Lunar interior properties from the GRAIL mission

James G. Williams, Alexander S. Konopliv, Dale H. Boggs, Ryan S. Park, Dah Ning Yuan, Frank G. Lemoine, Sander Goossens, Erwan Mazarico, Francis Nimmo, Renee C. Weber, Sami W. Asmar, H. Jay Melosh, Gregory A. Neumann, Roger J. Phillips, David E. Smith, Sean C. Solomon, Michael M. Watkins, Mark A. Wieczorek, Jeffrey C. Andrews-Hanna, James W. HeadWalter S. Kiefer, Isamu Matsuyama, Patrick J. McGovern, G. Jeffrey Taylor, Maria T. Zuber

Research output: Contribution to journalArticle

104 Scopus citations

Abstract

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±0.40kg/ m3, are limited by the accuracy of G. Values of the spherical harmonic degree-2 gravity coefficients J2 and C22, as well as the Love number k2 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 k2 determinations, with uncertainties of ~1%, differ by 1%; the average value is 0.02416±0.00022 at a 1month period with reference radius R=1738km. 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 J2 and C22 with LLR-derived (C-A)/B and (B-A)/C. The normalized mean moment of inertia of the solid Moon is Is/MR2=0.392728±0.000012. Matching the density, moment, and Love number, calculated models have a fluid outer core with radius of 200-380km, a solid inner core with radius of 0-280km 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%. Key Points The uncertainty in the lunar Love number is improved by a factor of 5 The moment of inertia of the solid Moon is improved by an order of magnitude Models fit a fluid outer and solid inner core plus low Q in the lower mantle

Original languageEnglish (US)
Pages (from-to)1546-1578
Number of pages33
JournalJournal of Geophysical Research: Planets
Volume119
Issue number7
DOIs
StatePublished - Jul 2014

Keywords

  • GRAIL
  • Moon
  • core
  • gravity field
  • lunar laser ranging (LLR)
  • tides

ASJC Scopus subject areas

  • Geophysics
  • Forestry
  • Oceanography
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Palaeontology

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  • Cite this

    Williams, J. G., Konopliv, A. S., Boggs, D. H., Park, R. S., Yuan, D. N., Lemoine, F. G., Goossens, S., Mazarico, E., Nimmo, F., Weber, R. C., Asmar, S. W., Jay Melosh, H., Neumann, G. A., Phillips, R. J., Smith, D. E., Solomon, S. C., Watkins, M. M., Wieczorek, M. A., Andrews-Hanna, J. C., ... Zuber, M. T. (2014). Lunar interior properties from the GRAIL mission. Journal of Geophysical Research: Planets, 119(7), 1546-1578. https://doi.org/10.1002/2013JE004559