Preliminary Design of a Rotary Brush Sampler for Asteroid Regolith Collection

Near-Earth Asteroids represent pristine time capsules from the early Solar System. Retrieving and analyzing asteroid surface samples on Earth is crucial for answering fundamental astrophysical questions, as well as for advancing planetary defense strategies and In-Situ Resource Utilization. However, excavating granular regolith in small celestial bodies is heavily hindered by extremely low surface gravity, where conventional drilling or scooping mechanisms are impractical due to the absence of sufficient spacecraft weight and the lack of complex anchoring systems. Furthermore, current state-of-the-art touch-and-go sampling technologies rely on single-use consumables, severely limiting their scalability for bulk material collection or multi-target missions. To overcome these operational constraints, this thesis focuses on the preliminary design and numerical sizing of an alternative, consumable-free technology: a mechanical rotary brush sampler. Sizing such a mechanism involves a complex engineering trade-off among bristle geometry, stiffness, rotational speed, and strict power and torque budgets. To address this challenge, a hybrid methodology is developed. A computationally efficient, modular analytical sizing tool is implemented in Python to rapidly evaluate thousands of design iterations. This reduced-order model utilizes Granular Resistive Force Theory to predict the lifting and resistive forces acting on individual bristles as they sweep through the medium. To ensure physical accuracy under asteroid microgravity and vacuum conditions, the empirical coefficients required by the RFT model are calibrated using Discrete Element Method simulations, which act as a virtual laboratory. The final outcome of this research is a validated computational tool and a robust set of design guidelines, providing a scalable and highly efficient solution for future asteroid sample return and deep-space exploration missions.