Ceres and the terrestrial planets impact cratering record

R.G Strom,S Marchi,R Malhotra

doi:10.1016/j.icarus.2017.11.013

R.G Strom, S Marchi + Show 1 more

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https://doi.org/10.1016/j.icarus.2017.11.013

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Journal: Icarus	Publication Date: Nov 10, 2017
Citations: 40	License type: cc-by

Affiliation: Southwest Research Institute, University of Arizona

Abstract

Dwarf planet Ceres, the largest object in the Main Asteroid Belt, has a surface that exhibits a range of crater densities for a crater diameter range of 5–300 km. In all areas the shape of the craters’ size-frequency distribution is very similar to those of the most ancient heavily cratered surfaces on the terrestrial planets. The most heavily cratered terrain on Ceres covers ∼15% of its surface and has a crater density similar to the highest crater density on <1% of the lunar highlands. This region of higher crater density on Ceres probably records the high impact rate at early times and indicates that the other 85% of Ceres was partly resurfaced after the Late Heavy Bombardment (LHB) at ∼4 Ga. The Ceres cratering record strongly indicates that the period of Late Heavy Bombardment originated from an impactor population whose size-frequency distribution resembles that of the Main Belt Asteroids.

Highlights

Ceres is the largest object in the main asteroid belt, with an orbit near the center of the belt at a semi-major axis of 2.77 AU, a moderate eccentricity (e=0.076) and inclination of 10.6 degrees to the ecliptic
Since the cratering record on Ceres is almost surely the result of Main Belt Asteroids it follows that the terrestrial planet heavily cratered terrain is consistent with an origin from main belt asteroids
The higher crater density on Ceres is plausibly due to the continuous impact of asteroids from the Main Belt during and after the Late Heavy Bombardment

Summary

Introduction

Ceres is the largest object in the main asteroid belt, with an orbit near the center of the belt at a semi-major axis of 2.77 AU, a moderate eccentricity (e=0.076) and inclination of 10.6 degrees to the ecliptic. The crater size-frequency distributions in the inner solar system indicate that the Moon and terrestrial planets were impacted by two primary populations of objects (Figure 2). An observed systematic shift of the peak of the R plots of the crater SFDs found on the heavily cratered terrains of Mars, Moon and Mercury is consistent with that expected from the systematic difference in the average impact velocity of projectiles sourced from the main belt and hitting these three different bodies (see Figure 15 in Strom et al 2015).

Results

Conclusion