T48 Friends of Hoth: Satellites of the Outer Solar System

Sunday, 25 September 2016
1:30 PM - 5:30 PM
Room 201

PLUTO SYSTEM CRATERING HISTORY AND SURFACE AGES

Paper number: T48-6
Program: Technical Sessions
Time: 2:45 PM – 3:00 PM

Authors

Abstract

Impact craters provide valuable clues for understanding the surface ages and geologic evolution of the Pluto system bodies. We will present crater mapping results from the best images from both the LORRI (LOng Range Reconnaissance Imager; Cheng et al., 2008, SSR, 140, 189-215) framing camera, and the Ralph/MVIC (Multispectral Visual Imaging Camera; Reuter et al., 2008, SSR, 140, 129-154; Howett et al., 2016, Icarus, under review) scanning imager. Pixels scales range from 77–850 m/px for Pluto and 154–865 m/px for Charon. Crater size frequency distributions have been derived for broad physiographic regions. No obvious secondary craters are observed on the encounter hemispheres of Pluto or Charon.

Pluto’s terrains display a diversity of crater retention ages and terrain types, indicating ongoing geologic activity and a variety of resurfacing styles including both exogenic and endogenic processes (Moore et al., 2016, Science, 351, 1284-1293). Charon’s informally named Vulcan Planum did experience early resurfacing, but crater densities suggest this is a relatively ancient surface, as are the northern terrains on Charon. The crater densities on Nix and Hydra indicate an old age similar to Charon’s (Weaver et al., 2016, Science, 351).

The crater size-frequency distributions for both Pluto and Charon break to shallower slope for craters smaller than 10 km in diameter. We observe this paucity of small craters (relative to a constant slope extrapolated from larger craters) on all terrains, despite adequate resolution to observe them. This lack of small craters cannot be explained by geological resurfacing alone. The lack of small craters on Pluto and Charon is more consistent with solar system formation models that result in fewer small impactors (e.g., Chiang and Youdin, 2010, AREPS, 38, 493-522; Nesvorny et al., 2010, AJ, 140, 785-793).

This work was supported by NASA’s New Horizons project.

Geological Society of America Abstracts with Programs. Vol. 48, No. 7

doi: 10.1130/abs/2016AM-284445

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