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Mercury's low‐degree geoid and topography controlled by insolation‐driven elastic deformation
Author(s) -
Tosi N.,
Čadek O.,
Běhounková M.,
Káňová M.,
Plesa A.C.,
Grott M.,
Breuer D.,
Padovan S.,
Wieczorek M. A.
Publication year - 2015
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2015gl065314
Subject(s) - geoid , geology , lithosphere , mercury (programming language) , geophysics , mantle (geology) , spherical harmonics , hydrostatic equilibrium , perturbation (astronomy) , geodesy , thermal , physics , seismology , tectonics , meteorology , computer science , programming language , measured depth , quantum mechanics
Mercury experiences an uneven insolation that leads to significant latitudinal and longitudinal variations of its surface temperature. These variations, which are predominantly of spherical harmonic degrees 2 and 4, propagate to depth, imposing a long‐wavelength thermal perturbation throughout the mantle. We computed the accompanying density distribution and used it to calculate the mechanical and gravitational response of a spherical elastic shell overlying a quasi‐hydrostatic mantle. We then compared the resulting geoid and surface deformation at degrees 2 and 4 with Mercury's geoid and topography derived from the MErcury, Surface, Space ENvironment, GEochemistry, and Ranging spacecraft. More than 95% of the data can be accounted for if the thickness of the elastic lithosphere were between 110 and 180 km when the thermal anomaly was imposed. The obtained elastic thickness implies that Mercury became locked into its present 3:2 spin orbit resonance later than about 1 Gyr after planetary formation.