Estimating Aerodynamic Properties of Planetary Surfaces Using Drone Attitude

The operation of aeolian processes on a world depends sensitively on the aerodynamic properties of the world’s surface. Key aerodynamic parameters include the surface roughness and wind shear. Typically, estimating these parameters involves bedecking a >1-meter mast with several, high-frequency anemometers pointing into the wind, then collecting and averaging wind speeds as a function of elevation. Under the right ambient conditions, these wind speeds increase logarithmically with height over a distance set by the roughness length and scaling with the shear velocity. Given the difficulty of erecting such a system, efforts to conduct such experiments on worlds other than Earth have been, not surprisingly, limited. However, the advent of drones for planetary exploration provides a novel and potentially transformative opportunity to conduct multiple, high-altitude wind measurements to constrain aerodynamic properties and further our understanding of extraterrestrial aeolian processes. One obvious impediment to drone-based wind measurements is the prop wash generated by the drone itself. Some recent terrestrial experiments have deployed drone-borne anemometers at the end of long booms (~1-m) to successfully recover wind speeds, but such an approach would, again, face technical obstacles on another world. Because a drone in flight has to compensate for wind drag, in principle, the wind speed and direction is implicitly encoded in the aircraft attitude. Again, recent work has compared anemometry and drone telemetry and shown reasonable success recovering wind speeds. Building on that work, proof-of-concept experiments show that the telemetry from a drone hovered at several altitudes consecutively can provide reasonable estimates of the wind profile and aerodynamic parameters.