Atop a bed of fire and smoke, United Launch Alliance's Atlas V rocket blasted off on its fiftieth flight on Wednesday, carrying a GPS satellite for the U.S. Air Force.br br Liftoff took place on schedule at 1321edt (1721gmt).br br Wednesday's launch takes place a day after an unmanned supply rocket, headed toward the International Space Station, exploded shortly after liftoff from a launch pad in Virginia, destroying supplies and equipment bound for the orbiting outpost.