Abstract EANA2025-138

Saturn's moon Enceladus has emerged as one of the most promising astrobiological targets in the Solar System due to the detection of plumes emanating from its south pole, indicative of a subsurface ocean in contact with a rocky core. In this study, we simulate two geochemical scenarios of water-rock interaction using PHREEQC to evaluate the habitability potential of Enceladus under distinct compositional conditions: (1) a primitive core modeled after ordinary chondrites, and (2) a mixed-core scenario incorporating cometary water and carbonaceous chondrite inclusions.

Each scenario was designed to replicate conditions potentially present within Enceladus' ocean, including low temperatures (0–5 °C), alkaline pH, and the presence of key solutes. The modeling results focused on three astrobiological indicators: (i) the generation of redox gradients via mineral precipitation and hydrogen production, (ii) the mobilization of bioessential elements such as phosphorus and nitrogen, and (iii) the formation of secondary minerals relevant to life-hosting environments, including carbonates, hydroxyapatite, and magnetite.

Our findings show that both scenarios produce mineral assemblages capable of supporting prebiotic or microbial processes. The mixed-core scenario, in particular, yielded higher concentrations of phosphate species and reducing compounds, making it especially favorable from an astrobiological standpoint. The implications of these findings are discussed in the context of hydrothermal activity, elemental cycling, and analogues in Earth's oceanic hydrothermal systems.

This work contributes to the ongoing effort to characterize extraterrestrial ocean worlds and provides a comparative framework for interpreting future data from missions such as Europa Clipper and potential Enceladus flybys.