Jeff Bezos' Blue Origin BE

Blue Origin representatives told Sheetz that no personnel were injured, and the company is currently investigating the cause. They added that they immediately contacted ULA and notified them of the incident. ULA reportedly doesn't now view the test failure as a major issue.

ATP failures are not uncommon. That's why we do them on every single serial number that comes off the line.

— Tory Bruno (@torybruno) July 11, 2023

In a post on Twitter, ULA President and CEO Tory Bruno highlighted that the BE-4 engine has passed its one-time qualification test, meaning the design is ready for flight. Every single engine, meanwhile, is put through an Acceptance Test (ATP), which is the type of test that led to the explosion.

"ATP failures are not uncommon," Bruno wrote. "That's why we do them on every single serial number that comes off the line."

When will Vulcan Centaur fly?

ULA is no stranger to spaceflight complications. The company intended to fly its Vulcan Centaur rocket for the first time in early May. The mission, meant to lift the private Peregrine lunar lander, was delayed when a Centaur upper stage exploded during tests on March 29 at NASA's Marshall Space Flight Center.

More recently, though, ULA's next-gen rocket passed a flight readiness firing (FRF) test on June 7. After that test, ULA wrote that it is "more than 98 percent complete with the Vulcan qualification program, with the remaining items associated with the final Centaur V testing."

"The team is reviewing the data from the systems involved in today’s test and, in parallel, continuing with the Centaur V test stand anomaly investigation. Pending the data review and the investigation results, we will develop a plan for launch," the update continued.

Blue Origin's New Glenn rocket, meanwhile, also has no exact date scheduled for its debut flight. It was initially meant to fly for the first time in 2020, but delays in the development of BE-4 have pushed the timeline back several times.

Vulcan Centaur and New Glenn are under contract to lift satellites to orbit for Amazon's Starlink-rivaling Project Kuiper internet satellites. Amazon signed the "largest commercial procurement of launch vehicles in history" last year for its Project Kuiper network.

ULA will operate 38 of those launches using Vulcan Centaur, European firm Arianespace will operate 18 with its upcoming Ariane 6 rocket, and 12 will be carried out by Blue Origin, which Amazon founder Jeff Bezos founded. None of those rockets are operational, as Ariane 6's debut flight has also been delayed. The first Project Kuiper launches are currently slated to take place next year.