Mechanical properties of benzene at cryogenic temperatures

The surface of Titan presents a complex, varied surfaced, with mountains, plains, dunes, rivers, lakes and seas, composed of a layer of organics over a water ice bedrock. The mechanical properties of these organics will play an important role in determining resistance to erosion and in modification of Titan's landscape. We have performed cryogenic mechanical compression experiments to measure the hardness of single benzene crystals at temperatures close to the surface temperature of Titan. We find that these organic crystals are remarkably strong, with deformation contact pressures exceeding 1 GPa. Molecular dynamics calculations show that the crystals densify during deformation. We compare our results to the recent work on the hardness of tholins and aromatics by Yu et al. (Yu, X. et al. 2018 JGR:Planets doi: 10.1029/2018je005651), and present some implications for the properties of Titan's dunes and mountains.