University of Chicago | 2016 Mar 28
[img3="This close-up view of Saturn’s moon Enceladus show a distinctive pattern of continuous, slightly curved and roughly parallel faults within the moon’s southern polar latitudes. Informally called ‘tiger stripes’ by imaging scientists, they mark the source of the moon’s long-lived geysers. (Credit: NASA/JPL/SSI)"]http://news.uchicago.edu/sites/all/file ... 160328.jpg[/img3][hr][/hr]The Cassini spacecraft has observed geysers erupting on Saturn’s moon Enceladus since 2005, but the process that drives and sustains these eruptions has remained a mystery. Now scientists at the University of Chicago and Princeton University have pinpointed a mechanism by which cyclical tidal stresses exerted by Saturn can drive Enceladus’ long-lived eruptions.
“On Earth, eruptions don’t tend to continue for long,” said Edwin Kite, assistant professor of geophysical sciences at UChicago. “When you see eruptions that continue for a long time, they’ll be localized into a few pipelike eruptions with wide spacing between them.”
But Enceladus, which probably has an ocean underlying its icy surface, has somehow managed to sprout multiple fissures along its south pole. These “tiger stripes” have been erupting vapor and tiny frost particles continuously along their entire length for decades and probably much longer.
“It’s a puzzle to explain why the fissure system doesn’t clog up with its own frost,” Kite said. “And it’s a puzzle to explain why the energy removed from the water table by evaporative cooling doesn’t just ice things over.”
What’s needed is an energy source to balance the evaporative cooling. “We think the energy source is a new mechanism of tidal dissipation that had not been previously considered,” Kite said. ...
Sustained Eruptions on Enceladus Explained by Turbulent Dissipation in Tiger Stripes - Edwin S. Kite, Allan M. Rubin
- Proceedings of the NAS (online 28 Mar 2016) DOI: 10.1073/pnas.1520507113 (pdf)
