A worker makes a final check on the Integrated Truss Structure Z1 waiting to be moved into the payload bay of Discovery.

A worker in the Payload Changeout Room of Launch Pad 39A makes a final check on the Integrated Truss Structure Z1 waiting to be moved into the payload bay of Discovery. The Z1 is the first of 10 trusses to be installed on the International Space Station. The truss will allow the first U.S. solar arrays on flight 4A, scheduled for Nov. 30, to be temporarily installed on Unity for early power. Space Shuttle Discovery is scheduled for launch on Oct. 5 at 9:38 p.m. EDT. It will be the 100th flight in the Shuttle program