Studying the deep structure of rocky celestial body using solid tide

Abstract

As a result of significant advances in geophysics, we have developed a rich arsenal of geophysical methods to infer the internal structure of the Earth. However, the method we could use to infer the internal structure of celestial bodies other than the Earth are still very limited, often relying on geodetic data from orbital probes, landers and astronomical observations. Among these geodetic method, solid tides are of great importance for the study of the celestial bodies' internal structure. Solid tidal deformation and the tidal dissipation provide key information about the internal structure of the rocky celestial bodies, especially the deep structure which contains core-mantle boundary and core. In this paper, we present a comprehensive overview of the research of the deep structure of rocky celestial bodies using solid tidal parameters, including tidal Love numbers and tidal quality factor. First, the basic theory of solid tides, tidal parameters, and viscoelastic models are introduced, and the relationship between the internal structural parameters of the celestial bodies and their solid tidal response is established. This is followed by a review and summary of existing work using solid tide parameters to study the internal structure of the rocky celestial bodies like Mercury, Venus, Mars, and the Moon. Examples include the study of the viscoelastic structure at the base of the lunar mantle using tidal parameters, and the use of tidal parameters to improve the uncertainty of the Martian core radius demonstrate that using solid tidal parameters is an effective method of constraining the deep structure of the celestial bodies. We further provide the contribution of high-precision observations to be acquired by future missions to the study of internal structure. However, there still are some problems in study the internal structure of celestial bodies by solid tidal parameters. For instance, the variability of dissipation strength between different viscoelastic models, the mismatch between short-period experimental data and macroscopic long-period theoretical calculations of viscoelastic models, and so on. We also discuss and analyzes these problems and provides a vision of future research direction.

Keywords

• solid tides
• tidal response
• viscoelasticity
• internal structure
• rocky celestial body