The next element to be added to the International Space Station the Port 3/4 truss segment is being moved to a payload canister.

The next element to be added to the International Space Station, the Port 3/4 truss segment is being moved to a payload canister for installation in the orbiter Atlantis. The cylinders shown are the mast canisters for the solar arrays. The truss is slated for launch on mission STS-115 no earlier than Aug. 28. The truss is the next major addition to the 11-segment integrated truss structure that will eventually span more than 300 feet on the station. The P3/P4 truss, with its two large solar arrays, will provide one-fourth of the total power-generation capability of the completed station. The P3/P4 truss is expected to be loaded into Atlantis's cargo bay around the beginning of August. Photo credit: NASA/Troy Cryder