Impact Cratering Experiments Using Lunar Highland Simulant as Target Material

The properties of a target material have long been known to influence the cratering process for relatively small impact events, where the material “strength” is more dominant than the local gravitational force[1]. Strength in granular materials, however, is dependent on the interactions among packing fraction, grain size, and cohesion[2], and can thus vary for the same bulk material at different porosities. Experimentally, this relationship has been demonstrated for the most commonly used target material in impact cratering studies, unconsolidated sand, where [3] observed a notable decrease in depth-diameter ratios(d/D)for more densely packed (higher packing fraction, or lower porosity) targets. In order to extend the applicability, or properly scale, those findings to relatively small lunar craters, for example, a more realistic analog material(in terms of physical properties) should be interrogated for use as a target medium. To this end, we have conducted a series of impact cratering experiments using a lunar-highlands regolith simulant to investigate the relationship between packing fraction and crater morphology/morphometry.