Planetary science: Enceladus' daily grind

Scientists may have worked out what powers the plumes of gas seen escaping from the surface of one of Saturn's moons. The energy may be generated by massive ice sheets grinding together, with the vapour produced being released through rifts that open and close periodically, papers suggest.
When Cassini flew by Enceladus, a small icy satellite of Saturn, a couple of years ago, cameras snapped active vapour plumes thought to emanate from rifts in the crust dubbed 'tiger stripes.' Francis Nimmo and colleagues now suggest that these 'tiger stripes' are like strike-slip fault zones, with sheets of ice grinding back and forth against one another. This, they say, could generate enough energy to power the gas plumes.
Terry A. Hurford and colleagues show that as Enceladus orbits Saturn, the parent planet's tides make the satellite's ice flex. This, they believe, causes the 'tiger stripes' to open and close periodically, exposing volatiles and allowing them to be released.
Tidal heating was previously proposed as a potential mechanism to explain Enceladus' vapour plumes, but scientists debate whether the energy generated from tidal heating is sufficient. The two new papers offer a plausible alternative.
CONTACT
Francis Nimmo (University of California, Santa Cruz, CA, USA) Author paper [2]
Tel: +1 831 459 1783; E-mail: fnimmo@es.ucsc.edu

Terry A. Hurford (NASA Goddard Space Flight Center, Greenbelt, MD, USA) Author paper [3]
Tel: +1 301 614 6455; E-mail: hurfordt@core2.gsfc.nasa.gov

Andrew J. Dombard (Johns Hopkins University, Laurel, MD, USA) N&V author
Tel: +1 240 228 1651; E-mail: andrew.dombard@jhuapl.edu