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

Abstract Jupiter’s icy moon Europa is an ocean world that 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, which may represent the most accessible liquid water bodies within our solar system. An intriguing possible example is the asterisk-shaped “spider” at the center of Manannán crater, identified by the Galileo mission, 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 modeling. 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 post-impact pressure and temperature conditions. We present laboratory experiments performed in a liquid nitrogen-cooled glove box 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.