Flaming rockets propel Space Shuttle Atlantis off Launch Pad 39B for a rendezvous with the International Space Station on mission STS-115. In the background is the Atlantic Ocean. Appearing above the nose of the orbiter is the end of the gaseous vent line that leads from the hood, or beanie cap, which has been moved away from the shuttle for liftoff. Liftoff was on-time at 11:14:55 a.m. EDT. After several launch attempts were scrubbed due to weather and technical concerns, this launch was executed perfectly. Mission STS-115 is the 116th space shuttle flight, the 27th flight for orbiter Atlantis, and the 19th U.S. flight to the International Space Station. During the 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 associated electronics and will provide one-fourth of the total power-generation capability for the completed station. STS-115 is scheduled to last 11 days with a planned landing at KSC