Geochemical mapping by spacecraft

Orbital geochemical analyses since the Apollo and Luna sample return missions have revolutionized our understanding of the composition of the crust and mantle. As an example, 

Lunar global iron content (Clementine data) 

Average lunar 1 highlands meteorites Average Apollo highlands rocks 

Distribution of iron on the lunar surface, as measured by the Clementine spacecraft, compared with the average iron contents (arrows) of Apollo highlands crustal rocks and lunar highlands meteorites. The meteorites, which presumably come from the nearside and farside, more closely match the global iron peak. The compositional ranges for various lunar rock types are shown as horizontal bars. 

Lunar prospector measurements of Al203 and magnesium number, Mg/(Mg+Fe) (black circles). These compositions are consistent with those of major lunar rock types from the Apollo collection (boxes). Modified from Prettyman et al. (2006). 

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