Blast Off!

    When the clock reaches zero, the countdown ends and the mission begins! First, the Space Shuttle's main engines light. These are the three engines at the end of the Orbiter. Then, the Solid Rocket Boosters fire. These are the two white rockets attached to the sides of the big orange External Tank. They provide the power needed to lift the Shuttle off the Earth. As they push gases downward at high speeds, the Shuttle "reacts" by moving forward.

    Seconds after the Solid Rocket Boosters light, the Shuttle has cleared the launch pad. Two minutes later, the boosters separate from the External Tank and fall into the ocean. (Special ships get them so they can be used again.) The Orbiter and the External Tank continue to fly higher! When the External Tank is empty, it separates from the Orbiter, too. It breaks apart, and its pieces fall in the ocean. The engines cut off as the crew arrives in orbit. It only takes eight and a half minutes for the Shuttle to arrive in space. It will be going over 27,000 kilometers per hour (17,000 miles per hour).