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T.A. Hurford, R.A. Beyer, R. Greenberg (University of Arizona)
Models of Europa's interior predict a liquid ocean underneath its icy outer shell. The thickness of this ice shell is not known, yet has important implications for future Europan spacecraft missions and the habitability of Europa's ocean. Early investigation of images sent back by the Galileo spacecraft showed a few clear cases of crustal flexure near ridges [1,2,3]. Those cases were observable because favorable lighting conditions highlighted the flexure, and yielded estimates of the thickness of the elastic portion of Europa's ice crust were ~200 m.
Now using photoclinometry, we are extending the investigation of flexure near ridges which allows determination of the elastic thickness at a variety of locations across Europa's surface. We have investigated the elastic thickness over a wide range of longitudes and latitudes and in a variety of geological settings. The amount of flexure seen yields an elastic thickness of generally ~300 m, consistent with earlier estimates. Intriguing preliminary indications of variations in the elastic thickness with proximity to chaos are observed. \\ \\ [1] Tufts, R., et al. 1997. Crustal displacement features on Europa. \emph{Geol. Soc. Am. Abstr. Programs} \textbf{29}, A-312 [2] Tufts, R. 1998. Lithospheric Displacement Features on Europa and their interpretation. Ph.D. Dissertation. University of Arizona. [3] Williams, K.K. and R. Greeley. 1998. Estimates of ice thickness in the Conamara Choas region of Europa. \emph{Geophys. Res. Lett.}, \textbf{25}, 4273-4276.
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Bulletin of the American Astronomical Society, 35 #4
© 2003. The American Astronomical Soceity.