Temporal morphological changes in the Imhotep region of comet 67P/Churyumov-Gerasimenko

TL;DR

This study documents the first observed temporal morphological changes on comet 67P's surface, revealing ice exposure and expansion of features over two months, with implications for understanding comet surface activity.

Contribution

It provides the first detailed observation of surface morphological changes on comet 67P, highlighting the role of ices and expanding features over time.

Findings

Surface features grew at 5.6-8.1×10^{-5} m/s.

Exposed ices indicated by bluer contours.

No significant dust activity changes observed.

Abstract

We report on the first major temporal morphological changes observed on the surface of the nucleus of comet 67P/Churyumov-Gerasimenko, in the smooth terrains of the Imhotep region. We use images of the OSIRIS cameras onboard Rosetta to follow the temporal changes from 24 May 2015 to 11 July 2015. The morphological changes observed on the surface are visible in the form of roundish features, which are growing in size from a given location in a preferential direction, at a rate of 5.6 - 8.1$\times$10$^{-5}$ m s$^{-1}$ during the observational period. The location where changes started and the contours of the expanding features are bluer than the surroundings, suggesting the presence of ices (H$_2$O and/or CO$_2$) exposed on the surface. However, sublimation of ices alone is not sufficient to explain the observed expanding features. No significant variations in the dust activity pattern are observed during the period of changes.