GRAIL, LLR, and LOLA constraints on the interior structure of the Moon

Isamu Matsuyama (1) , Francis Nimmo (2) , James Keane (1) , Ngai Chan (1) , G. Jeffrey Taylor (3) , Mark Wieczorek (4) , Walter Kiefer (5) , James P. Williams (6)

1 University of Arizona
2 Department of Earth and Planetary Sciences [Santa Cruz]
3 HIGP - Hawaii Institute of Geophysics and Planetology
4 IPGP (UMR_7154) - Institut de Physique du Globe de Paris
5 LPI - Lunar and Planetary Institute [Houston]
6 JPL - Jet Propulsion Laboratory

The interior structure of the Moon is constrained by its mass, moment of inertia, and k 2 and h 2 tidal Love numbers. We infer the likely radius, density, and (elastic limit) rigidity of all interior layers by solving the inverse problem using these observational constraints assuming spherical symmetry. Our results do not favor the presence of a low rigidity transition layer between a liquid outer core and mantle. If a transition layer exists, its rigidity is constrained to 43 +26 −9 GPa, with a preference for the high rigidity values. Therefore, if a transition layer exists, it is more likely to have a rigidity similar to that of the mantle (∼70 GPa). The total (solid and liquid) core mass fraction relative to the lunar mass is constrained to 0.0098 +0.0066 −0.0094 and 0.0198 +0.0026 −0.0049 for interior structures with and without a transition layer, respectively, narrowing the range of possible giant impact formation scenarios.

Domaines: Planétologie

Isamu Matsuyama, Francis Nimmo, James Keane, Ngai Chan, G. Jeffrey Taylor, et al.. GRAIL, LLR, and LOLA constraints on the interior structure of the Moon. Geophysical Research Letters, 2016, 43 (16), pp.8365-8375. ⟨10.1002/2016GL069952⟩. ⟨hal-02458624⟩