Northrop Grumman recently completed the first full-scale static test of an LGM-35A Sentinel solid rocket motor at its test facility in Promontory, Utah, marking yet another milestone on the road to potentially flying an example of the next-generation intercontinental ballistic missile later this year.
In partnership with the U.S. Air Force Nuclear Weapons Center, the stage-one motor test was completed on Thursday. Also called the Ground-Based Strategic Deterrent (GBSD) Sentinel is set to replace the Air Force’s silo-based Minuteman III fleet of intercontinental ballistic missiles by 2030 or so.
Sentinel will initially carry the W87-0 thermonuclear warhead, refurbished versions of the W87 from the Minuteman missiles. Later in its fielding the new missiles will be tipped with the W87-1 warhead: a newly manufactured copy of the Minuteman’s W78 warhead, but with a fresh plutonium pit. The National Nuclear Security Administration’s Lawrence Livermore National Laboratory will provide both warheads.
Sentinel is the Air Force’s program to modernize the land-based leg of the U.S. military’s nuclear triad, replacing the 1970s-vintage Minuteman III system with a next-generation intercontinental ballistic missile.
Sentinel features a three-stage booster rocket. Northrop, which has an in-house solid rocket motor business, will make missile’s the first- and second-stage solid motors. Aerojet Rocketdyne will make the third-stage motor.
Static testing of the solid rocket motor that will lift Sentinel “will further prove the Sentinel team’s design approach and gain confidence to move to the next stage of testing,” Northrop said in a prepared statement.
During the recent test event, the motor “fired for the anticipated duration and met performance parameters and objectives within expected ranges,” the company said.
The company said it employed advanced testing and data-gathering equipment during the most recent firing, which allowed for a better understanding of the motor’s performance characteristics.
A Defense Department report sent to Congress in September indicated a possible 10-month delay in the estimated $95.8 billion Sentinel development effort. Still, Air Force Brig. Gen. Ty Neuman, the service’s director of concepts, said Northrop is on track to perform a full-scale inaugural flight test in 2023.
“The first flight test is still on track, and are still scheduled for this year,” Neuman said in February at the Exchange Monitor’s 15th annual Nuclear Deterrence Summit. The Air Force has said Sentinel would fly in December.
