Air Force, United States Department of the, military department within the U.S. Dept. of Defense (see Defense, United States Department of). The Air Force traces its roots to the founding of the Aeronautical Division of the Army Signal Corps (1907), variously renamed before becoming a separate service under the National Security Act of 1947. In 1949 the National Security Act Amendments made the Air Force a military department within the newly organized Department of Defense. The chain of command goes directly from the President to the Secretary of Defense to the Secretary of the Air Force. The Air Force played an important role in World War I (see William Mitchell; Eddie Rickenbacker) and World War II (see H. H. Arnold; atomic bomb; James Harold Doolittle). After World War II, the Air Force quickly grew in importance, becoming the cornerstone of President Eisenhower's defense policy. The Air Force played a major part in the Korean War, the Vietnam War, and numerous cold war confrontations (see Berlin airlift, Cuban Missile Crisis). Its control of long-range, land-based guided missiles and the strategic bombers gives the Air Force monopolies on two major components of U.S. nuclear strategy. It has the leading role in the military exploration of space and uses aircraft and satellites to collect photo, video, and signal intelligence.

The Air Force Space Surveillance System, colloquially known as the Space Fence, is a multistatic radar system that detects orbital objects passing over America. It is a component of the US space surveillance network, and is claimed to be able to detect objects as small as 10cm (four inches) at heights up to 30,000 km (15,000 nautical miles.) Although formerly operated by the U.S. Navy and known as NAVSPASUR (short for "Naval Space Command Surveillance"), command passed to the Air Force 20th Space Control Squadron on October_1, 2004. The operation's headquarters are at Dahlgren, Virginia, while radar stations are spread out across the continental United States at roughly the level of the 33rd parallel north.

There are three transmitter sites in the system:

• 216.983 MHz at Lake Kickapoo, Texas (Master transmitter)
• 216.97 MHz at Gila River, Arizona ()
• 216.99 MHz at Jordan Lake, Alabama ().

The master transmitter at Lake Kickapoo is said to be the most powerful continuous wave (CW) station in the world, at 768 kW radiated power. Overhead imagery (see coordinates given above) of the Gila River and Jordan Lake sites suggests that the original design called for antennas of twice the present length with, presumably, greater radiated power.

There are 6 receiving stations:

• San Diego, California ()
• Elephant Butte, New Mexico ()
• Red River, Arkansas ()
• Silver Lake, Mississippi ()
• Hawkinsville, Georgia ()
• Tattnall, Georgia ().

The receiving stations at Elephant Butte and Hawkinsville are considered to be "High Altitude" stations with longer and more complex antenna systems that are designed to see targets at higher altitudes than the other four receiving stations.

References

External links

• 20th Space Control Squadron, Det 1 - Air Force Fact sheet about the Alternate Space Control Center and the AN/FPS-133 surveillance fence radar
• US Naval Space Command Space Surveillance System at the FAS website
• Rural site part of USA's oldest sat-tracking system from USA Today
• Naval Space Command - Maxwell-Gunter AFB