Disparities Between Geological Interpretations of Visible vs. Thermal-Infrared Airborne Hyperspectral Imagery of Schooner Crater

Introduction: In studies of Mars, detection of carbonates by orbiting spectrometers such as CRISM and TES has been an important focus because specific interpretations of the planet’s history vary with the results. Here we present results of a remote sensing study that uses the first simultaneous airborne measurements of reflective (0.4– 2.4 μm) and emissive (thermal-infrared, 7.5–13 μm) hyperspectral imagery of a Mars analog crater. This wide wavelength coverage is critical because the reflective and emissive wavelength ranges are sensitive to fundamentally different spectral processes, and the differences can cause confusion in interpretations unless they are well understood. For example, there are questions related to carbonate detections in the reflective wavelengths for CRISM [1] and in the emissive wavelengths for TES [2,3]. Here we focus on issues related to detection of carbonates in the different wavelength ranges. Schooner Crater: Craters made by nuclear detonations at the Nevada Test Site (NTS) provide unique test beds for exploration and identification of the geologic materials exposed by small craters [4,5,6,7]. Schooner is part of a series of craters made at the NTS to study excavation effects [8]. Schooner was made in 1968 using a nuclear detonation emplaced at 108 m depth [6,9]. The crater is 260 m diameter and has an apparent depth of 63 m [9]. Schooner has been long recognized as an analog to craters on the moon and Mars [5,6]. Schooner is in layered terrain [9], so it is also an interesting analog to craters in layered terrain on Mars. The NTS craters are particularly valuable because the controlled site access preserved them relatively undisturbed (Fig.1), and for the existing extensive geologic and drilling studies from the original project.