Sampling a planetary surface with a pyrotechnic rock chipper

We present experiments carried out with a lightweight, recoilless rock chipper, deployable for sample generation and collection on planetary surfaces. We study the cratering efficiency, penetration and fragmentation performance of the chipper over impact velocities between 80 and 125 m/s, a range which is not typically investigated in cratering experiments. This range of velocities was chosen because chemical alteration of the rock by shock processes is expected to be minimal. Our experiments show that the rock chipper typically excavates more material than is expected for strength-controlled cratering in the target rock types and velocities we consider. In fact, the lightweight, recoilless chipper generates abundant samples of particle sizes suitable for both in-situ analysis and sample return. In addition, the chipper samples depth that are typically greater than that expected based on the ratio of projectile momentum to area as suggested by the experiments of Anderson et al. (1996). However, the fragment-size distribution follows power rules very similar to those measured during previous impact disruption experiments in similar targets but at much higher velocities.