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GEOLOGICAL ACTIVITY

Enceladus' boiling

Cassini Sees Heat Below the Icy Surface of Enceladus - Paper in Nature Astronomy

A new study in the journal Nature Astronomy reports that the south polar region of Saturn's icy moon Enceladus is warmer than expected just a few metres below its icy surface. This suggests that Enceladus' ocean of liquid water might be only a couple of km 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 18 to 22 kilometers, with a thickness of less than 5 kilometers at the south pole.


"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." 

The Cassini mission is a cooperative project of NASAESA (the European Space Agency) and the Italian Space Agency.  

ASI is one of the partners of the Cassini mission: on the basis of a cooperation agreement with NASA it has developed for Cassini the high gain antenna with the incorporation of a low-gain antenna (that ensure telecommunications with the Earth for the entire duration of the mission), the VIMS spectrometer, the radio-science subsystem (RSIS) and the radar which also uses the high-gain antenna.  

ASI has also developed for the Huygens spacecraft the HASI instrument which measured the physical properties of the atmosphere and Titan's surface.