System Modeling and Simulation of TianWen-2 Sampling on an Asteroid Regolith Surface

As China’s first asteroid exploration mission, the TianWen-2 spacecraft mainly focuses on surface sampling on the near-Earth asteroid 2016 HO3. Different from the usual sampling strategy of releasing a small lander or ejecting a projectile, the whole TianWen-2 spacecraft will be controlled to achieve touchdown and sampling. However, sampling on a low-gravity regolith-covered surface with unknown physical properties is particularly challenging and risky. In order to successfully implement an in situ exploration, a comprehensive understanding and evaluation of spacecraft dynamics and control behavior during sampling is essential for system design. In this paper, a system-level simulation method for the interaction between the spacecraft and the regolith surface is proposed. The discrete element method is adopted for the simulation of granular material dynamics. Parametric comparisons with test data from microgravity low-speed intrusion drop-tower experiments are implemented to calibrate and verify the physical parameters of the discrete element method simulation model. An explicit multibody dynamics model of the spacecraft is developed to describe dynamic characteristics such as orbit and attitude motion, solar array vibration, and sampler deformation. Finally, numerical simulations of the interaction between granular dynamics, multibody dynamics, and control are performed to study the dynamics and control behaviors of TianWen-2 sampling on an asteroid regolith surface.