Titan's impact crater population after Cassini

Abstract

Titan is Saturn's largest moon and has a dynamic surface with methane rivers carved by an active hydrological cycle and sand seas shaped by aeolian processes. One way to study the rates of these processes is by examining Titan's impact craters, because they provide quantitative constraints on the level of degradation. With the end of the Cassini Mission in September 2017, we have reassessed the crater population using the entire Cassini Synthetic Aperture Radar (SAR) dataset, including 30 additional craters since the last assessment in 2012, for a total of 90 certain to possible impact craters on Titan. We adjust for incomplete coverage (~69%) of the moon by SAR imaging using a Monte-Carlo approach, and find no major change in Titan's inferred surface age from prior studies. We then used the SARTopo and stereo topography data sets to measure crater depths and diameters. For the first time, rim heights for twelve craters were also reported. On average, Titan's craters are shown to be shallower, with lower rims, than those observed on similarly sized icy moons (e.g. Ganymede). This suggests that the observed modification is due to a combination of sand and sediment infilling onto the crater floor and fluvial erosion of the rims with fluvial erosion playing a larger role than previously thought in crater degradation on Titan.