Tidally-induced melting events as the origin of south-pole activity on Enceladus

• Published in: Icarus (New York, N.Y. 1962) Vol. 219; no. 2; pp. 655 - 664
• Main Authors: Běhounková, Marie, Tobie, Gabriel, Choblet, Gaël, Čadek, Ondřej
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 01-06-2012; Elsevier
• Subjects: Astronomy; Earth, ocean, space; Enceladus; Exact sciences and technology; Ices; Interiors; Sciences of the Universe; Solar system; Thermal histories; Tides, Solid body; Antarctica, South Pole; Tides, Solid body; Ices; Interiors; Thermal histories; Enceladus; Eccentricity; Ice; Tectonics; Production rate; Thermal history; Saturn satellite; Modelling; Solar system; Heat transfer
• ISSN: 0019-1035; 1090-2643
• DOI: 10.1016/j.icarus.2012.03.024

► We model heat production and transfer in Enceladus’ ice shell in a full spherical geometry. ► Internal oceans with varying horizontal extension are considered. ► Tidal heating leads to ice melting at high latitudes for eccentricity enhanced by a factor of 3. ► Large volumes of water are produced during tidally-induced melting events. ► Stress due to water accumulation should break the ice lithosphere and trigger tectonic activities.
The intense activity at the south pole of Enceladus hints at an internal water reservoir. However, there is no direct evidence of liquid water at present and its long-term stability in the interior remains problematic. By modeling heat production and transfer in the ice shell in a spherical geometry, we show that tidal heating naturally leads to a concentration of convective hot upwellings in the south polar region, favoring the preservation of liquid water at depth. We show that large volumes of water are produced within the ice shell at the south pole during periods of elevated orbital eccentricity (3–5 times the present-day value). Strong lateral variations in the melt production and crystallization rates result in stress concentration in the south polar region, thus providing an explanation for the tectonic activity observed today. We predict that an internal ocean may be sustained over the long term as the consequence of repeated periods with elevated orbital eccentricity, leading to episodic melting and resurfacing events.