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This Defense Intelligence Reference Document from the Defense Intelligence Agency, dated 20 November 2010, was one of a series of advanced technology reports produced in FY 2010 under the Advanced Aerospace Weapon System Applications (AAWSA) Program. It reviews the theory of subsonic, supersonic and hypersonic flow. It then compares electromagnetic, optical, and acoustic and seismic methods for detecting and tracking hypersonic objects, and it makes four recommendations for progress over the next 30 years.
UNCLASSIFIED/ /l"e" Cl"l"!e1,it tl!!L e11t I ,,,~-----------------------------~ ,,, ' , "'"""' ,;,, K, Figure 14. Infrared Energy Spectra for Mach 3 (red line) and Mach 3.5 (blue dashed line). The peak wavelength changes for hypersonic aircraft with speeds that range from Mach 1 to Mach 100 are included in Figure 15. Satellite systems currently monitor 2.5- to 5-micron IR emissions and could detect aircraft with speeds as low as Mach 3. While Figure 15 plots the peak wavelength, aircraft at Mach 5 or higher have lower temperatures in the turbulent wake that would still be detectable. The peak temperatures are shown in Figure 16. Above 550 K, the perfect gas law cannot be used to accurately predict the peak temperature due to ionization and disassociation of molecules in the air. Figure 15 and Figure 16 use the "rule of thumb" described earlier in the theory of hypersonic vehicle flight to determine peak temperature and the corresponding wavelength. Military satellite systems monitor infrared energy emitted by objects on the surface of the Earth. Kidd and Caldwell 20 reported on the use of IR systems for defense support in 1992 and highlighted the problems in resolving missile launches and wakes from background "clutter" caused by the infrared emissions from other objects on the surface of the Earth. Typical satellite IR systems detect energy between 2 and 5 microns. To verify that an object is an actual missile, the object must be detected in the 2.6- to 3.2-micron band, which corresponds to the emission from water vapor in the hot exhaust of a rocket. It must simultaneously be identified in the 4.1- to 4.8-micron range to differentiate the missile from background clutter. One problem encountered in missile detection involves the "glint" that occurs as aircraft at high altitude passing over land at night reflects sunlight to an overhead satellite. Computer software to discriminate signals from background heat combined with detection in the two different infrared bands helps to identify actual missile launches. FUR (forward looking infrared) is also now used for atmospheric surveillance to detect objects in the 3- to 5-micron band and in the 5- to 14-micron band. 21 UNCLASSIFIED/, FOR OFFICIAL USE one,
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Report, from the dia collection. The PDF is mirrored here; the original link is above. 46 pages are in the text index: search them above, or from the library's search.