A Near-Earth Object Model Calibrated to Earth Impactors

Abstract The population of Earth-impacting meteoroids and their size-dependent orbital elements are key to understanding the origin of meteorites and informing planetary defense efforts. Outstanding questions include the role of collisions in depleting meteoroids on highly evolved orbits and the relative importance of delivery resonances. Those depend on size, with current dynamical models considering only asteroids larger than 10 m in diameter. Based on 1202 sporadic meteoroids observed by the Global Fireball Observatory, we created a debiased model of the near-Earth meteoroid population in the 10 g–150 kg size range (approximately 1 cm–0.5 m in diameter) as they dynamically evolved from the main asteroid belt onto Earth-crossing orbits. The observed impact population is best matched with a collisional half-life decreasing from 3 Myr for meteoroids of 0.6 kg (7 cm) or higher to 1 Myr below this size, extending to the model lower bound of 10 g. Placing our results in context with near-Earth object models for larger sizes, we find that the inner main belt continues to dominate feeding the small 1–10 m diameter population primarily via the ν 6 secular resonance and the 3:1J mean-motion resonance. We also evaluated the potential significance of physical processes other than collisions on Earth-impacting meteoroids, such as low-perihelion disruptions from thermal stresses.