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Sub-surface oceans on mid-sized icy satellites and large TNO's

Hussmann, H. und Sohl, F. und Spohn, T. (2005) Sub-surface oceans on mid-sized icy satellites and large TNO's. In: EOS Transcactions AGU Fall Meeting Suppl., 86 (52 Fall Meeting Suppl.), P22A-07. 2005 AGU Fall Meeting, 2005-12-05 - 2005-12-09, San Francicsco, CA (USA).

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Kurzfassung

The detection of induced magnetic fields in the vicinity of the Jovian satellites Europa, Ganymede, and Callisto was one of the most surprising findings of the Galileo mission to Jupiter. The observed magnetic signature cannot be generated in solid ice or in silicate rock. It rather suggests the existence of electrically conducting reservoirs of liquid water beneath the satellites' outermost icy shells that may contain even more water than all terrestrial oceans combined. The maintenance of liquid water layers at a depth of several tens of kilometers is closely related to the internal structure, chemical composition, and thermal state of the corresponding satellite interior. Controlling parameters for sub-surface ocean formation are the radiogenic heating rate of the silicate component, additional contributions due to, e.g., the dissipation of tidal energy in case of Europa, and the effectiveness of the heat transfer to the surface. Furthermore, the melting temperature of ice will be significantly reduced by small amounts of salts and/or incorporated volatiles such as methane and ammonia that are highly abundant in the outer solar system. In general, large icy bodies such as, e.g. the icy Galilean satellites, Titan and Triton, are more likely to harbour sub-surface oceans because of the slower cooling rate and the more intense radiogenic heating caused by their larger rock mass fractions, as compared to smaller icy bodies. However, depending on the amount of volatiles incorporated in the icy component during accretion, internal oceans cannot be ruled out for the largest of the medium-sized satellites of Saturn and Uranus and the biggest Transneptunian objects (TNO's), provided they are differentiated into a rock core and a water ice/liquid shell . Based on this assumption and using an equilibrium condition between the heat production rate in the rocky cores and the heat flow through the ice shell, we find that oceans are possible on Rhea, Titania, Oberon, Triton, and Pluto and on the largest TNO's Sedna and 2004 DW. The presence of oceans requires that small amounts of ammonia are available. The liquid sub-surface reservoirs are situated deeply underneath an ice-I shell of more than 100 km thickness. However, they may be indirectly detectable by their interaction with the surrounding magnetic fields and charged particles and by the magnitude of the satellite's response to tides exerted by the primary. The latter is strongly dependent on the occurrence of a sub-surface ocean which provides greater flexibility to the satellite's rigid outer ice shell. Time-dependent models show that even small satellites may have harboured oceans in the past due to the then higher radiogenic heat production rate. Apart from the above mentioned objects, past oceans are obtained for Dione, Iapetus, Ariel, Umbriel, Charon, the Kuiperbelt objects Quaoar and Ixion, and other 1000-km-class objects. We do not find indications for past oceans in case of Tethys, Enceladus, Miranda, and Mimas as the smallest object considered in this study.

elib-URL des Eintrags:https://elib.dlr.de/20196/
Dokumentart:Konferenzbeitrag (Vortrag)
Zusätzliche Informationen: LIDO-Berichtsjahr=2005,
Titel:Sub-surface oceans on mid-sized icy satellites and large TNO's
Autoren:
AutorenInstitution oder E-Mail-AdresseAutoren-ORCID-iDORCID Put Code
Hussmann, H.IAG-USP, Sao Paulo, BrazilNICHT SPEZIFIZIERTNICHT SPEZIFIZIERT
Sohl, F.NICHT SPEZIFIZIERTNICHT SPEZIFIZIERTNICHT SPEZIFIZIERT
Spohn, T.NICHT SPEZIFIZIERTNICHT SPEZIFIZIERTNICHT SPEZIFIZIERT
Datum:2005
Erschienen in:EOS Transcactions AGU Fall Meeting Suppl.
Open Access:Nein
Gold Open Access:Nein
In SCOPUS:Nein
In ISI Web of Science:Nein
Band:86
Seitenbereich:P22A-07
Name der Reihe:EOS Transactions AGU
Status:veröffentlicht
Stichwörter:Ices, Interior, Saturnian satellites, Trans-Neptunian objects
Veranstaltungstitel:2005 AGU Fall Meeting
Veranstaltungsort:San Francicsco, CA (USA)
Veranstaltungsart:internationale Konferenz
Veranstaltungsbeginn:5 Dezember 2005
Veranstaltungsende:9 Dezember 2005
Veranstalter :American Geophysical Union
HGF - Forschungsbereich:Verkehr und Weltraum (alt)
HGF - Programm:Weltraum (alt)
HGF - Programmthema:W - keine Zuordnung
DLR - Schwerpunkt:Weltraum
DLR - Forschungsgebiet:W - keine Zuordnung
DLR - Teilgebiet (Projekt, Vorhaben):W - keine Zuordnung (alt)
Standort: Berlin-Adlershof
Institute & Einrichtungen:Institut für Planetenforschung
Hinterlegt von: Pieth, Susanne
Hinterlegt am:03 Jan 2006
Letzte Änderung:24 Apr 2024 19:01

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