Lunar farside Th distribution measured by Kaguya gamma-ray spectrometer

Abstract Kaguya gamma-ray spectrometer measured thorium (Th) distribution on the lunar farside with the highest sensitivity among past gamma-ray remote sensing missions. The newly obtained Th map has revealed that two regions near the equator on the farside have the lowest Th abundances. We found that the variation of the Th abundance perfectly correlates with the crustal thickness in the farside and the southern nearside, and it could be a result of the crystallization of the lunar magma ocean.

[1]  L. Haskin.  The Imbrium impact event and the thorium distribution at the lunar highlands surface , 1998 .

[2]  R. Reedy,et al.  Some correlations between measurements by the Apollo gamma-ray spectrometer and other lunar observations , 1973 .

[3]  M. Ohtake,et al.  Magnesian anorthosites and a deep crustal rock from the farside crust of the moon , 2006 .

[4]  Meng‐Hua Zhu,et al.  Chang’E-1 gamma ray spectrometer and preliminary radioactive results on the lunar surface , 2010 .

[5]  J. J. Gillis,et al.  Major lunar crustal terranes: Surface expressions and crust‐mantle origins , 1999 .

[6]  Thomas H. Prettyman,et al.  Thorium abundances on the lunar surface , 2000 .

[7]  Masanori Kobayashi,et al.  Gamma-ray spectrometer (GRS) for lunar polar orbiter SELENE , 2008 .

[8]  Matthew E. Pritchard,et al.  The Constitution and Structure of the Lunar Interior , 2006 .

[9]  J. Longhi.  Pyroxene stability and the composition of the lunar magma ocean. , 1978 .

[10]  R. Korotev.  Concentrations of radioactive elements in lunar materials , 1998 .

[11]  L. Taylor,et al.  Constraints on the genesis and evolution of the Moon's magma ocean and derivative cumulate sources as supported by lunar meteorites , 1993 .

[12]  J. Papike,et al.  INVITED REVIEW. Magmatic evolution of the Moon , 1999 .

[13]  S. Maurice,et al.  Small‐area thorium features on the lunar surface , 2003 .

[14]  Hiroshi Araki,et al.  Crustal thickness of the Moon: Implications for farside basin structures , 2009 .

[15]  Gregory W. Corder,et al.  Nonparametric Statistics for Non-Statisticians: A Step-by-Step Approach , 2009 .

[16]  Manabu Kato,et al.  The Kaguya Mission Overview , 2010 .

[17]  M. Wieczorek,et al.  Structure and Formation of the Lunar Farside Highlands , 2010, Science.

[18]  E. Asphaug,et al.  Forming the lunar farside highlands by accretion of a companion moon , 2011, Nature.

[19]  Paul G. Lucey,et al.  Iron abundances on the lunar surface as measured by the Lunar Prospector gamma‐ray and neutron spectrometers , 2002 .

[20]  T. Takano,et al.  Farside Gravity Field of the Moon from Four-Way Doppler Measurements of SELENE (Kaguya) , 2009, Science.

[21]  R. Radocinski,et al.  Thorium concentrations in the lunar surface. I - Regional values and crustal content , 1977 .

[22]  Gordon R. Gilmore,et al.  Practical Gamma‐ray Spectrometry , 1995 .

[23]  S. Kobayashi,et al.  Determining the Absolute Abundances of Natural Radioactive Elements on the Lunar Surface by the Kaguya Gamma-ray Spectrometer , 2010 .

[24]  J. Oberst,et al.  Lunar Global Shape and Polar Topography Derived from Kaguya-LALT Laser Altimetry , 2009, Science.

[25]  S. Maurice,et al.  Global elemental maps of the moon: the Lunar Prospector gamma-Ray spectrometer. , 1998, Science.

[26]  Masanori Kobayashi,et al.  First Results of High Performance Ge Gamma-Ray Spectrometer Onboard Lunar Orbiter SELENE (KAGUYA) , 2009 .