A new geomorphic marker for the study of debris-covered glaciers on Mars

Mars hosts thousands of debris-covered glaciers across its mid-latitudes, containing the second-largest known reservoir of water ice on the planet. These glaciers are key targets for future in-situ resource utilization (ISRU) and preserve a record of climate conditions over the last billion years. However, the inventory is incomplete and our knowledge of their ages and dynamics is limited. Here, we report on the discovery of a widespread landform that results from the interaction of crater ejecta with these glaciers – Crater-Associated Irregular Cellular Structures (CAICS). Because they indicate an underlying glacier, their recognition enables the expansion of the inventory of glaciers on Mars by >50%. CAICS have formed on glacial surfaces throughout martian history so, dating ejecta outside the glacier provides the first reliable estimates of episodes of ice-deposition and glacier motion, enabling improved Amazonian climate reconstruction. As CAICS form via an interaction between ejecta and ice, future modelling should provide constraints on the composition and structure of the underlying glacier – important for ISRU. Finally, the analogue with Veiki moraines and ice-walled-lake plains which are formed in connection with liquid water and ice on Earth, opens up the possibility that CAICS may be an indicator for habitable glacial environments.