THE ROLE OF ICE IN CERES’ SURFACE FLOWS, LANDSLIDES, AND MASS WASTING

Dwarf planet Ceres, the largest body in the main asteroid belt and current target of the Dawn spacecraft, is significant for its proposed ice content. Early Dawn work suggested ground-ice was prevalent by identifying three main flow types as evidence: (1) the ice-cemented or ice-cored flows, analogous to terrestrial rock glaciers, (2) long run-out flows, and (3) sheeted flows, possibly linked to fluidized ejecta of an ice-rich surface (Schmidt et al., 2015). Ongoing work from various approaches has since been supporting and developing this picture, including increased hydrogen counts poleward as measured by the gamma ray and neutron detector (GRaND) (Prettyman et al., 2016) and a spectral signature of pure ice at Oxo crater (Combe et al., 2016).

Our continued work of flows and landslides, as well as newly resolved smaller flows, on Ceres addresses two fronts. First, we analyze the relationship between landslide surface area and volume, which reflects the ability of the active flow to either support the moving material, spread, or deposit, to suggest differences in ground-ice content and temperature among flow types; Terrestrial work has already demonstrated distinct volume-area power-law relationships between bedrock and soil landslides, the result of limitations in soil thickness only for shallow landslides. Second, we use first-order modeling of end-member flow and failure mechanisms to test variables including saturation and cohesion. These simple models explore landslide failure and glacial flow conditions using an infinite slope approach and Glens Flow Law, respectively. Overall, we are building on our initial work supporting ground ice at Ceres and how variations in latitude are influencing the ice content and temperature.

References:

Combe, J.-Ph., et al. (2016),, 47^th LPSC, Abstract #1820.

Larsen, I. J., Montgomery, D. R., and Korup, O., (2010), Nature Geoscience, v. 3, p. 247.

Prettyman, T.H., et al., (2016), 47^th LPSC, Abstract #2228.

Schmidt, B., et al., (2015), AGU Abstract, #2187