Momentum Enhancement from a 3 cm Diameter Aluminum Sphere Striking a Small Boulder Assembly at 5.4 km s−1

Abstract

An impact experiment was performed with a target of relevance to the upcoming DART impact. In this experiment, a collection of stones that is similar to a rubble pile was the target, though it was necessary to hold the stones in place (in this case with cement) since the target was hung vertically to perform the experiment. The stones–cement target has a higher density and a lower porosity than expected for Dimorphos, with the density being 2.92 g cm−3. A 3 cm diameter aluminum sphere was launched at a speed of 5.44 km s−1, which is similar to the anticipated 6.1 km s−1 impact speed of DART. The stones–concrete target was completely disassembled by the impact. The target was mounted on a pendulum. The swing of the pendulum was measured and from it the momentum enhancement was measured. Due to possible lateral expansion of debris material, this value is a lower bound on the momentum enhancement that would be imparted to an extended target.