Tidal Deformation of Mercury from Co-registration of Laser Altimeter Profiles and Implications for the Interior Structure of the Planet

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We focus on the radial deformation of planet Mercury, in its response to tidal forces exerted by the Sun. We will re-analyze altimeter profiles obtained by the MLA (Mercury Laser Altimeter) instrument on the MESSENGER spacecraft using new techniques of co-registration analysis that also includes a post-correction procedure based on pseudo cross-overs, which we have developed earlier for other applications and which we demonstrated successfully. Initially, we will create hemispheric maps of temporal and spatial patterns of the tidal deformation. Then, we will specifically measure the amplitude of the tidal parameter h2 which is a measure for the radial tidal deformation, including its associated errors. Next, we will create synthetic data of observations by the Laser Altimeter BELA on the upcoming BepiColombo mission. Using the same analysis techniques, we will investigate how measurements of h2 will be improved to achieve smaller error bounds. Also, the simulations will be studied for the instrument’s ability to measure the phase lag of the tidal bulge as well as the dependence of tidal bulge amplitudes on spectral components of the frequency dependent tidal forcing. Our measurements of h2 and expected improvements from BepiColombo, also including refined determination of the tidal potential Love number k2 and its phase lag from radio science experiments, will be used to discuss new bounds of interior structure parameters of the planet (e.g., size and physical state of the core, mantle rheology, temperatures at core/mantle boundary), which will greatly improve our understanding of Mercury’s thermal evolution and the workings of the magnetic dynamo.