LAST week we talked about a few of the doomsday scenarios that gullible people will believe – like the world will end in three months because the Mayans said so (they didn’t), or that the world will end because the magnetic poles might flip (they’re in the process of flipping right now and I haven’t noticed the world ending).

But there is one doomsday scenario that WILL happen (we just don’t know when) and that’s when the Earth is smacked by a really big rock. The last time it happened, it took out the dinosaurs and it WILL happen again. There are lots of big rocks out there with “Earth” written right across the front. (And in case you’re particularly gullible, that last sentence was hyperbole. There are NO big rocks with “Earth” written on them!)

So, what do we do about it? Well, despite all the movies, you do NOT blow ‘em up with nukes. That just creates a lot of little rocks and instead of a big splash, you get a ring of destruction that goes all the way around the Earth.

And of course, the other problem is, ‘How do you find them?’ Space is big and dark, and so are these rocks. Most of them are blacker than charcoal and with our current technology, by the time we see them, you might as well kiss your dåggan goodbye.

But researchers at the University of Strathclyde in Glasgow are developing an innovative technique based on lasers that could deflect a small asteroid – even when it’s quite close to Earth. They propose a swarm of relatively small satellites flying in formation and cooperatively firing solar-powered lasers at an incoming asteroid.

This approach targets the asteroid at close range. Unfortunately, the use of high power lasers is in its infancy and one of the main challenges will be to have high power, high efficiency and high beam quality all at the same time.

These lasers would be aimed at rocks about the size of a football field or smaller. It’s estimated that a rock this size caused the Tunguska event over Siberia early in the 20th century. Rocks like this hit Earth every few centuries and if one comes in over a large city, a lot of people will die.

The Earth runs over about a thousand rocks a day and most of them are the size of sand grains. About once a century, we get hit by a ‘Tunguska rock’ and 65 million years ago a rock about the size of central Guam took out the dinosaurs. The bigger the rocks are, the less frequently we encounter them with disastrous results.

We could reduce the impact of the smaller rocks with a flotilla of small agile spacecraft each equipped with a highly efficient laser. This is more feasible than detecting them early enough to deflect them farther out, and costs less and is more efficient than a big rock-killing spaceship. And probably more important in the long run, these small spacecraft could conceivably also be used to remove man-made space junk.

The number of orbiting objects now classified as debris is increasing exponentially and the researchers feel that space-borne lasers could be used to lower the original orbit of the space debris and reduce the congestion.

And ZAP, there goes another one!