UTIG RESEARCH PROJECTS ARCHIVE
 |
Europa Studies |
|
Terrestrial
Radar Sounding Studies of Thermal, Compositional and Structural Horizons
Analogous to Those Hypothesized for Europa’s Icy Mantle
Matthew E. Peters and Donald D. Blankenship Jupiter’s moon Europa is characterized by a pervasive icy mantle underlain by a global ocean. The distribution of free water and brines within Europa’s icy/watery shell and the processes within the ice that control the exchange of material both with the surface and the ocean will determine Europa’s suitability for harboring life. On Earth’s ice sheets, radar sounding has proven to be a powerful tool for both determining the volumetric distribution of free water/brines and understanding both ice/ocean and near-surface exchange processes. Here we review the working hypotheses for the formation and evolution of Europa’s icy shell from the perspective of the implied thermal, compositional and structural horizons that can be probed electromagnetically; this is paired with an identification of a suitable terrestrial analog for each horizon. An example of an electromagnetically probable thermal horizon on Europa would be one characterized by water (or brine) pockets lying along a eutectic at the base of cold brittle ice lying over warmer ductile ice (that is possibly convecting). Such an interface is hypothesized to lie within a few kilometers of Europa’s surface. An analogous electromagnetic horizon on Earth is the boundary between polar ice and the temperate ice that lies beneath it on the glaciers of Svalbard. A compositional horizon on Europa that might be electromagnetically probed would be the ice-ocean interface beneath a simple (thermally conducting) shell that has been modified by tidal/tectonic processes. Another compositional horizon would be the boundary with accreted ice that is hypothesized to lie beneath inactive “chaotic” zones in these models.
Many electromagnetic analogs for the compositional horizons in these tidal/tectonic models can be found in Antarctica’s floating ice shelves and subglacial lakes. One also expects ubiquitous near-surface structural horizons associated with both transform and normal faulting in the tidally/tectonically modified models of Europa’s icy mantle. The analogous electromagnetic horizons on Earth may be found in the shear margins and grounding zones of the Antarctic valley glaciers and ice streams. Our ultimate goal is to review the relevant radar studies of analogous polythermal glaciers and Antarctic ice shelves as well as to present new results from our most recent airborne radar studies of Antarctic ice streams, valley glaciers and subglacial lake analogs. |
Publications
|
Blankenship, Donald D., Winebrenner, Dale P., Campbell, Bruce A., Pappalardo, Robert T., and Sandwell, David T., 2003, A science foundation for orbital subsurface radar sounding of Jupiter's icy moons, submitted for AGU F03.
D.D.
Blankenship and the Instrument Definition Team for a Europa Radar
Sounder, 2001, Subsurface evaluation
of Europan ice-ocean interchange processes, using an orbiting ice-penetrating
radar, Lunar and Planetary Science XXXII |
