Enceladus gets squeezed This image shows Saturn, obviously, and 2 insets of the small moon Enceladus. One of the most fascinating discoveries of the Cassini mission has been that Enceladus is active, shooting jets of liquid water out of its south pole. Now Cassini has added another detail to how this operates. The small insets show images of Enceladus taken from a distance at 2 different points in its orbit. On the left, you see Enceladus far from Saturn; on the right you see it close up. There is some sunlight reflected from the moon in both images, but take a look at the area at the bottom of Enceladus. The pixels surrounding the moon are much brighter on the left, when Enceladus is far from Saturn. This brightness comes from sunlight reflecting off of water that has been ejected, and the amount of water shooting out is varying depending on the moon’s position in its orbit. The activity of Enceladus’s jets is varying with distance from Saturn. The moon is likely heated tidally; as it moves closer and farther from Saturn during its orbit, the changing gravity compresses and relaxes the whole moon. That process supplies the heat that keeps these jets going, and as shown here it also pressurizes and depressurizes the jets depending on where the Moon is. Cassini only does flyby analyses of Enceladus so it can’t monitor the jets close-up consistently (we’ll need a dedicated mission to do that, sitting constantly around Enceladus), but its image quality is sufficient that even from other places in orbit around Saturn, it can determine how much water is being ejected from Enceladus and give researchers the ability to better understand how that system works. -JBB Image credit: NASA/JPL-Caltech/University of Arizona/Cornell/SSI nasa.gov/mission_pages/cassini/multimedia/squeezing-releasing-enceladus
Posted on: Thu, 01 Aug 2013 00:17:30 +0000
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