Asteroid surface impact sampling

Space missions and remote thermal infrared observations have shown that the surfaces of most asteroids are covered with a layer of granular materials. The complex geology of the regolith layer may preserve the records of the surface modification experienced by asteroids. Additionally, organic matter and hydrated minerals within the regolith are expected to provide crucial information on the origin and evolution of the planets and lifes. Asteroid sampling return, therefore, has attracted the attention of many space agencies, e.g., NASA with OSIRIS-REx and JAXA with Hayabusa-2. China is also planning to develop an asteroid exploration mission with surface sampling included. Within the Chinese space program, then, understanding the impact dynamics related to granular regolith will facilitate the development of efficient anchoring tools and impact sampling mechanism design for future sample-return space missions.

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Impact sampler and various shaped projectiles (left). Collected mass in sampler canisters within 1 s sampling time (right).

Based on DEMBody, this paper studies the process of the low-speed impact sampling on granular regolith using projectiles of different shapes. The results demonstrate that the projectile shape significantly influences the excavation stage, forming cavities with different morphologies, i.e., cone-shaped, bowl-shaped and U-shaped. We further indicate that the different projectile shapes result in various amounts of collected mass in sampler canister, regarding which the \(60^{\circ}\) conical projectile exhibites preferable performance for impact sampling scheme. The results presented in this article are expected to provide further information on the optimal designs of impact sampling devices for future sample-return space missions.

Related paper: Cheng, B., Yu, Y., & Baoyin, H. Numerical simulations of the controlled motion of a hopping asteroid lander on the regolith surface, Monthly Notices of the Royal Astronomical Society, 2019, https://doi.org/10.1093/mnras/stz633