Profiling Martian Dust Using PIXL Images

<p>The Planetary Instrument of X-ray Lithochemistry (PIXL), onboard the Mars 2020 rover Perseverance, is designed to measure the chemical composition of Martian materials with a spatial resolution of around 100 &#181;m. The surface of Mars is notoriously dusty and even thin layers of dust within the measurement frame will impact the instrument signal, potentially leading to misinterpretation of an underlying chemical composition if not appropriately accounted for. Therefore, knowledge about the dust composition, concentration and distribution is important, both when deciding where to perform measurements and in data analyses.</p><p>Herein we present methods for generating high precision dust profiles of Martian surfaces by utilizing the Optical Fiducial System (OFS) component of the PIXL instrument. The OFS consist of a Micro Context Camera (MCC) and a FloodLight Illuminator (FLI). The MCC captures images with a resolution better than 50 &#181;m/pixel at the instrument&#8217;s nominal distance of 25 mm, directly enabling the optical characterization of dust, and other components, on these surfaces. The FLI is equipped with a total of 24 light emitting diodes (LEDs), in four groups centered at UV (385 nm), Blue (450 nm), Green (530 nm), and NIR (735 nm), enabling multispectral capabilities. This multispectral floodlight capability directly facilitates dust detection by the MCC, and utilizing the precision of the MCC, the spatial distribution of dust is better constrained.</p><p>We present dust profile maps acquired by the PIXL OFS on Martian surfaces and present similar results derived from the rover-mounted calibration targets. In demonstrating the quality of the maps produced, we can improve future scientific analyses while furthermore improving the operational efficiency and data quality of the Perseverance mission through the potential future implementation of a closed-loop autonomous dust-avoidance routine, utilizing the macro capabilities of the PIXL OFS.</p><p>&#160;</p><p>The author recognises the great contribution made by the PIXL Team and the broader Mars 2020 Team.</p>