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Thermally anomalous features in the subsurface of Enceladus’s south polar terrain

Alice Le Gall 1 Cédric Leyrat 2 Michael A. Janssen 3 Gael Choblet 4 Gabriel Tobie 4 Olivier Bourgeois 4 Antoine Lucas 5, 6 Christophe Sotin 4, 3 C. Howett 7 Randolph Kirk 8 R. D. Lorenz 9 Richard D. West 3 Aurélien Stolzenbach 1 M. Massé 4 A. H. Hayes 10 Léa Bonnefoy 11 G. Veyssière 12 F. Paganelli 13
1 PLANETO - LATMOS
LATMOS - Laboratoire Atmosphères, Milieux, Observations Spatiales
2 LESIA - Laboratoire d'études spatiales et d'instrumentation en astrophysique
3 JPL - Jet Propulsion Laboratory
4 LPG - Laboratoire de Planétologie et Géodynamique [UMR 6112]
5 IPGP - Institut de Physique du Globe de Paris
6 AIM (UMR_7158 / UMR_E_9005 / UM_112) - Astrophysique Interprétation Modélisation
7 SwRI - Southwest Research Institute [Boulder]
8 Astrogeology Science Center [Flagstaff]
9 APL - Johns Hopkins University Applied Physics Laboratory [Laurel, MD]
10 CRSR - Center for Radiophysics and Space Research [Ithaca]
11 LPL - Lunar and Planetary Laboratory [Tucson]
12 CNRM - Centre national de recherches météorologiques
13 APUS - American Public University System
Abstract : Saturn’s moon Enceladus is an active world. In 2005, the Cassini spacecraft witnessed for the first time water-rich jets venting from four anomalously warm fractures (called sulci) near its south pole (1,2). Since then, several observations have provided evidence that the source of the material ejected from Enceladus is a large underground ocean, the depth of which is still debated (3,​4,​5,​6). Here, we report on the first and only opportunity that Cassini’s RADAR instrument (7,8) had to observe Enceladus’s south polar terrain closely, targeting an area a few tens of kilometres north of the active sulci. Detailed analysis of the microwave radiometry observations highlights the ongoing activity of the moon. The instrument recorded the microwave thermal emission, revealing a warm subsurface region with prominent thermal anomalies that had not been identified before. These anomalies coincide with large fractures, similar or structurally related to the sulci. The observations imply the presence of a broadly distributed heat production and transport system below the south polar terrain with ‘plate-like’ features and suggest that a liquid reservoir could exist at a depth of only a few kilometres under the ice shell at the south pole. The detection of a possible dormant sulcus further suggests episodic geological activity.
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https://hal-insu.archives-ouvertes.fr/insu-01499557
Contributor : Catherine Cardon <>
Submitted on : Friday, March 31, 2017 - 4:03:26 PM
Last modification on : Wednesday, April 14, 2021 - 3:39:55 AM

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INSU | CNRS | OBSPM | LESIA | METEO | LATMOS | UPMC | DSM-IRFU | IRFU-AIM | UVSQ | UNIV-NANTES | CEA | IPGP | USPC | CEA-DRF | SORBONNE-UNIVERSITE | UNIV-PARIS7 | SU-SCIENCES | UNIV-ANGERS | LPG | UNIV-PARIS | UP-SCIENCES | AFRIQ | PSL | GS-ENGINEERING

Citation

Alice Le Gall, Cédric Leyrat, Michael A. Janssen, Gael Choblet, Gabriel Tobie, et al.. Thermally anomalous features in the subsurface of Enceladus’s south polar terrain. Nature Astronomy, Nature Publishing Group, 2017, 1, pp.0063. ⟨10.1038/s41550-017-0063⟩. ⟨insu-01499557⟩

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