CHICKEN Little may prove to have been right after all, according to the august Economist. The sky, in the form of asteroids, has fallen in the past, and it could again. Foolishly, the British news weekly says in a lead editorial, we are ignoring a quantifiable threat that could be dealt with at reasonable cost.
In this century there has been at least one cataclysmic collision of an asteroid into the Earth -- June, 1908, in Siberia. A farmer 125 miles away was almost blown off his feet by what he thought was a sudden hurricane. Scientists now believe it was a relatively small asteroid exploding on contact with the atmosphere about six miles up. It leveled nearly 800 square miles of uninhabited forest and prolonged daylight for hours over London.
The odds are an impact like that will come once a century, and there's no guarantee the next one would be over uninhabited land. Collisions of much larger asteroids -- there's evidence of one two-thirds of a mile in diameter -- would be an unparalleled catastrophe with the destructive force of a huge nuclear weapon, the Economist says.
Sound far-fetched? Not so, the Economist says. Playing with probability calculations, a group of scientists told Congress last year that the odds over a person's lifetime were no greater than getting killed in an air crash. We spend tens of millions of dollars to assure our safety in the skies, yet we spend virtually nothing to assure our safety from the skies.
And it wouldn't have to cost all that much, the Economist estimates. A warning system of telescopes scanning the heavens for asteroids could be created for $10 million a year for the next 30 years. If a large one was found on a collision course with the Earth, a nuclear missile could blow it sufficiently off course to miss us.
The alternative? It could be the sort of sudden winter that wiped out the dinosaurs and 60 percent of all species millions of years ago.