AN/FPS-133 Surveillance Fence Radar

On Oct. 1, 2004, the Navy Fence and Alternate Space Control Center missions, headquartered in Dahlgren, were officially transferred to the Air Force under the 20th Space Control Squadron. The detachment is headquartered in Dahlgren, Va., and the transmitters are located at Gila River, Ariz., Lake Kickapoo, Texas, and Jordan Lake, Ala. Receivers are located at Fort Stewart, Ga., Hawkinsville, Ga.. Silver Lake, Miss., Red River, Ark., Elephant Butte, N.M., and San Diego, Calif.

The Navy Fence was one of the military's first tracking assets, and the use of its technology was instrumental in the development of our current array of space surveillance sensors. In the 1950s, the Naval Research Lab formulated a space surveillance test program that used a United States Army ground-based transmitter at Fort Monmouth, N.J. to bounce signals off orbiting satellites, and tracking stations to receive the signals. This pioneering tracking system led to the concept of tracking satellites by reflecting signals off them. Following a successful demonstration of the experimental system in 1958, NRL immediately began construction of the world's first system capable of detecting satellites in orbit around the Earth. By 1959, a network of antenna sites stretching across the southern United States from Georgia to California was operational around the clock. Signals recorded at the sites as space objects passed through the high-energy radar were transmitted to the former Naval Ordnance Laboratory at Dahlgren. There, some of DoD's largest computers of that time calculated orbit predictions.

The utility of the space surveillance concept was proven on Feb. 11, 1960, when the capsule of Discoverer 8, which had been lost during a de-orbit attempt the previous year, was detected and identified. In November 1960, the Joint Chiefs of Staff placed the Navy's space surveillance sensor under the operational control of the North American Aerospace Defense Command to serve as an integral component of NORAD's space detection and tracking system.

The Fence can detect basketball-sized objects in orbit around the Earth out to an effective range of 15,000 nautical miles. Once the object's location and general direction of movement are determined, Fence operators notify JSpOC, which can then direct a tracking radar to make a more precise determination of the object's characteristics. More than 5 million satellite detections, or observations, are collected by the Fence each month.