Engineers in South Korea have built wheels that fold like origami. The wheels expand from 9 inches to 20 inches when needed.

The team is led by Seong-bin Lee at KAIST. The wheels are airless, so they cannot get punctured on rough ground.

The design was inspired by paper folding. The wheel changes shape to grip different surfaces. It can roll over rocks and soft soil.

The wheels are meant for a moon rover. Korea plans to land a robotic mission on the moon by 2030.

Airless wheels are useful in space. There is no air to fill tyres on the moon. Temperature swings also damage normal rubber.

The team tested the wheels on rocky tracks. They said the grip improved sharply when the wheel expanded.

The research could also help earth vehicles. Wheelchairs and off-road machines may use similar designs.

The wheel folds flat for transport. That saves precious cargo space on lunar missions. Engineers call the design a breakthrough for rough terrain.