Detection and High Resolution Tracking of Vehicles at Hypersonic Velocities

The Defense Intelligence Document titled "Detection and High Resolution Tracking of Vehicles at Hypersonic Velocities," produced under the Defense Intelligence Agency's Advanced Aerospace Weapons System Applications program in FY 2010, opens with a deceptively simple definition: an object is supersonic when its speed exceeds the local speed of sound, and the Mach number expresses that ratio. The document then draws a boundary that organizes its entire analysis. 7 kilometers per second.

"Low hypersonic" spans Mach 5 to roughly Mach 10, while "high hypersonic" runs from approximately Mach 10 to Mach 30 or above. At Mach 30, near Space Shuttle reentry velocity, the physics of flight and the physics of detection diverge sharply from anything encountered at lower speeds. The document's central premise is that this velocity band creates a distinct intelligence problem.

Few objects travel at hypersonic velocities, and the record identifies four classes: meteors entering the atmosphere, reentry vehicles…