We are thrilled to finally be able to share with our colleagues and the public a look at the first set of data that our Moon Mineralogy Mapper (M3) instrument collected!  M3’s first look at the Moon occurred on November 22, 2008 when we acquired some new data for the Orientale Basin.

The first image is a “context” image, whose purpose is to allow you to get a feel for where on the Moon the long, narrow M3 data strips are located.  It shows part of one orbit of Moon Mineralogy Mapper (M3) data superimposed on Lunar Aeronautical Chart (LAC) 108.  This LAC sheet covers the southern portion of the Orientale Basin, a large impact structure on the Moon’s western limb. North is up. Major geological features in this orbit of M3 data include basaltic materials in the basin center, impact melt related to basin formation, Orientale basin massifs (mountains), and dark pyroclastic volcanic materials in the south. The LAC sheet background image is the 750 nm Clementine UVVIS basemap.  The M3 strip is 40 km wide, and was acquired in the instrument’s lower-resolution mode at a spatial resolution of 140 m/pixel.  The blue box identifies the subset region shown in later figures.

This second image is a subset of a longer M3 “image-cube” acquired across the Oriental Basin. To create this image using a two-dimensional detector, one line of spatial information (40 km in width with 300 elements) is acquired simultaneously with all channels in the spectral dimension. As the Chandrayaan-1 spacecraft moves along an orbit from pole to pole, the second dimension of spatial information is obtained line by line forming the image shown. A full spectrum from 420 to 3000 nm is thus acquired for every spatial element within the scene ( altogether 182,000 spectra for this subset!). These M3 low-resolution data consist of 86 spectral channels continuously spaced from 420 to 2980 nm. Example spectra for four small areas are shown in the next image. The areas are located just to the left of the numbers in the figure above which correspond to the spectra labeled in the next image.

Our third image (really a figure) is a plot that shows some example visible to near-infrared spectra extracted from the M3 subset across the Orientale Basin. Number labels refer to the location of each spectrum in the previous image. Prominent absorption features (arrows) are seen near 1000 and 2000 nm for the two small craters #2 and #4. These spectral features are due to iron-bearing pyroxene at those locations. Subtle differences between the shape and wavelength of these pyroxene features indicate differences in pyroxene composition associated with magnesium, calcium, and iron content. Most lunar soil spectra, such as spectrum #3, have very weak absorption features, but exhibit an overall trend in which reflectance increases toward longer wavelengths (we call this trend a red-sloped continuum). Spectrum #1 exhibits no evidence for the presence of iron-bearing minerals but is very bright. This mountain, and several like it in this scene, is composed almost entirely of the mineral plagioclase forming a rock called anorthosite. The presence of anorthosite plays a central role in the early “magma ocean” formation of the lunar crust.

Finally, we have a set of three images of the subset of M3 data for the Orientale region. These images contain 300 spatial elements (pixels) across the 40 km field of view, providing 140 m resolution. On the left is one spectral band at 750 nm in which the signal is entirely reflected solar light. The middle figure is a color composite of processed data that accentuates compositional differences. The blue to red colors represent the slope of the lunar continuum in the near-infrared. The green color is an indication of the abundance of iron-bearing minerals such as pyroxene ( as measured by an integrated band depth derived from 26 channels of continuum removed data between 790 and 1290 nm). The image on the right is a single M3 spectral band at 2940 nm. This image contains significant thermal emission in the signal and is particularly sensitive to small variations in local morphology.  These new data provide mineralogical constraints on geologic processes that occur within the Orientale Basin. The dark mare region in the north-east part of the image contains the greatest abundance of iron-rich minerals and is basaltic in composition.  Although a few small areas of iron-bearing minerals occur within the impact melt formed by the basin impact (seen along the left and bottom of the image), this material is very plagioclase rich, and several mountains and blocks are essentially pure anorthosite.

Please check back to this site for updates!  New results will be released periodically!