Turbulent dissipation sustains eruptions on Enceladus

In July 2005 the Cassini spacecraft flew within 170 km of Saturn’s moon Enceladus and discovered an icy landscape strewn with house-sized boulders and tectonic features. Among those features are so-called “tiger stripes,” four fractures, each roughly 130 km long and flanked by a band of warm ice, that continuously spew plumes of ice, water vapor, and other gases into space. (See the article by John Spencer, Physics Today, November 2011, page 38.) Edwin Kite (University of Chicago) and Allan Rubin (Princeton University) have produced a simple model that explains the local warmth and constant eruptions. Enceladus’s surface is thought to be an ice shell roughly 35 km thick that floats on a salty liquid-water ocean. The researchers posit that the tiger stripes are open fissures a meter wide that run through the shell. As shown in the diagram, the ocean fills a fissure with water up...