Crater Ejecta Across Maxwell Montes, Venus, and Possible Effects on Future Rock Type Measurements

Venus highlands such as Maxwell Montes are an exploration target in the search for a past water-rich environment. We combine Magellan and Arecibo radar data to characterize surface properties across Maxwell for orbital or landed investigations. Arecibo data reveal a region surrounding and west of the 90-km crater Cleopatra with lower radar echoes and circular polarization ratio despite increased surface reflectivity. Modeling of microwave emissivity shows that the surface undergoes step-like reflectivity shifts at similar to 6056.2 km and similar to 6,061 km radius, such that the changes in radar echo between these altitudes are not due solely to dielectric effects. We propose that fine-grained Cleopatra ejecta mantles much of Maxwell Montes, consistent with Venus distal crater ejecta patterns and the longevity of mantling debris in the highlands. Future orbital or landed studies must consider the thickness of ejecta, source material, and effects of shock or melting on ejecta mineralogy.