Origami style lunar rover wheel expands to climb steep caves

by Riko Seibo
Tokyo, Japan (SPX) Dec 18, 2025

A joint team from the Korea Advanced Institute of Science and Technology KAIST and the Unmanned Exploration Laboratory UEL has developed a transformable airless wheel designed to help small rovers access steep lunar pits and lava tubes. The wheel targets subsurface sites considered promising for future human habitats because they shield against cosmic radiation and extreme temperature swings.

The study introduces an origami inspired deployable wheel that can change its diameter to overcome obstacles that would halt conventional fixed geometry rover wheels, and the research appears in the December issue of Science Robotics. The concept supports mission architectures that use multiple small rovers instead of a single large vehicle, providing redundancy so exploration can continue even if some units fail.

Small rovers typically struggle on the sharp slopes and rugged terrain at the entrances to lunar pits because their compact wheels limit traction and obstacle clearance. Variable diameter wheels have been proposed as a solution, but implementing them for lunar conditions has been difficult because hardware must remain light while withstanding abrasive dust and vacuum conditions that promote cold welding of metal parts.

To address this, the team led by Professor Dae-Young Lee of KAISTs Department of Aerospace Engineering created a compliant wheel that avoids complex mechanical joints. The design draws on the structural principles of the Da Vinci bridge and origami patterns so the wheel transforms through controlled deformation of its structure rather than through traditional hinge mechanisms.

The wheel can expand from a compact 230 millimeters to 500 millimeters in diameter, allowing a rover to stay small and low during transport but increase its effective size to climb larger obstacles once deployed on the Moon. The structure uses an elastic metal frame and fabric tensioners instead of conventional hinges, which supports reliable operation in vacuum and reduces the risk of cold welding and failures caused by fine lunar dust.

The researchers tested the wheel in artificial lunar soil simulants, where it showed strong traction on loose slopes. Drop tests indicated that the structure could withstand impact loads equivalent to a 100 meter fall under lunar gravity, demonstrating that the wheel can tolerate severe mechanical shocks during operations.

The project involved experts from several Korean space institutes to examine the technical feasibility for future missions. Prof. Lee described the wheel as a practical and reliable option for traversing demanding lunar terrain and noted that this technology could support Koreas participation in upcoming lunar exploration efforts even though challenges in areas such as communication and power remain.

From a scientific standpoint, Dr. Chae Kyung Sim, Head of the Planetary Science Group at the Korea Astronomy and Space Science Institute KASI, described lunar pits as "natural geological heritages" and stressed that the new wheel design lowers technical barriers to reaching these targets. Dr. Jongtae Jang, Principal Researcher at the Korea Aerospace Research Institute KARI, explained that the team optimized and verified the wheel with mathematical thermal models so it can endure temperature swings of about 300 degrees on the Moon.

Research Report:Soft deployable airless wheel for lunar lava tube intact exploration