Meteoroid structure from radar head echoes

The Advanced Research Project Agency (ARPA) Long Range Tracking and Instrumentation Radar has recorded thousands of head echoes from small meteoroids, which include detailed trajectory information as well as ionization measurements. In total, 25 complete ionization curves have been matched using a detailed model of meteoroid ablation, though the solutions are not necessarily unique. While measurements of the spread along the trajectory of the echoes indicate that most meteors in this size range do not have large separations among fragments, the ionization curves are consistent with fragmenting bodies in the most cases. Very precise radar measurements of meteors can be a valuable source of data on the chemical and physical properties of small meteoroids.