Reflectance study of ice and Mars soil simulant associations -- I. H$_2$O ice

TL;DR

This study investigates how different mixing modes of water ice and dust affect their spectral reflectance, providing criteria to interpret planetary surface spectra, especially for Mars, based on laboratory experiments.

Contribution

It introduces spectral criteria and color analysis methods to distinguish mixing modes of ice and dust in reflectance spectra, aiding planetary surface analysis.

Findings

Frost increases reflectance and flattens spectral slopes.

Presence of water ice affects absorption bands.

Laboratory data aids interpretation of Martian spectra.

Abstract

The reflectance of water ice and dust mixtures depends, amongst other parameters, on how the components are mixed (e.g. intimate mixture, areal mixture or coating) (Clark et al. 1999). Therefore, when inverting the reflectance spectra measured from planetary surfaces to derive the amount of water ice present at the surface, it is critical to distinguish between different mixing modes of ice and dust. However, the distinction between mixing modes from reflectance spectra remains ambiguous. Here we show how to identify some water ice/soil mixing modes from the study of defined spectral criteria and colour analysis of laboratory mixtures. We have recreated ice and dust mixtures and found that the appearance of frost on a surface increases its reflectance and flattens its spectral slopes, whereas the increasing presence of water ice in intimate mixtures mainly impacts the absorption bands. In particular, we provide laboratory data and a spectral analysis to help interpret ice and soil reflectance spectra from the Martian surface.