06.08.07 – 7:10 p.m. EDT
The closeout crew has left the lauch pad and the astronauts continue final checks inside the orbiter during the built-in hold in the countdown.
When the hold ends at the nine-minute mark in the countdown, a computer on the ground at the Kennedy Space Center — known as the Ground Launch Sequencer — takes over management of the countdown and will monitor the space shuttle’s systems until the final moments before launch.
At the 31-second mark, Atlantis’ onboard computers take control and ignite the solid rocket boosters and orbiter main engines.
When Atlantis lifts off from Launch Pad 39A, it will be the first launch from that launch pad in over 4 years.
Image above: At Launch Pad 39A, Space Shuttle Atlantis awaits liftoff on mission STS-117. Image credit: NASA