Moon caves would make good homes for astronauts and should therefore be mapped out, a space scientist argues.
The Moon appears to possess long, cave-like structures called lava tubes that are similar to ones on Earth. They form when the surface of a stream of lava solidifies and the molten rock inside drains away, leaving a hollow tube of rock.
Some of the tubes on Earth are big enough to drive a car through, and those on the Moon could be even larger. Apollo 15 astronauts discovered that Hadley Rille 鈥� a lunar channel that may be a partially collapsed lava tube 鈥� was 1 kilometre wide.
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For decades, engineers and space scientists have discussed the possibility of using these caves as astronaut housing because they are sheltered from space radiation and micrometeorite impacts. But the idea should now be revisited in light of NASA鈥檚 push to send astronauts back to the Moon, says Austin Mardon of the Antarctic Institute of Canada in Edmonton, Alberta.
Meteorite-proof
At a meeting of the International Lunar Exploration Working Group (ILEWG) in Beijing, China, last week, he argued that robotic probes should be sent to potential lava tubes to see if they are suitable for habitation.
He says erecting pressurised tents inside a cave would be easier and faster than trying to construct a rigid structure on the surface. 鈥淚nstead of assembling structures that have to be meteorite-proof on the surface, or burying them, you鈥檇 have tent-like structures inside these tubes,鈥� Mardon told New 杏吧原创. 鈥淚t鈥檚 like being cavemen on the Moon.鈥�
鈥淚t鈥檚 a potentially very inviting place to put infrastructure,鈥� agrees Mark Robinson of Northwestern University in Evanston, Illinois, US. He says sections of the lava tubes with roofs still intact appear to be very stable, having survived for 3 billion years or more since their formation.
But he points out that the lava tubes may not be located where NASA would like to send astronauts. For example, the polar regions 鈥� which may harbour water ice that could be used to support a lunar base 鈥� appear to bear no sign of the ancient lava flows associated with lava tubes.
Rocks in the road
And the tubes could be full of rubble, he adds. Haym Benaroya of Rutgers University in Piscataway, New Jersey, US, agrees and says it might take a lot of work to make the lava tubes usable. 鈥淢aybe the opening is not big enough. Maybe there are boulders in the way,鈥� he told New 杏吧原创.
鈥淟ava tubes are not ruled out, but the question is: at what stage of lunar development would they be feasible?鈥� he says. Benaroya thinks the first lunar base is likely to be a more traditional metal-walled structure built on the surface.
NASA has no plans for a dedicated robotic mission to search for lava tubes, but NASA鈥檚 Lunar Reconnaissance Orbiter should shed some light on the matter when it launches in 2008. Although not specifically designed to search for lava tubes, the images it sends back 鈥渨ill help find good candidate lava tubes鈥�, says Robinson, a member of the mission.
