The meteorite that rattled Siberia has suddenly brought new life to efforts to deploy adequate detection tools, in particular a space telescope that would scan the solar system for dangers.
For decades, scientists have been on the lookout for killer objects from outer space that could devastate the planet.
But warnings that they lacked the tools to detect the most serious threats were largely ignored, even as skeptics mocked the worriers as Chicken Littles.
No more. The meteorite that rattled Siberia on Friday, injuring hundreds of people and traumatizing thousands, has suddenly brought new life to efforts to deploy adequate detection tools, in particular a space telescope that would scan the solar system for dangers.
A group of young Silicon Valley entrepreneurs who helped build thriving companies like eBay, Google and Facebook has put millions of dollars into the effort and saw the shock wave on Friday as a turning point in raising hundreds of millions more.
"Wouldn't it be silly if we got wiped out because we weren't looking?" said Edward Lu, a former NASA astronaut and Google executive who leads the detection effort. "This is a wake-up call from space. We've got to pay attention to what's out there."
Astronomers know of no asteroids or comets that pose a major threat to the planet. But NASA estimates that fewer than 10 percent of the big dangers have been discovered.
Dr. Lu's group, called the B612 Foundation after the imaginary asteroid on which the Little Prince lived, is one team of several pursuing ways to ward off extraterrestrial threats. NASA is another, and other private groups are emerging, like Planetary Resources, which wants not only to identify asteroids near Earth but also to mine them.
"Our job is to be the first line of defense, and we take that very seriously," James Green, the director of planetary science at NASA headquarters, said in an interview Friday after the Russian strike. "No one living on this planet has ever before been hurt. That's historic."
Dr. Green added that the Russian episode was sure to energize the field and that an even analysis of the meteor's remains could help reveal clues about future threats. "Our scientists are excited," he said. "Russian planetary scientists are already collecting meteorites from this event."
The slow awakening to the danger began long ago, as scientists found hundreds of rocky scars indicating that cosmic intruders had periodically reshaped the planet.
The discoveries included not just those with obvious features, like Meteor Crater in Arizona, but also wide zones of upheaval. A crater more than 180 kilometers, or 110 miles, wide beneath the Yucatan Peninsula, in Mexico suggested that 66 million years ago, a speeding rock from outer space had raised enough planetary mayhem to end the reign of the dinosaurs.
Some people remain skeptical of the cosmic threat and are glad for taxpayer money to go toward urgent problems on earth rather than outer space. But many scientists who have examined the issues have become convinced that better precautions are warranted in much the same way that homeowners buy insurance for unlikely events that can result in severe damage to life and property.
Starting in the 1980s and 1990s, astronomers turned their telescopes skyward with increasing vigor to look for killer rocks. The rationale was statistical. They knew about a number of close calls and calculated that many other rocky threats whirling about the solar system had gone undetected.
In 1996, with little fanfare, the U.S. Air Force also began scanning the skies for speeding rocks, giving credibility to an activity once seen as reserved for doomsday enthusiasts. It was the world's first known government search.
NASA took a lead role with what it called the Spaceguard Survey. In 2007, it issued a report estimating that 20,000 asteroids and comets orbited close enough to the planet to deliver blows that could destroy cities or even end all life. Today, with limited financing, NASA supports modest telescopes in the Southwestern United States and in Hawaii that make more than 95 percent of the discoveries of the objects coming near the Earth.
Scientists lobbied hard for a space telescope that would get high above the distorting effects of the Earth's atmosphere. It would orbit the Sun, peering across the solar system, and would have a much better chance of finding large space rocks.
But with the United States immersed in two wars and other earthly priorities, the government financing never materialized. Last year, Dr. Lu, who left the NASA astronaut corps in 2007 to work for Google, joined with veterans of the space program and Silicon Valley entrepreneurs to accelerate the asteroid hunt.
The B612 Foundation refers to its planned telescope as the world's first private mission to deep space. Private groups, it says on its Web site, can carry out "audacious projects that previously only governments could accomplish -- and at lower cost."
The plan is to launch a large telescope known as Sentinel that can find 90 percent of the asteroids larger than 140 meters, or 460 feet, in diameter that pass through the Earth's part of the solar system. They also want to discover smaller asteroids down to a diameter of 30 meters.
Such asteroids are much bigger than the meteor that hit the atmosphere over Russia, and the telescope would thus be blind to those kinds of smaller threats.
Last October, the B612 Foundation, based in Mountain View, California, signed a contract with Ball Aerospace to create prototype sensors for the Sentinel mission. The space telescope is to have a diameter of 50 centimeters, or 20 inches. In theory, the system could be ready for launching by 2017 or 2018.
In an interview, Dr. Lu said the overall cost of the mission was now estimated at $450 million, which covers its launching, insurance and operations. The group, far from that goal, has been soliciting money from citizens.
The close approach to Earth of an asteroid named 2012 DA14 on Friday, as well as the much smaller object whose shock wave broke windows and bones in Russia, prompted thousands of hits to the foundation's Web site and Twitter account, said Diane Murphy, a spokeswoman for the group.
"Everybody is calling," she said. "They see us as the solution. They're saying, 'When are you going to have the telescope up?"'
B612 is just one player. Last April, Planetary Resources unveiled plans to mine asteroids that zip close by Earth, both to provide supplies for future interplanetary travelers and to bring back metals like platinum.
The venture attracted some big-name investors, including Larry Page and Eric Schmidt of Google. The company also has plans to develop telescopes that would hunt for rocky intruders coming near the planet.
Dr. Green of NASA said the agency was preparing to launch a mission in 2016 that will fly to an asteroid and, in 2023, return a sample to Earth for detailed analysis. The insights are expected to help scientists learn more about the makeup of the threats whizzing through the cosmic shooting gallery.
"If you're going to protect the planet, you have to know your enemy," he said. "You have to get up close and personal."