The tech firm Deep Space Industries (DSI) is headquartered on the second story of an aging office building at the edge of NASA’s Ames Research Center, not far from the town of Mountain View, California. Established in 1939 as a laboratory for the National Advisory Committee for Aeronautics, a predecessor to NASA, Ames is now part government research site, part industrial park, and part open-air museum — visitors pass rows of decommissioned rockets and the hulking skeleton of Hangar One, where the Navy once parked its experimental blimps in the 1930s. Shimmering nearby in the Pacific coast sun lies the sprawling aerospace facility owned by Google’s Sergey Brin and Larry Page.

“The first time I came to Ames, I had the feeling I was standing between the history of spaceflight and its future,” Sagi Kfir, an aviation attorney, told me when I visited earlier this year. “You’ve got NASA labs here, but at the same time you’re in Silicon Valley,” he said. “Hard to think of a more exciting place to be.”

Kfir is 43, with a high forehead, tawny hair he wears tied in a bun, and the kind of leanness that comes from hours of yoga practice. (His wife, Britta, is an instructor.) Since 2012, he has served as DSI’s chief lawyer, a job that encompasses both legal-counsel duties — liaising with legislators, vetting contracts — and the full-time proselytization of his company’s mission: laying the foundation for an asteroid mining industry that one day will lead to a sprawling and profitable space economy.

To evangelists of asteroid mining, the heavens are not just a frontier but a vast and resource-rich place teeming with opportunity. According to NASA, there are potentially 100,000 near-Earth objects — including asteroids and comets — in the neighborhood of our planet. Some of these NEOs, as they’re called, are small. Others are substantial and potentially packed full of water and various important minerals, such as nickel, cobalt, and iron. One day, advocates believe, those objects will be tapped by variations on the equipment used in the coal mines of Kentucky or in the diamond mines of Africa. And for immense gain: According to industry experts, the contents of a single asteroid could be worth trillions of dollars.

Kfir pitched me on the long-term plan. First, a fleet of satellites will be dispatched to outer space, fitted with probes that can measure the quality and quantity of water and minerals in nearby asteroids and comets. Later, armed with that information, mining companies like DSI will send out vessels to mechanically remove and refine the material extracted. In some cases, the take will be returned to Earth. But most of the time, it will be processed in space — for instance, to produce rocket fuel — and stored in container vessels that will serve as the equivalent of gas stations for outbound spacecraft.

This possibility isn’t so unrealistic, Kfir said. Consider the recent and seismic growth of the space industry, he suggested, as we climbed the stairs to DSI’s second-floor suite. Every year, the private spaceflight sector grows larger, and every year the goals become grander. Jeff Bezos, founder of Amazon and the space exploration company Blue Origin, has spoken of the day “when millions of people are living and working in space”; Elon Musk’s SpaceX is expected to reveal a Mars colonization plan this year.

“But how are they going to sustain this new space economy?” Kfir asked rhetorically. He nudged open DSI’s office door. “Easy: by mining asteroids.” Bezos, Musk, and the other billionaires who plan to be cruising around space in the near future won’t be able to do so without celestial pit stops.

In his book, Asteroid Mining 101: Wealth for the New Space Economy, John S. Lewis, professor emeritus of Cosmochemistry and Planetary Atmospheres at the University of Arizona’s Lunar and Planetary Laboratory and DSI’s chief scientist, envisions a future where “ever more remote and ever more massive reservoirs of resources” take astronauts farther and farther from our planet. “First to the Near Earth Asteroids and the moons of Mars, then to the asteroid belt, then to…[the] Trojan asteroids and the outer moons of Jupiter, then to the Saturn system and the Centaurs,” and so on, to infinity.

Copies of Lewis’s book lined two shelves in DSI’s headquarters, where the vibe was more nerd lair than sleek startup. A poster for the new Star Wars movie hung on a wall; a chunk of real meteorite, found over a century ago in Namibia, stood on display; and cans of Coke cluttered the snack table. Working inside what appeared to be an old utility closet, chief engineer Grant Bonin hunched over a desktop computer, designing the code that will help power the first asteroid probes that DSI plans to launch in 2017. Behind him, an electrical panel spouted a bouquet of colorful wires.

Kfir pointed me in the direction of his office. A resident of San Diego, Kfir commutes once a week to Ames, 1,000 miles round trip, but if the constant travel was wearing on him, it didn’t show — his eyes were bright, his skin SoCal bronze. He wore slacks and a button-down, with cactus-patterned socks.

“You get used to the pace,” he said, taking a pull from a large coffee mug marked “Kiss my Asteroid.” “It’s the life of a startup. You go, go, go seven days a week. Because you believe.”

For now, belief — and a fervid sense of enthusiasm — represent the core of the DSI business model. After all, the company, and its only major competitor in the asteroid mining arena, Washington-based Planetary Resources, are dealing in hypotheticals: equipment that remains largely in the planning phase, a market that won’t fully emerge for years, if not decades, and a science that has yet to be tested in any meaningful way.

Perhaps it’s not surprising, then, that some critics have suggested Planetary Resources, which is backed by millions in venture capital — including cash from Eric Schmidt of Google — and the scrappier, less-moneyed DSI, are nothing more than vanity projects. Writing on the Discovery News website in April 2012, the month Planetary Resources co-founder Peter Diamandis unveiled his company’s mission, space journalist Ian O’Neill dismissed the venture as “deliberately vague (who knows how many technological iterative steps are needed before a sustainable mining operation can begin anyway?).” He also argued it was wholly unrealistic: “In short, the only thing that seems unique about today’s announcement is that a group of very well-respected and smart entrepreneurs and billionaires have clubbed together and thought asteroid mining seemed cool.” For O’Neill and other skeptics, asteroid mining is, for the time being, a glitzy but far-fetched venture that will distract both attention and dollars from eminently more achievable — and perhaps more scientifically vital — missions, such as continuing the exploration of Mars.

For the 12-person team at DSI, and the 50-person team at Planetary Resources, however, asteroid mining isn’t just a dream. It’s the future — one in which all those deep-pocketed private spaceflight companies (to say nothing of NASA) will be eager to pay by the bucket load for access to space’s riches. DSI and Planetary Resources, both of which are determined to profit from a 21st-century extraterrestrial gold rush, might be the equivalent of the mining barons of yore.

But first, they have to get to the rocks.