A United Launch Alliance Delta II rocket blasts off with the Air Force's Global Positioning System IIR-21 satellite from Space Launch Complex-17A Aug. 17 at 6:35 a.m. (Eastern Daylight Time). This was the 48th successful and last in a series of GPS launches on a Delta II rocket, ending an era that began in February 1989. During that time, the Delta II/GPS tandem boasted a 98 percent mission success rate. (United Launch Alliance photo/Carleton Bailie)