Lockheed Martin and the Air Force American have completed a new flight test of the Mk21Athe reentry vehicle developed for the future intercontinental ballistic missile LGM-35A Sentinel. The company points out in a statement that the device took off from the base of Vandenbergin California, and flew over the Peaceful without nuclear load, which has made it possible to evaluate the technologies necessary to transport and protect the weapons of the system that will replace the Minuteman III.
A reentry vehicle is the structure that houses a warhead and protects it during its journey through space and its return to the Earth’s atmosphere towards the target. It initially travels in the front part of the missile and, after separating from the system that drives it, it must withstand heating and the forces of descent while keeping its load intact and operational.
In the case of the Mk21A, Lockheed Martin starts from the previous Mk21 to develop a vehicle adapted to the new nuclear warhead W87-1. The person in charge of taking it into space will be the Sentinel, an intercontinental ballistic missile launched from silos developed by Northrop Grumman and that it will have three stages of solid fuel. It will have a range greater than 9,650 kilometersan approximate speed of 24,140 km/h at the end of the propulsion phase and uses a modular design that will make it easier to incorporate new technologies during its useful life.
Upon return to the atmosphere, the compression of the air in front of the vehicle and the aerodynamic heating generate an extreme thermal environmentwhich during re-entry can reach thousands of degrees. The thermal shield must limit the heat that reaches the warhead and electronics and the structure supports the mechanical loads of flight.
To verify that the design resists these conditions, the company combines high-fidelity simulations and digital engineering with data obtained from real flights. The results of the last test will be used to introduce adjustments and prepare the following tests before the critical review of the system design, scheduled for March 2027, in which its technical maturity will be evaluated.
The load for which the Mk21A is developed, the W87-1, is a thermonuclear warhead intended to replace the veteran W78 in the American arsenal. Its design derives from the W87-0 and incorporates safety improvements, updated components and conventional explosives less sensitive to accidental initiation. By leveraging previously proven nuclear designs and components, can be certified without carrying out new nuclear tests. He Lawrence Livermore National Laboratory places the first production unit in fiscal year 2033.
The Sentinel is also planned to carry the W87-0which already equips part of the Minuteman III and will be used in its initial configuration together with the reentry vehicle Mk21. Later the combination will be incorporated Mk21A and W87-1.
Although the known plan is to use a warhead for Sentinel, This does not imply that its capacity is necessarily limited to only one. The Federation of American Scientists points out that statements by military officials and representations of the design point to the possibility of transporting severalalthough the Air Force has not confirmed the maximum number of reentry vehicles that each missile can carry.
The current forecast places its initial operating capacity in the early 2030swith the first test flight of the full missile scheduled for 2027. However, the program accumulates delays and cost overruns and its restructuring continues to condition the replacement of the Minuteman III.
He LGM-30G Minuteman IIIis another solid-fuel ICBM that entered service in June 1970 and has received successive modernizations since then. The United States maintains a force of 400 of these missiles, which form the land component of its nuclear triad along with submarine-launched missiles and nuclear-capable bombers.