Astronaut Clayton Anderson dons his helmet as he gets ready for launch of Space Shuttle Atlantis from Launch Pad 39A.

Astronaut Clayton Anderson dons his helmet as he gets ready for launch of Space Shuttle Atlantis at 7:38 p.m. EDT from Launch Pad 39A. Anderson will join the Expedition 15 crew aboard the International Space Station, exchanging his seat on the return trip for Flight Engineer Suni Williams. The shuttle is delivering a new segment to the starboard side of the International Space Station's backbone, known as the truss. Three spacewalks are planned to install the S3/S4 truss segment, deploy a set of solar arrays and prepare them for operation. STS-117 is the 118th space shuttle flight, the 21st flight to the station, the 28th flight for Atlantis and the first of four flights planned for 2007. Photo credit: NASA/Kim Shiflett