Soft Robotics for Space Applications: Cryogenic Performance of Modular Metallic Cable Structures.

Soft robotic systems are promising for diverse space applications due to their embedded compliance, promising locomotion methods, and efficient use of mass and volume. Space environments are harsher and more varied than those on Earth; extreme temperature, pressure, and radiation may impact the performance and robustness of soft robots. Cryogenic temperatures on celestial bodies such as the Moon or Europa pose significant challenges to the flexibility and actuation performance of conventional soft systems. We present a soft robotic design methodology using novel metallic-based soft robotic structures specifically tailored to extreme space environments. Structures are presented as tunable, reconfigurable modules for soft systems. Module behavior under compression is characterized while submerged in liquid nitrogen, and structural changes are investigated using scanning electron microscopy (SEM). The structures retained flexibility at -196 °C, with a limited 5% increase in peak stiffness over 100 cycles while maintaining a full range of motion. A soft robotic limb was constructed from these modules and demonstrated successful 2D manipulation and grasping of objects at -196 °C. SEM analysis showed no physical signs of microfracture or deformation after cryogenic cycling, indicating changes to the underlying grain structure consistent with properties observed in cold-working stainless steels at cryogenic temperatures in the literature. Our findings demonstrate that metallic soft robotic structures maintain flexibility and exhibit promising performance in cryogenic, analogue space environments. This metal-based cable structure design approach provides a foundation for the development of functional, robust, and reconfigurable soft robots capable of operating in extreme space environments.