WASHINGTON — The U.S. Space Force is exploring whether it can resume flights of United Launch Alliance’s Vulcan rocket without using the solid rocket boosters now under investigation, a workaround that could allow some missions to proceed even as the vehicle remains grounded for national security launches.
“We think we can change the manifest slightly and eliminate the need for solids,” Lt. Gen. Philip Garrant, head of Space Systems Command, said last week at the Space Symposium.
Vulcan has been sidelined since its Feb. 12 USSF-87 mission, when a performance anomaly appeared on one of its solid rocket boosters shortly after liftoff. The rocket still delivered its payload to geosynchronous orbit, but the Space Force halted further launches pending a joint investigation with ULA. Officials are reviewing flight data and imagery to determine the cause, with no timeline for a return to flight.
In the interim, some missions have been reassigned to SpaceX, leaving the Space Force dependent on a single provider for critical national security launches.
Garrant said the service is now evaluating whether Vulcan can fly missions that do not require boosters built by Northrop Grumman, which are central to the investigation. Vulcan can be configured with zero, two, four, or six solid boosters depending on mission requirements, giving planners some flexibility.
Lower-energy missions — such as launching batches of satellites for the Space Development Agency into low Earth orbit — could potentially fly without boosters. Higher-energy missions, including direct insertions into geosynchronous orbit or heavier payloads, typically require multiple boosters and are harder to shift.
“We are looking at opportunities to change the manifest so we don’t have to rely on solids. I’m committed to supporting that and keeping the mission going,” Garrant said. “If it doesn’t rely on solids, there’s no reason why we can’t launch.”
Reworking the manifest would require moving lower-energy missions forward while delaying or reassigning those that depend on higher performance. At the same time, the Space Force continues to work with ULA and Northrop Grumman to identify the root cause of the anomaly. “We have some test activities coming up,” Garrant said. “We have confidence in ULA’s ability to return to flight.”
The disruption has broader implications for how the Pentagon buys launch services. With Vulcan grounded, the Space Force’s two-provider model designed to ensure assured access to space has effectively collapsed into reliance on SpaceX for near-term missions.
Garrant said the experience is likely to influence the next round of National Security Space Launch contracts, known as Phase 4, expected later this decade. “The challenges with Vulcan will absolutely shape the next phase of NSSL,” he said, as officials look for ways to reduce the risk that problems with a single vehicle can delay multiple missions.
A third provider would help to restore balance. Blue Origin is working toward certification of its New Glenn rocket, which requires four successful orbital launches. But a setback on its third flight April 19 adds uncertainty to that timeline, complicating the Space Force’s effort to expand its roster of launch providers at a time when supply is constrained.
