Enceladus--A complicated (if not complex) system way out at Saturn

Susan Kieffer, Charles R. Walgreen Chair, Department of Geology, University of Illinois at Urbana-Champaign

Enceladus is a tiny (500 km diameter) frigid satellite of Saturn. Equatorial temperatures are less than 80 K, but the tectonically active south polar region has hot spots up to 145 K. A plume that has a discharge of ~100 kg/s (similar to Old Faithful geyser in Yellowstone) spews gases and ice crystals into the E- rings of Saturn. The origin of this plume is highly controversial. One model, dubbed "Cold Faithful" asserts that liquid water at 273 K could be as shallow as 7 m under the surface. This has cause intense interest in exploring Enceladus for possible life. Our model, "Frigid Faithful", suggests that the plume is the result of decomposition of gas hydrates (ice with dissolved gases) driven by the active tectonics. This model does not imply or require liquid water.