Workers check the controls on movement of the Integrated Truss Structure Z1 into the PCR from the payload canister.

Inside the Payload Changeout Room (PCR), workers check the controls on movement of the Integrated Truss Structure Z1 behind them into the PCR from the payload canister. Once sealed inside the PCR, workers will get ready to move the Z1 into the payload bay of Space Shuttle Discovery. 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