Enceladus’ geysers may persist for millions of years

(credit: Cassini Imaging Team, SSI, JPL, ESA, NASA)

Saturn's moon Enceladus is a relatively small body, only a bit over 500km across. That's not big enough to have retained much heat from its formation, nor to have a huge cache of radioactive material that can provide heat. Yet all indications are that the moon has an extensive under-surface ocean, which fuels geysers near the moon's south pole. Thermal imaging suggests that there are Gigawatts worth of heat being released in the area around the geysers.

All of which should be unsustainable. Most of the heat inside Enceladus must be produced by tidal forces, which deform the moon over the course of its orbit, creating internal friction. And there's no indication that these can generate sufficient heat. This implies that the geysers, and the E-ring of Saturn that they create, are a very temporary phenomenon, and we're lucky to have sent Cassini there while the geysers were active. But that may not be the case. Some scientists are now suggesting that Enceladus may be relatively young, and a separate study is saying that the geysers may be stable for up to a million years.

The new study is based on an attempt to create a physical model of Enceladus' plumes. These originate in a series of fissures known as the tiger stripes, shown on the left side of the moon in the image above. Together, these fissures add up to roughly 500km of active venting.

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