Either one or both of the OMS engines can fire, depending upon the orbital maneuver. The engines can start and stop 1,000 times and have a total of 15 h burn time. As the shuttle rests on the pad fully fueled, it weighs about 4.5 million pounds or 2 million kg. The engines build up to more than 90 percent of their maximum thrust. T plus 60 s - shuttle engines are at maximum throttle.
Main engines continue firing.
Parachutes deploy from the SRBs. Ships will recover the SRBs and tow them back to Cape Canaveral for processing and re-use. T plus 8.5 min - main engines shut down. T plus 9 min - ET separates from the orbiter. The ET will burn up upon re-entry.