Cavalier Air Force Station is a United States Air Force installation in Pembina County, North Dakota, home to the 10th Space Warning Squadron of the 21st Space Wing based at Peterson Air Force Base in Colorado.
The station monitors and tracks potential missile launches against the United States with a AN/FPQ-16 Perimeter Acquisition Radar Characterization System (PARCS), a phased array radar system housed in a 37m-tall structure. Both American and Canadian military members are assigned to the facility, as well as contractor employees.
PARCS observes sub-orbital and orbital objects in support of NORAD's early warning and space surveillance programs. Its single-faced phased array radar is pointed northward over Hudson Bay. PARCS can spot an object the size of a basketball at 3000 km. It analyzes more than 20 000 tracks per day, from giant satellites to space debris.