An improved geometric lunar figure from Chang’E-1 and SELENE laser altimetry

Abstract

This study calibrates the footprint positions of 8.5 million Chang'E-1 and 8.8 million SELENE laser altimetry measurements against accurately known lunar laser reflector locations. The resulting datasets are used to estimate triaxial, biaxial and spherical models of the lunar figure based on the two datasets individually. The equatorial semi-major, minor and polar axes of the Chang'E-1 and SELENE solutions differ by 143 m, 3 m and 49 m respectively. The differences between their geometric centers and the lunar center of mass along the three axes are 186 m, 3 m, and 52 m. The complete laser altimetry datasets from the two missions reveal a lunar figure that is more spherical than previously thought. Furthermore, the Chang'E-1 and SELENE solutions are in better agreement with each other than either is with the ULCN 2005 lunar figure.