  We have analysed the orbits and ablation characteristics in the atmosphere of
59 earth-impacting fireballs, produced by meteoroids one meter in diameter or
larger, described here as meter-scale. 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. Two events, Sumava and USG 20131121, have exceptionally high
(relative to the remainder of the population) heights of peak brightness. These
are physically most consistent with high microporosity objects. We also find
three events, including the Oct 8, 2009 airburst near Sulawesi, Indonesia,
which display comparatively low heights of peak brightness, consistent with
strong monolithic stones or iron meteoroids. 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-scale impactors.
