“Physical Structure And Origin Of Meter-Sized Earth Impactors”<\/p>\n
Summary<\/strong> Using heights at peak luminosity as a proxy for strength, we determine that there is roughly an order of magnitude spread in strengths of the population of meter-scale impactors at the Earth. We use fireballs producing recovered meteorites and well documented fireballs from ground-based camera networks to calibrate our ablation model interpretation of the observed peak height of luminosity as a function of speed. The orbits and physical strength of these objects are consistent with the majority being asteroidal bodies originating from the inner main asteroid belt. We find a lower limit of ~10-15% of our objects have a possible cometary (Jupiter-Family comet and\/or Halley-type comet) origin based on orbital characteristics alone. Only half this number, however, also show evidence for weaker than average structure.<\/p>\n Several events have exceptionally high (relative to the remainder of the population) heights of peak brightness. These are physically most consistent with high microporosity objects, though all are on asteroidal-type orbits.<\/p>\n We also find three events, which display comparatively low heights of peak brightness, consistent with strong monolithic stones or iron meteoroids.<\/p>\n Based on orbital similarity, we find a probable connection among several events in our population with the Taurid meteoroid complex; no other major meteoroid streams show probable linkages to the orbits of our meter-scale population. Our impactors cover almost four orders of magnitude in mass, but no trend in height of peak brightness as a function of mass is evident, suggesting no strong trend in strength with size for meter-sized NEOs.<\/p>\n
\nBased on data from US Government sensors the orbits and ablation characteristics in the atmosphere of over 100 earth-impacting fireballs produced by meteoroids one meter in diameter or larger has been documented.<\/p>\n