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A Multispectral Micro-Imager for Lunar Field GeologyField geologists routinely assign rocks to one of three basic petrogenetic categories (igneous, sedimentary or metamorphic) based on microtextural and mineralogical information acquired with a simple magnifying lens. Indeed, such observations often comprise the core of interpretations of geological processes and history. The Multispectral Microscopic Imager (MMI) uses multi-wavelength, light-emitting diodes (LEDs) and a substrate-removed InGaAs focal-plane array to create multispectral, microscale reflectance images of geological samples (FOV 32 X 40 mm). Each pixel (62.5 microns) of an image is comprised of 21 spectral bands that extend from 470 to 1750 nm, enabling the discrimination of a wide variety of rock-forming minerals, especially Fe-bearing phases. MMI images provide crucial context information for in situ robotic analyses using other onboard analytical instruments (e.g. XRD), or for the selection of return samples for analysis in terrestrial labs. To further assess the value of the MMI as a tool for lunar exploration, we used a field-portable, tripod-mounted version of the MMI to image a variety of Apollo samples housed at the Lunar Experiment Laboratory, NASA s Johnson Space Center. MMI images faithfully resolved the microtextural features of samples, while the application of ENVI-based spectral end member mapping methods revealed the distribution of Fe-bearing mineral phases (olivine, pyroxene and magnetite), along with plagioclase feldspars within samples. Samples included a broad range of lithologies and grain sizes. Our MMI-based petrogenetic interpretations compared favorably with thin section-based descriptions published in the Lunar Sample Compendium, revealing the value of MMI images for astronaut and rover-mediated lunar exploration.
Document ID
20090023412
Document Type
Conference Paper
Authors
Nunez, Jorge (Arizona State Univ. Tempe, AZ, United States)
Farmer, Jack (Arizona State Univ. Tempe, AZ, United States)
Sellar, Glenn (Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Allen, Carlton (NASA Johnson Space Center Houston, TX, United States)
Date Acquired
August 24, 2013
Publication Date
January 1, 2009
Subject Category
Geophysics
Report/Patent Number
JSC-CN-18454
Meeting Information
Lunar Science Forum(Moffett Field, CA)
Distribution Limits
Public
Copyright
Other