Building cities on the moon’s surface poses many challenges when it comes to constructing habitats suitable for human colonization. Surface buildings would have to be able to withstand cosmic radiation, meteorite impacts and severe temperature extremes. Therefore, establishing safe, lunar dwellings could involve an expensive and complicated feat of engineering.
But now the natural environment of the moon could provide an alternative, in the form of massive underground tube-like, lava tunnels, which would provide protection from the dangers above.
A theoretical study was presented at the Lunar and Planetary Science Conference on March 17 by Jay Melosh, a distinguished professor of earth, atmospheric and planetary sciences from Purdue University.
Science Daily quotes Professor Meloch, who explained how they form.
“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.”
The evidence that they might exist comes from sinuous rilles, which are the volcanic features of large channels, which look like river valleys and can be seen frequently on the lunar surface in photographs. Its believed that these were made by lava flows.
The large size of the sinuous rilles suggests that tunnels exist, and they could be from half a mile (0.8 km) to 6 miles (9.6 km) wide.
According to Space.com, the existence of lava tunnels has been confirmed by sightings of “skylights” in a number of locations. These are the surface holes of underground voids, and they may also provide suitable sites for the building of man-made structures.
A key factor in estimating the tunnels’ suitability for habitation is their structural stability. This depends on their width, the thickness of their roofs and the stress state of the cooled lava.
Working with Antonio Bobet, a Purdue professor of civil engineering, they used data on lunar rock and the moon’s environment and applied it to civil engineering technology used to design tunnels on Earth.
The researchers simulated a number of possible models and concluded that, if the tubes have a strong arched shape, they would be stable even up to several miles wide.
David Blair, a graduate student in Purdue’s Department of Earth, Atmospheric and Planetary Sciences, who led the study into their structural feasibility, said that such tunnels wouldn’t be viable on Earth, but added that,
“Gravity is much lower on the moon and lunar rock doesn’t have to withstand the same weathering and erosion. In theory, huge lava tubes — big enough to easily house a city — could be structurally sound on the moon.”
The team will be continuing their research into the maximum possible size of the lunar tunnels and the possibilities for underground construction work.
