WASHINGTON — A new version of the solid rocket booster being developed for the Space Launch System experienced an anomaly during a test firing in Utah June 26.
Northrop Grumman performed the first demonstration test of the Booster Obsolescence and Life Extension (BOLE) version of the five-segment solid rocket booster for the SLS at its Promontory, Utah, test site. The booster, fixed in a horizontal position, fired for a little more than two minutes, as it would on an actual launch.
A little more than 100 seconds into the test, exhaust appeared from come out from the side of the nozzle. Seconds later, debris scattered from the vicinity of the nozzle, as seen in NASA’s webcast of the test.
“Whoa!” said one person on the webcast, which had been carrying audio from test controllers, after the debris scattered. That was followed by a sigh.
The motor continued to burn for the remainder of the test. NASA and Northrop Grumman officials did not mention the incident in comments on the webcast shortly after the test concluded.
“While the motor appeared to perform well through a harsh burn environment, we observed an anomaly near the end of the two-plus minute burn,” Jim Kalberer, vice president of propulsion systems at Northrop Grumman, said in a statement issued a few hours after the test. The company did not release additional details about the anomaly.
He added in the statement that the company “pushed the boundaries of large solid rocket motor design” in the test. “As a new design, and the largest segmented solid rocket booster ever built, this test provides us with valuable data to iterate our design for future developments.”
The BOLE design is intended for use on SLS missions starting with Artemis 9 in the 2030s. It replaces the shuttle-era steel casings for the solid rocket motors with new carbon fiber composite designs. It also uses a new propellant formulation and incorporates other advances that result in a booster whose performance is increased by more than 10%, adding five metric tons of payload for SLS missions to the moon.
It is uncertain, though, if the BOLE design will ever fly. NASA’s fiscal year 2026 budget proposal seeks to cancel the SLS after the Artemis 3 mission. A provision in the Senate version of a budget reconciliation bill would add funding for two additional SLS missions, through Artemis 5, but says nothing about the future of the vehicle beyond that.
This is the second time in less than a year that a solid rocket booster built by Northrop Grumman suffered a nozzle issue. The nozzle fell off one of two GEM 36XL solid rocket boosters — far smaller than the BOLE booster — on the second launch of United Launch Alliance’s Vulcan rocket in October 2024. The lost nozzle degraded the booster’s performance somewhat but did not prevent Vulcan from completing its mission.
ULA said in March that a manufacturing defect in one of the internal parts in the nozzle caused it to come off. Fixes to correct the problem were confirmed in a test firing at Northrop’s site in February.
