Crater depth-to-diameter ratios on asteroid 162,173 Ryugu d/D of craters on Ryugu

Abstract The near-Earth asteroid 162,173 Ryugu, the target of the Hayabusa2 mission, is noted to be a spinning top-shaped rubble-pile. Craters are among the most prominent surface features on Ryugu. Their shapes, particularly their depth-to-diameter ratio (d/D), can provide an important proxy for probing both the internal structure and surface processes of planetary bodies. Here, we report d/D of every impact crater on Ryugu using a shape model derived from stereo-photoclinometry. We found that the average, standard deviation, and observed range of d/D for the entire set of craters are 0.09, 0.02, and 0.03–0.15, respectively. Except for possible pit craters, the maximum d/D of large craters on Ryugu (D > 50 m) is close to 0.13, which is comparable with those of fresh simple craters on rocky asteroids, such as Gaspra and Ida. Conversely, the d/D of small craters (D