T minus 10, 9, 8, 7, 6, 5, 4, 3, 2, 1. Liftoff!

T minus zero , the holddown explosive bolts and the T-O umbilical explosive bolts are blown by command from the on-board computers and the SRBs ignite. The Pony is now committed to launch. The mission elapsed time is reset to zero and the mission event timer starts. The Pony lifts off the pad and clears the tower at about T plus 7 seconds. Mission control is handed over to JSC after the tower is cleared.