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Potentially Hazardous Asteroids and meteorites are delivered to near-Earth space via the same mechanisms, and for modelling purposes it is often assumed that they are similarly distributed across orbital space. Thanks to 9 years of large meteoroid impact monitoring by the Desert Fireball Network, we have direct evidence that the two populations are dynamically different. We find that a key transition happens in the unobserved gap between meteoroids that regularly drop meteorites (0.1-1 m) and the sizes covered by Near-Earth Objects models (>35 m). Asteroids are preferentially on evolved and inclined orbits, whilst meteoroids tend to have larger semi-major axes and retain a better orbital connection to their main asteroid belt origin. The cause for this is the size-dependent strength of the Yarkovsky effect, much stronger on smaller objects, that effectively shortens the delivery time from the main asteroid belt to Earth impacting orbits for meteoroids. We find that the meteoroid/meteorite population is more sensitive to short-term main belt weather (moderate size collisions). Whereas the larger asteroid population is only sensitive to the biggest storms (family forming events). This implies that the meteorite mix currently falling onto Earth is not in a steady state over more than a few million years.
Devillepoix et al. (Wed,) studied this question.