HR: 10:25h
AN: P11C-01 INVITED     [PDF]
TI: Understanding Active Processes at the Surfaces of Jupiter's Icy Moons
AU: Moore, W B
EM: bmoore@ess.ucla.edu
AF: University of California, Los Angeles, 3806 Geology Bldg. Box 951567, Los Angeles, CA 90095-1567 United States
AU: * Makris, N
EM: makris@mit.edu
AF: Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 United States
AB: Exploration of Jupiter's icy moons, and Europa in particular, is of paramount interest to astrobiology. Europa is considered one of the most likely places in the solar system for extraterrestrial life because it appears to have a liquid ocean and may be able to tap into a vast supply of tidal energy (like its neighbor Io) to drive internal dynamics. Jupiter's other icy moons, Ganymede and Callisto, may also harbor liquid oceans, but these oceans are most likely sandwiched between high-density and low-density phases of solid ice and so have less astrobiological potential. Great uncertainty remains, however, in our knowledge of the depths to and extents of these oceans. In order to even begin searching for life on these icy moons, we must answer the basic questions: how thick is the ice? and how (and where and when) does the ocean communicate with the surface? Providing answers to these questions will require investigating the processes that are currently acting to shape or re-shape the surfaces of Jupiter's icy moons and alter their physical and chemical state. In two image data sets obtained from Voyager and then Galileo, no evidence has yet emerged to indicate geologic change over the intervening twenty years. It is possible that in future missions higher resolution imagery and other techniques employing radar interferometry may indirectly detect and localize active deformation events including impacts, fracturing, flows, relaxation and mass wasting. Thermal anomalies due to possible active deformation or vertical transport may also be detectable. Seismic sensors placed on the surface may directly detect the deformation of the surface and, with several sensors, localize regions of activity. Seismic sensors can also be used to determine the thickness of the ice and underlying ocean by tomography. The causes of such geologic activity could then be potentially identified by correlation with driving mechanisms such as tidal motion, convection, non-synchronous rotation, libration, static topography, impacts and thermal stress. It would also be important to determine the processes by which material is transported to and from the surface, including characterization of the relative importance of exogenic and endogenic contributions to surface composition. A system-wide analysis of chemical transport from Ganymede to Jupiter may be necessary to properly constrain the transport mechanisms.
DE: 5410 Composition
DE: 5420 Impact phenomena (includes cratering)
DE: 5470 Surface materials and properties
DE: 5714 Gravitational fields (1227)
DE: 6019 Gravitational fields
SC: Planetary Sciences [P]
MN: 2003 Fall Meeting