Killer Asteroids

NASA is widening their search for asteroids that threaten to hit Earth. Up until now, NASA was focused on searching space to find debris and rocks larger than one kilometer headed our way. Now that they have that under control, their new mission is looking for smaller space objects that could have a major impact here on earth.

From sci-fi to cold hard facts, the reality of it is that "we have about 100 tons of material hitting the earth's atmosphere every day," says astronomer Donald Yeomans. It's this mans job to track them and figure out a way to stop them!

"They run the gamut from wimpy excometary fluff-balls to shattered rock and solid rock to slabs of solid iron." Yeomans manages the Near Earth Object program at NASA's Jet Propulsion Laboratory. It's here where they track debris from outer space that could threaten us here on earth.

"Most of it is sand size and comes in as shooting stars. A basketball-sized object comes in every day creating a fireball. Volkswagen-sized objects come in a couple times a year. Some of them actually reach the ground."

The last impact -- October 2008. A meteorite the size of an SUV slammed into the Sudan desert. It was discovered just 20 hours before impact by telescopes in Arizona, Australia and Hawaii.

"They stare at a region of space and take an image and come back 15 minutes later and take another image. Fifteen minutes later, take another image," says Yeoman. If an object moves through the photos, it's an asteroid. But once one is discovered, how do you stop it?

"One of the simplest techniques is to run into it. If you hit it, you can speed it up and slow it down." But if that fails, they could use a gravitational tractor. "You can actually bring a spacecraft up next to it and use the gravitation attraction between asteroid and spacecraft which is thrusting and move it."

What are the chances of an asteroid, similar to the meteorite that hit Earth and destroyed the dinosaurs 65 million years ago, heading towards Earth anytime in the near future? "We're in charge of tracking them for at least 100 years into the future and so far there's no problem." But that can change in a flash.

Dr. Yeoman says these asteroids are not just flying debris. They are valuable, full of minerals, water and oxygen which could some day help sustain life in space or become fueling stations for inner-planetary travel.

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