ULA isn't making the Space Force's GPS interference problem any easier
Source: Ars Technica
Capability on the Ground
Officials expect the investigation into a booster anomaly on ULA’s Vulcan rocket to last multiple months.
Four solid rocket boosters and two BE‑4 main engines power United Launch Alliance’s Vulcan rocket off its launch pad at Cape Canaveral Space Force Station, Florida, on February 12 2026.
Credit: United Launch Alliance
GPS – The Backbone of Modern Navigation
DENVER — The Global Positioning System (GPS) is one of the few space programs that touches nearly every human life. The stewards of the satellite navigation network are eager to populate the fleet with the latest and greatest spacecraft.
The U.S. Space Force owns and operates the GPS constellation, providing civilian and military‑grade positioning, navigation, and timing signals to:
- Cell phones
- Airliners
- Naval ships
- Precision munitions
- And countless other applications
Why Launch New GPS Satellites?
- Constellation replenishment – Old satellites degrade and die; new ones must replace them. At least 24 GPS satellites are needed for global coverage, and additional satellites improve navigation precision. Currently, 31 GPS satellites are operational, orbiting more than 12,000 mi (20,000 km) above Earth.
- Modernization – Replace the oldest satellites (some launched in the late 1990s) with newer, more capable spacecraft. Since 2005, GPS has carried additional civilian signals for aviation and interoperability with Europe’s Galileo system, and introduced the M‑code military‑grade signal designed for warfare.
M‑code is:
- More resistant to jamming
- Encrypted, making spoofing (fake‑signal attacks) harder
- Capable of denying adversaries GPS access during conflict while preserving it for U.S. and allied forces
Growing Threats
Interference with navigation signals is rising, especially in the Middle East, the eastern Mediterranean, and around Russia and Ukraine. U.S. officials attribute much of the interference to Russian actions as its military combats drone attacks.
- A 2024 incident (see Azerbaijan Airlines Flight 8243) resulted in a fatal crash, killing 38 people.
- The International Air Transport Association reported a 500 % increase in GPS spoofing incidents in 2024 (IATA press release, 2025‑02‑26).
Because of these threats, the Space Force is prioritizing launches of GPS satellites that can better repel jamming and spoofing. Currently:
- 26 of 31 operational satellites carry M‑code (enough for global coverage but with little margin).
- 19 of 31 broadcast the higher‑power civilian L5 signal, which is more resistant to interference than older civilian signals.
Visual Reference
Credit: Lockheed Martin
Not Delivering
The road toward GPS modernization hasn’t been easy. RTX, formerly known as Raytheon, was years late and billions of dollars over budget in delivering new control software to operate the newest GPS satellites. Read more.
The rocket the Space Force planned to use for launches of the last few GPS satellites has also faced delays.
United Launch Alliance – Vulcan
Vulcan has launched four times, all successfully, but it has twice had to overcome serious anomalies with its solid‑rocket boosters (SRBs).
- 2024 – second launch: One of the strap‑on motors supplied by Northrop Grumman lost its exhaust nozzle shortly after liftoff. The problem kept the rocket grounded for ten months while industry and military officials investigated the malfunction.
- 2024 – third launch (August): The flight proceeded without incident.
- 2024 – fourth launch (Feb. 12, 2026): A remarkably similar problem occurred with another SRB. Ars Technica coverage.
Despite the booster anomaly, Vulcan’s upper stage released the payloads into an on‑target orbit, and officials declared the mission successful. However, military officials are reluctant to test Vulcan’s ability to overcome such a dramatic problem again.
“Any time there’s an anomaly, my team is going to be actively engaged with the contractors to make sure we understand what happened and we correct that issue,” said Col. Eric Zarybnisky, program acquisition executive for Space Systems Command’s space‑access program. “We’re still in the initial phases of that investigation, so we’ll continue to work with United Launch Alliance and their suppliers to make sure we’ve got the right level of insight and we understand where that investigation is headed.”
— Roundtable at the Air Force and Space Force Association’s Warfare Symposium, near Denver.
Zarybnisky told reporters that it was too early to provide details on the direction of the investigation but predicted a “many‑months process” to identify the exact technical issue and the corrective actions required to prevent recurrence.
Visual
Credit: Paul Hennessy/Anadolu via Getty Images
Investigation Findings & Current Status
- After the first booster issue in 2024, investigators identified a manufacturing defect in a carbon‑composite insulator (heat shield) inside the nozzle.
- The latest incident suggests the defect was either not fully corrected or that a separate problem exists with Northrop’s boosters.
Because of the ongoing concerns, the Space Force is pausing future Vulcan launches. With a potential month‑long wait for Vulcan to return to flight, the service is looking at other options—primarily SpaceX’s Falcon 9.
“We are going to work through this anomaly before I go back and continue launching with United Launch Alliance on the Vulcan,” Zarybnisky said. “I’m going to look for every flexibility I have to make sure that I can deliver warfighter capability as quickly as possible. I’ve got a number of tools in my toolkit to do that, but until this anomaly is solved, we will not be launching national‑security space missions on Vulcan.”
Outlook
The next military launch on Vulcan was expected to be another new GPS satellite.
“I’ve not made a change at this point, but I’m absolutely looking at all the ways that I can get capability on orbit fast,” Zarybnisky added.
The investigation continues, and the Space Force will decide whether to resume Vulcan flights or shift permanently to alternative launch providers.
Rocket roulette
In a little more than a year, the Space Force has launched three GPS satellites on SpaceX Falcon 9 rockets. All three were originally booked for ULA’s Vulcan rocket. The first of these newest GPS satellites—manufactured by Lockheed Martin—was declared complete and ready for launch in August 2021. Three years later, with Vulcan still not ready, the Space Force switched the launch to a SpaceX vehicle.
Space Systems Command, which oversees most of the Space Force’s spacecraft and launch procurement, gave ULA contracts to launch future GPS satellites as compensation for the swap.
The status of several more Vulcan military launches scheduled for this year is also unclear. One of the Space Force’s most expensive satellites ever—a missile‑warning satellite estimated at more than $4 billion—was supposed to launch on a Vulcan in the coming months. The satellite will sit in geosynchronous orbit to detect the heat plumes of ballistic and hypersonic missiles.
The Pentagon’s dissatisfaction with the Vulcan program is not new. In May 2024, the defense official then in charge of procuring space hardware wrote a letter to Boeing and Lockheed Martin—ULA’s corporate parents—outlining his concerns about Vulcan’s entry into service.
“Currently there is military satellite capability sitting on the ground due to Vulcan delays,” wrote Frank Calvelli, the assistant secretary of the Air Force for space acquisition under the Biden administration.
Moving GPS launches to the Falcon 9 is relatively straightforward for the Space Force. Falcon 9s have launched most of the newest batch of GPS satellites, so engineers understand how to integrate the spacecraft with SpaceX’s rocket quickly. The new geosynchronous missile‑warning satellites, however, are booked on ULA’s Vulcan, so a last‑minute swap might not be easy.
“It was tremendously beneficial for the past decision to make GPS qualified on multiple providers,” said Menschner, deputy commander at Space Systems Command. “I think that we have seen the benefits of that. The ability to switch from one provider to another is present in those vehicles. That just isn’t [available] in some of the other families of vehicles.”
Author
Stephen Clark is a space reporter at Ars Technica, covering private space companies and the world’s space agencies. He writes about the nexus of technology, science, policy, and business on and off the planet.
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