1.6 How Enceladus works
This video explains how the eruption plumes of Enceladus might be generated as ‘cold geysers’. Remember that you saw a video that attempted to explain the general processes involved in tidal heating (‘Tidal heating explained’ [Tip: hold Ctrl and click a link to open it in a new tab. (Hide tip)] ) near the end of Week 1.
Download this video clip.Video player: moons_1_vid029.mp4
The so-called ‘cold geyser’ process needs a source of heat to work. Varying tidal forces during Enceladus’s orbit around Saturn cause the moon to deform. Friction during deformation generates heat. This is what is known as tidal heating.
This frictional tidal heating causes temperatures to build up below the moon’s surface. The rising temperatures melt some of the ice, creating pockets of pressurised icy liquids trapped underground. These pockets are mainly composed of water, with ammonia and other impurities acting as antifreeze.
This pressurised liquid then escapes through cracks in the surface. As the liquid escapes, it expands and freezes into ice particles that are jetted into space as plumes that show up brightly when they’re sunlit. Plume material that falls back coats the surface in icy dust, which makes the surface bright.
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- Enceladus ocean ‘must be global’. BBC news report on the global nature of Enceladus’s internal ocean
- Cassini Finds Global Ocean in Saturn’s Moon Enceladus. NASA press release that reports that Enceladus’s internal ocean must be global.
- The previous concept: Enceladus’s ‘great lake’. Our understanding as it was 18 months before the global ocean was demonstrated.
- Enceladus tidal heating news. A story that broke in November 2017, with a mechanism to produce tidal heat in Enceladus’s rocky core over tens of millions to billions of years.