A new data reduction approach for the clementine NIR data set: Application to Aristillus, Aristarchus and Kepler

Research areas:
Year:
1999
Authors:
Journal:
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
Volume:
104
Number:
E2
Pages:
3833-3843
Month:
FEB 25
ISSN:
0148-0227
BibTex:
Abstract:
The Clementine spacecraft, launched in January 1994, has performed a
nearly global surface mapping of the moon in eleven broad spectral bands
at a resolution of similar to 200 m. The UV-visible (UV/VIS) camera
performed observations in five bands ranging from 0.415 to 1.0 mu m,
while the near infrared camera (NIR) acquired data in six spectral bands
ranging from 1.1 to 2.78 mu m. UV/VIS images are calibrated to similar
to 4\%. The calibrated NIR data set is yet to be finalized due to
instrumental problems. Independently of the calibration effort for the
full data set which is under the responsibility of the PI team, we
present here the first results of a heuristic approach to extract
mineralogical information from raw images in regions of particular
interest. We processed images of craters Aristillus, Aristarchus, and
Kepler. We computed band ratios using 0.75, 0.9, 0.95, 1.0, 1.1, 1.25,
1.5, and 2.0 mu m images to map the compositional heterogeneity and to
discriminate between pyroxene, olivine, or feldpar rich areas. Absolute
reflectance spectra have been derived using telescopic spectra as ground
truth. High orthopyroxene and clinopyroxene contents have been detected
and spatially mapped on Aristillus. Our results are in good agreement
with previous studies in the case of Aristarchus and show additional
details due to the improved registration. Two regions exhibit spectra
consistent with a high proportion of olivine with <25\% pyroxene. The
rim of Kepler exhibits a strong feature at 2 mu m correlated with the 1
mu m feature, suggesting either a high orthopyroxene content or a very
immature soil. Our method could be of interest for further
investigations of the lunar surface using Clementine NIR data.