SpaceX's newly designed Crew Dragon capsule, which the crew has dubbed Resilience, was set for liftoff atop a SpaceX Falcon 9 rocket at 7:27 p.m. Eastern time (0027 GMT on Monday) from NASA's Kennedy Space Center in Cape Canaveral, Florida. Mission personnel left the launchpad, and the crew access arm - the walkway between the launch tower and rocket - retracted, setting the stage for the spacecraft's launch escape system to be armed and mission teams to start loading the Falcon 9 rocket with fuel. An air leak caused an unexpected drop in capsule pressure less than two hours before launch, NASA officials said.