bomber and the introduction of the B-21 Raider stealth bomber.

The Sentinel ICBM, officially designated as the LGM-35A Sentinel, is an intercontinental ballistic missile designed and produced in the United States. The Sentinel is slated to enter service in 2030, according to current proposals, and will be utilized by the United States Armed Forces.

The development of this weapons system is being carried out by Northrop Grumman, a well-known defense and aerospace company recognized for its contributions to large-scale military projects. The Sentinel missile is fitted with W87 mod 0 thermonuclear warheads, each with an explosive power of 300 kilotons of TNT, equivalent to 1.3 terajoules of energy. There is also a modernized version of this nuclear warhead, the W87 mod 1, whose yield is not publicly disclosed.

To accurately reach its target, the Sentinel employs a guidance system that combines astro-inertial and GPS, allowing it to navigate with high precision to its destination. The missile is powered by a three-stage solid-fuel rocket engine, which gives it the capability to travel long intercontinental distances.

In summary, the LGM-35A Sentinel is a key component of the renewal of the United States' nuclear deterrence capability, with deployment scheduled for the end of this decade. It represents a combination of advanced technology in weaponry and guidance systems, strengthening the strategic posture of the United States in defense.

The refresh of the nuclear arsenal, initiated during the Obama administration, has been sustained by subsequent administrations, with the Biden administration recently announcing plans for a new design of a nuclear gravity bomb, the B61-13, in response to the 2022 Nuclear Posture Review.