(09/13/2000) -- At Launch Pad 39A, the payload canister at left draws closer to the Rotating Service Structure where it will be lifted to the Payload Changeout Room. There its cargo, the Integrated Truss Structure Z1, will be removed and later transferred to Space Shuttle Discovery’s payload bay. Discovery is at right, sitting atop the Mobile Launcher Platform. 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