An Analysis of Impact Craters on Small Bodies Throughout the Solar System
Session 14.04 Spectroscopy
Friday 06-28 | 15:30 - 16:00
The crater size-frequency distributions (SFDs) for small bodies (asteroids, Kuiper belt objects, and small moons) offer a unique view into impactor populations and surface processes, both of which have the potential to reveal information about the bodies' history. Collisional evolution models for small impactors predict a collisional equilibrium differential slope of q3.5 (cumulative q2.5) (Bottke et al 2005). However, crater populations on many bodies have SFD slopes that diverge from this slope. Our findings show initial results for the analysis of nine small bodies, which we found all had a slope much shallower than the canonical value of q=3 or -3.5, often closer to -2 or even shallower. Previously the shallow slope on asteroids was considered mostly an effect of small craters being erased post-formation, and not a reflection of the impactor population. The shallow SFD slopes found on outer solar system bodies where no apparent erasure has occurred (e.g., Arrokoth and Charon) motivate revisiting this topic. This analysis will be pushed further to encompass all available small bodies with images of high enough resolution to determine the presence, or absence, of small craters. The composition, interior structure and porosity, age, migration history, location, size, and image resolution available for these small bodies will all be considered along with their respective impact statistics. So far, a sampling of these factors shows that all these bodies have an overall shallow SFD slope despite different sizes, compositions, interior structures, and locations in the solar system. We will consider the myriad of surface processes for small bodies that might alter their impact records (e.g., seismic shaking, spin-up/down, thermal processes, mass wasting, and landform evolution from continued cratering) as well as compare with the most up-to-date telescopic observations of extant small body populations.
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