Photo: U.S. Geological Survey/NASA

Lunar mosaic of approximately 1500 images of the south pole of the moon, taken by the space probe Clementine.

Bill Stone, an engineer and renowned cave explorer, has been diving into the bowels of the Earth to get ready to explore the furthest regions of space. Stone’s expeditions, covered in National Geographic and other magazines, have taken him and his teams into some of Mexico’s longest and most dangerous underwater caves and tunnels, known as sumps. In 1994, at the end of a harrowing and much-documented expedition that claimed the life of a young diver, he and his then-girlfriend, Barbara am Ende, traveled more than 3.3 ­kilo­meters into the San Agustin Sump, the deepest point in Sistema Huautla in Oaxaca, Mexico. To get there, they had to get past eight other treacherous sumps, the last one some 1500 meters underground. Stone and am Ende found themselves in an enormous subterranean chamber 100 meters in diameter, where they spent several days. Their footprints are the only ones that have ever been left there.

Stone is an exceedingly rare engineer. He not only designs and builds advanced technology, he uses it to explore the most extreme niches of this world—and others. His latest creation is the DEPTHX autonomous probe, whose testing is the subject of Senior Editor Jean Kumagai’s story “Swimming to Europa” in this issue. Once again the scene of the action is Mexico, where Kumagai found a considerably mellower Stone than the notoriously hard-charging one of the Huautla mission 13 years ago.

But if age has mellowed Stone, it has not touched his passion for exploration. He’s not just interested in sending an unmanned probe to Jupiter’s ice-bound moon Europa. He wants to go to our moon—himself. According to Stone, 90 percent of the weight of present-day space vehicles, and much of the exorbitant cost of spaceflight, comes from the fuel needed to break through the Earth’s atmospheric chains. He is convinced that if you could set up a “water-mining” operation on the moon you could use the water to make liquid oxygen rocket fuel and then port it back to a low-Earth-orbit “gas station,” where new kinds of spacecraft could fuel up and take off for the stars.

Just how much water the moon holds is still debatable, but Stone is one of a group of scientists and technologists who are convinced that a vast icy lunar waterworks resides beneath the moon’s south pole, at the Shackleton Crater, named after the intrepid Antarctic explorer Ernest Shackleton.

So Stone is hard at work raising money and interest in his Shackleton Crater Expedition, a complex and ambitious project to send what he calls “an industrial Lewis and Clark mining expedition,” led by himself, to the crater by 2014. His plan calls for the spacecraft used in this mission to carry enough fuel for the outbound flight—but expedition members will need to make their own moon-water fuel to get back, providing proof-of-principle of his idea. And proof that it won’t take a trillion dollars and 20 years to work.

Stone and other like-minded folks believe that space travel and space exploration should not be the sole purview of government agencies like NASA. The U.S. space agency is too crippled, they say, by bureaucracy and risk avoidance to make any significant progress in manned space exploration over the coming decades. Billionaires like Virgin Airways’ Richard Branson and Microsoft cofounder Paul Allen are already supporting the development of suborbital passenger spacecraft and are looking for other ways to break into the space business. Stone hopes people like these will help bankroll his commercial moon-mining project.

What does NASA think of all this? Not much. With the specters of Apollo 13 and the Challenger disaster haunting its halls, it is reluctant to even consider putting its crews at such great risk. But Stone is following in the “no guts, no glory” footsteps of the great explorers, like Shackleton, who believed that while careful preparation was essential to successful exploration, the danger of going where no human had ever gone before was also intrinsic to the effort.

At the end of the Technology Entertainment Design Conference talk he gave in Monterey, Calif., earlier this year, Stone showed a slide of the ad Shackleton is said to have placed in a London newspaper seeking volunteers for his 1914 Imperial Trans-Antarctic Expedition, which sought to cross the southern continent: “Men Wanted: For Hazardous Journey. Small Wages, Bitter Cold, Long Months of Complete Darkness, Constant Danger, Safe Return Doubtful. Honour and Recognition in Case of Success.”

Twenty-eight men signed on. If Stone has his way, we’ve no doubt there will be men and women who will be ready to join him. Is it lunacy? Of course it is. But then again, perhaps the Great Age of 21st Century Space Exploration is about to begin. Thank heavens for lunatics like Stone.