A SpaceX Starship spacecraft, the upper portion of the most powerful launch system ever built, exploded during its eighth test flight Thursday, disrupting air traffic and marking the second consecutive failure for the vehicle this year.

The uncrewed Starship mission lifted off at 5:30 p.m. CT (6:30 p.m. ET) from SpaceX’s Starbase facility in South Texas, with the spacecraft riding atop a 232-foot-tall (71-meter-tall) Super Heavy rocket booster.