Quantifying Morphological Changes & Sediment Transport Pathways on Comet 67P/Churyumov-Gerasimenko

Abstract

Comets are active geological worlds with primitive surfaces that have been shaped to varying degrees by sublimation-driven sediment transport processes. Rosetta’s rendezvous with comet 67P/Churyumov-Gerasimenko (67P) in 2014 provided data with the necessary spatial and temporal resolutions to observe how micro-gravity worlds evolve. Rosetta’s observations have thus far revealed that the majority of changes to the surface occurred within 67P’s smooth terrains, vast sedimentary deposits that blanket a significant fraction of the nucleus. Understanding the global context of these changes, and therefore the sediment transport pathways that govern the evolution of 67P’s surface requires a thorough description of their changing morphologies, and an evaluation of existing global-scale spatial and temporal trends. Accordingly, we present a time-resolved synthesis of erosion and deposition activity on comet 67P as it passed through its August 13, 2015 perihelion from September, 2014 to August, 2016. Our mapping results indicate that, around perihelion, sediment is globally redistributed inter-regionally from 67P’s more active south to the north. Equally important, however, are local, topographically-influenced sediment transport processes, with large volumes of sediment moving intra-regionally over sub-kilometer scales. We also show evidence for regions of near-zero net erosion/deposition between approximately 30–60° latitude, which may act as terminal sedimentary sinks, with remobilization of these materials hindered by multiple factors. This work provides a complete mapping of the sediment transport processes and pathways across 67P observed by the Rosetta misison, and represents a critical step toward understanding the global landscape evolution of cometary surfaces.

Measuring Erosional and Depositional Patterns Across Comet 67P's Imhotep Region

“…The data acquired by the Rosetta mission have allowed us to resolve material transport across a cometary surface for the first time. These observations, detailed in multiple previous studies (Barrington et al., 2023; Birch et al., 2019; El‐Maarry et al., 2017; Fornasier et al., 2017; O. Groussin et al., 2015; Keller et al., 2017; Jindal et al., 2022) have shown that, while sediment may broadly migrate northward through time, local processes significantly modify 67P's surface geology over timescales far shorter than a single orbit. How much of 67P's global geology is set by global, seasonally driven processes versus local (<100m scale) processes, and whether the presently observed smooth terrains are terminal deposits for sedimentary particles, therefore, remain poorly constrained.…”

“…The dune‐like crests (hereafter “crests”) that are found within many smooth deposits on 67P (Barrington et al., 2023; Jia et al., 2017; N. Thomas et al., 2015) were also frequently observed to move back‐and‐forth in a random pattern. Such crests do not appear to move in any preferred direction but instead migrate locally while staying broadly within their original locations.…”

“…(2017). The smooth terrains also host the most rapid changes on 67P that Rosetta observed (Barrington et al., 2023; Birch et al., 2019; El‐Maarry et al., 2017; Fornasier et al., 2017; O. Groussin et al., 2015; Jindal et al., 2022), unlike the consolidated material (Pajola et al., 2017) which displayed very few changes, most of which were traced back to outbursts. Understanding the processes driving the evolution of 67P's smooth terrains is, therefore, crucial to understanding 67P's overall geological evolution.…”

“…The large lobe consists of regions of smooth terrains in both the southern and northern parts of the comet and is therefore an opportune place to look for evidence of sediment transport from the south to the north. Most of the observed surface changes in this region took place between 05/2015 and 01/2016 (Barrington et al., 2023; El‐Maarry et al., 2017; O. Groussin et al., 2015; Jindal et al., 2022). To measure the total change in the sediment in these regions, we employ a shape‐from‐shading technique to create Digital Elevation Models (DEMs) for our regions of interest (ROIs) from images obtained before and after changes are observed on the surface (Section 2).…”

Quantifying Morphological Changes and Sediment Transport Pathways on Comet 67P/Churyumov‐Gerasimenko

“…ArcMap software is available at https://www.esri.com/en-us/arcgis/products/arcgis-for-personal-use/buy with registration and fee. All relevant shapefiles, layers, and basemaps are available at Cornell University's eCommons (Barrington et al., 2023).…”