Aardvark Daily

The world's longest-running online daily news and commentary publication, now in its 30th year. The opinion pieces presented here are not purported to be fact but reasonable effort is made to ensure accuracy.

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The sky really is falling

3 December 2008

Around a week ago a meteor, believed to weigh as much as 10 tonnes, streaked across the night skies over Canada before breaking up and plunging to the ground in smaller fragments.

There's nothing too unusual in this, one only has to spend half an hour or so outside on a clear moonless night staring up at the blackness to realise that meteor trails litter the heavens. And that's because the planet is constantly being bombarded by tiny chunks of flotsam from space.

Fortunately for us, the vast majority of these bits of space-rock are so small that they are quickly vapourised by their brief encounter with the earth's atmosphere and thus pose no risk to those living below.

However, as witnessed by the number of very large impact craters that can be seen around the world, and events such as that in Tunguska early last century, some are much larger.

Of course sci-fi writers and movie-makers have loved to ponder the prospect of earth being threatened by a meteor or comet large enough to wipe out a significant amount (or all) of the life on Earth.

Heroic actors such as Bruce Willis are frequently portrayed as saving the planet thanks to clever technology and huge acts of heroism, but can we really save ourselves from annihilation if a big space rock is on an intercept path with our fragile blue sphere?

Well maybe they've been watching too many Hollywood blockbusters, but the United Nations leading asteroid scientist seems to think we might have a chance.

Professor Richard Crowther is pushing for global cooperation on dealing with the inevitable threat that such potential impacts represent and he'll be addressing the UN in February when they meet to discuss the issue.

So just how long before we find ourselves on-course to be smacked by a huge asteroid?

Well the Association of Space Explorers, a group composed largely of scientists plus a few former astronauts thrown in for good measure, claims that it could be in less than 20 years. They point to a predicted "close encounter" with the asteroid Apophis which is due to pass very close to earth at that time and set the odds of an actual collision at just 45,000 to one.

Now the big question is "just what can be done to avert disaster?"

Well apparently, we only have to worry about those bits of space-rock that are at least 200m across. Anything smaller will be either totally ablated by its encounter with the atmosphere or will likely break up into comparatively harmless small fragments before reaching earth's surface.

That does, of course, still leave the issue of how to avoid becoming a celestial snooker ball when something bigger comes along.

At this stage, the only really viable option seems to be to detect potential threats early enough that we can use gravity or some kind of comparatively gentle force to change the asteroid's path enough to miss the earth.

Right now it would appear that we simply don't have the technology required to perform this "course adjustment" so we're stuck with just keeping an eye-out for incoming objects.

Perhaps the single largest dilemma that will face any group that is charged with responsibility for detecting such objects is what to do if they find one. Should they just keep their fingers crossed and hope it misses -- or should they warn the world that a good number (if not all) of us are due to become space-toe-jam?

So, next time you see a shooting star flash across the heavens, make a wish...

Wish that the really big ones miss us by a wide margin, because there's nothing we can do if they don't.

Is it even worth us having an early-warning system to detect objects on a collision course for planet earth?

What practical good would such a system serve?

What would you do if you were told that earth was going to be hit by a massive chunk of space rock in 48-hours time and there was nothing that could be done to stop such a collision?

Have you thought about such a possibility? Have you made plans?

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