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A Near-Earth Object Model Calibrated to Earth Impactors

Sophie E. Deam, Hadrien A. R. Devillepoix, David Nesvorný, Patrick M. Shober, Eleanor K. Sansom, Jim Albers, Eric Anderson, Zouhair Benkhaldoun, Peter G. Brown, Luke Daly, George DiBattista, Hasnaa Chennaoui Aoudjehane, Christopher D. K. Herd, Tom Herring, Jonathan Horner, Peter Jenniskens, Derek C. Poulton, Martin D. Suttle, Anna Zappatini

Abstract

The population of Earth-impacting meteoroids and its size-dependent orbital elements are key to understanding the origin of meteorites and informing on planetary defence 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 10m in diameter. Based on 1,202 sporadic meteoroids observed by the Global Fireball Observatory, we created a debiased model of the near-Earth meteoroid population in the 10g - 150kg in size (approximately 1cm - 0.5m) 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 3Myr for meteoroids of 0.6kg (7cm) or higher, to 1Myr below this size, extending to the model lower bound of 10g. 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 1m to 10m 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.

A Near-Earth Object Model Calibrated to Earth Impactors

Abstract

The population of Earth-impacting meteoroids and its size-dependent orbital elements are key to understanding the origin of meteorites and informing on planetary defence 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 10m in diameter. Based on 1,202 sporadic meteoroids observed by the Global Fireball Observatory, we created a debiased model of the near-Earth meteoroid population in the 10g - 150kg in size (approximately 1cm - 0.5m) 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 3Myr for meteoroids of 0.6kg (7cm) or higher, to 1Myr below this size, extending to the model lower bound of 10g. 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 1m to 10m diameter population primarily via the 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.

Paper Structure

This paper contains 4 sections, 1 figure.

Table of Contents

  1. Introduction
  2. Data: Earth Impactors and Debiasing
  3. Methods: Model Building
  4. Data Binning

Figures (1)

  • Figure 1: The GFO observed meteoroids used as calibration data plotted by their semi-major axis, eccentricity, and inclination. The sizes represent their masses at the top of the atmosphere, and the colours represent their relative weighting used for debiasing, derived from their Earth impact probability and detectability as a function of mass and speed.