Asteroid surface impact sampling: dependence of the cavity morphology and collected mass on projectile shape

Abstract

In-situ exploration and remote thermal infrared observation revealed that a large fraction of Solar System small bodies should be covered with granular regolith. The complex and varied geology of the regolith layer may preserve the historical records of the surface modification and topographic evolution experienced by asteroids, especially cratering processes, in which the projectile shape plays a crucial role. Regarding the impact sampling scheme, the projectile-shape dependence of both the cavity morphology and the collected mass remains to be explored. 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 velocity distributions of the ejecta curtains due to the various projectile shapes result in various amounts of collected mass in sampler canister, regarding which the 60° conical projectile exhibits preferable performance for impact sampling scheme. The results presented in this article are expected to reveal the dependence of the excavation process on projectile shape under micro gravity and provide further information on the optimal designs of impact sampling devices for future sample-return space missions.

Discrete element modeling of boulder and cliff morphologies on comet 67P/Churyumov-Gerasimenko

“…For example, it has been used to simulate impact processes on the asteroids Eros and Itokawa to explain the origin of exposed boulders on their surfaces via the Brazil nut effect (Tancredi et al 2012), the removal of surface materials on asteroids by strong centrifugal forces resulting from rapid rotation (Hirabayashi et al 2015), and catastrophic collisional disruptions of planetesimals and reaccumulation of their fragments to explain the formation and the bilobate shape of several comets including 67P (Schwartz et al 2018). The DEM has also been used to address engineering problems such as hopping mechanisms to relocate landers on asteroids (Cheng et al 2019) and techniques to sample material from asteroid surfaces (Cheng et al 2017). However, DEM modeling has not yet been widely used to study the surface morphology or mechanical properties of cometary material -a material in a low-gravity environment that, in addition to dust, consists of ices, and where the ices may form sinter bonds and sublime.…”

Accelerating Polyhedral Discrete Element Method with CUDA

“…The mesh with the higher spatial resolution is utilized to compute the contact force. For each active contact element, the normal and tangential contact force can be ascertained by using the Hertz contact model and Coulomb friction model as (Hertz 1881;Cheng et al 2017Cheng et al , 2018 (2022) for the calculations of δ nk and δ sk , as well as more details of the contact model. Assume the total number of the active contact elements for a pairing of contacting bodies is N. The resulting contact force acting on the two contact bodies, i and j, yields…”

Deep networks as approximators of optimal low-thrust and multi-impulse cost in multitarget missions

“…Multitarget missions that are already being conducted are focused mostly on small celestial bodies in our solar system (except multi-gravity-assist missions). Small celestial bodies attract vast research interest because of their great significance in various aspects [1][2][3][4]. NASA's Near Earth Asteroid Rendezvous (NEAR) Shoemaker performed a flyby of the asteroid 253 Mathilde on the way to the asteroid 433 Eros [5].…”