In the movie Armageddon,an asteroid the size of Texas is hurtling towards Earth.

All seems lost, but then Bruce Willis sacrifices his own life to detonate a thermonuclear bomb on the asteroid.

<detonation movie clip> Then you hear this from mission control:<"The two halves are going to miss us by 400 miles,and most of the small particles have been vaporized!" > Breaking a rock that big into two halves,that somehow miraculously dodge the Earth?

A bit of Hollywood magic.

But scientists are studying what would really happen in such a scenario.

"A big part of what we do is looking at how things break.

Smashing things together and what happens after that." Charles El Mir is a mechanical engineer who studies planetary science at Johns Hopkins University.

He and his colleagues modeled what might happen if you smashed up a 15-mile-wide asteroid, made of basalt.

They started by assuming the asteroid has some tiny cracks already running through it, based on studies of real rock.

Then,they struck the hypothetical space rock with another, smaller rock—just a mile wide—hurtling towards the asteroid at more than 11,000 miles per hour.