Examining topographic variability within chaos terrain on Europa

Chaos terrain is a unique and prevalent surface feature on the Galilean satellite Europa that forms as a result of the disruption of subcircular regions of the satellite's surface. Evidence suggests that these features are endogenic and that they form via processes involving the interaction of a mobile substrate with a brittle surface. Based on the morphology and relative topography of prominent and well-imaged examples of chaos terrain, models have been proposed suggesting that the mobile substrate could be either liquid water or ductile ice. Using a digital elevation model (DEM) of Conamara Chaos, Schenk and Pappalardo (2004) alluded to the presence of several prominent domes within the margins of the feature. They concluded that this was best described by a formation mechanism for chaos involving the diapiric upwelling of a ductile ice substrate, with the coalescence of several individual diapirs in the shallow subsurface. To explore this result in more detail, we use Fourier analysis to examine the long-wavelength components of the topography of several regions of chaos utilizing DEMs of Europa's surface produced utilizing stereo-controlled photoclinometry. Through this analysis, we identify the presence, size, and distribution of domes within the boundaries of chaos terrain and, with this information, examine how topographic variability within chaos terrain can be used to constrain proposed formation mechanisms for this unique feature-type.