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Titan's gravity field and interior structure after Cassini

Durante, Daniele and Hemingway, D. J. and Racioppa, P. and Iess, L. and Stevenson, D. J. (2019) Titan's gravity field and interior structure after Cassini. Icarus, 326 . pp. 123-132. ISSN 0019-1035. doi:10.1016/j.icarus.2019.03.003.

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Since its arrival at Saturn in 2004, Cassini performed nine flybys devoted to the determination of Titan's gravity field and its tidal variations. Here we present an updated gravity solution based on the final data set collected during the gravity-dedicated passes, before Cassini's plunge into Saturn's atmosphere. The data set includes an additional flyby (T110, March 2015, primarily devoted to imaging Titan's north polar lakes) carried out with the low-gain antenna. This flyby was particularly valuable because the closest approach occurred at a high latitude (75°N), over an area not previously sampled. Previously published gravity results (Iess et al., 2012) indicated that Titan is subject to large eccentricity tides in response to the time varying perturbing potential exerted by Saturn. The magnitude of the response quadrupole field, expressed in the tidal Love number k_2, was used to infer the existence of an internal ocean. The new gravity field determination provides an improved estimate of k_2 of about 0.62, accurate to a level of a few percent. The value is higher than the simplest models of Titan suggest and the interpretation is unclear; possibilities include a high density ocean (as high as 1300 kg/m^3), a partially viscous response of the deeper region, or a dynamic contribution to the tidal response. The new solution includes higher degree and order harmonic coefficients (up to 5) and offers an improved map of gravity anomalies. The geoid is poorly correlated with the topography, implying strong compensation. In addition, the updated geoid and its associated uncertainty could be used to refine the gravity-altimetry correlation analysis and for improved interpretation of radar altimetric data.

Item Type:Article
Related URLs:
URLURL TypeDescription
Durante, Daniele0000-0002-7888-3021
Stevenson, D. J.0000-0001-9432-7159
Additional Information:© 2019 Published by Elsevier. Received 16 November 2018, Revised 28 February 2019, Accepted 6 March 2019, Available online 8 March 2019. The work of D.D., P.R., and L.I. has been supported in part by the Italian Space Agency under ASI-INAF contract 2017-10-H.O. D.J.H. was supported in part by the Miller Institute for Basic Research in Science at the University of California, Berkeley.
Group:Astronomy Department
Funding AgencyGrant Number
Agenzia Spaziale Italiana (ASI)2017-10-H.O
Miller Institute for Basic Research in ScienceUNSPECIFIED
Subject Keywords:Geophysics; Orbit determination; Radioscience; Titan interior
Record Number:CaltechAUTHORS:20190308-103045285
Persistent URL:
Official Citation:Daniele Durante, D.J. Hemingway, P. Racioppa, L. Iess, D.J. Stevenson, Titan's gravity field and interior structure after Cassini, Icarus, Volume 326, 2019, Pages 123-132, ISSN 0019-1035, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:93651
Deposited By: George Porter
Deposited On:08 Mar 2019 22:03
Last Modified:16 Nov 2021 16:59

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