Thermal and Chemical Evolution of Small, Shallow Water Bodies in Europa's Ice Shell

Abstract

AbstractThe highly modified surface of Europa's ice shell hides a global, salty ocean that may hold conditions favorable for life, and cycles in the ice shell likely impact those conditions by allowing material transfer between the surface and subsurface ocean. The Galileo spacecraft observed a number of young geologic features that indicated Europa's ice shell was recently or presently active, including lenticulae. Lenticulae, a collection of quasi‐elliptically shaped surface disruptions, have been suggested to form above relatively small bodies of water (∼10 km diameter) emplaced in the ice shell as shallow as 1 km below the surface. Here, we use numerical models to quantify the longevity of small bodies of water in Europa's ice shell and explore their chemical evolution to understand how shallow water impacts the composition of the ice shell and regional surface geology over time. We find that lenticulae are more geologically transient than previously described, and that if the reservoirs contain salts, up to meters‐thick layers of salt may precipitate during the solidification process. Our results imply that, if depressions are the first signs of liquid water emplaced in the ice shell, lenticulae may be actively forming at present day, suggesting liquid water may still be present in Europa's shallow ice which could form water plumes and affect its habitability.