Volume 633, January 2020
|Number of page(s)||8|
|Section||Planets and planetary systems|
|Published online||15 January 2020|
Prospects for measuring Mercury’s tidal Love number h2 with the BepiColombo Laser Altimeter
1 Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
2 Technische Universität Berlin, Institute of Geodesy and Geoinformation Science, Straße des 17, Juni 135, 10623 Berlin, Germany
3 DLR Institute of Planetary Research, Rutherfordstraße 2, 12489 Berlin, Germany
4 Department of Geophysics, Stanford University, 397 Panama Mall, Stanford, CA 94305, USA
5 Department of Mechanical and Aerospace Engineering, Sapienza University of Rome, Via Eudossiana, 18, 00184 Roma, RM, Italy
Accepted: 13 December 2019
Context. The Love number h2 describes the radial tidal displacements of Mercury’s surface and allows constraints to be set on the inner core size when combined with the potential Love number k2. Knowledge of Mercury’s inner core size is fundamental to gaining insights into the planet’s thermal evolution and dynamo working principle. The BepiColombo Laser Altimeter (BELA) is currently cruising to Mercury as part of the BepiColombo mission and once it is in orbit around Mercury, it will acquire precise measurements of the planet’s surface topography, potentially including variability that is due to tidal deformation.
Aims. We use synthetic measurements acquired using BELA to assess how accurately Mercury’s tidal Love number h2 can be determined by laser altimetry.
Methods. We generated realistic, synthetic BELA measurements, including instrument performance, orbit determination, as well as uncertainties in spacecraft attitude and Mercury’s libration. We then retrieved Mercury’s h2 and global topography from the synthetic data through a joint inversion.
Results. Our results suggest that h2 can be determined with an absolute accuracy of ± 0.012, enabling a determination of Mercury’s inner core size to ± 150 km given the inner core is sufficiently large (>800 km). We also show that the uncertainty of h2 depends strongly on the assumed scaling behavior of the topography at small scales and on the periodic misalignment of the instrument.
Key words: planets and satellites: individual: Mercury / planets and satellites: interiors / planets and satellites: surfaces
© R. N. Thor et al. 2020
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Open Access funding provided by Max Planck Society.
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