When the first Mars colonists hop in their cars and drive around town, they may travel through lava tubes. In a new study from the University of Padova and the University of Bologna, researchers compared lava tubes on Earth, the moon, and Mars, using hi-resolution satellite data, and determined that these openings could provide space for homes, streets, and even communities.

Lava tubes are created in two ways. Over-crusted tubes form when lava flows close to the surface and a crust hardens like a calzone. After the eruption, the lava filling drains out and leaves the crust with a tunnel just a few yards underneath the surface. The other formation, inflated tubes, are created when lava ends up squeezing through cracks and crevasses left over from previous eruptions, which create a web of tunnels leading up to the surface.

On Earth, some of these networks can extend up to forty miles. On the moon and Mars, scientists have noticed what looks like lava tubes that have had their roofs cave in. Gravity data collected by NASA suggests subsurface caverns that are likely the result of volcanoes.

“The comparison of terrestrial, lunar and Martian examples shows that, as you might expect, gravity has a big effect on the size of lava tubes, “Riccardo Pozzobon, one of the researchers who spearheaded the study, said in a statement. “On Earth, they can be up to thirty meters (98.5 feet) across. In the lower gravity environment of Mars, we see evidence for lava tubes that are 250 meters (820 feet) in width. On the moon, these tunnels could be a kilometer (0.62 miles) or more across and many hundreds of kilometers in length.”

In a related study, researchers have suggested how future spacecraft can use radar to scan the moon’s surface and detect networks of tunnels underneath. Today’s remote sensing systems don’t have the capacity to detect features of lava tubes through the surface.

“These results have important implications for habitability and human exploration of the Moon but also for the search of extraterrestrial life on Mars,” Pozzobon said. “Lava tubes are environments shielded from cosmic radiation and protected from micrometeorites flux, potentially providing safe habitats for future human missions. They are also, potentially, large enough for quite significant human settlements – you could fit most of the historic city center of Riga into a lunar lava tube.”

The European Space Agency has begun training astronauts using data collected by Pozzobon and her team. The research was presented last weekend at this year’s European Planetary Science Congress in Riga, Latvia.

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