At Launch Complex 40 on Cape Canaveral Air Station, the Mobile Service Tower has been retracted away from the Titan IVB/Centaur carrying the Cassini spacecraft, marking a major milestone in the launch countdown sequence. Retraction of the structure began about an hour later than scheduled due to minor problems with ground support equipment. The launch vehicle, Cassini spacecraft and attached Centaur stage encased in a payload fairing, altogether stand about 183 feet tall; mounted at the base of the launch vehicle are two upgraded solid rocket motors. Liftoff of Cassini on the journey to Saturn and its moon Titan is slated to occur during a window opening at 4:55 a.m. EDT, Oct. 13, and extending through 7:15 a.m