Enceladus's Tidally Driven 'Tiger Stripes'

摘要

One of the most surprising discoveries made by the Cassini spacecraft as it travelled through the Saturnian system was in 2005, when it was found that the small, icy moon Enceladus was venting material into space. Subsequent passes by Cassini revealed four tears in the surface, near the south pole. These were dubbed "tiger stripes," though to me they look more the kind of cuts made by a big cat with its claws (Figure 1). Over the next few years, the plumes were found to be salty water, with some organic (carbon-based, but nothing to do with life) material mixed in. The tiger stripes had elevated temperatures, so there was fairly rapid agreement that tidal stresses arising from Enceladus's eccentric orbit were heating subsurface material-either water or ice-that was boiling off into space.