Lunar interior properties from the GRAIL mission

摘要

abstract_textpThe 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 3 month GRAIL Primary Mission data at the Jet Propulsion Laboratory and the Goddard Space Flight Center. The two k(2) determinations, with uncertainties of similar to 1, differ by 1; the average value is 0.02416 +/- 0.00022 at a 1 month period with reference radius R = 1738 km. Lunar laser ranging (LLR) data analysis determines (C - A)/B and (B - A)/C, where A B C are the principal moments of inertia; the flattening of the fluid outer core; the dissipation at its solid boundaries; and the monthly tidal dissipation Q = 37.5 +/- 4. The moment of inertia computation combines the GRAIL-determined J(2) and C-22 with LLR-derived (C - A)/B and (B - A)/C. The normalized mean moment of inertia of the solid Moon is I-s/MR2 = 0.392728 +/- 0.000012. Matching the density, moment, and Love number, calculated models have a fluid outer core with radius of 200-380 km, a solid inner core with radius of 0-280 km and mass fraction of 0-1, and a deep mantle zone of low seismic shear velocity. The mass fraction of the combined inner and outer core is = 1.5./p/abstract_text