A numerical model examines how the ice shells of moons like Europa and Enceladus affect tidal energy in their interiors. Studying such processes on icy worlds is important in understanding if these bodies could be habitable for life as we know it.

The new model examines how ice shells affect ocean tidal heating, and the results show variations between smaller and larger bodies. For ice shells on larger bodies, such as Europa or Ganymede, the effect of tidal heating from eccentricity forcing is enhanced. The researchers put this increase down to self-gravity of the ice shell. Conversely, tidal heating from eccentricity forcing is suppressed on smaller worlds like Enceladus due to the ice shell’s mechanical forcing. For both large and small worlds, the model indicates that an ice shell causes an increase in obliquity tidal heating with one notable exception, Neptune’s moon Triton. This indicates that obliquity tides are likely to be the most influential on tidal heating of oceans on icy satellites.

The paper includes a number of case studies of moons in the Solar System, including Ganymede, Europa, Titan, Encaldus, Dione and Triton.

The study, “Nonlinear tidal dissipation in the subsurface oceans of Enceladus and other icy satellites,” was published in the journal Icarus. The work was supported through NASA’s Habitable Worlds Program. The NASA Astrobiology Program provides resources for Habitable Worlds and other Research and Analysis programs within the NASA Science Mission Directorate (SMD) that solicit proposals relevant to astrobiology research.