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- Northrop Grumman confirmed no solid rocket motors were damaged in a Promontory explosion on Wednesday
- The explosion destroyed one building where an ingredient in rocket propellant was produced, the company said.
- Operations and solid rocket motor production, including within Sentinel program, were unaffected.
PROMONTORY, Box Elder County — No solid rocket motors were lost or damaged in an explosion Wednesday in remote Promontory, a company spokesperson for Northrop Grumman told KSL.com Friday.
A building was destroyed in an explosion and fire at the company's Promontory site at about 7:35 a.m. Wednesday, the Box Elder County Sheriff's Office reported.
Northrop Grumman said the incident was "specific to just one building" used to produce an ingredient in solid rocket motor propellant.
"The investigation is ongoing, and we need to better understand what exactly did happen," the spokesperson said, emphasizing that progress on "any Northrop Grumman programs, operations or solid rocket motor production" will not be impacted.
Initially, the company reported no "significant injuries" to employees from the explosion; some were working in or near the building when it happened, the spokesperson said. They were evacuated, and one employee received medical care for "small abrasions and a muscle sprain that was sustained from a fall during the evacuation process."
Everyone in or near the building was taken to onsite medical services after the incident, according to the spokesperson.
Safety protocols for employees are "under near constant review both internally as well as by peer organizations and onsite government entities," the company says, calling employees their "greatest asset."
The Promontory site has over 800 buildings and 20,000 acres of land, according to Northrop Grumman, and is one of a number of locations across the country supporting the company's solid rocket motor production and testing.
Those motors have gone into recent U.S. Space Force missions, as well as the joint Boeing and Lockheed Martin venture called United Launch Alliance, which is working to compete with SpaceX's reusable rockets.
The stage-one solid rocket motor for the Sentinel intercontinental ballistic missile, the replacement for the aging Minuteman III weapon system, was tested in a static firing at the facility on March 6, according to a press release. The test followed static fire tests of second- and third-stage motors.
Results from that test are being analyzed by the Air Force Nuclear Weapons Center and Northrop Grumman.
A company spokesperson for the Sentinel program told KSL.com that "the facility is not related to the LGM-35A Sentinel intercontinental ballistic missile and our operations will not be affected."
Correction: A previous version incorrectly stated the Northrop Grumman facility is at Promontory Point. It is in Promontory.
