Live coverage: Atlas 5 countdown and launch journal

SpaceX test-fired the Crew Dragon spacecraft’s eight SuperDraco abort engines Wednesday at Cape Canaveral, paving the way for a high-altitude rocket escape test and demonstrating engineers have apparently fixed the problem that triggered an explosion during a similar ground firing in April.

The launch of a United Launch Alliance Delta 4-Heavy rocket from Cape Canaveral was aborted three seconds before a planned liftoff at 3:28 a.m. EDT (0728 GMT). The rocket was set to loft a classified payload for the National Reconnaissance Office, the U.S. government’s spy satellite agency.

Sunday’s flight of the United Launch Alliance Atlas 5 rocket from Vandenberg Air Force Base in California was scrubbed due to a wildfire burning south of the pad. The launch delay allows crews to remain in place to battle the blaze. The lack of Range availability this week means the next launch try won’t come until Sept. 26.