Momentum enhancement in hypervelocity impact

Momentum enhancement is the increase in momentum transferred to a target due to ejecta material being thrown backwards during crater formation. Quantitative estimates of momentum enhancement are of interest in determining the effectiveness of hypervelocity impactors in deflecting potentially hazardous cosmic objects. This paper explores the influence of impactor density and shape on momentum enhancement when striking aluminum, rock, and ice for impacts up to 10 km/s. Computations are performed and compared to the relatively sparse available data for validation. The computations show that momentum enhancement is most sensitive to the tensile fracture stress of the target material. Further, it is shown that for consolidated (low porosity) targets, momentum enhancement is maximized when the density of the impactor is similar to that of the target and the shape of the impactor is close to a sphere.