Hidden below the Moon’s pockmarked exterior are vast lava tubes and deep shafts—natural caverns that could one day protect lunar habitats from cosmic radiation and extreme temperature changes. These underground formations are among the most scientifically important sites in the solar system, yet reaching them remains a major and difficult obstacle.
The openings to these caves are surrounded by steep, uneven ground littered with rocks and loose lunar soil. While small rovers are ideal for Moon missions—since deploying many of them reduces overall risk—they have a built-in drawback. Their small wheels can’t roll over obstacles much taller than the wheels themselves. A fleet of small rovers can keep going even if a few fail, but relying on a single large rover means one breakdown could end the entire mission.
Big Mobility Gains in a Brutal Lunar Environment
Expandable wheels offer a promising solution. By increasing their diameter to clear obstacles and shrinking again for easier travel, they could greatly improve mobility. However, designing such wheels for the Moon has been extremely difficult. The lunar environment is harsh on machinery: fine, abrasive dust seeps into every gap, and the vacuum causes exposed metal parts to fuse together through cold welding. Under these conditions, conventional hinges and joints wear out quickly.
To overcome this, a research team led by Professor Dae-Young Lee at the Korea Advanced Institute of Science and Technology turned to ideas from the past. Drawing inspiration from Leonardo da Vinci’s self-supporting bridge and combining it with origami folding techniques, they created a wheel that can change shape without relying on traditional mechanical joints.
The wheel is built around a flexible metal framework paired with fabric tension elements that bend instead of rotating. This allows it to grow from a compact 230 millimeters to about 500 millimeters in diameter, more than twice its original size. With these wheels, a small rover can stay low and compact during transport, then gain the obstacle-climbing capability of a much larger machine once operating on the Moon.
Rigorous Testing on Simulated Lunar Terrain
Researchers subjected the wheel to extensive trials using simulated lunar soil. The design showed excellent grip on loose, sloped terrain and withstood an impact comparable to a 100-meter fall under lunar gravity. The metal structure was supple enough to repeatedly change shape, yet strong enough to carry the rover’s weight over unstable regolith.
Dr. Chae Kyung Sim of the Korea Astronomy and Space Science Institute highlighted the scientific value of lunar pits, describing them as “natural geological heritage sites” that this new technology could finally make accessible. Meanwhile, Dr. Jongtae Jang from the Korea Aerospace Research Institute explained that the wheel’s design was refined using thermal modeling to survive the Moon’s extreme 300°C temperature swings between day and night.
Professor Lee shared confidence that, although challenges remain in areas such as communications and power supply, this innovative approach puts the team in a strong position to lead future missions aimed at exploring the Moon’s largely unknown underground regions.
Read the original article on: Tech Xplore
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