アイテム詳細

要旨

Kupalo is a ∼4 Ma old, 26-km diameter impact crater on dwarf planet Ceres, which exhibits extensive areas of bright bluish material. Here we describe, for the first time, the geology of Kupalo on a regional and local scale in detail, based on Dawn Framing Camera (FC) imagery. We find the crater has a complex geology consistent with a brittle and heterogeneous crust in this area. Through analyses of the FC colour data, we identify a correlation between the geologic units and the spectral variations, which can be explained by a mixture of subsurface materials in response to the impact. The brightest sites of Kupalo, located at the upper west wall and the central ridge, show similar FC colour and spectral IR data, which suggest that the bright material in these locations likely has the same origin. To explain the distribution of the bright bluish material in the crater and its vicinity, we propose two scenarios for the structure of the upper Cerean crust. Both require deep-seated brine or salt reservoirs, possibly connected to a brine ocean at the crust-mantle transition.