After nozzle failure, Space Force is “assessing” impacts to Vulcan schedule - Ars Technica

"It was a successful Cert flight, and now we’re knee deep in finalizing certification."

United Launch Alliance has started assembling its next Vulcan rocket—the first destined to launch a US military payload—as the Space Force prepares to certify it to loft the Pentagon's most precious national security satellites.

Space Force officials expect to approve ULA's Vulcan rocket for military missions without requiring another test flight, despite an unusual problem on the rocket's second demonstration flight earlier this month.

ULA has launched two Vulcan test flights. Military officials watched closely, gathering data to formally certify the rocket is reliable enough to launch national security missions. The first test flight in January, designated Cert-1, was nearly flawless. The Cert-2 launch October 4 overcame an anomaly on one of Vulcan's strap-on solid rocket boosters, which lost its exhaust nozzle but kept firing with degraded thrust.

The rocket's twin BE-4 main engines, made by Blue Origin, corrected for the asymmetric thrust from the two strap-on boosters. Vulcan's Centaur V upper stage also fired its engines longer than planned to make up for the shortfall in performance from the damaged strap-on solid motor. Ultimately, the rocket reached its planned trajectory and delivered a dummy payload into interplanetary space.

Col. James Horne, who oversees launch execution for Space Systems Command, called the test flight a "successful launch" in an interview with Ars. The nozzle failure caused a "significant loss of thrust" from the damaged booster, he said.

The Vulcan rocket's ability to overcome the dramatic nozzle failure, which was easily visible in video of the launch, "really demonstrated the robustness of the total Vulcan system," Horne said.

"They nailed the orbit, probably one of the most accurate orbital insertions that I've seen them fly yet," he said. "And at the end of the mission, they did some extended duration testing ... which was not part of the orbital insertion. And even after that extended mission, they still had substantial performance reserve left over."

Horne said the Space Force is still analyzing data from the October 4 launch, but so far, officials expect to approve certification for the Vulcan rocket. An agreement between the Space Force and ULA requires two successful flights of the Vulcan rocket before the military will entrust it with a national security mission.

"For the purposes of the certification plan, which requires that the certification flight deliver the satellite or payload—in this case, the mass simulator—to its specified orbit successfully ... that's what happened," Horne said. "So this was a successful completion of that mission."

He added that early assessments by the Space Force show that, had the same booster anomaly happened on either of the first two military missions slated to fly on Vulcan, the rocket could have still achieved an on-target orbit, with performance margin.

"So it was a successful Cert flight, and now we’re knee deep in finalizing certification," Horne said.

But it could take a little longer than the Space Force or ULA planned to sign the final paperwork to close out the certification process.

Engineers from ULA, the booster supplier Northrop Grumman, the Space Force, the National Reconnaissance Office, and NASA are participating in the inquiry into the nozzle malfunction. Last week, a ULA spokesperson told Ars the company recovered fragments of the nozzle that fell from the rocket near the launch pad to aid in the investigation.

“I think, when folks zoom in on the video, they see thrust, hot gas burn-through, potentially, in the bottom of the rocket section," Horne said.

The second flight of ULA's Vulcan rocket is on the way to orbit.

There was an unusual plume from one of the solid rocket boosters, accompanied by slag or sparks, that appeared at about T+37 seconds.

However, ULA reported nominal performance from the early stage of the flight. pic.twitter.com/VewQyxfOdp

— Stephen Clark (@StephenClark1) October 4, 2024

Tory Bruno, ULA's chief executive, posted on X shortly after the October 4 launch that initial findings suggested the rocket casing itself did not suffer a burn-through, which would allow super-hot gas to escape the booster. However, there were visual indications of a plume of hot exhaust appearing just above the bell-shaped nozzle, possibly near where it was bolted onto the booster's main body.

That's the focus area of the investigation, Horne said. "How did we get that burn-through, and then how do we mitigate that going forward? But it's early days," he told Ars.

Horne said the Space Force is "assessing schedule impacts" to the next couple of Vulcan launches as engineers probe the booster malfunction. Military officials hoped to launch the first two national security missions on the Vulcan rocket by the end of this year. That's still the hope, Horne said, but he expects there will be "some impact" to the schedule for the next two Space Force missions, named USSF-106 and USSF-87.

"Right now, it's TBD what the launch dates will be," Horne said. "We'll need to take some time to mitigate this particular issue and make sure we're good to fly on those missions."

While ULA awaits the final go-ahead for launch of the USSF-106 missions, preparations for the mission took a key step forward this week. ULA teams transported Vulcan's core stage from a storage hangar to a vertical assembly building near the launch pad, then raised the nearly 18-foot-diameter (5.4-meter) rocket onto its mobile launch platform.

The rocket assembly milestone, known as Launch Vehicle On Stand, happened Monday at Cape Canaveral Space Force Station, Florida.

This kicks off the launch campaign for ULA's third Vulcan rocket. In the coming days, ground crews will install four strap-on solid rocket boosters around the bottom of the Vulcan core stage. This next flight, USSF-106, will employ four of the side-mounted boosters instead of the two strap-on motors used on both Vulcan demo missions. The following Vulcan flight, USSF-87, will use the same configuration as USSF-106.

Closer to the launch date, ULA will hoist the Centaur upper stage atop the Vulcan rocket, then add the payload fairing containing the Space Force payloads for the USSF-106 mission. The primary payload on the USSF-106 launch will be Navigation Technology Satellite-3 (NTS-3), an experimental spacecraft heading toward geosynchronous orbit to test technologies for next-generation GPS satellites.

ULA is on contract to launch a little more than half of the military's national security space missions over the next few years, and SpaceX is booked for the rest of the missions. The Space Force is now procuring launches for the next slate of national security missions, and last week, SpaceX won all of the contracts put up for bids in the first round of competition.

Next year, ULA predicts up to 20 launches, evenly mixed between the new Vulcan rocket and the soon-to-be-retired Atlas V rocket it will replace. Horne said there are currently five national security launches scheduled to fly on Vulcan rockets in 2025, including three GPS satellites, the WGS-11 communications satellite, and a classified mission.

But before any of those can fly, ULA needs the final sign-off from the Space Force. This is an extensive undertaking, and the military wants to maintain its 25-year record of 100 percent mission success on launches of its most important national security payloads. These are typically satellites responsible for spying on adversaries, providing advance warning of missile attacks, or broadcasting GPS signals underpinning military operations and civilian life.

Horne said there are about 175 people across the government and its research support organization, Aerospace Corporation, working on Vulcan certification. The first two phases of the effort, known as assessment and evaluation, are now complete.

"There are 52 different certification criteria that we have to clear, and that includes more than 180 discrete tasks embedded in those criteria," Horne said.

The certification review includes 18 major subsystem reviews on the Vulcan rocket, and the Space Force has completed 114 audits of ULA's quality control practices.

"That is the process that we are working through and finalizing," Horne said. "We started that in 2015, and then we're posturing to complete that over the next few weeks and months."