CAPE CANAVERAL, Fla. -- SpaceX will have to wait at least another day to launch from NASA's historic moon pad.Last-minute rocket trouble forced SpaceX to halt Saturday's countdown at Florida's Kennedy Space Center.The unmanned Falcon rocket remains at Launch Complex 39A, waiting to soar on a space station delivery mission. It's the same pad where Americans flew to the moon almost a half-century ago, and where the shuttle program ended in 2011.This will be SpaceX's first Florida launch since a rocket explosion last summer.The next launch attempt could come as early as Sunday morning.