Influence of the Surface Temperature Evolution over Organic and Inorganic Compounds on Iapetus

Abstract

In this manuscript, there were performed simulations of the evolution of the surface temperature for each of the two hemispheres of Iapetus. This icy moon of Saturn shows the most differentiated albedo dichotomy of the Solar System. The dark leading side has a lower albedo than the bright trailing side. Spectral data on the visible light reveal the existence of two types of materials on the surface. The darkening in the leading side is thought to be due to the presence of organic material and carbonaceous compounds on the surface, while the trailing side is covered by water ice due to migration processes from the dark side. On airless bodies like Iapetus, the surface escape speed is greater than the speed of water molecules, resulting in the retention of a H2O atmosphere that allows some species to diffuse through it. Results showed a slow yet steady increment of temperatures for both sides, with a steeper slope for the dark hemisphere. It was also simulated how much energy can be accumulated on both sides and the consequences of that. Finally, we calculated the diffusion coefficients for ammonia, methane, and water ice. The results allowed us to infer how these compounds could evolve over time.