Viscoelastic Tides of Mercury and the Determination of its Inner Core Size
G. Steinbrügge (Deutsches Zentrum für Luft- und Raumfahrt (DLR), The University of Texas at Austin)
S. Padovan (Deutsches Zentrum für Luft- und Raumfahrt (DLR))
H. Hussmann (Deutsches Zentrum für Luft- und Raumfahrt (DLR))
T. Steinke (TU Delft - Aerospace Engineering)
A. Stark (Deutsches Zentrum für Luft- und Raumfahrt (DLR))
J. Oberst (Deutsches Zentrum für Luft- und Raumfahrt (DLR))
More Info
expand_more
Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons.
Abstract
We computed interior structure models of Mercury and analyzed their viscoelastic tidal response. The models are consistent with MErcury Surface, Space Environment, GEochemistry, and Ranging mission inferences of mean density, mean moment of inertia, moment of inertia of mantle and crust, and tidal Love number k2. Based on these constraints we predict the tidal Love number h2 to be in the range from 0.77 to 0.93. Using an Andrade rheology for the mantle the tidal phase-lag is predicted to be 4° at maximum. The corresponding tidal dissipation in Mercury's silicate mantle induces a surface heat flux smaller than 0.16 mW/m2. We show that, independent of the adopted mantle rheological model, the ratio of the tidal Love numbers h2 and k2 provides a better constraint on the maximum inner core size with respect to other geodetic parameters (e.g., libration amplitude or a single Love number), provided it responds elastically to the solar tide. For inner cores larger than 700 km, and with the expected determination of h2 from the upcoming BepiColombo mission, it may be possible to constrain the size of the inner core. The measurement of the tidal phase-lag with an accuracy better than ≈0.5° would further allow constraining the temperature at the core-mantle boundary for a given grain size and therefore improve our understanding of the physical structure of Mercury's core.