Air Force Space Surveillance System

The AN/FPS-133 Air Force Space Surveillance System, colloquially known as the Space Fence, was a U.S. government multistatic radar system built to detect orbital objects passing over the United States. It was a component of the U.S. Space Surveillance Network, and according to the U.S. Navy was able to detect basketball sized (75 cm (30 in)) objects at heights up to 30,000 km (19,000 mi).