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Enceladus: An Active Cryovolcanic Satellite

Spencer, John R. und Barr, Amy C. und Esposito, Larry W. und Helfenstein, Paul und Ingersoll, Andrew P. und Jaumann, Ralf und McKay, Christopher P. und Nimmo, Francis und Waite, J. Hunter (2009) Enceladus: An Active Cryovolcanic Satellite. In: Saturn from Cassini-Huygens Springer. Seiten 683-724. ISBN 978-1-4020-9216-9.

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Kurzfassung

Enceladus is one of the most remarkable satellites in the solar system, as revealed by Cassini's detection of active plumes erupting from warm fractures near its south pole. This discovery makes Enceladus the only icy satellite known to exhibit ongoing internally driven geological activity. The activity is presumably powered by tidal heating maintained by Enceladus' 2:1 mean-motion resonance with Dione, but many questions remain. For instance, it appears difficult or impossible to maintain the currently observed radiated power (probably at least 6 GW) in steady state. It is also not clear how Enceladus first entered its current self-maintaining warm and dissipative state- initial heating from non-tidal sources is probably required. There are also many unanswered questions about Enceladus' interior. The silicate fraction inferred from its density of 1:68gcm−2 is probably differentiated into a core, though we have not direct evidence for differentiation. Above the core there is probably a global or regional liquid water layer, inferred from several models of tidal heating, and an ice shell thick enough to support the ~1 km amplitude topography seen on Enceladus. It is possible that dissipation is largely localized beneath the south polar region. Enceladus' surface geology, ranging from moderately cratered terrain to the virtually crater-free active south polar region, is highly diverse, tectonically complex, and remarkably symmetrical about the rotation axis and the direction to Saturn. South polar activity is concentrated along the four “tiger stripe” fractures, which radiate heat at temperatures up to at least 167K and are the source of multiple plumes ejecting ~200kgs−2 of H2O vapor along with significant N2 (or C2H4), CO2, CH4, NH3, and higher-mass hydrocarbons. The escaping gas maintains Saturn's neutral gas torus, and the plumes also eject a large number of micron-sized H2O ice grains that populate Saturn's E-ring. The mechanism that powers the plumes is not well understood, and whether liquid water is involved is a subject of active debate. Enceladus provides perhaps the most promising potential habitat for life in the outer solar system, and the active plumes allow the unique opportunity for direct sampling of that zone. Enceladus is thus a prime target for Cassini's continued exploration of the Saturn system, and will be a tempting target for future missions.

Dokumentart:Beitrag in einem Lehr- oder Fachbuch
Zusätzliche Informationen:DOI: 10.1007/978-1-4020-9217-6_21
Titel:Enceladus: An Active Cryovolcanic Satellite
Autoren:
AutorenInstitution oder E-Mail-Adresse der Autoren
Spencer, John R.Southwest Research Institute, Boulder, USA
Barr, Amy C.Southwest Research Institute, Boulder, USA
Esposito, Larry W.LASP, University of Colorado, Boulder, USA
Helfenstein, PaulCenter for Radiophysics and Space Research, Cornell University, USA
Ingersoll, Andrew P.Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, USA
Jaumann, RalfNICHT SPEZIFIZIERT
McKay, Christopher P.NASA Ames Research Center, Mountain View, USA
Nimmo, FrancisDept. Earth and Planetary Sciences, University of California Santa Cruz, Santa Cruz, USA
Waite, J. HunterSouthwest Research Institute, San Antonio, USA
Datum:2009
Erschienen in:Saturn from Cassini-Huygens
Referierte Publikation:Ja
In ISI Web of Science:Nein
Seitenbereich:Seiten 683-724
Herausgeber:
HerausgeberInstitution und/oder E-Mail-Adresse der Herausgeber
Dougherty, Michele K.NICHT SPEZIFIZIERT
Esposito, Larry W.NICHT SPEZIFIZIERT
Krimigis, Stamatios M.NICHT SPEZIFIZIERT
Verlag:Springer
ISBN:978-1-4020-9216-9
Status:veröffentlicht
Stichwörter:Enceladus, Cassini, active plumes
HGF - Forschungsbereich:Verkehr und Weltraum (alt)
HGF - Programm:Weltraum (alt)
HGF - Programmthema:W EW - Erforschung des Weltraums
DLR - Schwerpunkt:Weltraum
DLR - Forschungsgebiet:W EW - Erforschung des Weltraums
DLR - Teilgebiet (Projekt, Vorhaben):W - Vorhaben CASSINI (alt)
Standort: Berlin-Adlershof
Institute & Einrichtungen:Institut für Planetenforschung
Hinterlegt von: Susanne Pieth
Hinterlegt am:09 Dez 2009 14:36
Letzte Änderung:09 Dez 2009 14:36

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