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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/ iF&lil: 8FFI1il.t.k Wfili &,.kY ionized wake. This technique for detecting hypersonic meteors is not fully developed and appears to be employed only by hobbyists. Since a receiver can be tuned to a specific over-the-horizon transmitter, it may be possible to develop a network of radio receivers to provide information on high-speed objects in the atmosphere. Multiple stations would allow triangulation of the object to determine velocity and position as a function of time, i.e., tracking and path prediction. The sound files also contain information that could provide information on the hypersonic object. Detection of the shock provides information on the position of the object while the transient "whistles" reflected from the ionized wake may provide information on the Strauhal eddy frequency that could directly infer the object's velocity. This detection technology should be further developed. Hypersonic Aircraft ----------- Radio Receiver The radio receiver is not in line-of-sight with the transmitter, yet receives reflected energy from the transmitter by the aircraft Radio Transmitter Figure 11. Radio Reflection Detector. OPTICAL METHODS Sky Cameras and Photographic Methods A classic example of a hypersonic object passing through the Earth's atmosphere is a meteor. Meteorite hunters and astrophysicists have worked to develop methods to detect these objects as they fall to the Earth. Motion-detection video systems provide information on location and direction of meteors passing through the atmosphere by detecting their visible wake. The El Paso All Sky Camera project 14 is one example and even provides live streaming video of meteoric events. Photographs of objects in orbit with diameters ranging from 0.1 meter to several meters have been used to determine their expected trajectory as meteors as they entered and fell through the Earth's atmosphere. 15 This technique was first used to monitor the Pribram meteorite simultaneously by several observatories in 1959. This technique was even used to locate a 1.75-kg enstatite chondrite meteorite called Neuschwanstein reported in 2003. The 16 UNCLASSIFIED/ /F8lil: 8FFI1il.«1k W&liii SHIL¥
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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.