Enceladus's and Dione's floating ice shells supported by minimum stress isostasy
Beuthe, M.; Rivoldini, A.; Trinh, A. (2016). Enceladus's and Dione's floating ice shells supported by minimum stress isostasy. Geophys. Res. Lett. 43(19): 10088-10096. https://dx.doi.org/10.1002/2016GL070650
In: Geophysical Research Letters. American Geophysical Union: Washington. ISSN 0094-8276; e-ISSN 1944-8007, more
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| Author keywords |
Enceladus; Dione; isostasy; gravity; crust; subsurface ocean |
| Abstract |
Enceladus's gravity and shape have been explained in terms of a thick isostatic ice shell floating on a global ocean, in contradiction of the thin shell implied by librations. Here we propose a new isostatic model minimizing crustal deviatoric stress and demonstrate that gravity and shape data predict a 38 4km thick ocean beneath a 23 4kmthick shell agreeing withbut independent oflibration data. Isostatic and tidal stresses are comparable in magnitude. South polar crust is only 7 4km thick, facilitating the opening of water conduits and enhancing tidal dissipation through stress concentration. Enceladus's resonant companion, Dione, is in a similar state of minimum stress isostasy. Its gravity and shape can be explained in terms of a 99 23km thick isostatic shell overlying a 65 +/- 30km thick global ocean, thus providing the first clear evidence for a present-day ocean within Dione. |
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