How Saturn is devouring its moon: Stunning images reveal Enceladus' ghostly tendrils being sucked in by the gas giant's rings
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Stunning Cassini images have revealed how material from Saturn's icy moon, Enceladus, is slowly being eaten up by the gas giant's rings.
The 310 mile (500km) wide moon, which astronomers say may harbour alien life, has a network of geysers pumping out tiny chunks of ice-water at 800mph (1287km/h).
But these geysers won't be there forever as images show how long, sinuous, tendril-like structures near Enceladus are transferring material from the moon into Saturn's rings.
Stunning Cassini images have revealed how material from Saturn's icy moon, Enceladus, is slowly being eaten up by the gas giant's rings. Nasa researchers used computer simulations (right) to follow the trajectories of ice grains ejected from individual geysers
These ghostly tendrils have long been known to follow Enceladus in its orbit around the gas giant – but this is the first time scientists have been able to track its source.
'We've been able to show that each unique tendril structure can be reproduced by particular sets of geysers on the moon's surface,' said Colin Mitchell, a Cassini imaging team associate at the Space Science Institute in Colorado.
Mitchell and colleagues used computer simulations to follow the trajectories of ice grains ejected from individual geysers.
The tendrils reach into Saturn's E ring - the ring in which Enceladus orbits - extending tens of thousands of miles away from the moon.
This Cassini spacecraft image and computer simulation shows how long, sinuous features from Enceladus can be modeled by tracing the trajectories of tiny, icy grains ejected from the moon's south polar geysers
These ghostly tendrils have long been known to follow Enceladus in its orbit around the gas giant – but this is the first time scientists have been able to track its source. In this image, small water ice particles fly from fissures in the south polar region of Saturn's moon Enceladus
The study revealed that tendril structures of different shapes correspond to different sizes of geyser particles, allowing them to zero in on the sizes of the particles forming them.
They found the tendrils are composed of particles with diameters no smaller than about a millionth of a metre.
As the researchers examined images from different times and positions around Saturn, they also found that the detailed appearance of the tendrils changes over time.
'It became clear to us that some features disappeared from one image to the next,' said John Weiss, an imaging team associate at Saint Martin's University in Lacey, Washington.
In 2012, Cassini captured this view of Enceladus in front of Saturn's rings and bigger moon sibling Titan in the background
This graphic plots locations of the geysers scientists on Enceladus' south polar terrain. The 36 most active geysers, or jets, are marked by circles
The authors suspect that changes in the tendrils' appearance likely result from the cycle of tidal stresses.
This is the result of squeezing and stretching of the moon as it orbits Saturn. It also has control over the widths of fractures from which the geysers erupt.
The stronger the tidal stresses raised by Saturn at any point on the fractures, the wider the fracture opening and the greater the eruption of material.
'As the supply lanes for Saturn's E ring, the tendrils give us a way to ascertain how much mass is leaving Enceladus and making its way into Saturn orbit,' said Carolyn Porco, team leader for the imaging experiment and a coauthor on the paper.
'So, another important step is to determine how much mass is involved, and thus estimate how much longer the moon's sub-surface ocean may last.'
An estimate of the lifetime of the ocean is important in understanding the evolution of Enceladus over long timescales.
This is an important piece of information for astronomers who believe Enceladus jas liquid, possibly life-containing oceans beneath its icy surface.
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