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Researchers plan for global armageddon threats

It's no ordinary meeting when a bad decision could spell global catastrophe. For the experts assembled at a conference hall in Italy this spring, the choices were agonizing. A gigantic space rock was bearing down on Earth. If it slammed into the planet, it could damage an area the size of Ireland. But a campaign to push the rock, known as an asteroid, off course could shatter it, possibly widening the devastation, if not done correctly.

The officials opted to shift the monster's path, and it prevented unfathomable devastation. There was just one small problem: a chunk of the asteroid broke away and made a beeline for Bangladesh.

The looming space rock was imaginary — and utterly realistic. Researchers crafted every last detail of the scenario, which was unveiled at a scientific meeting to test how the world would respond to an incoming asteroid. And it was only one of a slew of recent efforts to ensure that if a dangerous asteroid takes aim at our planet, it won't catch us unprepared.

While it may sound like science fiction, real researchers are designing asteroid deflection tools and sketching out rocket missions to large space rocks. A pair of telescopes slated to come online by the end of 2015 will give humanity a last-minute alert of an invader headed our way. Big telescopes are already scanning the sky to give us longer warning times. Scientists and others declared June 30 the world's first "Asteroid Day" in hopes of raising public awareness of the threat even further.

After decades of skepticism, "there is real planning going on, and we're actually making progress," says the University of Hawaii's John Tonry, head of the late-alert telescopes. "People are starting to realize that it's not just a totally stupid idea that an asteroid might cause big damage."

As if to prove the point, a space rock exploded over Chelyabinsk, Russia, in 2013, shattering thousands of windows and inflicting sunburns on unlucky observers. Yet the Chelyabinsk asteroid, at 55 to 65 feet, was a trifle. More than 600,000 asteroids that swing close to Earth are 150 feet wide or bigger — big enough to destroy New York City in a direct hit.

Scientists are trying to ensure nothing sneaks up on us. Observatories in Hawaii and Arizona, among others, sniff out large asteroids on a dangerous trajectory. Tonry's telescopes will give a week's warning for a swimming pool-sized rock on its "final death plunge," he says, and will also will spot asteroids far in advance of their passage close to Earth.

If something big does come this way, researchers are working on the "death ray" technique, as it was dubbed on Twitter. Still in early testing, it would send a spaceship to aim powerful lasers at an asteroid's surface. The jet of vaporized debris would propel the rock out of its original path.

"You don't carry the propellant to the asteroid. … We use the asteroid itself as fuel," says designer University of California, Santa Barbara physicist Philip Lubin.

There's also the Hypervelocity Asteroid Intercept Vehicle, which would carry a nuclear bomb to shatter the asteroid into harmless bits. Researchers have calculated that, in theory, a rocket now commercially available could ferry the proposed spacecraft to an asteroid while it was still a good distance from Earth, even with only a few hours' warning.

"We're preparing ourselves in case we don't want to take the hit," says NASA Goddard Space Flight Center's Brent Barbee, who helped analyze the vehicle's abilities. "We've checked that box."

Nudging asteroids off course would be less spectacular but possibly just as effective, at least if there's plenty of warning. For this "kinetic impactor" method, a massive spaceship slams into the asteroid's surface at more than 20,000 mph, pushing the rock onto a new path through the solar system. A spaceship that's too small or too slow would botch the job, so researchers have been laboring to predict how a collision affects rocks of different shapes and compositions.

They've learned, for example, that compared to a solid asteroid, a fluffy one will demand a harder hit from either a bigger spacecraft or several smaller ones. It's also becoming clear that whacking a smallish asteroid with too much force could break it into a flying debris field that might be more dangerous than the original body.

"We have made definite progress … and have narrowed down the possibilities of what would happen," says University of Washington planetary scientist Keith Holsapple. The recent research "gives us a much better idea of what we can do, what our limits are."

Recent analysis has given us "a bit of a head start," agrees Mark Boslough of Sandia National Laboratories in New Mexico. "If we were going to make it up from scratch, it would take more time."

Luckily these rocks, though numerous, don't dive to Earth often. An object that could obliterate a city hits Earth, on average, only once every 500 years or so, Boslough says. Most such outer-space visitors will plummet into the sea or empty land. But given the damage one could cause, it's worth planning for, researchers say.

"This is probably the greatest natural disaster that is potentially preventable by our actions," says Paul Miller of the Lawrence Livermore National Laboratory in California. "If we were unlucky enough (to face) a very large object, it's a very serious matter, and you want to get it right."
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