In a statement released later that day, Northrop Grumman said: “There was an incident in one building at our Promontory, Utah, facility this morning and we are working to determine the cause. Employees working in or near the building today are accounted for and there are no significant injuries reported.”
Local officials have not reported any casualties at this time. The U.S. Air Force, which is closely linked to operations at the facility, referred all inquiries to Northrop Grumman.
A company spokesperson declined to provide further details on the function of the building or confirm whether it was involved in the production of solid rocket motors (SRMs). Northrop’s Innovation Systems, previously known as Orbital ATK, supplies nearly 90 percent of the United States’ SRM capacity, serving both defence and commercial space needs.
Aerial footage from a local television station showed severe structural damage but no visible fire at the scene. The Promontory site, often referred to as “Rocket Ranch,” is known for developing and testing large SRMs, including those used in the new LGM-35A Sentinel intercontinental ballistic missile.
The Sentinel programme, run by the U.S. Air Force, will eventually field 400 missiles in silos and 259 additional units for testing and demonstration. Northrop conducted a full-scale static test fire of the Sentinel’s stage-one solid rocket motor at the same facility on 6 March.
Situated north of the Great Salt Lake and near the Ogden Air Logistics Complex, the Promontory facility plays a key role in strategic missile sustainment. The site’s history dates back to the original Thiokol company, which underwent several mergers before becoming part of Northrop Grumman in 2018.
Due to Northrop’s dominant position in the SRM market, it was required to act as a merchant supplier to Boeing during the Ground Based Strategic Deterrent competition. Boeing ultimately withdrew from the competition in 2019, citing Northrop’s in-house SRM production advantage, and Northrop secured the contract the following year.
The only other major SRM producer in the United States is Aerojet Rocketdyne, which became part of L3Harris in 2023.
