SoylentNews

takyon [soylentnews.org] writes:

Data collected by the Cassini spacecraft during a 2011 flyby of Saturn's moon Enceladus suggests that an internal liquid ocean may be closer to the surface than previously thought [esa.int]. Ice near the south pole of Enceladus, where plumes of water vapor have been detected, was found to be up to 20 K warmer than expected:

"These observations provide a unique insight into what is going on beneath the surface. They show that the first few metres below the surface of the area that we investigated, although at a glacial 50-60 K, are much warmer than we had expected: likely up to 20 K warmer in some places," [Alice Le Gall] adds. "This cannot be explained only as a result of the Sun's illumination and, to a lesser extent, Saturn's heating so there must be an additional source of heat."

The detected heat appears to be lying under a much colder layer of frost, as no similar anomaly was found in infrared observations of the same region – these probe the temperature of the surface but are not sensitive to what is underneath. [...] Even if the observations cover only a small patch of the southern polar terrains, it is likely that the entire region is warm underneath and Enceladus' ocean could be a mere 2 km under the icy surface. The finding agrees well with the results of a recent study, led by Ondrej Cadek [doi.org] [DOI: 10.1002/2016GL068634] and published in 2016, which estimated the thickness of the crust on Enceladus. With an average depth of 18–22 km, the ice shell appears to reduce to less than 5 km at the south pole.

Thermally anomalous features in the subsurface of Enceladus's south polar terrain [nature.com] (open, DOI: 10.1038/s41550-017-0063) (DX [doi.org])

Original Submission