Brian May, the longtime guitarist of the rock band Queen, is also an astrophysicist. He started his career, in 1970, as a Ph.D. student at Imperial College, London, but four years later, after Queen released its second album, he put his studies on hold. In 2008, he finally finished his doctorate, with a thesis on zodiacal light, the faint patch of interstellar radiance that’s sometimes visible on the horizon at night. Last Wednesday, May joined Lord Martin Rees, the U.K.’s Astronomer Royal, at London's Science Museum to discuss asteroids and the threats they pose to life on Earth.

“The more we learn about asteroid impacts, the clearer it becomes that the human race has been living on borrowed time,” May said. About a million near-Earth asteroids are thought to be on a possible collision course with our planet, but only ten thousand or so have actually been charted. May and Rees were among a hundred scientists, astronauts, artists, and technologists calling for a worldwide campaign to identify, and eventually deflect, these asteroids. “In astronomical terms, this is very down home, very much on our back doorstep,” Rees said. The advocacy campaign is united around what is known as the 100x Declaration, which aims to persuade governments and the private sector to discover and track a hundred thousand asteroids each year over the next decade. The declaration calls for the adoption of a global Asteroid Day on June 30, 2015, the hundred and seventh anniversary of the Tunguska event, in which a small asteroid exploded over Siberia, destroying eight hundred square miles of remote forest and releasing a hundred and eighty-five times as much energy as the atomic bomb that was dropped on Hiroshima.

The timing of the press conference was fittingly premature; May and Rees were promoting a ceremonial date—not even an event—that was itself many months away. Space exploration, with its vast distances and time lags, is an exercise in delayed gratification. The night before the Science Museum summit, to great fanfare, Japan launched the Hayabusa 2, a spacecraft that will land on an asteroid, deploy three exploratory rovers, and return samples to Earth for study. It won’t enter asteroid orbit until 2018, and isn’t due back until 2020.

Puny and remote as they might seem, asteroids are commanding increasing attention on Earth, not only as threats but also as destinations. Asteroids are the solar system’s most veteran castaways: rocky bodies, in orbit around the sun, left over from the formation of the solar system. Too small to be planets, too big to be ignored, they can reveal a great deal about our primordial history. Asteroids are also thought to be rich in water and metals such as nickel, platinum, and cobalt. Private companies with names like Planetary Resources and Deep Space Industries are attempting to mine some of these objects as they career through space. Their plan is to send out surveyors—small automated spacecraft—followed by multi-ton extractors, which will harvest material and secure it for processing. (Water, for example, could be broken down into its component elements of hydrogen and oxygen and used to fuel rockets.) Some experts say that mining could be a reality within the next decade or so. In this vision, asteroids may serve as way stations of sorts, supplying fuel and other resources for missions deeper into space. “Think of asteroid mining this way: it’s the Internet in 1986,” Rosanna Sattler, a space-law expert based in Boston, told me.

Asteroids also fill an existential void. For much of the time since the United States first entered space, we have been at a loss for what, exactly, to do up there. The moon has lost its lustre and is costly to reach, and a manned mission to Mars—the only remotely habitable destination in our solar system—is decades away, at best. Shortly after President Obama took office, in 2009, he sought to eliminate projects that relied on expensive, heavy-lift rockets; this included the Constellation program, which had, as one of its goals, a human landing on the moon by the twenty-twenties. The political blowback was even fiercer than expected. Senators in Florida and Texas clamored to save jobs at plants that risked being shuttered. Stalwarts at NASA and the State Department smarted, as did the international community, which had long focussed on returning to the moon. The Administration was politically exposed: in nixing plans to visit the moon, it couldn’t immediately point to a new destination for government-led space travel. Recognizing his vulnerability, Obama asked the Office of Science and Technology Policy, his advisers on science and space matters, to identify another place for the agency to go.

The answer, in short order: asteroids. On April 15, 2010, Obama delivered an address at the Kennedy Space Center, in Florida, to make the case. “I just have to say pretty bluntly here: we’ve been there before,” the President said, of the moon. “We’ll start by sending astronauts to an asteroid for the first time in history.” Last year, NASA announced the creation of the Asteroid Redirect Mission (ARM), which aims to identify a near-Earth asteroid, capture it, bring it into steady orbit around the moon, and then send astronauts to explore and analyze it. (The capturing phase is due to launch around 2019.) David Gump, the vice-chairman of Deep Space Industries, which was recently awarded two contracts to consult on how to complement ARM with “private-sector initiatives,” sees the program as critical to another of Obama’s proposals—getting a manned orbital mission to Mars within the next two decades. “It’s extremely costly—and unwieldy—to pack a giant rocket with enough fuel to get to Mars,” he told me in an e-mail. If NASA could use fuel that’s already in space—mined from or stored on an asteroid—its Mars program would stand a better chance of sticking to its budget.

“Those who say we’ve got to go back to the moon, instead of an asteroid, well, show me the money,” Senator Bill Nelson, the chairman of the Senate’s space-science subcommittee, told the Times last year. “With the money that’s being allocated, you’ve got to do what you can with the resources that you have.” The asteroid mission is meant, in part, to help train NASA in handling heavy objects in space, which could also entail warding off asteroids.

Still, the fate of the asteroid program is as precarious as ever, particularly after last month’s midterm elections. In the past, NASA’s most ambitious plans have generally evinced bipartisan support and healthy budget allocations, but in January Nelson will be succeeded by Ted Cruz, the Texas Republican whose reputation precedes him; his allies have roundly dismissed NASA’s asteroid program as a “costly distraction.” By contrast, Nelson, a former astronaut, has gone further even than NASA in touting the benefits of asteroid hunting. If the specimen that NASA corrals under the auspices of ARM ends up being interesting, he told the Times, “then we’ve got the possibility of the science of mining an asteroid.”

For now, asteroid mining is strictly the province of private companies such as Planetary Resources, whose investors include Ross Perot, Jr., Richard Branson, and Google’s Eric Schmidt and Larry Page. “Planetary Resources is the new Dutch East India Company,” Sattler said. Chris Lewicki, the president and chief engineer of Planetary Resources, likens asteroid mining to the California gold rush and the exploration of the American West. Now, as then, government ability lags behind that of the pioneers. “We can adopt newer approaches than NASA,” he told me. “NASA is a large, bureaucratic government entity—it couldn’t do this.” Lewicki pointed out that the NASA computer running Curiosity, the two-and-a-half-billion-dollar rover on Mars, is more than twenty years old. “My cell phone has more computing power,” he said. Planetary Resources was on the verge of starting its long-term mining mission with the launch of Arkyd 3, a satellite about the size of a loaf of bread, which was to conduct preliminary flight tests and beam back results before burning up on reëntry into Earth’s atmosphere. But, on October 28th, the satellite was lost when the Antares rocket that it was aboard exploded shortly after takeoff. The company is retooling, and is optimistic about sending off another satellite by next year, a company spokesperson told me, though the loss was draining. There’s a saying about private enterprise in space: the fastest way to become a millionaire is to invest a billion dollars.

Last fall, a piece of legislation called the American Space Technology for Exploring Resource Opportunities in Deep Space (ASTEROIDS) Act floated through the House but stalled in committee. Its aim was to create a legal framework in space so that private companies could mine asteroids without worrying about having to relinquish the stuff they harvest. (Existing laws are essentially silent on private-property rights so far from home.) The act was seen less as a serious legal proposal than as an overture to the private sector. “For years, asteroids have been the orphans of outer space,” Gump, of Deep Space Industries, told me. At last, they’re being claimed—in name, if not yet in body. Martin Rees, the British astronomer, is dubious about the prospect of mining asteroids (“It’s rather shaky economics,” he said at the Science Museum), although he does want to “find common cause” with private ventures if it means charting more asteroids. “We’ve got to find the asteroids first,” Brian May said—before they find us.