(05/18/2000) -- After rollback of the Rotating Service Structure, Space Shuttle Atlantis can be seen atop the mobile launcher platform (MLP) on Launch Pad 39A. Below the MLP is the flame trench, part of the flame deflector system that insulates pad structures from the intense heat of launch. Made of concrete and refractory brick, the trench is 490 feet long, 48 feet wide and 40 feet high. At the top of the orange external tank can be seen the Gaseous Oxygen Vent Hood, often called the 'beanie cap.' The hood helps vent gaseous oxygen vapors away from the Space Shuttle. The hood will be raised and retracted two and a half minutes before launch. Abutting the side of Atlantis is the orbiter access arm with the environmental chamber known as the White Room at the end. The White Room provides access to the crew compartment. This will be the third assembly flight to the International Space Station. Liftoff of Space Shuttle Atlantis for the 10-day mission is scheduled for about 6:12 a.m. EDT from Launch Pad 39A. Landing is targeted for May 29 at 2:19 a.m. EDT. This is the 98th Shuttle flight and the 21st flight for Shuttle Atlantis