FROZEN FRACTALS ALL AROUND: HOW FRACTURE AND FAILURE PROCESSES LEAD TO UNIQUE LANDSCAPES ACROSS ICY SURFACES AROUND THE SOLAR SYSTEM

Here, we present a study of how fracturing processes may manifest themselves in ice-ocean worlds. Fracturing is one of the most ubiquitously-observed surface-modifying processes in the solar system. After all, fracture and failure of surfaces are not only observable records of stress and historical activity, they are also key mechanisms in the interaction of surface and subsurface material. That makes these features crucial aspects in the study of crustal overturn, and thus ice shell habitability. Despite the ubiquity, the fracture of the icy shells of ocean worlds–in particular, how fractures form and why–remains a poorly characterized phenomenon. While most are linked to tidal dynamics and tectonic activity, there has also been an insufficient synthesis of observations of the fractures in icy shells to formulate a complete picture of propagation and terrain formation, particularly with regard to how these processes may contribute to what we can observe on the surface. For example, recent observations have shown that water vapor plumes may be erupting from the surface of Europa, similar to the south polar plumes of Enceladus, at least at first. The source for the initial detection was suggested to be long surface fractures in the area of interest, similar to the tiger stripes of Enceladus. However, tensile fractures that penetrate all the way from the surface to Europa’s subsurface ocean remain unproven. It may be that the putative plumes emanate from geologically active regions, for example Europa’s chaos terrains, likely formed due to failure of a much thinner “ice lid” over near-surface water pockets. The Dawn spacecraft has imaged features on the surface of Ceres that suggest cryovolcanic activity; studies suggest overpressurization and/or volatiles drive fluids from a possible subsurface reservoir. Here, we analyze how pressure changes in a subsurface chamber could drive fractures towards the surface, enabling surface deformation and possibly surface deposits. In addition to fracture morphology, we also discuss timescales of these processes, an important consideration in the discussion of geophysical effects on habitability. Overall, we present how different fracture mechanisms lend themselves to a variety of surface features, and infer impacts on surface/subsurface interaction and evolution.