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's 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.

We present a new method exploiting intensity variations of an image by photoclinometry in order to produce a high-quality, large digital elevation model (DEM) from an initial DEM with a lower lateral resolution such as a photogrammetric initial product. The method integrates an intensity model of the image based on a novel radiative transfer scheme and a realistic bidirectional reflectance distribution function (BRDF) model of the surface. Two carefully crafted regularization terms are also introduced ensuring the smoothness of the solution and the consistency with the photogrammetric information at large scales. The regularized inversion of the model based on an efficient numerical optimization scheme allows the method to recover details missing or degraded in the photogrammetrically generated DEMs. In addition, for processing challenging scenes, a coarse-to-fine strategy is put forward. The refined DEMs are validated and carefully characterized by multi-scale analysis. The experiments are performed using images of Mars acquired by the Context Camera (CTX) and the High Resolution Imaging Science Experiment (HiRISE) of the Mars Reconnaissance Orbiter. The method insures a spatial resolution that is comparable to that of the imagery and allows measuring heights with a relative precision down to 15 cm with HiRISE imagery.

We introduce a novel ultra-high-resolution Digital Terrain Model (DTM) processing system using a combination of photogrammetric 3D reconstruction, image co-registration, image super-resolution restoration, shape-from-shading DTM refinement, and 3D co-alignment methods. Technical details of the method are described, and results are demonstrated using a 4 m/pixel Trace Gas Orbiter Colour and Stereo Surface Imaging System (CaSSIS) panchromatic image and an overlapping 6 m/pixel Mars Reconnaissance Orbiter Context Camera (CTX) stereo pair to produce a 1 m/pixel CaSSIS Super-Resolution Restoration (SRR) DTM for different areas over Oxia Planum on Mars—the future ESA ExoMars 2022 Rosalind Franklin rover’s landing site. Quantitative assessments are made using profile measurements and the counting of resolvable craters, in comparison with the publicly available 1 m/pixel High-Resolution Imaging Experiment (HiRISE) DTM. These assessments demonstrate that the final resultant 1 m/pixel CaSSIS DTM from the proposed processing system has achieved comparable and sometimes more detailed 3D reconstruction compared to the overlapping HiRISE DTM.

The evolution of the Ladon basin has been marked by intense geological activity and the discharge of huge volumes of water from the Martian highlands to the lowlands in the late Noachian and Hesperian. We explore the potential of the ExoMars Trace Gas Orbiter/Color and Stereo Surface Imaging System color image data set for geological interpretation and show that it is particularly effective for geologic mapping in combination with other data sets such as HiRISE, Context, and Compact Reconnaissance Imaging Spectrometer for Mars. The study area displays dark lobate flows of upper Hesperian to early Amazonian age, which were likely extruded from a regional extensional fault network. Spectral analysis suggests that these flows and the underlying rocks are ultramafic. Two distinct altered levels are observed below the lobate flows. The upper, yellow‐orange level shows hundreds of structurally controlled narrow ridges reminiscent of ridges of listwanite, a suite of silicified, fracture‐controlled silica‐carbonate rocks derived from an ultramafic source and from serpentine. In addition to serpentinite, the detected mineral assemblages may include chlorite, carbonates, and talc. Kaolin minerals are detected in the lower, white level, which could have formed by groundwater alteration of plagioclase in the volcanic pile. Volcanism, tectonics, hydrothermal activity, and kaolinization are interpreted to be coeval, with hydrothermal activity and kaolinization controlled by the interactions between the aquifer and the hot, ultramafic lobate flows. Following our interpretations, East Ladon may host the first listwanite ridges described on Mars, involving a hydrothermal system rooted in a Hesperian aquifer and affecting ultramafic rocks from a magmatic source yet to be identified.