Detection and High Resolution Tracking of Vehicles at Hypersonic Velocities

This Defense Intelligence Reference Document, produced in 2010 under the Advanced Aerospace Weapons System Applications (AAWSA) Program, provides a technical overview of the challenges and methodologies associated with the detection and high-resolution tracking of vehicles traveling at hypersonic velocities (Mach 5 and above). The document establishes the theoretical framework for hypersonic flight, detailing the physics of shock waves, boundary layers, and the ionized wakes generated by objects moving through the atmosphere at extreme speeds. It explains how these physical phenomena—specifically the ionization of air and the creation of turbulent wakes—can be exploited for detection purposes.

The report categorizes detection technologies into three primary domains: electromagnetic (RADAR, radio reflection), optical (sky cameras, infrared, LIDAR, chronographs), and acoustic/seismic methods. Each method is evaluated for its ability to determine an object's position, velocity, and trajectory. The document highlights that while traditional RADAR is effective for many applications, it faces limitations with hypersonic objects due to the 'line-of-sight' nature of high-frequency waves and the potential for stealth materials to reduce cross-sections. Consequently, the report emphasizes the importance of multispectral infrared detection and LIDAR systems, which can analyze the chemical composition and temperature of the ionized wake left by a hypersonic vehicle.

A significant portion of the document is dedicated to the 'Vision of Progress Over the Next 30 Years,' outlining the evolution of hypersonic technology in military and space applications, including single-stage-to-orbit (SSTO) vehicles, manned military fighters, and stealth missiles. The document concludes with four specific recommendations to enhance detection capabilities: building a comprehensive database of wake characteristics for existing aircraft, exploiting the specific features that allow hypersonic aircraft to fly efficiently, exploring methods to detect vehicles designed to be 'undetectable' (such as those using plasma-based drag reduction), and developing novel detection technologies. The document includes extensive mathematical appendices detailing the thermodynamic properties of airflow around hypersonic vehicles, reinforcing its role as a technical reference for intelligence and defense personnel.