A highly anticipated test firing of a next-generation solid rocket booster intended for NASA’s Artemis moon missions ended with an unexpected anomaly on Wednesday, raising new questions about the future of the Space Launch System (SLS) amid shifting budget priorities.
Debris flies away from the nozzle of the BOLE solid rocket booster during a static-fire test. Credit: NASA webcast
Northrop Grumman conducted the first full-scale ground test of the Booster Obsolescence and Life Extension (BOLE) solid rocket motor at its Promontory facility in Utah. The horizontally mounted booster, developed as an upgraded version of the current SLS solid boosters, was ignited for a two-minute firing—designed to simulate real launch conditions.
Roughly 100 seconds into the burn, the test took an unexpected turn. Observers on NASA’s official livestream noticed abnormal exhaust venting from the side of the nozzle. Moments later, debris was visibly ejected near the nozzle area. The incident was followed by an audible “Whoa!” and a collective gasp from the test control team, whose audio had been broadcast live.
Despite the issue, the booster completed its planned firing duration. NASA and Northrop Grumman officials made no immediate mention of the anomaly during post-test remarks. Hours later, Northrop issued a brief statement acknowledging the incident.
“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,” said Jim Kalberer, Northrop Grumman’s Vice President of Propulsion Systems. He added that the test “pushed the boundaries of large solid rocket motor design” and would yield valuable data for further refinements.
The BOLE booster is being developed for use beginning with Artemis 9—a mission tentatively scheduled for the early 2030s. It replaces the aging steel casings used since the space shuttle era with lighter, carbon fiber composite structures. It also features a new propellant formulation and design enhancements that increase overall thrust performance by more than 10%, potentially enabling the SLS to carry an additional five metric tons of payload to lunar orbit.
However, the future of the BOLE booster—and the broader SLS program—remains in flux. NASA’s FY2026 budget proposal recommends canceling the SLS program after Artemis 3, currently planned for later this decade. While a Senate bill proposes funding for missions up to Artemis 5, it provides no long-term assurance for the continued use of SLS or the BOLE booster design.
This latest anomaly is the second in less than a year involving Northrop Grumman-built solid rocket boosters. During the second launch of United Launch Alliance’s Vulcan Centaur rocket in October 2024, a nozzle on one of two much smaller GEM 36XL boosters detached mid-flight. Though the failure impacted performance, the mission was ultimately successful. An investigation traced the cause to a manufacturing flaw in the nozzle’s internal components, which was later addressed in follow-up testing.
NASA and Northrop Grumman have yet to release detailed findings from the BOLE test. Engineers are expected to thoroughly analyze the data collected to determine the root cause of the anomaly and its implications for the future of the SLS program.
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