Supplementary data and modeling code file for: Soft deployable airless wheel for lunar lava tube in-tact exploration

Lunar pits and lava tubes hold promise for future human habitation,
offering natural protection and stable environments. However, exploring
these sites entails challenging terrain, including steep slopes along cave
funnels and vertical cliffs. Here, we present a soft, deployable airless
wheel to address these challenges. By achieving a high deployment ratio,
multiple rovers can be stowed efficiently without sacrificing mobility,
thereby improving mission reliability and flexibility. The proposed wheel
incorporates a reconfigurable reciprocal structure of elastic steel strips
arranged in a woven helical pattern, enabling shape transformations while
preserving load-bearing capacity. This reciprocal arrangement also allows
for safe vertical descents and mitigates damage from accidental falls
within caves. By distributing strain throughout the wheel’s body, reliance
on delicate mechanical components is minimized—a critical advantage under
extreme lunar conditions. The wheel can be stowed at a diameter of 230
millimeters and deployed to 500 millimeters. Experimental results show
successful traversal of 200 millimeters obstacles, stable mobility on
rocky and lunar soil simulant surfaces, and resilience to drop impacts
simulating a 100 meters descent under lunar gravity. These findings
underscore the wheel’s suitability for future pit and cave exploration,
even in harsh lunar environments.