Exploring the Moon’s surface is challenging enough, but reaching what lies beneath it is even harder.
Deep pits and long lava tubes on the Moon are some of the most promising places for future human missions, as they offer natural protection from radiation and extreme temperature swings.
However, getting robotic explorers into these steep, rugged environments has remained a major technical obstacle—until now.
A joint research team from the Korea Advanced Institute of Science and Technology (KAIST) and the Unmanned Exploration Laboratory (UEL) has developed a new kind of wheel designed specifically for these extreme lunar conditions.
Inspired by origami, the wheel can dramatically change its size, allowing small robotic rovers to overcome obstacles that would normally stop them in their tracks.
The research was published in Science Robotics.
One promising strategy for exploring dangerous lunar terrain is to send many small rovers instead of one large one.
If one rover fails, others can continue the mission. Small rovers are also cheaper, lighter, and easier to transport.
But they come with a serious drawback: small wheels struggle on steep slopes, loose soil, and large drops, especially around the entrances of lunar pits.
Engineers have long imagined wheels that could change size when needed, staying compact during transport and expanding to tackle difficult terrain.
The problem is that traditional mechanical systems rely on joints, hinges, and moving parts that do not work well on the Moon.
Fine lunar dust can jam mechanisms, and the vacuum environment can cause metal components to fuse together, a phenomenon known as cold welding.
To solve these issues, the KAIST-led team designed a wheel that avoids complex joints altogether.
Led by Professor Dae-Young Lee, the researchers combined ideas from origami engineering and a structure known as the “Da Vinci bridge,” which uses clever geometry rather than hinges for stability. The result is a compliant, flexible wheel that changes shape using the elasticity of its materials.
The wheel can expand from about 23 centimeters in diameter to roughly 50 centimeters.
This allows a rover to remain small and lightweight during launch and travel, then transform once on the Moon to climb over steep edges and loose ground. Instead of traditional hinges, the wheel uses an elastic metal frame and fabric-like tension elements, making it more reliable in dusty, airless conditions.
Extensive testing showed impressive results. Using artificial lunar soil, the wheel demonstrated strong grip on loose slopes and maintained its shape under heavy stress. It even survived impact tests equivalent to a 100-meter fall under lunar gravity, showing it could endure accidental drops into pits.
Experts involved in the project believe the technology could play a key role in future lunar missions. Scientists see lunar pits as valuable natural sites that could reveal the Moon’s history and support long-term human presence.
By lowering the technical barriers to reaching these locations, the new wheel brings real exploration closer to reality.
While challenges like power supply and communication underground still remain, this shape-shifting wheel marks a major step forward. It shows how creative engineering, inspired by simple folding patterns, could unlock some of the Moon’s most mysterious and valuable environments.
