Col. Nina Armagno, 21st Operations Group commander, hands the 10th Space Warning Squadron guidon to Lt. Col. Lorinda Frederick as she assumes command of the squadron June 14, 2011, at Cavalier Air Station, N.D. The squadron, located 15 miles south of the Canadian and U.S. border, is a geographically separated unit of the 21st Space Wing, Peterson Air Force Base, Colo. The squadron operates and maintains the world's most capable phased-array radar system. The Perimeter Acquisition Radar Attack Characterization System continuously provides critical missile warning and space surveillance data by monitoring and tracking more than half of all earth-orbiting objects to enable space situational awareness and space control. (U.S. Air Force photo by Staff Sgt. Suellyn F. Nuckolls)