Pressure-Driven Eruption of Liquid Reservoirs in Titan’s Ice Shell

Abstract:

Titan’s organic-rich atmosphere and subsurface water ocean make it a target of interest in the search for extraterrestrial life. To investigate Titan’s habitability, it is important to identify mechanisms for transfer of potential biosignatures from the ocean to the surface where they might be detected by future missions. In this study we model the ascent of liquid water through a fracture due to the pressurization caused by progressive freezing of liquid in a spherical subsurface reservoir within Titan’s ice shell. By extending a pressure-driven eruption model that has been applied to resurfacing on Europa, we calculate the volume fraction of the reservoir that needs to freeze to generate the critical reservoir pressure to produce an eruption, and the time required for that degree of freezing to be achieved as a function of reservoir depth and volume. For reservoirs at depths between 5 and 30 km and volumes of 10⁸-10¹⁰ m³ we find that 8–30% of the reservoir needs to freeze to cause eruption; this requires a freezing time of ~8–1000 years. Freezing timescales will be compared to the timescales of potential downward transport of liquids due to the gravitational instability caused by the density contrast between liquid water and ice. The numerical model developed in this study will therefore explore the feasibility of pressure-driven eruption as a transport mechanism through Titan’s ice shell.