Image of the Day: Caves of the Moon


In 2009, the Japanese Aerospace Exploration Agency (JAXA) lunar orbiter, Kaguya, spotted a big hole in the moon – sixty five meters across and at least eighty meters deep shown above, and potentially part of a much larger "lava tube."  These hark back to the moon's youth when there was still hot stuff and surface volcanic activity.  It's possible for a flow of molten rock to encase itself as the outside cools and hardens into a crust.  Normally the whole thing eventually solidifies, but sometimes the tube of rock empties as the hot lava flows out of the shell it left behind.

Such subsurface tunnels would be extraordinarily useful for off-wold habitation: the rocky roof forms natural radiation shielding (one thing most people forget is that empty space really wants to kill you, or if it doesn't, it's extremely careless with cosmic ray levels), and a large tube is an excellent shell for constructing a compartmentalized base.

Of course there are problems: a hundred thousand kilometers away isn't a great place for cave exploration (just ask a Star Trek redshirt), and a seleneological spelunking accident is a guaranteed fatality.  Another problems with pits formed by molten rock is they can be blocked pretty much anywhere by extremely solid non-molten rock.  For now, the work will be to confirm if this lunar lacuna really is part of a suspected sub-surface tunnel, or some other excavation.  But then we can work on how we're going to move in.

Today, while the USA and NASA appear to put aside any ambitions to return to the Moon with human missions, Russia says it may consider sending cosmonauts to the lunar surface to set up a colony using the natural caves and possible volcanic tunnels as protection from the harsh lunar environment.

“If it turns out that the Moon has a number of caves that can provide some protection from radiation and meteor showers, it could be an even more interesting destination than previously thought,” said veteran cosmonaut Sergei Krikalev, quoted in an article by Reuters.

Krikalev served on board two different space stations and flew on the space shuttle. He now leads Russia’s Star City cosmonaut training center outside Moscow. He and Russian scientists discussed the possibllity of a Moon base by 2030 at a forum on the future of manned spaceflight.

The image above is from the Lunar Reconnaissance Orbiter showing a cave or pit found in the Sea of Tranquility. Scientists have estimated the depth of the pit at over 100 meters, and several other caves have been found with orbiting spacecraft. Lunar scientists are studying the images to determine if an extended lava tube system still exists beneath the surface.

“This new discovery that the moon may be a rather porous body could significantly alter our approach to founding lunar bases,” said Krikalev. “There wouldn’t be any need to dig the lunar soil and build walls and ceilings. It would be enough to use an inflatable module with a hard outer shell to — roughly speaking — seal the caves.”

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