Characterization and mapping of surface physical properties of Mars from CRISM multi-angular data: Application to Gusev Crater and Meridiani Planum

Abstract

The analysis of particle physical properties (grain size, shape and internal structure) and its organization (surface porosity, roughness, and grain size distribution) provides information about the geological processes which formed and modified planetary surfaces. CRISM (Compact Reconnaissance Imaging Spectrometer for Mars) multi-angular observations (varied emission angles) allow for the characterization of the surface scattering behavior, which depends on the composition and on the material physical properties such as the grain size, shape, internal structure, and the surface roughness. After an atmospheric correction (compensating mineral aerosol effects) by the Multi-angle Approach for Retrieval of the Surface Reflectance from CRISM Observations (MARS-ReCO), the surface reflectances at different geometries were analyzed by inverting the Hapke photometric model depending on six parameters: single scattering albedo, 2 phase function terms, macroscopic roughness and 2 opposition effects terms. In this work, surface photometric maps are created to observe the spatial variations of surface scattering properties as a function of geological units. Information regarding the single scattering albedo, the particle phase function and the macroscopic roughness are provided at the CRISM spatial resolution (200m/pixel). This article describes the application of this methodology to the data covering the Mars Exploration Rover (MER) landing sites located at Gusev Crater and Meridiani Planum where orbital and in situ observations are available. Complementary orbital observations (e.g., CRISM spectra, THermal EMission Imaging System (THEMIS), High Resolution Imaging Science Experiment, (HiRISE) images) were used for interpreting the modeled Hapke photometric parameters in terms of physical properties which can be used to constrain the geological processes. Available MER in situ observations were used as ground truth to validate the interpretations of the Hapke parameters. Varied scattering properties were observed within a CRISM observation (5x10km) suggesting that the surfaces are controlled by local geological processes (e.g., volcanic resurfacing, aeolian and impact processes) rather than regional or global processes. Results are consistent with the in situ observations, thus validating the approach and the use of photometry for the characterization of Martian surface physical properties.Citation: Fernando, J. et al. (2015), Characterization and mapping of surface physical properties of Mars from CRISM multi-angular data: application to Gusev Crater and Meridiani Planum, Icarus

Wavelength dependence of scattering properties in the VIS–NIR and links with grain-scale physical and compositional properties

“…To quantify the evolution of the photometric behavior of each sample with the wavelength, we used the procedure developed by Fernando et al (2013Fernando et al ( , 2015 using the fast implementation strategy of Schmidt and Fernando (2015). This methodology uses a Bayesian approach to estimate photometric parameters from the Hapke model (Hapke, 1993).…”

“…Helfenstein and Veverka, 1989;Helfenstein et al, 1994Helfenstein et al, , 1996Domingue et al, 2002;Newburn et al, 2003;Hillier et al, 2011) and planets (e.g. Veverka et al, 1988;Johnson et al, 2006a,b;Jehl et al, 2008;Fernando et al, 2013Fernando et al, , 2015 have been studied. These photometric studies are generally performed at one or a couple of wavelengths in the visible and/or very near-IR.…”

Asteroid (21) Lutetia: Disk-resolved photometric analysis of Baetica region

“…Their study has found that w, b, c andθ follow a unimodal distribution around the solution and the parameters can be described with a mean and standard deviation when uncertainties are lower than about 5%. Fernando et al (2015a) state that a phase angles > 90 • and phase angle coverage > 50 • are required to constrain the degeneracy, which is, in fact, satisfied by the OSIRIS data in Baetica region. Since it is not the scope of the work to test once more the validity of the Hapke parameters, we have taken Fernando et al results into consideration when developing our inversion procedure.…”

“…In the case of the Hapke model, the entangling of its parameters, mainly the w, g sca andθ , have been widely criticized for a few decades (Helfenstein and Veverka, 1989). Nevertheless Fernando et al (2013), Fernando et al (2015a) and Schmidt and Fernando (2015) have recently applied a Bayesian inversion to study the probabilistic density function of each Hapke parameter and their degeneracy. Their study has found that w, b, c andθ follow a unimodal distribution around the solution and the parameters can be described with a mean and standard deviation when uncertainties are lower than about 5%.…”

Realistic uncertainties on Hapke model parameters from photometric measurement

“…We test the BRDF observation, sampled 48 times at 2 incidence angles 40 (Jehl et al, 2008;Fernando et al, 2013;Fernando et al, 2015).…”