The highly anticipated maiden flight of the ULA Vulcan rocket has been delayed. During the qualification tests, a hydrogen leak destroyed a Centaur upper stage.

The March incident prompted United Launch Alliance (ULA) to implement a fix. And Vulcan's inaugural launch will be pushed back to the latter part of this year. 

ULA CEO Tory Bruno provided insights into the March 29 failure and the remedial measures being undertaken to ensure the rocket's success.

The BE-4 first stage engines of United Launch Alliances' first Vulcan rocket were successfully test-fired on June 7 at the Cape Canaveral Space Force Station. This was a major milestone on the road to the rocket's maiden flight.

The Vulcan rocket, developed by ULA, is set to replace the Delta 4 and Atlas 5 rockets. With American-made engines. The Vulcan offers enhanced cost-efficiency compared to its predecessors. 

The beta testing revealed a weak laser weld between two triangular panels forming the dome's structure. The structural issues coupled with the pressure push caused a failure in the qualification tests.

ULA Vulcan rocket being fixed

The engineers have been redesigning and extensively testing all components, including the booster. Everything is fully qualified, except for the structure of the Centaur 5. 

The Centaur is now undergoing modifications to strengthen its resilience, leading to the delay in the Vulcan's maiden flight.

 CEO Tory Bruno explained that the March 29 test failure was due to higher-than-anticipated pressures. This caused a hydrogen leak in the Centaur's hydrogen tank's upper dome. 

ULA is implementing corrective actions, including welding a stainless steel ring around the top of the dome and adding stainless steel strips over the seams joining the dome segments.

Bruno emphasized that despite the delay the Vulcan's development is nearly complete.

He expressed confidence in the rocket's overall performance and stated that all the necessary adjustments are low-risk and straightforward.

Bruno also provided updates on the future launch schedule, mentioning that the Vulcan's first flight will carry payloads such as Astrobotics' Peregrine robotic moon lander, Blue Origin's prototype Kuiper internet satellites, and a Celestis memorial with cremated remains.

The subsequent launch will involve Sierra Nevada's Dream Chaser cargo ship, followed by the first national security launch a few months later.