Sunday, October 22, 2017

Underground Towns on the Moon and Mars: Future Human Habitats Could Be Hidden in Lava Tubes

ESA astronauts training in terrestrial lava tubes in Lanzarote during the PANGEA 2016 course. Photo Credit: ESA/L. Ricci

New research conducted by European scientists shows that underground caves on the Moon and Mars created by volcanic activity could be large enough to house even underground towns. The so-called ‘lava tubes’ could be therefore excellent hidden locations for future human habitats.

“Our research, conducted jointly by University of Padova and University of Bologna scientists, provides new insights on the size of lava tubes to be expected on Moon and Mars,” Riccardo Pozzobon of the University of Padova in Italy told Astrowatch.net.

The researchers have carried out the first systematic comparison of lava tube candidates on the Earth, Moon and Mars, based on high-resolution Digital Terrain Models (DTM) created from data from spacecraft instrumentation. They found that lava tubes on Mars could be up to 820 feet (250 meters) in width and on the Moon these caves could be even 3,300 feet (one kilometer) or more across and many hundreds of miles in length. On Earth, lava tubes are only up to 100 feet (30 meters) across.

“By analyzing the collapse pits found along the lava tube paths on digital terrain models compared with the largest ones on Earth, we have calculated that the size of the voids on Moon and Mars can be up to one or even two orders of magnitude,” Pozzobon noted.

The new findings are in agreement with a recent research conducted by Dave Blair from Purdue University suggesting that such large lava tubes can be stable in low gravity conditions. The study conducted by Pozzobon and his colleagues confirms that huge voids could exist on the subsurface of Mars and the Moon.

Moreover, the existence of one large open lava tube on the Moon was lately confirmed by scientists analyzing radar data from Japan’s SELENE lunar orbiter. The spacecraft was orbiting the Moon between October 2007 and June 2009, studying its origins and geologic evolution. The data by SELENE allowed the researchers to find an enormous cavern stretching for about 30 miles (50 kilometers) in the Marius Hills region.

Lava tubes are naturally occurring channels formed by flowing lava which moves beneath the hardened surface of a lava flow. They could be important for future space exploration mission, providing shelter from cosmic radiation, extreme temperature and meteorite impacts.

“The possibility to establish a settlement within a lava tube provides benefits both in economic and safety terms. The thick roofs shields from cosmic radiation and meteorites, but also reduces daytime/nighttime thermal excursion, providing a thermally controlled environment as happens in terrestrial caves,” Pozzobon said.

Largest voids on the Moon and on Mars could easily contain a human settlement. For instance, lunar lava tubes are large enough to host significant settlements like underground towns with streets.

However, in order to better understand lava tubes beyond Earth and to precisely pinpoint their location, more studies are still needed in this matter. According to Leonardo Carrer of the University of Trento in Italy, one of the co-authors of the new research paper, future robotic missions equipped in specialized instruments could help us improve our knowledge about extraterrestrial lava tubes.

“Our research, performed at the Remote Sensing Laboratory (RSLab) of the University of Trento, shows that, by using an orbiting radar using very low electromagnetic frequencies, it is possible to directly probe the subsurface of the Moon and infer the concealed lava tubes size and physical composition. Therefore our concept study proves that a future orbital mission carrying this type of instrument could greatly improve our knowledge regarding these structures and their location. Moreover, the global mapping would be a crucial information for selecting the best site for establishing a human outpost,” Carrer told Astrowatch.net.

He added that Mars rovers could help us estimate the local environmental conditions, morphologies and to verify the actual volume of the voids. Sending human-made objects within such cavities would also push forward remote operations in difficult environments and develop new roving capabilities.

Currently, Pozzobon and Carrer are in the process of scanning the interior of one of the largest terrestrial lava tubes to better understand extraterrestrial caverns. They want to relate the results with digital terrain models of the collapsed roof traces seen from satellite, to have a complete understanding of its surface-subsurface three-dimensional framework.

The researchers also hope that lava tubes can also be find on other celestial bodies, besides the Moon and Mars.

“Regarding other planetary bodies, up to now there is no evidence of lava tubes on other bodies apart from Moon and Mars, but I have great expectations on the data that will eventually come out from ESA-JAXA BepiColombo mission to Mercury, that is going to be launched next year,” Pozzobon concluded.

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