The payload canister inside begins its journey up the side of the Rotating Service Structure to the Payload Changeout Room.

With the onset of dawn, the payload canister (left) with the Integrated Truss Structure Z1 inside begins its journey up the side of the Rotating Service Structure to the Payload Changeout Room. There the Z1 truss will be removed and later transferred to Space Shuttle 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