Comparative morphometric analysis suggests ice-cored pingo-shaped landforms on the dwarf planet Ceres

Abstract

The NASA Dawn mission revealed that the floor of Occator crater on the dwarf planet Ceres (in the main asteroid belt between Mars and Jupiter) is populated with small quasi-conical hills. Many of these features exhibit morphometric properties that are like those of ice-cored periglacial hills called pingos. Alternatively, some of these Cerean hills have also been hypothesized to be cryovolcanic in origin. If these hills are analogous to pingos, they represent ice-rich environments that are attractive targets for future exploration. We report new constraints on the morphologies of the Occator hills that aid in determining their origin. We also directly test how morphologically similar the hills in Occator are to pingos and volcanic cones on Earth using comparative statistical analyses. Using a novel application of kernel density estimation and Markov chain Monte Carlo methods we show that the morphologies of terrestrial pingos and volcanic cones are quantifiably distinct, and that the Cerean hills share significant morphometric similarities with pingos on Earth. Our findings indicate that a statistical treatment of morphometry alone can be a powerful tool for classifying and comparing planetary surface features, and that the majority of the resolved Cerean hills are morphometrically more similar to pingos than to small terrestrial volcanic cones.