The Space Shuttle Made Simple

We're ready to launch! On the day of the launch, NASA headquarters first consults detailed satellite weather photos. If everything looks clear, then a detailed launch procedure follows. The procedure starts 6 hours before launch time when the OMS Tank is pressurized and all the SRB components are verified and temperatures tested. From then on numerous tests and sensors read data and transfer fuel.

We have Liftoff! After liftoff the shuttle shoots upward and quickly burns fuel. The SRBs are then jettisoned right as the shuttle leaves the atmosphere. The main engines then burn through the remaining fuel before the external tank is jettisoned. Remember that the SRBs will be recovered.