A three-minute test flight Tuesday morning over Cape Canaveral will help ensure NASA’s Orion crew capsule — the vehicle being built to carry astronauts back to the moon — can safely escape from a catastrophic failure on launch.

Near-perfect weather for launching a rocket into space is expected at Cape Canaveral on Saturday when an Atlas 5 rocket is scheduled to fly.

United Launch Alliance teams ran through an 11-hour countdown Friday at Cape Canaveral to rehearse procedures before the first flight of a modified Atlas 5 rocket with Boeing’s Starliner crew capsule Dec. 20.