Flow-field center migration during vertical and oblique impacts

The downrange-directed momentum from an oblique impact affects crater excavation. Ejecta dynamics were measured within growing ejecta curtains for experimental impacts with incidence angles of 90°, 45°, and 30° above horizontal, all impacting at velocities near 1.0 km/s. These ejecta dynamics constrain the horizontal migration of the flow-field center between the impact point and the crater center for three curtain segments (uprange, lateral, and downrange) during oblique impacts and are compared with vertical impacts. At angles as high as 45°, the flow-field center migration occurs throughout a substantial portion of crater growth, thereby demonstrating that impact angle affects crater excavation even at relatively high angles. Stationary point sources are found unable to account for this detailed excavation flow during oblique impacts.