Open AccessVariations in the abundances of potassium and thorium on the surface of Mercury: Results from the MESSENGER Gamma‐Ray Spectrometer
Author(s) -
Peplowski Patrick N.,
Lawrence David J.,
Rhodes Edgar A.,
Sprague Ann L.,
McCoy Timothy J.,
Denevi Brett W.,
Evans Larry G.,
Head James W.,
Nittler Larry R.,
Solomon Sean C.,
StockstillCahill Karen R.,
Weider Shoshana Z.
Publication year - 2012
Publication title -
journal of geophysical research: planets
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2012je004141
Subject(s) - exosphere , mercury (programming language) , northern hemisphere , thorium , spectrometer , planet , abundance (ecology) , imaging spectrometer , astrophysics , physics , atmospheric sciences , analytical chemistry (journal) , chemistry , environmental chemistry , uranium , optics , ecology , nuclear physics , ion , quantum mechanics , computer science , biology , programming language
A technique for converting gamma‐ray count rates measured by the Gamma‐Ray Spectrometer on the MESSENGER spacecraft to spatially resolved maps of the gamma‐ray emission from the surface of Mercury is utilized to map the surface distributions of the elements Si, O, and K over the planet's northern hemisphere. Conversion of the K gamma‐ray count rates to elemental abundances on the surface reveals variations from 300 to 2400 ppm. A comparison of these abundances with models for the maximum surface temperature suggests the possibility that a temperature‐related process is controlling the K abundances on the surface as well as providing K to the exosphere. The abundances of K and Th have been determined for several geologically distinct regions, including Mercury's northern smooth plains and the plains interior to the Caloris basin. The lack of a significant variation in the measured Th abundances suggests that there may be considerable variability in the K/Th abundance ratio over the mapped regions.