THE INTRIGUING WORLD OF ENCELADUS.

Enceladus is one of Saturn’s most interesting moons. It had long been suspected that there may have been a small ocean lying under the icy crust of the satellites south pole: images of geysers shooting jets ice and dust have often been imaged by the Cassini probe orbiting Saturn.

NASA have now discovered (15th. September 2016) that there is a global ocean hidden beneath the ice covering the whole moon. The finding implies the fine spray of water vapor, icy particles and simple organic molecules Cassini has observed coming from fractures near the moon’s south pole is being fed by this vast liquid water reservoir.

Cassini scientists analysed more than seven years’ worth of images of Enceladus taken by the spacecraft, which has been orbiting Saturn since 2004. They carefully mapped the positions of features on Enceladus — mostly craters — across hundreds of images, in order to measure changes in the moon’s rotation with extreme precision.

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The icy surface of Enceladus.

As a result, they found Enceladus has a tiny, but measurable wobble as it orbits Saturn. Because the icy moon is not perfectly spherical — and because it goes slightly faster and slower during different portions of its orbit around Saturn — the giant planet subtly rocks Enceladus back and forth as it rotates.

Using computers to measure this wobble, or libration, scientists have worked out that there the ocean must be moon-wide as anything smaller would result in a much smaller libration.

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How Enceladus’ may look.

Saturn lies 1.4 billion kilometres from the Sun (that’s eight times further away than Earth is from the Sun) a year on Saturn is 29.5 earth years long. Because it is so far away the Sun is not as powerful as it is on Earth and so temperatures are much lower, so much lower that liquid water shouldn’t exist on any body that far away and yet it does.

How is that possible? Well that is a mystery although some astronomers think possibility that tidal forces due to Saturn’s gravity could be generating much more heat within Enceladus than previously thought. Saturn is much bigger than Enceladus and as the moon orbits the planet its surface is gently pulled in and out of shape by Saturn’s gravitational force possibly generating heat that allows water to flow. This pulling on a smaller a body is what is meant by a tidal force.

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Cassini’s image of jets.

Scientists first detected signs of the moon’s icy plume in early 2005, further discoveries have been made: in 2015 they shared results that suggest hydrothermal activity is taking place on the ocean floor. On Earth hydrothermal vents are found on the floors of oceans, raising the temperature of the water nearby by many degrees, this in turn allows for all kinds of unusual and unexpected creatures to be found in regions where it had been thought there could be no life.

The material ejected from Enceladus may also help keep Saturn’s magnificent rings topped up with material. How the rings have survived for so long under the tidal forces of the gas giant’s gravity has long been a mystery but this may go some way to solving that puzzle.

All these findings raise the inevitable but intriguing question; could there be some form of life lurking in the Ocean of Enceladus? Cassini will continue to examine the plumes of material ejected from the moon to try and detect signs that something even more amazing may be waiting to be found.

In fact Cassini is scheduled to make a close flyby of Enceladus on the 28th. October, in the mission’s deepest ever dive through the moon’s active plume of icy material. The spacecraft will pass just 30 miles (49 kilometers) above the moon’s surface. there is a lot more to learn about this and the other amazing moon of Saturn.

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Published in: on September 27, 2016 at 09:53  Leave a Comment  
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