UNCLASSIFIED // PUBLIC RELEASERELEASE 06 · SEPTEMBER 18, 2026
PENTAGON UFO FILE · DOCUMENT · DOW-UAP-D148AAWSAP DIRD, Detection and High-Resolution Tracking of Vehicles at Hypersonic Velocities, November 2010
This DIRD, dated November 2010 and written for the AAWSAP program, deals with a problem that has since become central to air defense: spotting and following vehicles that fly at hypersonic speeds, usually defined as above five times the speed of sound. The release describes a sensor survey.
Using the vehicle’s own disturbance
A hypersonic vehicle disturbs the air violently. It drags shock waves, a sheath of ionized gas and a long turbulent wake, and its skin gets very hot. The paper reviews ways of exploiting each of those signatures: radar, infrared sensors, optical cameras, LIDAR (laser radar), passive systems that use radio signals reflected from the disturbed air, and even low-frequency sound and ground vibrations.
Radar and infrared, the author judges, were the strongest tools in actual use, while wake-based techniques using LIDAR and passive radio deserved special attention for sharper tracking and for telling vehicles apart. The overall conclusion is that no single sensor is enough and that combining several gives the best result.
Relevance to UAP reporting
Some military UAP reports describe sensor tracks of objects said to be unusually fast. The paper, as summarized, is a reminder of how fast-moving objects are actually detected, and of how much each method depends on the physical traces a vehicle leaves. Related: MHD Air Breathing Propulsion and Power for Aerospace Applications.
The official description
From war.gov/UFO, released September 18, 2026, quoted in full
This document is a Defense Intelligence Reference Document (DIRD), a technical reference format used by the Defense Intelligence Agency (DIA) to capture baseline knowledge on a specific topic for later analytic use. DIRDs are best understood as reference and synthesis products rather than as original research. It is one of 38 DIRDs produced under the Advanced Aerospace Weapon System Applications Program (AAWSAP) between 2009 and 2011. Because AAWSAP’s scope permitted a broad range of supporting topics, not every DIRD in the series directly concerns aerospace systems or future threat assessment. The following summary reflects the DIRD’s scope and framing at the time of writing and should not be read as implying current validation of the concepts discussed.
This DIRD surveys how hypersonic vehicles may be detected and tracked by exploiting the physical effects they create in flight, especially shock waves, ionized gas, hot surfaces, and turbulent atmospheric wakes. The report reviews a broad set of detection methods, including radar, infrared sensing, optical imaging, LIDAR, passive radio reflection, infrasound, and seismic techniques, and argues that the most effective systems will likely combine multiple sensor types, because each captures different features of a high-speed vehicle’s passage through the atmosphere. It presents radar and infrared sensing as the strongest existing tools for operational detection, while giving particular attention to wake-based methods such as LIDAR and passive radio techniques for improving tracking, identification, and discrimination of future hypersonic aircraft. The paper identifies hypersonic vehicles as an evolving surveillance problem in which future progress will depend on better multi-sensor integration, improved wake characterization, and novel signature-exploitation techniques.