Habitability of Hydrocarbon Worlds: Titan and Beyond

We are investigating Titan as a potential habitable world as part of the NASA Astrobiology Institute program. Titan is a unique world in our solar system and likely a model for worlds beyond: it is an ocean world, an icy world, and an organic world. Recent models of the interior suggest that Titan's subsurface ocean may be in contact with the ice-rock core, potentially providing redox gradients and heavier elements critical for a habitable environment. Further above, at the contact of the ice shell and ocean, Titan's abundant surface organics, deposited from the atmosphere, could be delivered to the aqueous environment through processes such as potential convective cycles in the ice shell. At the surface, liquid water delivered from Titan's depths through processes such as cryovolcanic activity or from impact melt could create transient habitable environments. This proposal will investigate the pathways for materials and potential organisms to be transported from atmosphere to ocean/core and from ocean/core to atmosphere. The goal and single compelling question our investigation addresses is: Where are habitable environments on Titan and what resulting potential biosignatures should we look for? We will present our investigation plans and preliminary work, which focuses on the following objectives: (i) Determine the pathways for organic materials to be transported (and modified) from the atmosphere to surface and eventually to the subsurface ocean (the most likely habitable environment). (ii) Determine whether the physical and chemical processes in the ocean create stable, habitable environments. (iii) Determine what biosignatures would be produced if the ocean is inhabited. (iv) Determine how biosignatures can be transported from the ocean to the surface and atmosphere and be recognizable at the surface and in the atmosphere. This work is funded by NASA's Astrobiology Institute.