Twenty Starlink satellites were prematurely released during a failed SpaceX rocket launch last week — and now, observations have confirmed they all burned up in the upper atmosphere after falling back to Earth. Experts are currently investigating what happened, and the rockets responsible will remain grounded until this investigation is concluded.

On July 11, SpaceX launched a Falcon 9 rocket from the Vandenberg Space Force Base in California at 10:35 p.m. ET, one day later than originally planned. The launch initially went as expected, and the rocket’s first stage successfully detached from the satellite-laden second stage, before landing on a drone ship in the Pacific Ocean. However, the second stage then failed to complete its second burn due to a liquid oxygen leak, leaving it stranded in a low orbit around Earth. (It is currently unclear if the leak caused the delayed launch.)