Quantifying the Ejecta Thickness From Large Complex Craters on (1) Ceres

Quantifying the ejecta thickness distribution from complex craters is key to understanding surface-evolving processes on Ceres. Using the Park et al. (2019, https://doi.org/10.1016/j.icarus.2018.10.024) shape model, we estimated the ejecta thickness of five complex craters located in Ceres' equatorial region by analyzing 1,778 smaller, simple craters in their continuous ejecta deposits. In addition, we constrained their rim-crest ejecta thickness following Sharpton (2014, https://doi.org/10.1002/2013JE004523). The ejecta thicknesses range from similar to 3 to 73 m and similar to 96-223 m around complex craters and at their rim crest localities, respectively. We find that ejecta thicknesses on Ceres are thinner than those on the Moon. Meltwater likely facilitates thin ejecta deposits on Ceres, given that fluid pressure conditions allow transient liquid water stability at shallow depths (similar to 1.8 m). Such water must be short-lived because the atmospheric pressure on Ceres is too low (greater than or similar to 2.09 x 10(-8) Pa) to allow a stable liquid phase. Our findings are consistent with previous work that ascribes fluidized appearing ejecta morphologies to the melting of subsurface water ice.

Automated summary

We estimated the ejecta thickness of five complex craters on Ceres' equatorial region by analyzing smaller, simple craters in their ejecta deposits. The ejecta thickness ranges from 3 to 73 m around complex craters and 96-223 m at their rim crest localities. The thinner ejecta thicknesses on Ceres compared to the Moon are likely due to the presence of meltwater, which is supported by previous studies on subsurface water ice melting.