IRDIS two-color observation of Europa (left), and simulated visible-light reference image of Europa from Becker (2013; right). The two-color IRDIS observation is produced using the K1 filter at 2.1 μm (filter width 0.051 μm), shown in yellow, and the K2 filter at 2.251 μm (width 0.055 μm), shown in blue. Water ice has a broad absorption band around 2 μm, so the blue areas are icy and yellow areas are dominated by non-icy species.