The wobblings of the warm and perhaps welcoming Enceladus, moon of Saturn, are said by top boffins to offer a surefire clue that wetness able to sustain life is to be found within.
It seems that top boffins at Cornell uni have finally become willing to go firm on the matter following lengthy observations of the moon's motion, particularly its wobble.
The wobble by itself doesn't tell us there's an ocean beneath the Moon's icy surface: Saturn's gravitational pull means the moon's speed is variable. Throw in the moon's asymmetry and the “jets” near the south pole that have often been seen venting particles into space and there's plenty to ponder about Enceladus' behaviour.
A quartet of boffins have now called it: in a paper titled Enceladus’s measured physical libration requires a global subsurface ocean the authors say the moon's jets show the body “must have a liquid reservoir or active melting.” The paper's assessment of Enceladus’ wobble posts that it is “... too large to be consistent with Enceladus’s core being rigidly connected to its surface, and thus implies the presence of a global ocean rather than a localized polar sea.”
Cassini will drop by for a closer look at Enceladus on October 28, when it will pass within 49 kilometers of the moon's surface. That trip will take the craft through the jets to give us a better idea of just what Enceladus is venting into space. We're also keen to know why Enceladus isn't frozen all the way down. Previous observations suggest warm liquid welling up to the moon's surface, which suggests the moon's core is producing heat.
And just possibly waves, too. ®