Researchers from the University of Padova and the University of Bologna in Italy believe that lava tubes, or underground caves created by volcanic activity, could be used as protected habitats to house human settlements on Mars and the moon. The research was presented at the European Planetary Science Congress 2017 in Riga, Lativa, which ran from Sept. 17-22.

“Lava tubes are environments shielded from cosmic radiation and protected from micrometeorites flux, potentially providing safe habitats for future human missions,” said Riccardo Pozzobon, a professor in the Department of Geosciences at the University of Padova, in a Europlant press release. “They are also, potentially, large enough for quite significant human settlements.”

Tomasz Czajkowski via Adobe Stock

Lava tubes form when low-viscosity lava flows close to the surface of the earth during a volcanic eruption, forming a hard crust that creates a “roof” above the lava stream. After the eruption, the liquid lava is drained and a tunnel is left behind. Alternately, these tubes can be formed when lava is injected into cavities from a previous lava flow or fissures in layers of rock. These underground caverns exist in highly volcanic areas of Earth such as Hawaii, Iceland, and the Galapagos Islands. Researchers say that, while these networks of connected galleries under the surface can reach up to 65 kilometers (approximately 213,255 feet) deep, on the moon or Mars these tunnels could be a kilometer wide (3,281 feet) and hundreds of kilometers in depth, due to gravitational differences.

Digital Terrain Models (DTM) are being used by researchers to create the first comparison of lava tubes on Earth with those in space, based on data they have collected from spacecraft instrumentation. The NASA GRAIL mission on the moon in 2012 also provided data that suggests the presence of lava tubes, showing enormous voids under its surface.

The research is already being employed by The European Space Agency’s PANGAEA project, a planetary geology training course. The program has launched a test campaign in the Canary Islands of Spain to familiarize astronauts with lava tubes and geological research that could be conducted in space.