May 16, 2012

THERE ARE LOTS OF DIFFERENT WAYS TO MAKE AN IMPACT; BUT CAN YOU CAUSE CHAOS? STUDIES OF JUPITER'S MOON EUROPA

Speaker: Dr. Rónadh Cox, Williams College

Europa is a world of mysteries and enigmas. A subsurface water ocean probably hides at relatively shallow depth beneath Europa’s ice crust, and the frozen surface is marked by unique geomorphologic features. Chaos terrain is one of Europa’s signature topographic structures, consisting of ice blocks set in a slushy-appearing matrix. Chaos areas probably represent breakage of the brittle surface ice and exposure of underlying water, although how this happens is unclear. Most
explanations have focussed on endogenic mechanisms and energy sources, but all models are disputed. We have proposed that crust-penetrating bolide impacts are an alternative mechanism by which chaos terrain could be produced: for ice thicknesses on the order of a couple of 10s of km, impacts of sufficient energy could break through to the underlying water. A range of different kinds of evidence
support this hypothesis, including impact experiments and image analysis of the sizes and distribution of chaos areas. This talk will describe chaos on Europa, and present our evidence for its origin by impact.

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