Characterizing Space Debris Reentry using NEXRAD Doppler Radar
Dr. Vishnu Reddy, Assistant Professor, University of Arizona Mike Hankey, Hankey LLC Dr. Richard Linares, Assistant Professor, University of Minnesota
NEXRAD Doppler Radar
• 160 high-resolu on S-band radars operated by Na onal Weather Service. • Covers most of the United States, South Korea including the DMZ, Puerto Rico, Guam, Okinawa and the Azores. • Doppler reflec vity data to 400 km and range data to 230 km available online in near real me. Why Radar?
• Loca on of incoming debris (even when observed by mul ple op cal sta ons) is highly uncertain during dark flight and strongly affected by prevailing wind.
• Doppler radar can track incoming debris during dark flight down to an al tude of 4000 feet and enable rapid recovery of both natural and ar ficial debris. Proof of Concept
Video shot by Pokémon Go players out at night.
Chinese Long March 7 rocket launched on June 25, 2016 Expected to be the workhorse with 70% of future launches Second stage reentered over California on June 28, 2016 Several thousand eyewitness accounts and videos Proof of Concept
• Eyewitness reports to the American Meteor Society online repor ng tool developed by Co-I Hankey showing the direc on of the incoming debris cloud from Long March 7 second stage. • The ini al me and heading from these accounts enabled us to extract the appropriate NEXRAD Doppler radar data from KCIX sta on in Cedar City, UT. • Doppler Reflec vity data showing the debris fragments from the event as they rained down over central Utah around 4:41 Zulu on 28th June 2016. • Debris field stretches 120 miles from West to East at an angle of 73 deg. If we assume mass sor ng of individual debris fragments, the heaviest fragments would be to the far upper right (YF-11 engines) and the lightest fragments (aluminum HAMR fragments) would be to the le . • Due to lack of funds to recover any fragments, Doppler data were shared to meteorite hunters who went to the field to search for debris. • They recovered two helium COPV (Composite overwrapped pressure vessel) tanks below the radar returns within hours a er reaching the loca on. Long March 7 second stage showing the loca on of four COPV helium tanks.
• Picture of the COPV tank from Long March 7 second stage recovered below our Doppler radar signatures. • Two of the four COPV tanks were recovered and each is about 24 inches across. • The tanks have been handed over to federal authori es by the collectors. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 PredictionFigure 1: Concept of behind Reentries an object-oriented tool [Lips and Fritsche (2005)]. 25 •26 NORAD TLEs and re-entry 27 dynamic can be used to 28 29 predict where S/C is expect 30 to re-enter 31 •32 With predic on re-entry 33 loca on the right Doppler 34 35 radar data can be used to 36 find object 37 •38 Trajectory es ma on 39 Kalman filter can be used 40 41 to improve predic on 42 43 Monte Carlo analysis and the concept behind Figure 2: Monte Carlo analysis and the concept behind an object-oriented tool [Parigini 44 an object-oriented tool 45 et al. (2015)]. fpa = flight-path angle. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 27 60 61 62 63 64 65 Development of a prediction tool • Orbital propaga on tool to predict re-entry loca on uncertainty and debris field • Es mated loca on used to determine which radar sites to use along with any eyewitness reports • Re-entry data can be used to update models and physics and to recover space objects