The warmth within: Cassini discovers heat beneath the icy surface of Saturn's moon Enceladus!

Image courtesy: NASA/JPL-Caltech/Space Science Institute

New Delhi: NASA's Cassini mission is currently on its last leg and is inching toward its graceful finish in 2017. At present, the spacecraft is performing flybys of the planet Saturn, making its closest approaches to the rings.

The mission, which is about to end some time this year, has definitely been a fruitful one, owing to all the wonderfully insightful information scientists have managed to glean from it.

Every new image beamed back by Cassini carries some evolutionary secret or shows an unpredictable side of the planet or a feature that would have otherwise been impossible to find out.

Now, with another magnificent image delivered by the spacecraft, Saturn's icy moon Enceladus has been revealed to have a warmer south polar region than expected.

A new study in the journal Nature Astronomy suggests that Enceladus' ocean of liquid water might be only a couple of miles beneath this region – closer to the surface than previously thought.

The excess heat is especially pronounced over three fractures that are not unlike the "tiger stripes" – prominent, actively venting fractures that slice across the pole – except that they don't appear to be active at the moment. Seemingly dormant fractures lying above the moon's warm, underground sea point to the dynamic character of Enceladus' geology, suggesting the moon might have experienced several episodes of activity, in different places on its surface.

The finding agrees with the results of a 2016 study by a team independent of the Cassini mission that estimated the thickness of Enceladus' icy crust. The studies indicate an average depth for the ice shell of 11 to 14 miles (18 to 22 kilometers), with a thickness of less than 3 miles (5 kilometers) at the south pole, said NASA.

"Finding temperatures near these three inactive fractures that are unexpectedly higher than those outside them adds to the intrigue of Enceladus," said Cassini Project Scientist Linda Spilker at NASA's Jet Propulsion Laboratory, Pasadena, California. "What is the warm underground ocean really like and could life have evolved there? These questions remain to be answered by future missions to this ocean world," NASA reported.