Lake Stars as an Earth Analog for Europa’s Manannán Crater Spider Feature

Jupiter’s icy moon Europa is an ocean world which is a prime candidate in our search for potential extraterrestrial habitability and life beyond Earth. Europa’s surface hosts many features proposed to originate from brine sources within its icy shell (Fagents, 2003), which may represent the most accessible liquid water bodies within our Solar System (Lesage et al., 2022). An intriguing possible example is the asterisk-shaped ‘spider’ at the center of Manannán crater, identified by the Galileo mission (Moore et al., 2001), for which we propose the informal name Damhán Alla. We present a new formation hypothesis for Damhán Alla based on morphological analysis and preliminary analog modelling. We suggest that the feature may originate from a process similar to that forming dendritic ‘lake stars’; seasonal features found on frozen ponds and lakes on Earth, but under elevated pressure and temperature post-impact conditions. We present laboratory experiments performed at NASA’s Jet Propulsion Laboratory, which indicate that similar patterns can form in Europa granular ice simulant under lower temperature regimes expected after impact, and we present initial calculations to describe the hypothesized process.