Space Shuttle Discovery is bathed in light on Launch Pad 39B after rollback of the rotating service structure.

Space Shuttle Discovery is bathed in light on Launch Pad 39B after rollback of the rotating service structure after midnight. Beneath Discovery's wings are the tail masts, which provide several umbilical connections to the orbiter, including a liquid-oxygen line through one and a liquid-hydrogen line through another. Seen above the golden external tank is the vent hood (known as the "beanie cap") at the end of the gaseous oxygen vent arm, extending from the FSS. 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 it, also extending toward Discovery from the FSS, is the orbiter access arm with the White Room at the end. The crew gains access into the orbiter through the White Room. Discovery is scheduled to launch on mission STS-116 at 9:35 p.m. today. On the mission, the crew will deliver truss segment, P5, to the International Space Station and begin the intricate process of reconfiguring and redistributing the power generated by two pairs of U.S. solar arrays. The P5 will be mated to the P4 truss that was delivered and attached during the STS-115 mission in September. Photo credit: NASA/George Shelton