Diversity of the Morphological Evolution of Comet 67P/ Churyumov-Gerasimenko

Abstract:

AGU Abstract

Comets represent time capsules from the birth of our Solar System, recording presolar history and the initial states of planet formation, as well as likely contributing prebiotic organics to the early Earth. As such, studying comets will ultimately provide unparalleled knowledge about presolar history through the initial stages of planet formation to the origin of life. To date, the comet we know the most about is the target of ESA’s Rosetta mission, 67P/Churyumov-Gerasimenko. Rosetta images of 67P show two primary kinds of terrain, rugged and smooth. 67P’s smooth terrains are sedimentary basins formed by falling debris that is liberated during sublimation of the more rugged terrain. By studying temporal changes in 67P’s smooth terrains over the course of the Rosetta mission, we can develop a better understanding of how the comet’s surface evolves. In 67P’s the surface is divided into several regions. Herein, we discuss a catalog of observed surface changes in the Imhotep, Ma’at, and Hatmehit regions. In the Ma’at region, the most common changes that were detected are burial, pit/scarp, exposure, and boulder migration. In the southwest of the region, many small boulders were being gradually buried and migrated. On the other hand, in the northeast of the region, small boulders were slowly exposed, and few boulders and pit/scarp were migrating slightly. In Hamehit, there were some crucial changes. The most significant changes that occur in this region were scarp and boulder burial. In the course of time, scarps and boulders were disappearing. Then, there were some small changes such as boulder migration and exposure. We will discuss these changes in the context of the comet’s orbit and variations in solar insolation. As the comet approaches perihelion, some modifications in smooth terrains become more prevalent. Our results demonstrate a clear correlation between the position of the comet and the character and evolution of changes observed in the smooth terrains.