From flybys to sample return: A review of space probes and robotic sampling technologies for small bodies

As a crucial puzzle piece of deep space exploration, exploring small bodies can provide significant scientific insights and valuable mineral resources. Unlike missions to the Moon and Mars, small-body missions pose distinct technical challenges, including communication delays, weak gravity, and uncertain environments. This paper reviews a full mission spectrum of probe-based small-body missions to analyze the current status and core technologies, tracing from flyby detection to orbital observation, impact detection, in-situ sampling and analysis, and sample-return missions. Since sampling missions act as a bridge between detection and exploitation, robotic sampling has become one of the most cutting-edge and core technologies for space robotic probes. Space robots are the synergy of robotics and autonomy: robotics provides the physical capability for sample acquisition, while autonomy enables the robot to perceive environments, make decisions, and plan actions independently for robust and efficient sampling. Therefore, we investigate the state-of-the-art robotic sampling and onboard autonomy technologies, including robotic sampler design, autonomous touchdown, and compliant interaction. Given the significant uncertainties associated with small bodies, we propose a trade-off cobweb model to evaluate the comprehensive performance of various robotic samplers. Additionally, we review mainstream microgravity simulation technologies for testing robotic samplers on the ground. Finally, we analyze key lessons learned from past missions and discuss directions for future small-body exploration. This review aims to serve as a comprehensive and useful reference for researchers in the field.