Lunar interior properties from the GRAIL mission. Issue 7 (14th July 2014)

• Record Type: Journal Article
• Authors: Williams, James G.; Konopliv, Alexander S.; Boggs, Dale H.; Park, Ryan S.; Yuan, Dah‐Ning; Lemoine, Frank G.; Goossens, Sander; Mazarico, Erwan; Nimmo, Francis; Weber, Renee C.; Asmar, Sami W.; Melosh, H. Jay; Neumann, Gregory A.; Phillips, Roger J.; Smith, David E.; Solomon, Sean C.; Watkins, Michael M.; Wieczorek, Mark A.; Andrews‐Hanna, Jeffrey C.; Head, James W.; Kiefer, Walter S.; Matsuyama, Isamu; McGovern, Patrick J.; Taylor, G. Jeffrey; Zuber, Maria T.
• Is Part Of: Journal of geophysical research. Volume 119:Issue 7(2014:Jul.)
• Page Start: 1546
• Page End: 1578
• Publication Date: 2014-07-14
• Subjects: Planets -- Periodicals; Geophysics -- Periodicals; 559.9
• DOI: 10.1002/2013JE004559
• Languages: English
• ISSNs: 2169-9097

Abstract

<abstract abstract-type="main"> <title>Abstract</title> <p>The Gravity Recovery and Interior Laboratory (GRAIL) mission has sampled lunar gravity with unprecedented accuracy and resolution. The lunar <italic>GM</italic>, the product of the gravitational constant <italic>G</italic> and the mass <italic>M</italic>, is very well determined. However, uncertainties in the mass and mean density, 3345.56 ± 0.40 kg/m<sup>3</sup>, are limited by the accuracy of <italic>G</italic>. Values of the spherical harmonic degree‐2 gravity coefficients <italic>J</italic><sub>2</sub> and <italic>C</italic><sub>22</sub>, as well as the Love number <italic>k</italic><sub>2</sub> 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 <italic>k</italic><sub>2</sub> determinations, with uncertainties of ~1%, differ by 1%; the average value is 0.02416 ± 0.00022 at a 1 month period with reference radius <italic>R</italic> = 1738 km. Lunar laser ranging (LLR) data analysis determines (<italic>C</italic> − <italic>A</italic>)/<italic>B</italic> and (<italic>B</italic> − <italic>A</italic>)/<italic>C</italic>, where <italic>A</italic> < <italic>B</italic> < <italic>C</italic> are the principal moments of inertia; the flattening of the fluid outer core; the dissipation at its solid boundaries; and the monthly tidal dissipation <italic>Q</italic> = 37.5 ± 4. The moment of inertia computation combines the GRAIL‐determined <italic>J</italic><sub>2</sub> and <italic>C</italic><sub>22</sub> with LLR‐derived (<italic>C</italic> − <italic>A</italic>)/<italic>B</italic> and (<italic>B</italic> − <italic>A</italic>)/<italic>C</italic>. The normalized mean moment of inertia of the solid Moon is <italic>I<sub>s</sub></italic>/<italic>MR</italic><sup>2</sup> = 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>