Sebastiano Padovan¹, Jean-Luc Margot^1,2, Steven A. Hauck II³, William B. Moore^4,5 and Sean C. Solomon^6,7

¹Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, California, USA
²Department of Physics and Astronomy, University of California, Los Angeles, California, USA
³Department of Earth, Environmental, and Planetary Sciences, Case Western Reserve University, Cleveland, Ohio, USA
⁴Department of Atmospheric and Planetary Sciences, Hampton University, Hampton, Virginia, USA
⁵National Institute of Aerospace, Hampton, Virginia, USA
⁶Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York, USA
⁷Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, District of Columbia, USA

The combination of the radio tracking of the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft and Earth-based radar measurements of the planet’s spin state gives three fundamental quantities for the determination of the interior structure of Mercury: mean density ρ, moment of inertia C, and moment of inertia of the outer solid shell C_m. This work focuses on the additional information that can be gained by a determination of the change in gravitational potential due to planetary tides, as parameterized by the tidal potential Love number k₂. We investigate the tidal response for sets of interior models that are compatible with the available constraints (ρ, C, and C_m). We show that the tidal response correlates with the size of the liquid core and the mean density of material below the outer solid shell and that it is affected by the rheology of the outer solid shell of the planet, which depends on its temperature and mineralogy. For a mantle grain size of 1 cm, we calculate that the tidal k₂ of Mercury is in the range 0.45 to 0.52. Some of the current models for the interior structure of Mercury are compatible with the existence of a solid FeS layer at the top of the core. Such a layer, if present, would increase the tidal response of the planet.

Reference
Padovan S, Jean-Luc Margot J-L, Hauck II SA, Moore WB and Sean C. Solomon SC (in press) The tides of Mercury and possible implications for its interior structure. Journal of Geophysical Research: Planets
[doi:10.1002/2013JE004459]
Published by arrangement with John Wiley & Sons

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