TCS Daily

Spelunking in the Solar System

By Kenneth Silber - October 25, 2005 12:00 AM

One sign of technological progress in the 21st century will be if a rising number of humans live in caves. The caves in question are on the moon and Mars, and they are assets of considerable scientific, technological, economic and cultural potential. Indeed, they may turn out to be some of the most valuable real estate in the solar system.

Caves on Earth are used for various purposes, including tourism and adventure, mining and scientific exploration, military and civil-defense uses, and commercial storage. Caves at Altamira, Spain, and Lascaux, France, among others, are preserved as examples of early human habitations and artwork. Wines and cheeses have long been aged in caves.

The Mormons' vast genealogical archive is stored in granite vaults in a Utah canyon, and Pennsylvania's Iron Mountain underground facility houses items ranging from classified federal documents to original recordings by Frank Sinatra and Elvis Presley.

A similar, or perhaps greater, diversity of uses might be found for caves on celestial bodies. Both the moon and Mars present evidence of extensive lava tubes, underground caves formed by ancient flows of molten material. Mars may also have caves carved out by long-ago or recent flows of water. Such features have gotten growing attention as focal points for future exploration efforts, including as possible abodes for human explorers and settlers. Extraterrestrial caves offer protection against cosmic rays and harsh surface conditions, as well as logical venues for searching for possible alien life.

NASA's Institute for Advanced Concepts has shown interest in this approach, funding studies led by Penelope Boston, a biologist and cave expert now at the New Mexico Institute of Mining and Technology. Boston has developed ideas for human habitats in "inner space," such as inflatable cylinders that would be set up inside Martian lava tubes. Such cylinders would have airlocks, maintaining an environment in which people could operate without spacesuits. Sunlight would enter via radiation-resistant skylights drilled to the surface, while inflatable greenhouse modules would supply oxygen and food.

Such bases would be well-positioned to search for past or present life on Mars. Traces of past life might have endured in the relatively protected environs of the Martian underground, rather than on the cold, dry, radiation-bombarded surface. These could include fossils of any surface life that may have existed when Mars was far warmer and wetter. Or possibly, the Martian underground is home to some type of life that exists today. Scientific interest in such possibilities has risen in recent years with growing recognition of the pervasiveness of bacterial and other life beneath the surface of Earth.

Caves on Earth's moon may serve as testing grounds for subsurface missions to Mars. However, they offer considerable interest in their own right. They too could serve as abodes for human explorers, providing shelter from radiation, dust and extreme temperatures. Moreover, they may also be ideal for extremely secure storage. Peter Kokh, a longtime space exploration advocate and current president of the Moon Society, has argued that the moon's airless, geologically inactive caves would be the safest place in the solar system to place documents or other artifacts of civilization to ensure their survival. Indeed, he once speculated, if aliens long ago passed through this system and sought to leave a message behind, the lunar caves are where they would have left it.

In any event, speleology and space exploration, two disciplines that long went their separate paths, have begun to converge in ways that could have a significant impact on humanity's future. In the excellent 1999 film October Sky, based on space enthusiast Homer Hickam's memoir of growing up in West Virginia in the late 1950s, there is a poignant scene of young Homer descending despairingly to his new job in a coal mine as the stars pass from view above him. In the coming decades, however, it may turn out that having some experience below the ground is a prerequisite for getting beyond the Earth.


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