At Launch Complex 40 on Cape Canaveral Air Station, the Mobile Service Tower is rolled 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 countdown clock for the Cassini mission began ticking earlier today at the T-26-hour mark. Other upcoming prelaunch milestones include activation of the final launch sequence for the Cassini spacecraft at the T-180-minute mark in the countdown, to be followed about an hour later by initiation of loading of the Titan IVB's Centaur stage with its complement of liquid hydrogen and liquid oxygen. 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 KSC-97PC1539