The payload canister left with the Integrated Truss Structure Z1 moves slowly up the crawlerway ramp in the background.

Before dawn, the payload canister (left) with the Integrated Truss Structure Z1 moves slowly up the crawlerway ramp on Launch Pad 39A toward Space Shuttle Discovery in the background. The canister will be lifted up the Rotating Service Structure to the Payload Changeout Room where the Z1 will be removed and transferred to Discovery’s payload bay. The Z1 truss is the first of 10 that will become the backbone of the International Space Station, eventually stretching the length of a football field. Along with its companion payload, the third Pressurized Mating Adapter, the Z1 is scheduled to be launched aboard Discovery Oct. 5 at 9:38 p.m. EDT