The most recent flybys of Enceladus made by NASA's Cassini spacecraft have provided new signs of ongoing changes on and around the moon. The latest high-resolution images of Enceladus show signs that the south polar surface changes over time. Close views of the southern polar region, where jets of water vapor and icy particles spew from vents within the moon's distinctive "tiger stripe" fractures, provide surprising evidence of Earth-like tectonics. They yield new insight into what may be happening within the fractures. The latest data on the plume — the huge cloud of vapor and particles fed by the jets that extend into space — show it varies over time and has a far-reaching effect on Saturn's magnetosphere.
The tiger stripes are analogous to the mid-ocean ridges on Earth's sea floor where volcanic material wells up and creates new crust. Using Cassini-based digital maps of the moon's south polar region, the possible history of the tiger stripes was reconstructed by working backward in time and progressively snipping away older and older sections of the map, each time finding that the remaining sections fit together like puzzle pieces. Images from recent close flybys also have bolstered an idea the Cassini imaging team has that condensation from the jets erupting from the surface may create ice plugs that close off old vents and force new vents to open. The opening and clogging of vents also corresponds with measurements indicating the plume varies from month to month and year to year.
Enceladus' output of ice and vapor dramatically impacts the entire Saturnian system by supplying the ring system with fresh material and loading ionized gas from water vapor into Saturn's magnetosphere. With water vapor, organic compounds and excess heat emerging from Enceladus' south polar terrain, scientists are intrigued by the possibility of a liquid-water-rich habitable zone beneath the moon's south pole.
(On Oct. 5, 2008, just after coming within 25 kilometers (15.6 miles) of the surface of Enceladus, NASA's Cassini captured this stunning mosaic as the spacecraft sped away from this geologically active moon of Saturn. Image credit: NASA/JPL/Space Science Institute.)
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