When Asteroids Attack: Will Killer Rocks Hit the Earth?

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In the most famous example of rock-on-rock catastrophe, the Earth was slammed 65 million years ago by a massive rock formation that created an enormous crater in the Yucatan Peninsula and probably caused the extinction of the dinosaurs. Everyone recognizes the devastating effect of the dino-death asteroid, Jaroff points out, but many people are still hesitant to assign any real significance to asteroid studies. "The scientists who began looking for information back in the 1970s were hamstrung by a general lack of funding. They were greeted in Congress by giggles."

This reaction, while not uncommon, is not realistic given the history of serious collisions, says Jaroff, and the possibility of future events. "We now have a catalog of 200-odd asteroids more than a kilometer across whose trajectories bring them very close to Earth's orbit. A piece of rock that's a kilometer or larger would have worldwide consequences if it hit the planet." Specifically, the sky would go dark with ash, plant life would die and existence would be generally much less enjoyable. And even if a relatively small asteroid were to make contact with a major metropolitan area, Jaroff says, the resultant injury would not be wholly dependent on the rock's size. "An asteroid 300 yards across would cause immense damage in a large city. The speed at which these things travel means that if one came to a sudden stop, as in a collision, the energy of the speed would be converted into almost inconceivable amounts of heat."

The force of these grim tidings is tempered by the knowledge that U.S. government agencies have been working alongside the country's most prestigious research facilities to conjure up ways of dealing with these hurtling rocks should an asteroid ever establish itself as a threat. "Once they've identified the asteroid," Jaroff says, "scientists can predict years, even decades ahead of time whether it will intersect the Earth's orbit at a moment when the Earth is there." And should scientists discover such a scenario looming on the horizon, Jaroff says there are many ways to engage, deflect or destroy the giant rocks, including the controlled use of nuclear bombs, whose blasts could nudge the asteroids off their collision course with Earth. While all this research costs a taxpayers pretty penny, Jaroff points out the money is really pretty insignificant, especially when "the alternative is total annihilation."

This is a case where the public and scientists search for a state of mind that eschews panic but retains its focus. The chance of a truly devastating asteroid hitting the Earth is "small but real," says TIME science writer Jeffrey Kluger. "But let's face it," he adds, "it's like a big billiard table out there," with rocks and planets and moons zipping around each other in space. Some folks may never admit that there is any risk, and reject the need for taxpayer-funded research: Even after the widespread success of the summer disaster movies, "Armageddon" (which Jaroff calls "ridiculous") and the "far more realistic" "Deep Impact," legions of nonbelievers remain. And while Jaroff sometimes finds it difficult to educate the most die-hard skeptics of the real risk posed by asteroids, he keeps trying. "I used to tell people that even if an asteroid were to break into relatively small pieces, each of those pieces would have the power to destroy Cleveland. But," he muses, "no one seemed to care."

NASA's Asteroids and Comets Fact Sheet