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Measurement Methods for Ganymede's Librations from Laser Altimetry Observations

Steinbrügge, Gregor and Steinke, Teresa and Thor, Robin and Stark, Alexander and Hussmann, Hauke (2019) Measurement Methods for Ganymede's Librations from Laser Altimetry Observations. EPSC-DPS Joint Meeting 2019, 15.-20. Sept. 2019, Genf, Schweiz.

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Official URL: https://meetingorganizer.copernicus.org/EPSC-DPS2019/EPSC-DPS2019-317-2.pdf

Abstract

We investigate the potential for the Ganymede Laser Altimeter (GALA) on board the JUICE (JUpiter ICy moons Explorer) mission to measure the tidal deformations and the rotational state of Ganymede, in particular physical librations. A subsurface ocean would cause the upper ice shell to librate decoupled from its interior. Two distinct iterative least-squares inversion routines have been implemented to estimate simultaneously for the topography, the orientation of the rotation pole, the mean rotation and the libration amplitudes and tidal deformations using synthetic laser altimetry data. We follow the approach of a global expansion of spherical harmonics and as a second method the parametrization in 2D B-splines. Results indicatet hat a global ocean could only be found for a very thin ice shell thickness, if the ice shell is elastic and fully decoupled of the interior. However, to prove the non-existence of an ocean is difficult due to small libration amplitudes and their possibly ambiguous interpretation. In this case independent observations, such as the Love numbers, provide more unique constraints on the interior structure.

Item URL in elib:https://elib.dlr.de/132292/
Document Type:Conference or Workshop Item (Poster)
Title:Measurement Methods for Ganymede's Librations from Laser Altimetry Observations
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Steinbrügge, GregorInstitute for Geophysics, University of Texas at Austin, USAUNSPECIFIED
Steinke, TeresaUniversity of DelftUNSPECIFIED
Thor, RobinMax Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, 37077 Göttingen, GermanyUNSPECIFIED
Stark, Alexanderalexander.stark (at) dlr.dehttps://orcid.org/0000-0001-9110-1138
Hussmann, HaukeHauke.Hussmann (at) dlr.deUNSPECIFIED
Date:2019
Refereed publication:No
Open Access:Yes
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Volume:13
Page Range:p. 317
Series Name:EPSC Abstracts
Status:Published
Keywords:Laser Altimetry, Ganymede, Librations, JUICE
Event Title:EPSC-DPS Joint Meeting 2019
Event Location:Genf, Schweiz
Event Type:international Conference
Event Dates:15.-20. Sept. 2019
Organizer:Europlanet Society
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Science and Exploration
DLR - Research area:Raumfahrt
DLR - Program:R EW - Erforschung des Weltraums
DLR - Research theme (Project):Project JUICE JANUS and GALA
Location: Berlin-Adlershof
Institutes and Institutions:Institute of Planetary Research > Planetary Geodesy
Deposited By: Stark, Alexander
Deposited On:09 Dec 2019 11:18
Last Modified:09 Dec 2019 11:18

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