KENNEDY SPACE CENTER, FLA. - The sky is finally clear behind Launch Pad 39B where Space Shuttle Atlantis still sits after the scrub of its launch on mission STS-115. Atlantis was originally scheduled to launch at 12:29 p.m. EDT on this date, but a 24-hour scrub was called by mission managers due to a concern with fuel cell 1. Just above the orange external tank is the vent hood (known as the "beanie cap") at the end of the gaseous oxygen vent arm. Vapors are created as the liquid oxygen in the external tank boil off. The hood vents the gaseous oxygen vapors away from the space shuttle vehicle. Below, the orbiter access arm extends toward the cockpit of Atlantis with the White Room at the end. The White Room provides access into the cockpit of the vehicle. During the STS-115 mission, Atlantis' astronauts will deliver and install the 17.5-ton, bus-sized P3/P4 integrated truss segment on the station. The girder-like truss includes a set of giant solar arrays, batteries and associa