A perfect on time launch for Space Shuttle Discovery at 7:17 p.m. EDT.

A perfect on-time launch for Space Shuttle Discovery at 7:17 p.m. EDT. This marks the 100th launch in the history of the Shuttle program. Discovery carries a payload that includes the Integrated Truss Structure Z-1, first of 10 trusses that will form the backbone of the Space Station, and the third Pressurized Mating Adapter that will provide a Shuttle docking port for solar array installation on the sixth Station flight and Lab installation on the seventh Station flight. Discovery’s landing is expected Oct. 22 at 2:10 p.m. EDT