A new theoretical study carried out by researchers at Purdue University says that though harsh environment on the surface of the Moon negates the possibility of setting up colonies on Moon, structurally stable lava tubes on Earth’s natural satellite could be used to set up entire cities.
“We found that if lunar lava tubes existed with a strong arched shape like those on Earth, they would be stable at sizes up to 5,000 meters, or several miles wide, on the moon,” said David Blair, a graduate student in Purdue’s Department of Earth, Atmospheric and Planetary Sciences, who led the study.
Researchers say that these volcanic features are an important target for future human space exploration because they could provide shelter from cosmic radiation, meteorite impacts and temperature extremes.
These kinds of structures aren’t possible in Earth because of Earth’s gravity, but the much lower gravity on the Moon and no weathering and erosion of lunar rock could mean that in theory, huge lava tubes – big enough to easily house a city – could be structurally sound on the moon.
For the uninitiated, lava tubes are sort of 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.
Jay Melosh, a Purdue University distinguished professor of earth, atmospheric and planetary sciences, says that there has been an ongoing discussion on whether lava tubes might exist on the moon and there have been some evidence, like the sinuous rilles observed on the surface, which hint at the possibility that if these lunar laval tubes do exist, they might be really big.
Sinuous rilles are large channels visible on the lunar surface thought to be formed by lava flows. The sinuous rilles range in size up to 10 kilometers wide, and the Purdue team explored whether lava tubes of the same scale could exist.
The team found that 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. The researchers also modeled lava tubes with walls created by lava placed in one thick layer and with lava placed in many thin layers, Blair said.