Workers watch as the Integrated Truss Structure Z1 an element of the International Space Station is moved to another stand.

In the Space Station Processing Facility, workers watch as the Integrated Truss Structure Z1, an element of the International Space Station, is moved to another stand to check its weight and balance. The Z1 truss is the first of 10 trusses that will become the backbone of the 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 Space Shuttle Discovery Oct. 5 at 9:38 p.m. EDT. The launch will be the 100th in the Shuttle program