A Megaton Distraction - asteroids divert from more immediate dangers - Brief Article

FEAR OF AN ASTEROID STRIKE, SAYS PETER BUNYARD, MAY BE IRRELEVANT IF WE DON'T ATFIEND TO MORE PRESSING MATTERS.

TRUE, THE EARTH has been struck untold times by rocks hurtling into it over the past few billion years: true, when the rocks have been the size of Everest they have brought about mass extinctions. True too, in a bizarre twist of fate, we probably owe our existence to the asteroid that struck off the coast of Mexico's Yucatan some 65 million years ago. That blast, equivalent to some 10 million atom bombs, put paid to the dinosaurs, leaving the small, seemingly unobtrusive therapsid prototype mammal just scraping through. Lucky us and our fellow mammals, for suddenly the field was clear for our own explosive evolution. But for how long can we expect our luck to hold before it's our turn to be obliterated?

Who knows, the asteroid with our number on it, may already be lined up on a collision course with the earth, spinning its way towards us, until it gets caught in our gravitational field, accelerating faster and faster towards us until it is travelling at thousands of miles an hour before impact. But should we really be worrying about such an event? Well, according to the statistics we should be getting our knickers in a twist. In fact, says Duncan Steel, of the University of Salford and an expert in space technology, we face a considerably greater risk of being wiped out by an asteroid than of dying in an airliner, a risk about three times greater. It's the one-off event that virtually takes all with it that gives the statistics the twist and makes the asteroid the bigger risk. In historical times we have records of asteroid strikes, the most recent being the 15-megaton event that in 1908 flattened a 5,000 square kilometre swathe of forest in Siberia, and which would have completely taken out a city the size of London, were its course just a little different. And tens of thousands were killed by an impact over China in the 15th century.

Each year some 40,000 tons of fine debris get burnt up in the atmosphere. But it's the bigger bits that are the worry. On average we get struck by a rock 100 metres wide every 10,000 years and by one a kilometre wide every 100,000 years, equivalent in impact to thousands of hydrogen bombs and enough of an explosion to take out a good chunk of the human population. All too real, and a government task force led by Harry Atkinson, who has worked both for the European Space Agency and NASA, has now come up with its recommendations that we help set up a surveillance system of telescopes to keep watch over the heavens for unwelcome fragments from space. Then what? Perhaps Bruce Willis and Armageddon were not so fanciful after all.

The scientists concerned with the dangers from asteroids may be sincere in urging us and governments to take the risks seriously. But what we are really talking about is space war technology, no less. And who do we trust with both the development of that technology and the means to deploy it? Will Russia and China, or anywhere else in the world accept that the United States is forging ahead with 'Star Wars', simply to protect the rest of us? Or will we have to create a new role for an organisation such as the United Nations to be the guarantor that any such technology will be used for peaceful purposes only?

The mind boggles as to the implications of a war on asteroids, and in this cynical world, it is easy to imagine that the United States will relish the newfound earth-saving justification for nuclear weapons, as indeed may Russia, Britain, France, China or even India and Pakistan, let alone Israel and Iraq. At the same time, the statistics, as put out by Duncan Steel and the task force, are not particularly fruitful, since they indicate that unless we achieve a virtually impregnable earth defence system, it really doesn't matter what we do, for all is likely to be blown away in the twinkling of an eye. And just imagine the US, or whoever, unleashing a bevy of missiles, supposedly on the pretext of defending us all, and what that would mean for trigger-happy defence systems.

But should we really be comparing the statistics of dying in an air-crash with those of annihilation from an asteroid? If we had any sense, we should rather be comparing the likelihood of destroying our fellow creatures and ourselves in a series of climatically-induced waves of extinction than worrying about what was like to fall in on us from space. The reality is that we are rapaciously destroying ecosystems and burning fossil fuels as if there were no tomorrow.

But, of course, concern over a Heaven-sent apocalyptic end to the earth is a powerful distraction from such mundane matters as fuel taxes, the World Trade Organisation and the occasional violent storm. Surely, before we start burying our heads in the stars we need to keep our feet on the ground and get our own house in order.

Peter Bun yard is the science editor of The Ecologist. His latest book is The Breakdown of Climate (Floris Books, [pound]9.99).

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