Mapping of Spectral Variations on the Surface of Mars from High Spectral Resolution Telescopic Images

Abstract

We analyze a high spectral resolution (R≃ 200) visible and near infrared (0.44–1.02 μm) telescopic spectral image of Mars to explore surface material variations across the observed face of the planet, which is centered on Sinus Meridiani. Two independent analysis methods are employed, linear mixture modeling and supervised spectral pattern classification with an artificial neural network. Four endmember type regions are identified with linear mixing. Further refinement is achieved with the nonlinear neural network classification algorithm, separating eight units of geological significance. Differences in spectral features among the mapped units are characterized. Among the medium- to high-albedo units northern lowlands typified by Chryse Planitia show far less evidence of bulk crystalline hematite than western Arabia or any other highland regions. The relationship of these bright units to the globally distributed aeolian dust is not yet clear. Within our image, low-albedo regions with the most pronounced crystalline hematite signature primarily correlate with the classic “dark regions,” with the exception of Acidalia Planitia. Spectral evidence for pyroxenes also correlates well with most of the classic low albedo regions, but again, Acidalia Planitia is the major exception. Significant spectral anomaly is also found in an equatorial region, Deucalionis Regio. A companion paper in this issue discusses the soil properties of Deucalionis. Our data and analysis support a compositional trend that is consistent with the global geologic crustal dichotomy of Mars, namely that the younger northern lowlands contain less bulk crystalline hematite than southern highlands.