Dynamic Phenomena In The Lakes And Seas Of Titan
Earth and Titan are unique in the Solar System as the only planetary bodies with active hydrologic cycles that include reservoirs of stable, surface liquid. Titan's lakes and seas are primarily composed of methane, ethane, and nitrogen. The buoyancy of frozen solids in these ternary systems is studied. Assuming thermodynamic equilibrium, it is found that frozen solids will float in methane-rich systems for all temperatures below the freezing point. Frozen solids in ethanerich systems will float if the solid has an air porosity of greater than 10% by volume. For smaller porosities, the buoyancy of the solid in ethane-rich systems changes with temperature and this temperature dependence may result in seasonal oscillations that are unique to Titan. These results have implications for the climatology, geology, and habitability of Titan. Titan's methane hydrologic cycle has been observed to include exchange between the surface and atmospheric reservoirs that is driven by seasonal variation in the distribution of solar energy. Recently, as the summer season approaches in the northern hemisphere, where greater than 99% of Titan's liquids are located, the Cassini orbiter has detected anomalously bright features in the seas. These features are unlikely to be SAR image artifacts or permanent geophysical structures and thus their appearance is the result of an ephemeral phenomenon on Titan. They are found to be more consistent with floating and/or suspended solids, bubbles, and waves than tides, sea level change, and seafloor change and based on the frequency of these phenomena in terrestrial settings, waves is considered to be the most probable hypothesis. Titan's northern seas are therefore not stagnant liquid bodies but environments where dynamic processes occur. The timing of their appearance suggests that these transients are an expression of the changing seasons.
Titan; Hydrology; Geological processes
Campbell,Donald B.; Hayes,Alexander G.; Pritchard,Matthew
Ph.D. of Astronomy
Doctor of Philosophy
dissertation or thesis