Georeferenced Lunar Prospector maps


USGS Map-a-Planet provides maps and tables of elemental abundances at the surface of the Moon derived from data collected by the Lunar Prospector mission. This data is low-resolution, ranging from 5 degrees/solid-color pixel (the "5d" images) to 1/2 degree/pixel (the "hd" images: that's half-degree, not high definition) for Th and Fe, but nevertheless contains an enormous amount of information about the global geology and geochemistry of the Moon.

Map-a-Planet provides .jpgs made from this data. Here's a map showing the abundance of thorium at the surface of the the Moon. I georeferenced these .jpgs in ArcGIS and overlaid them on Google Moon. Below, I've made available for download 1) a file geodatabase with these georeferenced elemental abundance maps and a high-resolution Moon basemap derived from Clementine data and 2) a .kmz file containing all these maps as image overlays for Google Earth's Moon view--try making the maps semi-transparent and see how lunar features match up to elemental abundances. Full disclosure: the USGS cautions that these .jpgs are "not a science product". I figure this is because there are prominent compression artifacts in the 5d maps, so that the 5-degree solid-color pixels aren't really solid-color, and because resolution in elemental abundance is lost when the table gets binned into an 8-bit jpeg. So be careful if you're using these to do anything important!

File geodatabase containing Lunar Prospector elemental abundance maps Google Earth .kmz file containing Lunar Prospector elemental abundance maps

Here's an example of what you can do with this data. I used ArcGIS to map high-Th regions on the surface of the Moon. (I considered high-Th regions to be half-degree pixels with 15 to 20.284 ppm Th, where 20.284 is the max ppm Th measured.

High-Th regions on the near side of the Moon

Map of half-degree pixels with 15-20.284 ppm Th on the near side of the Moon

High-Th regions on the far side of the Moon

Map of half-degree pixels with 15-20.284 ppm Th on the far side of the Moon

There's a profound asymmetry: high-Th regions are all on the near side of the Moon, and concentrated in the lunar region called Oceanus Procellarum. Th is a rare earth element and behaves geochemically like other rare earth elements, so we can use it as a tracer for the lunar geochemical component KREEP. Why there so much KREEP at the surface of Oceanus Procellarum? Th is radioactive and its decay produces heat, which is a driver for igneous processes. Could this be related to the lava flows on the floor of Procellarum? This Th anomaly lead Bradley Joliff to describe the Moon globally in terms of three terranes--one being the Procellarum KREEP Terrane, this Th-rich region--rather than traditionally, in terms of two regions, mare basalt and ancient anorthosite. See http://www.psrd.hawaii.edu/Aug00/newMoon.html for more info, and try looking at the Lunar Prospector data yourself.


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Will Vaughan. Last revision January 23, 2010.