The Airborne Surveillance Testbed (AST) project is a technology demonstration program that supports development and evaluation of defensive systems to counter intercontinental and theater ballistic missiles (ICBMs and TBMs) and their warheads. The AST, a modified 767 with a large cupola housed above the fuselage, also carries a long-wavelength infrared sensor in the cupola's forward module. This primary sensor, which is sensitive enough to detect the heat of a human body at a distance of more than 1,000 miles, has demonstrated an unmatched capability to detect, track and discriminate rocket or missile targets from other components, debris and decoys.