Under a sky Space Shuttle Discovery is ready for launch of mission STS-116 from Launch Pad 39B.

Under a clear blue sky, Space Shuttle Discovery is ready for launch of mission STS-116 from Launch Pad 39B. Atop the fixed service structure at left looms the 80-foot-high lightning mast, part of the lightning protection system on the pad. 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/Ken Thornsley