Surface reflectance of Mars observed by CRISM/MRO: 2. Estimation of surface photometric properties in Gusev Crater and Meridiani Planum

TL;DR

This study introduces a Bayesian inversion method using the Hapke model to accurately estimate Martian surface photometric properties from CRISM multi-angle data, validated against in situ measurements and improving surface reflectance mapping.

Contribution

It presents a novel Bayesian approach for estimating Martian surface photometric parameters from CRISM data, validated against in situ measurements, and demonstrates the superiority of non-Lambertian surface assumptions.

Findings

Validated photometric parameters match in situ measurements.

Non-Lambertian assumptions improve accuracy over Lambertian models.

Method enables future orbital mapping of Martian surface properties.

Abstract

The present article proposes an approach to analyze the photometric properties of the surface materials from multi-angle observations acquired by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on-board the Mars Reconnaissance Orbiter. We estimate photometric parameters using Hapke model in a Bayesian inversion framework. This work also represents a validation of the atmospheric correction provided by the Multi-angle Approach for Retrieval of Surface Reflectance from CRISM Observations (MARS-ReCO) proposed in the companion article.The latter algorithm retrieves photometric curves of surface materials in reflectance units after removing the aerosol contribution. This validation is done by comparing the estimated photometric parameters to those obtained from in situ measurements by Panoramic Camera instrument at the Mars Exploration Rover (MER)-Spirit and MER-Opportunity landing sites. Consistent photometric parameters with those from in situ measurements are found, demonstrating that MARS-ReCO gives access to accurate surface reflectance. Moreover the assumption of a non-Lambertian surface as included in MARS-ReCO is shown to be significantly more precise to estimate surface photometric properties from space in comparison to methods based on a Lambertian surface assumption. In the future, the presented method will allow us to map from orbit the surface bidirectional reflectance and the related photometric parameters in order to characterize the Martian surface.