Title of article :
Simultaneous determination of global topography, tidal Love number and libration amplitude of Mercury by laser altimetry
Author/Authors :
Koch، نويسنده , , Christian and Christensen، نويسنده , , Ulrich and Kallenbach، نويسنده , , Reinald، نويسنده ,
Issue Information :
روزنامه با شماره پیاپی سال 2008
Abstract :
Solar tidal forces generate elevation changes of Mercuryʹs surface of the order 1 m within one Hermean year, and solar torques on the non-symmetric permanent mass distribution of the planet cause an uneven rotation of Mercuryʹs surface with a libration amplitude of the order of 40 arcsec. Knowledge of the precise reaction of the planet to tidal forcing, expressed by the Love numbers h 2 and k 2 , as well as accurate knowledge of the amplitude of forced libration Φ lib , puts constraints on the internal structure, for example the state and the size of the core. The MESSENGER and BepiColombo missions to Mercury carry laser altimeters, whose primary goal is to accurately map the topography. Here we investigate if the Love number h 2 and the amplitude of forced libration can be determined together with the static topography of the planet from a global altimetry record. We do this by creating synthetic altimeter data for the nominal orbit of BepiColombo over the nominal mission duration of approximately four Mercury years and inverting them for the static and time-dependent parts of the topography. We assume purely Gaussian noise. We find that it is possible to extract both parameters h 2 and Φ lib with an accuracy of approximately 10%, while the static topography coefficients of a spherical harmonic expansion can be determined simultaneously with an accuracy at the centimetre level. Extraction of the static topography to higher harmonic degrees improves the precision of the measurement of h 2 and Φ lib . The simulation results demonstrate that it seems feasible to test current models on Mercuryʹs interior with sufficient precision using BepiColombo Laser Altimeter data.
Keywords :
Tidal Love number , BepiColombo , Long-wavelength topography , Forced libration amplitude , mercury , Spherical harmonic expansion
Journal title :
PLANETARY AND SPACE SCIENCE
Journal title :
PLANETARY AND SPACE SCIENCE