ULA Fires Vulcan First Stage Engines in Crucial Step Toward First Flight

United Launch Alliance (ULA) briefly test-fired the first-stage engines on its new Vulcan Centaur rocket on Wednesday evening (June 7), completing a crucial milestone for the booster’s first flight.

The flight readiness firing (FRF) of the twin BE-4 engines took place at 9:05 pm EDT at Space Launch Complex-41 at the Cape Canaveral Space Force Station in Florida.

“Nominal run!” CEO Tory Bruno tweeted after the burn ended.

ULA said in a press release that the engine start sequence began at T-4.88 seconds, with the engines throttling up to the target level for two seconds before powering down. The FRF lasted for six seconds.

Engineers will now review the results of the firing of the methane-liquid oxygen BE-4 engines, which were supplied by Blue Origin.

“Nothing sweeter in rocketry than the word nominal. Congrats to you, Tory, and the whole team!” Blue Origin Founder Jeff Bezos tweeted.

The engines were installed on the white-and-red Vulcan first stage, which stood on its launch pad without its Centaur second stage.

“We are more than 98% complete with the Vulcan qualification program. The remaining items are associated with the final Centaur V testing,” ULA said. “The team is reviewing the data from the systems involved in today’s test and, in parallel, continue with the Centaur V test stand anomaly investigation. Pending the data review and the investigation results, we will develop a plan for launch. Testing is an integral part of our launch vehicle development program, and we will fly when we believe it is safe to launch.”

A Centaur upper stage failed during a qualification test on March 29. The stage was on a test stand at the NASA Marshall Space Flight Center in Huntsville, Ala.

ULA is gearing up for the first Vulcan Centaur launch, which is likely to occur in July. The rocket’s primary payload will be Astrobotic Technology’s Peregrine lunar lander, which will carry payloads for NASA and private companies under the space agency’s Commercial Lunar Payload Services program.

Vulcan Centaur will also carry the KuiperSat-1 and KuiperSat-2 demonstration satellites for Amazon. The spacecraft will demonstrate technology for the company’s 3,236-satellite broadband constellation.

Vulcan Centaur is designed to replace ULA’s current fleet of Atlas V and Delta IV Heavy launch vehicles. The first stage can be supplemented with strap-on solid rocket boosters for heavier payloads.