On Launch Pad 39B the cargo in Space Shuttle Atlantis' payload bay is seen before the closing of the bay doors.

On Launch Pad 39B, the cargo in Space Shuttle Atlantis' payload bay is seen before the closing of the bay doors. The cargo is the 17-and-a-half-ton P3/P4 truss segment for the International Space Station. Scheduled to launch Aug. 27, Atlantis will fly on mission STS-115 with a crew of six to deliver and install the P3/P4 segment to the port side of the integrated truss system on the orbital outpost. The truss includes a new set of photovoltaic solar arrays. When unfurled to their full length of 240 feet, the arrays will provide additional power for the station in preparation for the delivery of international science modules over the next two years. STS-115 is expected to last 11 days and includes three scheduled spacewalks. Photo credit: NASA/Jack Pfaller