Space Shuttle Atlantis roars off the launch pad for a rendezvous with the International Space Station on mission STS-115.

Space Shuttle Atlantis roars off the launch pad for a rendezvous with the International Space Station on mission STS-115. In the foreground is the countdown clock, marking launch and mission-elapsed time, on the grounds of the NASA News Center. After launch attempts were scrubbed Aug. 27 and 29 and Sept. 3 and 8 due to weather and technical concerns, this launch was executed perfectly. 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 associated electronics and will provide one-fourth of the total power-generation capability for the completed station. This mission is the 116th space shuttle flight, the 27th flight for orbiter Atlantis, and the 19th U.S. flight to the ISS. STS-115 is scheduled to last 11 days with a planned landing at KSC. Photo credit: NASA/Webb Dillard