US Space Force pauses national security launches on ULA Vulcan rocket due to booster glitch

The U.S. Space Force is halting all national security launches on Vulcan Centaur rockets after a booster malfunction reoccurred during the vehicle's most recent mission.

United Launch Alliance (ULA)'s new Vulcan Centaur rocket debuted in January 2024 and now has four launches under its belt. On two of those missions, Vulcan suffered an anomaly in one of its solid rocket boosters during flight. Although the rocket's core-stage engines managed to compensate both times, leading to overall mission success, the reoccurrence has raised eyebrows at the Space Force, which is pressing pause on the Vulcan missions it has lined up until ULA can get to the bottom of things.

"This is going to be a many-months process as we work through the exact technical issue that happened and the corrective actions we need to make sure, we need to take, to make sure this doesn’t happen again," Space Force Col. Eric Zarybnisky said during a media round robin during the Air Force Association’s Warfare Symposium on Feb. 25, as reported by Breaking Defense.

Vulcan's latest launch occurred on Feb. 12. That national security mission, known as USSF-87, carried two reconnaissance satellites for the United States' Geosynchronous Space Situational Awareness Program (GSSAP). About 20 seconds after liftoff, one of Vulcan's four solid rocket boosters suffered a visible anomaly, but it was corrected for by Vulcan's two BE-4 first-stage engines.

Both satellites were delivered safely to a geosynchronous transfer orbit, where they were successfully deployed to assume a seemingly stationary position above Earth.

Vulcan experienced a similar issue in October 2024, during its national security payload certification launch. On that flight, a manufacturing defect caused on one of the solid rocket booster nozzles to fall off, and the vehicle to veer temporarily off course. It's unclear what exactly happened on the more recent USSF-87 mission; ULA's investigation is still ongoing.

“We are going to work through this anomaly until we launch again on Vulcan,” Zarybnisky told reporters on Feb. 25, according to Breaking Defense. "Until this anomaly is solved we will not be launching Vulcan missions."

ULA has booked its Vulcan Centaur rocket for more than two dozen national security launches over the next several years, so the temporary grounding could be a significant disruption for ULA during an already tumultuous time. Longtime ULA CEO Tory Bruno resigned from the company at the end of 2025 and accepted a position as president of national security at ULA competitor Blue Origin (which also makes Vulcan's BE-4 engines).