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Cover: Top left: Numerical model of an impact into a sandstone target. The simulation is an iSALE model that uses a material model developed and validated in MEMIN for wet and dry porous sandstones. In this simulation, 25% water saturation of the pore space is modeled. Top right: Plan view of an 18 cm diameter impact crater formed in sandstone by a 1 cm steel projectile at 3.4 km/s. (Experiment 3232) Bottom left: A high speed image of an impact of a 1.2 cm iron meteorite at 4.6 km/s into a 50% water-saturated sandstone target (Experiment E3-3384). The image (3.36 microseconds after impact) shows a well-developed ejecta cone that has transitioned into the “ejecta tube,” a phenomenon that may be connected to pressure wave refl ections in the target. (High speed video courtesy of Fraunhofer EMI.) Bottom right: The experimental setup of a cratering experiment at Fraunhofer EMI’s “Space” light gas gun. The photo shows the target chamber after experiment A11-5181. The back of a 20 cm sandstone cube that was saturated with water to 90% is visible. Three different types of ultrasound and pressure sensors are attached to the target’s surfaces that measured the pressure wave of the impact. In the background, an “ejecta catcher”, composed of Vaseline-coated tiles and phenolic foam blocks, shows an imprint of the ejecta cone. (Photograph courtesy of Fraunhofer EMI.)