This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
It’s summer in the northern hemisphere of a small, damp, planet orbiting a middle-aged star in a spiral galaxy of matter enjoying a brief heyday before colliding with another galaxy in some 4 billion orbits of the same small, damp, planet. Time for some brief stories.
The south polar region of Enceladus. A place of geysers and who knows what else... (Credit: NASA/JPL/Space Science Institute)
The NASA/ESA Cassini mission to Saturn first spied plumes or geysers of water vapor erupting from Saturn's icy moon Enceladus some 10 years ago. For the past 7 years Cassini's camera's have been snapping shots of the moon's southern region, building a detailed map and catalog of where these geysers come from and, most critically, their relationship to temperature 'hot spots' (a relative term when the environment is around 70 Kelvin and the hottest hot spot is about 190 Kelvin) in the wrinkled, cracked 'tiger stripes' terrain (shown in the above image)
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The result? 101 distinct geysers seen over this period, located precisely at these hot spots - which are themselves only a few dozen feet across. The small hot spot size indicates that these features are not produced by surface friction (icy plates rubbing together), but rather by warm vapor condensing onto cracks walls - in other words, the warm vapor of the geysers is causing the hot spots rather than the hot spots causing the geysers.
This further supports the idea that the geysers are venting from much deeper inside the moon, from a subsurface dark sea or ocean. Here's a map of 98 of the observed geysers (for details check out Porco et al. 2014).
