The paper, produced by researchers at the Harbin Institute of Technology, covers the full landscape of approaches developed and flown to date, drawing on lessons from missions including Hayabusa, Hayabusa2, OSIRIS-REx, and the Philae lander, and identifies the coupled nature of surface interaction forces as the central engineering challenge for next-generation systems.
Robots operating on small bodies face conditions that have no close analog on the Moon or Mars. Gravity is extremely weak, terrain is irregular, and surface material properties are largely unknown before arrival. In that environment, even a minor sampling force, landing impact, or thruster firing can cause a spacecraft or robot to rebound, drift, lose attitude control, or break contact with the surface entirely.
The review classifies sampling approaches into three broad categories. Touch-and-go sampling - demonstrated on Hayabusa, Hayabusa2, and OSIRIS-REx - minimizes contact time and operational risk and has proven feasible at multiple targets. Landing or anchoring-assisted sampling can support larger sample volumes and subsurface acquisition but demands more complex system design and higher operational reliability. Non-contact sampling, in which particles ejected from the surface are captured without a direct landing, may prove useful at volatile-rich or structurally hazardous surfaces.
For surface mobility, the review surveys hopping, climbing, anchoring-assisted locomotion, creeping, wriggling, and hybrid strategies. Conventional wheeled locomotion is largely impractical given the minimal gravity and traction available on small bodies. Hopping and short-contact motion have therefore emerged as the practical baseline for near-term missions, while bio-inspired crawling, anchoring-assisted movement, and hybrid schemes are seen as candidates for tackling more complex future terrain.
Anchoring receives particular attention as a capability that underpins both mobility and sampling. The authors group existing methods into mechanical penetration, grasping-based anchoring, adhesive-based anchoring, and hybrid combinations. The failure of the Philae lander's harpoon-based anchoring system on comet 67P/Churyumov-Gerasimenko is cited as a concrete demonstration that a single anchoring strategy can prove insufficient when surface conditions deviate from predictions. Future systems, the review argues, will need intelligent multimodal anchoring that can adapt across crusted, rocky, dusty, or loosely packed surfaces.
The review's central argument is that the three capability areas interact in ways that must be accounted for at the system level. Sampling can induce rebound or drifting; mobility alters the contact state and the stability boundary; inadequate anchoring amplifies the risk of cascading system instability. Contact impulse, reaction force, attitude disturbance, surface interaction, and anchoring capacity are all coupled in microgravity, and treating each subsystem independently leads to designs that may perform well in isolation but fail under combined operational loads.
The authors outline several directions for advancing the field: AI-powered autonomy for real-time decision-making under uncertain surface conditions; diversified and multimodal sampling mechanisms; adaptive hybrid mobility systems; intelligent anchoring that blends mechanical and bio-inspired elements; modular and lightweight structural architectures; and integrated optimization spanning the complete mission chain from descent to sample containment.
Taken together, those developments are intended to support longer-duration, higher-frequency surface operations on small bodies, with downstream applications in sample return science and in situ resource utilization as both scientific and commercial interest in asteroid and comet exploration expands.
Research Report: Sampling, Mobility, and Anchoring in Small-Body Sampling Robots: A Comprehensive Review
Related Links
Harbin Institute of Technology
Asteroid and Comet Mission News, Science and Technology
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