1047
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B4. Beijing 2008
the USGS “geologic” unit map. The minimum noise fraction
(MNF) method is an efficient method to derive noise-free
principle components that can be used to delineate the Martian
geologic units. It is found that the MNF band 1 is mostly related
(positively or negatively) to the albedo (r up to 0.83 - 0.98) of
the hyperspectral imagery, while the MNF bands 2, 3, and 4
contained almost all lithologies information for making an
informative and useful geologic unit map.
The two spectral matching methods (spectral feature fitting and
spectral angle mapper) have different performances in matching
lithologies and minerals. The SFF method especially
emphasizes the overall similarity of positions and depths of
absorption bands for two spectral curves, while the SAM
method emphasizes the overall similarity of the two spectral
curves and does not care much about the position and depth of
absorption bands. Three good examples found in this study are
seen in the Table 2, in which the copiapite and kieserite have
the highest SFF scores (0.90 - 0.93), while the SAM matching
scores for them are very low (0.29 - 0.37). This suggests that
the existence of those two minerals are questionable, even
kieserite was reported in the region by the Gendrin et al. (2005).
But another explanation for the difference is that as mentioned
in,the method section, the unit spectrum used in the study is
actually the spectral average of a small area. So the unit
spectrum is extremely mixed spectral signature which might
good for lithologic unit mapping but not for individual mineral
identification. So the minerals matched using this method are
only for reference only. This also explains that the Unit-2 of
Maridiani Planum area, best matched mineral is not hematite,
but hematite was found widely distributed in the area by the
TES and Opportunity Rover. Overall, the two matching
methods (SFF and SAM) complement each other and should be
always used together. If both give a high score, the matching
results should be much confident than only one high matching
score.
REFERENCES
Arvidson, R. E., F. P. Seelos IV, S. Deal, et al., 2003. Mantled
and exhumed terrains in Terra Meridiani, Mars, J. Geophys.
Res., Vol.l08,No.E12, pp. 14-1 to 14-20.
Bibring, J.P., Combes, M., Langevin, Y., et al., 1989. Results
from the ISM experiment. Nature, Vol.341, pp.591-593.
Bibring, J. P., S. Erard, 2001. The Martian Surface Composition.
Space Science Reviews. Vol.96, pp. 197-230
Bibring, J.P., Langevin, Y., et al. 2005. Mars Surface Diversity
as Revealed by the OMEGA/Mars Express Observations,
Science, Vol.307, pp. 1576-1630.
Bell, J.F., Squyres, S., Arvidson, R.E, et al. 2004. Pancam
Multispectral Imaging Results from the Opportunity Rover at
Meridiani Planum. Science, Vol.306, pp. 1703-1709
Christensen, P.R., Morris, R.V., Lane, M.D., and Bandfiled,
J.L., and Malin, M.C.. 2001.Global mapping of Martian
hematite mineral deposits: remnanets of water-driven processes
on early Mars. Journal of Geophysical Research, Vol. 106, pp.
23, 873-23, 885.
Clark, R. N., A. J. Gallagher, G. A. Swayze, 1990. Material
absorption band depth mapping of imaging spectrometer data
using the complete band shape least-squares algorithm
simultaneously fit to multiple spectral features from multiple
materials. Proceedings of the Third Airborne Visible/Infrared
Imaging Spectrometer (AVIRIS) Workshop. JPL Publication,
Vol. 90-54, pp. 176-186.
Edgett, K.S.. 2005. The sedimentary rocks of Sinus Meridiani:
Five key observations from data acquired by the Mars Global
Surveyor and Mars Odyssey orbiters, Mars, No.l, pp.5-58
Gendrin, A., Mangold, N., et al. 2005. Sulfates in Martian
Layered Terrains: The OMEGA/Mars Express View. Science,
Vol. 307, pp.1587-1591.
Kruse, F. A., Lefkoff, A. B., Boardman, J. B., Heidebrecht, K.
B., Shapiro, A. T., Barloon, P. J., et al. (1993). The spectral
image processing system (SIPS) — Interactive visualization and
analysis of imaging spectrometer data. Remote Sensing of
Environment, Vol.44, pp. 145-163.
Hynek, B.M., Arvidson, R.E., et al. 2002. Geologic setting and
origin of Terra Meridiani hematite deposit on Mars. Journal of
Geophysical Research, Vol. 107, No.ElO, pp. 18-1 to 18-14.
Hynek, B.M.. 2004. Implications for hydrologic processes on
Mars from extensive bedrock outcrops throughout Terra
Meridiani. Nature, Vol.431, pp. 156-159
Maustard, J.F., Poulet, F. et al. 2005. Olivine and Pyroxene
Diversity in the Crust of Mars. Science, Vol.307, pp. 1594-1597.
Squyres, S., Arvidson, R.E et al. 2004.The Opportunity rover’s
Athena Science Investigation at Meridiani Planum, Mars.
Science Vol.306, pp. 1698-1703.
USGS. 1986 and 1987. Geologic map of the eastern, western,
and polar regions of Mars. Available at: http://astrogeology.
usgs.gov/Projects/webgis/.
ACKNOWLEDGEMENTS
The authors would like to thank Yves Langevin, John Mustard,
Joe Zender, and Aline Gendrin for their directions on the
OMEGA data pre-processing and atmospheric corrections.
Special thanks also go to ESA and OMEGA/Mars Express
Science team for acquiring data and making data available to
rest of the world. The first author would like to thank the
Chinese State Scholarship Fund Award (2005-2006) to him to
make this collaborative study possible. The project is supported
by NSFC program “OMEGA/Mars Express Surface Spectra
Retrieve Methods and Mineral Detection (40772200) ”