ULA Vulcan Rocket Fails 10 Minutes Into Launch, Losing 40 Amazon Leo Satellites

ULA added that it would work with its customer to find the cause and return to flight "as quickly as possible." It also pledged transparency, saying Amazon would have visibility into the investigation.

What went wrong in flight

The solid-fuel boosters appeared to work normally, according to the account of the launch. The first stage's two methane-burning BE-4 engines then took over, though they appeared to fire longer than ULA's pre-launch timeline had suggested.

After stage separation, the hydrogen-fueled Centaur upper stage was due to burn for 12 minutes and 15 seconds. ULA's update said something went wrong during that burn. It gave no further detail.

The BE-4 is built by Blue Origin, which retrofitted the engines used Sunday with a fix. That followed a catastrophic on-pad explosion of Blue Origin's New Glenn rocket last May, which was traced to an oxygen valve problem in one of its BE-4 engines.

Impact on Amazon Leo

Sunday's flight was the first of 38 Vulcan launches Amazon bought for its Leo constellation, which is meant to compete with Elon Musk's Starlink. ULA has already flown eight Leo missions on Atlas 5 rockets.

Amazon has also booked 24 launches on Blue Origin's New Glenn, 24 on Europe's Ariane 6 and 13 on SpaceX's Falcon 9. The network needs more than 3,300 satellites. Sunday's flight would have lifted the total launched to 436.

Amazon now has to wait for ULA's investigation before flying on Vulcan again. It is also waiting for New Glenn to return to flight.

"There is risk with any launch, and that's especially true for inaugural missions like LV-01," Amazon Leo said in a post on X. It added that it believes ULA will "learn from this mission and deliver on their long-term plans for Vulcan."

A fifth flight, and a grounding ahead

It was only the fifth Vulcan flight, and the first in nine months. ULA and booster supplier Northrop Grumman had spent that time resolving nozzle problems on the strap-on boosters that affected two earlier flights.

Vulcan is replacing ULA's Atlas 5 fleet. Engineers will now review flight data, and the rocket faces a potentially significant grounding while fixes are made.

NASA Administrator Jared Isaacman offered help on X. "Appreciate you quickly keeping the public and your partners informed," he wrote, adding that NASA's team is available to assist with the investigation.