Lunar interior properties from the GRAIL mission

摘要

The Gravity Recovery and Interior Laboratory (GRAIL) mission has sampled lunar gravity with unprecedented accuracy and resolution. The lunar GM, the product of the gravitational constant G and the mass M, is very well determined. However, uncertainties in the mass and mean density, 3345.56 ± 0.40 kg/m~3, are limited by the accuracy of G. Values of the spherical harmonic degree-2 gravity coefficients J_2 and C_(22), as well as the Love number k_2 describing lunar degree-2 elastic response to tidal forces, come from two independent analyses of the 3month GRAIL Primary Mission data at the Jet Propulsion Laboratory and the Goddard Space Flight Center. The two k_2 determinations, with uncertainties of ~1%, differ by 1%; the average value is 0.02416 ± 0.00022 at a 1month period with reference radius R = 1738 km. Lunar laser ranging (LLR) data analysis determines (C-A)/B and (B-A)/C, where A