The young Marcia crater on Vesta displays several interesting features, including pitted and smooth terrains, exposure of relatively bright and dark material, and enrichments of hydrated material in the ejecta. Several questions arise about the origin of Marcia and of the dark material (exogenic material vs volcanic or impact melts) and the smooth and pitted terrains. Here we describe the results of the spectral and thermal analysis of the Marcia crater, with a particular effort to assess the composition of the different units, identifying the presence of OH and its correlation with dark material. Detailed studies of the Marcia crater wall, smooth and floor units reveal a compositional rich terrain with small areas enriched in diogenites with respect to the general eucritic regolith dominating the equatorial region of Vesta. The signature of OH is particularly clear in the pitted floor, dark material, smooth unit, and ejecta. The pitted terrains, beside their appearance, also show thermal anomalies, being colder with respect to the surrounding terrains. The presence of OH, concentrated in darker layers, and the pitted crater floor indicate that the area where the Marcia impact event occurred was rich in volatiles. The results show how the relatively young impact events have modified the surface of Vesta, disrupting a layer of dark material once present on Vesta's equatorial terrain and exposing fresh, bright material rich in pyroxene.

Prior to the arrival of the Dawn spacecraft at Ceres, the dwarf planet was anticipated to be ice-rich. Searches for morphological features related to ice have been ongoing during Dawn's mission at Ceres. Here we report the identification of pitted terrains associated with fresh Cerean impact craters. The Cerean pitted terrains exhibit strong morphological similarities to pitted materials previously identified on Mars (where ice is implicated in pit development) and Vesta (where the presence of ice is debated). We employ numerical models to investigate the formation of pitted materials on Ceres and discuss the relative importance of water ice and other volatiles in pit development there. We conclude that water ice likely plays an important role in pit development on Ceres. Similar pitted terrains may be common in the asteroid belt and may be of interest to future missions motivated by both astrobiology and in situ resource utilization.