Ejecta entrainment by impact-generated ring vortices: Theory and experiments

Laboratory experiments indicate that an advancing ejecta curtain displaces the atmosphere and creates strong winds that entrain large amounts of fine-grained ejecta. A theoretical model describing the interaction between an atmosphere and the outward moving ejecta curtain allows one to estimate the magnitude and velocity of the winds in the induced ring vortex in order to establish the importance of such winds at planetary scales. Model estimates for the initial magnitude of the flow within the basal vortex match experimental results within observational uncertainty and reveal that the flow in the ring vortex is turbulent. Successful comparisons of the vortex generation model with experiments allow preliminary applications to be made at much broader scales. Curtain generated winds by a 30-km-diameter crater should entrain ejecta particle diameters smaller than 5 mm on Mars, 30 cm on Earth, and 8 m on Venus.