The Air Force broke ground Feb. 13 on a prototype silo for the Northrop Grumman LGM-35A Sentinel future intercontinental ballistic missile at the company’s Promontory, Utah, site, officials said at the Air & Space Forces Association’s warfare symposium.
The prototype is to allow engineers to test and refine modern construction techniques, validating the new silo design before work begins in the missile fields, the Air Force has said.
The Sentinel missile will replace the Boeing Minuteman III intercontinental ballistic missile. The National Nuclear Security Administration’s plutonium pit production program at Los Alamos National Laboratory plans to make the fissile cores for the W87-1 warhead, which will top the Sentinel missile.
In the last year, the service decided to build new silos for Sentinel, rather than re-using those housing Minuteman IIIs. Environmental factors in the Minuteman III silos include asbestos, lead paint, and tilting in a small number of silos due to their variations in their concrete thickness.
“The pivot to the new silos was not driven by the size of the [Sentinel] missile,” a Sentinel program official told reporters, including Exchange Monitor affiliate publication Defense Daily, last week at the symposium. “It is a little bit larger, and there are some things that come along with that, heavily focused on how we transport it, how it’s emplaced is different that Minuteman III, what vehicles are required to try to make sure that it is transportable on commercial roads and bridges, that we’ve got vehicles that don’t need special handling and things of that nature.”
The Air Force plans to build modular Sentinel silos that would use pre-cast concrete and standardized components to reduce construction cost and time, but the approach may also mean less silo hardening and present logistical challenges in transporting the large modules, which would be dropped into place at existing sites under the 90th Wing at F.E. Warren Air Force Base (AFB), Wyo., the 91st Wing at Minot AFB, N.D., and the 341st Missile Wing at Malmstrom AFB, Mont. The 90th is to be the first to receive Sentinel, followed by the 341st, and, finally, the 91st.
The Sentinel program official said that variability in the Minuteman III silos and a desire to reduce cost were key in the Air Force’s decision to build new ones.
Exchange Monitor affiliate Defense Daily first published a version of this story.