When human settlers one day reach distant worlds, they might take refuge inside extensive underground networks known as planetary caves. Scientists in recent years have proposed volcanic caves as a potential place for safe habitats on the moon and Mars. But, to understand how this might work, we must first look at similar systems here at home. A team of ESA-backed researchers recently ventured into the La Cueva de los Verdes lava tube in Spain to map the nearly 5 mile (8 kilometer) 'lava tube' in unprecedented detail, revealing the intricate features of the'volcanic wormhole.' The team used what's known as the point cloud technique to map La Cueva de Los Verdes in unprecedented detail, capturing millions of measurements with lasers and cameras.