Mars: Interpretation of spectral reflectivity of light and dark regions

Abstract

New spectral reflectivity curves for the light and dark areas of Mars and for seasonal changes of the dark regions were modeled in the laboratory. Light areas are more oxidized and are probably composed of finer particles than the dark areas. Curves for both regions indicate a combination of ferric iron oxide and mafic silicate rock such as basalt. Seasonal changes in the spectral reflectivity of Syrtis Major are not compatible with wind transport of materials or with surface chemical changes. Models of local seasonal condensation of ice or moisture or of growth of macroscopic very dark gray vegetation satisfy the spectral data.

Multiple techniques for mineral identification on Mars:

“…This lab study is only a beginning; these studies need to be performed on a broader range of samples in the lab and in the field. Remote sensing of Mars has included thermal-IR spectrometers on the Mariner missions (Hanel et al, 1972;Pimentel et al, 1974), the TES on Mars Global Surveyor (Christensen et al, 2001b) and THEMIS on Mars Odyssey (Christensen et al, 2003), as well as VNIR telescopic and orbiter measurements (Adams and McCord, 1969;McCord et al, 1982;Bell et al, 1990;Bibring et al, 1990;Erard et al, 1991;Murchie et al, 2000). Typically these datasets have been analyzed in isolation because of the lack of correlated lab and field studies and because of the lack of spatial overlap on Mars.…”

Near-Infrared Spectral Variations of Martian Surface Materials from ISM Imaging Spectrometer Data

“…Its strong UV absorption edge and weak absorptions near 0.53, 0.66, and 0.86 µm are well fit by ferric oxides, occurring mostly in nanophase form with a small amount of a crystalline ferric phase. The crystalline phase is widely thought to be hematite (Adams and McCord 1969, McCord et al 1977, 1982, Singer et al 1979, Morris et al 1989, Bell et al 1990, Bell 1992. At near-infrared (NIR) wavelengths, a strong absorption at 3 µm shows that some molecular water is present, probably bound as mineral hydrates (Moroz 1964, Houck et al 1973, Pimental et al 1974.…”

Searching for the source regions of martian meteorites using MGS TES: Integrating martian meteorites into the global distribution of igneous materials on Mars

“…Early visible and near-infrared reflectance spectra from telescopic observations of martian dark (albedo <~0.24) regions showed ~1.0 and 2.0 µm absorption features interpreted to indicate the presence of mafic mineralogies (e.g., Adams and McCord 1969;Singer 1980;Singer and McSween 1993). More recent data collected by the Imaging Spectrometer for Mars (ISM) experiment aboard the Soviet Phobos 2 spacecraft are consistent with these earlier interpretations, identifying a pyroxene component (Bibring et al 1990;Mustard et al 1993), specifically, a combination of high-and low-calcium pyroxene (likely augite and pigeonite [Mustard and Sunshine 1995]).…”