Updated view on Titan’s habitability: interior and surface aqueous environments

Saturn’s moon Titan is the only world beyond Earth where abundant organic molecules and liquid water are expected to interact. Crucially, these interactions yield prebiotic molecules central to terrestrial biochemistry. Characterizing this prebiotic chemistry is one of the main science goals of NASA’s upcoming Dragonfly mission. Here we synthesize the current state of knowledge on the habitability and prebiotic potential of Titan’s three aqueous settings: its interior hydrosphere, its putative cryovolcanic flows, and its impact-melt pools. For each setting, we identify the enabling factors and the principal bottlenecks that limit prebiotic complexification. Titan’s interior is likely pervaded by liquid water in contact with organic material delivered from the surface and released from the core, though the longevity of its liquid water has recently been called into question. Cryovolcanic regions transiently expose surface organics to ammonia-bearing aqueous melts but are constrained by short freezing timescales. Impact-melt pools, by contrast, are warm and long-lived environments whose prebiotic chemistry is limited by the scarcity of ammonia. Dragonfly will return ground-truth data not only for Titan’s habitability, but also for organic-rich aqueous environments across the Solar System and beyond. The years before its arrival are the last in which predictive work can still shape Dragonfly’s investigations.