Improving Venus Digital Elevation Map Absolute Accuracy Using 3D Localization of Ground Control Features

The Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy (VERITAS) mission is designed to produce the first Digital Elevation Map (DEM) of another planet using bi-static Synthetic Aperture Radar (SAR). To achieve its scientific goals, the DEM is required to reach 300 m posting and 10 m vertical accuracy. While these metrics are routinely surpassed in Earth observation projects, spacecraft orbit uncertainties and atmospheric influences make the Venus case more challenging. As an alternative to reference stations not available on the surface of Venus, naturally-occurring radar-bright features have been proposed to provide additional constraints for the absolute referencing of DEM and orbit calibration. In this study, we present simulation results of localizing such Ground Control Features (GCFs) in 3D under noisy conditions similar to the ones expected from VERITAS. We also consider the influence of spatiotemporally-variable atmospheric delays affecting the radar measurements in X-band (the frequency applied by the VERITAS SAR instrument). Finally, we discuss the potential of 3D GCF localization to provide the necessary constraints to achieve the DEM vertical accuracy requirements as determined by the mission.