Riddle of Saturn’s moon may have been answered
Daily Times
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Scientists believe they can explain a mystery that enshrouds Enceladus, a moon of Saturn that could be the best bet for looking for life elsewhere in the Solar System.
Orbiting eccentrically in Saturn’s outermost ring, Enceladus is a strange and tiny world of white. It measures just 504 kilometres (315 miles) across, thus defying its name as a giant of Greek mythology, and has brilliant shell of ice that is pristine except for some odd-looking grooves and pockmarks from recent space impacts.
Just as its surface is a frigid hell, counter-intuitively, beneath the ice Enceladus seems to be relatively balmy. Flybys by the US probe Cassini have shown plumes of water vapour that vent from its surface, shooting crystal jets upwards for hundreds of kilometers (miles).
A pair of American space scientists believe they have the answer for this. Spinning bodies are most stable if most of their mass is close to the equator. Any redistribution of mass within a rotating object causes the axis of spin to become unstable.
In the case of Enceladus, the large blob of low-density material — either warm water or hot silicate at its rocky core — would cause the moon to roll over. The spin axis would remain fixed, but the blob, known as a diapir, would end up on the south pole.
June 05, 2006
Daily Times
________
Scientists believe they can explain a mystery that enshrouds Enceladus, a moon of Saturn that could be the best bet for looking for life elsewhere in the Solar System.
Orbiting eccentrically in Saturn’s outermost ring, Enceladus is a strange and tiny world of white. It measures just 504 kilometres (315 miles) across, thus defying its name as a giant of Greek mythology, and has brilliant shell of ice that is pristine except for some odd-looking grooves and pockmarks from recent space impacts.
Just as its surface is a frigid hell, counter-intuitively, beneath the ice Enceladus seems to be relatively balmy. Flybys by the US probe Cassini have shown plumes of water vapour that vent from its surface, shooting crystal jets upwards for hundreds of kilometers (miles).
A pair of American space scientists believe they have the answer for this. Spinning bodies are most stable if most of their mass is close to the equator. Any redistribution of mass within a rotating object causes the axis of spin to become unstable.
In the case of Enceladus, the large blob of low-density material — either warm water or hot silicate at its rocky core — would cause the moon to roll over. The spin axis would remain fixed, but the blob, known as a diapir, would end up on the south pole.
June 05, 2006
