Hiding Titanʹs ocean: densification and hydrocarbon storage in an icy regolith

The problem of regolith densification is examined with application to Titan, with the objective of establishing the pore volume in the regolith. A large pore volume could store the large volume of hydrocarbons required to exist on Titanʹs surface by photochemical models, forming a “buried ocean”, a surface model more compatible with observational constraints than the global ocean model favored in the last decade. A sophisticated coupled model of methane diffusion and regolith densification is presented. It is found that several hundred meters equivalent “ocean” depth can be concealed in the regolith. Further, methane diffusion through the regolith is fast enough to maintain the atmospheric methane concentration against photolysis. “Hydrothermal” methane circulation may play a significant role in surface chemistry and heat transport.