New findings suggest lava tubes on the Moon large enough to house cities could be structurally stable.

A study by Purdue University researchers believe these tubes are an important target for future human space exploration because they could provide shelter from cosmic radiation, meteorite impacts and temperature extremes.

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Lava tubes are tunnels formed from the lava flow of volcanic eruptions. The edges of the lava cool as it flows to form a pipe-like crust around the flowing river of lava. When the eruption ends and the lava flow stops, the pipe drains leave behind a hollow tunnel, said Jay Melosh, researcher and a Purdue University distinguished professor of earth, atmospheric and planetary sciences.

Provided the lunar lava tubes have strong arched shapes like those found here on Earth, they may be stable at widths of up to several miles (5,000 meters), said Study lead investigator David Blair. While structures like this would not be possible on Earth, the reduced gravity on the Moon and the fact lunar rock does not need to withstand the same degree of erosion and weathering makes it theoretically possible.

The team found a lava tube's stability depended on the width, roof thickness and the stress state of the cooled lava, and the team modeled a range of these variables. They also modeled lava tubes with walls created by lava placed in one thick layer and with lava placed in many thin layers, Blair said.

"Our group has been using GRAIL gravity data to search for empty subsurface lava tubes. This search is difficult because the signature of lava tubes is at the limit of what the GRAIL data can tell us. While we do not yet have definitive evidence of the existence of large lava tubes, we wanted to find the maximum size limits of possible lunar lava tubes," Melosh said.

If these caves confirmed, they would be "ready-made" lunar shelters.

TagsResearchers Reveal Moon May Have Huge Lava Tubes, moon, lava tubes, lunar shelters, space exploration, cosmic radiation, meteorite impacts, temperature extremes, volcanic eruptions