Enceladus' south pole is warm under the frost

Press Release ESA, 13 March 2017

 Over the past decade, the international Cassini mission has revealed intense activity at the southern pole of Saturn's icy moon, Enceladus, with warm fractures venting water-rich jets that hint at an underground sea. A new study, based on microwave observations of this region, shows that the moon is warmer than expected just a few metres below its icy surface. This suggests that heat is produced over a broad area in this polar region and transported under the crust, and that Enceladus' reservoir of liquid water might be lurking only a few kilometres beneath.

 In 2005, observations by the NASA/ESA/ASI Cassini mission revealed plumes of water vapour and ice spraying into space from the south pole of Enceladus, the sixth-largest moon of Saturn. These jets originate from the so-called 'tiger stripes' – four warm fractures in the moon's icy surface. The salty composition of these jets points to an underground sea of liquid water that might interact with Enceladus' rocky core, similar to the sub-surface ocean that is thought to exist on Jupiter's moon, Europa.

Many of Cassini's flybys of Enceladus have been dedicated to understanding the structure of the interior of this fascinating body and its potentially habitable water reservoir. Now, a study based on data collected during a close flyby in 2011 indicates that the moon's hidden sea might be closer to the surface than previously thought.

 "During this flyby, we obtained the first and, unfortunately, only high-resolution observations of Enceladus' south pole at microwave wavelengths," says Alice Le Gall from Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), and Université Versailles Saint-Quentin (UVSQ), France. Alice is an associate member of the Cassini RADAR instrument team and the lead scientist of the new study, published today in Nature Astronomy... Read more


> References :

"Thermally anomalous features in the subsurface of Enceladus’s south polar terrain" by A. Le Gall, C. Leyrat, M.A. Janssen, G. Choblet, G. Tobie, O. Bourgeois, A. Lucas, C. Sotin, C. Howett, R. Kirk, R.D. Lorenz, R.D. West, A. Stolzenbach, M. Massé, A.H. Hayes, L. Bonnefoy, G. Veyssière and F. Paganelli. (2017) is published in Nature Astronomy; doi: 10.1038/s41550-017-0063.


Cassini Enceladus south pole RADAR LeGall 400px

Tiger stripes on the south pole of Enceladus. The region studied is indicated by the coloured band.

Credit: NASA/JPL-Caltech/Space Science Institute