The surface composition of Iapetus: Mapping results from Cassini VIMS

► Iapetus' surface is mainly composed of H2O ice, CO2, metallic iron, and iron oxide. ► Bound H2O, H2 and/or OH-bearing minerals, and trace organics are also present. ► The dark material on the satellites and rings has a common composition. ► Multiple lines of evidence point to an external origin for the Iapetus dark material. ► Small particles in the surfaces creates Rayleigh scattering and varying colors.