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Project Progress

The general stratigraphy and evolution of the Europan crust was synthesized, in which the key regions of astrobiological interest were identified (Doggett et al., 2009). These areas include locations where there appears to have been “communication” between the subsurface putative ocean of liquid salt water with the surface, evidenced by distinctive signatures in the Galileo Near Infrared Mapping Spectrometer (NIMS) data and terrain in which the icy crust has been severely disrupted. These and other material units exposed on the surface have been placed in a geologic sequence and compared to terrestrial planet geologic histories, demonstrating the extreme youth of Europa’s surface. Chemical composition of the icy crust and putative ocean on Europa was summarized in Zolotov and Kargel (2009). Specific attention was devoted to concentrations of biologically important elements and chemical sources of energy which may support life. In Sohl et al. (2010) we reviewed chemical processes responsible for formation and evolution of oceans on icy moons and use Europa as the relatively well-studied example. The future exploration of Europa was summarized by Greeley et al. (2009), in which a “flagship class” mission would orbit Europa to meet the goals identified by the National Research Council in its first “Decadal Survey” report as the highest priority project for the Outer solar system. The principal goal for this mission is to determine the habitability of outer planets satellites using the set of Galilean satellites as the type example not only for our solar system but for the more than 400 exoplanets that have been identified. This mission was identified as the first priority for implementation by NASA and the European Space Agency.