An unwelcome visitor

Did you ever sit alone, staring at an absolutely still pond? Most of us have. Most of us have also tossed a pebble into that pond, just to stir things up a bit. We watched the ripples spread out in all directions, on and on, with unforeseen effects on objects in their path. If the pond was wide enough, and the pebble large enough, disasters perhaps occurred to tiny objects, unsuspecting little "people," far from the original impact, long after the pebble was thrown.

Located between the orbits of Mars and Jupiter is the band of asteroids. About 160 million years ago, an asteroid about 110 miles in diameter was hit by a smaller asteroid, causing it to shatter. Some pieces flew off in all directions, but most remained in the same general area, creating the Baptistina family of asteroids

One piece that went astray is now believed to have created the "Cretaceous-Tertiary extinction event," ramming into the earth in the Yucatan peninsula in Mexico about 65 million years ago -- nearly 100 million years after the original collision of asteroids. The fragments from the Yucatan impact have the same mineral composition as the Baptistina asteroids. That impact's effects on the planet are believed to have wiped out Earth's population of dinosaurs.

The gigantic Tycho crater near the Moon's south pole is believed to have been created by impact from another Baptistina fragment, 108 million years ago.

Even small asteroidal fragments can cause great damage when hitting a planet at full speed. An extraterrestial object, about 100 to 200 meters in diameter, exploded in the atmosphere over an unpopulated area of Siberia on June 30, 1908. The explosion had a power one thousand times that of the atomic bomb dropped on Hiroshima, and knocked down trees over 830 square miles.

Which now brings us to the asteroid Apophis, aptly named after an Egyptian god of destruction, discovered only in 2004. It's about 350 meters -- nearly four football fields -- in diameter. It weighs a lot, as you might guess. On April 13, 2029 -- 22 years from now -- it will pass so close to the Earth as to fly by below the orbits of the communication satellites circling our planet. At present, scientists do not think it will actually strike the Earth, but of course it's hard to be too certain about differences of a few miles in orbit, expected to occur 22 years from now. The results would be devastating if today's scientists are wrong.

Suggestions have been made that we send up a space probe, destined to encounter Apophis in 2014, that would keep an eye on it for about three years. This period of watching would give our best scientific brains about 15 years to figure out what to do, if a reasonable chance should then appear that "little" Apophis would drop in for a visit, via crash landing.

The best way to handle such a problem would be to somehow nudge the asteroid into a slightly different path, one that would cause it to sweep by a decade or so later at a more comfortable distance from your and my homes. Nudging an asteroid out of an existing orbit isn't all that easy, of course. It's never been tried before. It's sort of like using a fishing boat to nudge an oil tanker onto a different course in mid-ocean. But rest assured that the good people at NASA are mulling over the situation, even as we speak.

But aside from the scientific and engineering questions raised by such a threat, think of the psychological implications should we learn in 2014 that Apophis had plans for a terrestial visit in 2029. Democrats couldn't blame the problem on the Republicans. Americans couldn't blame it on the Arabs. The Senate couldn't hold endless hearings on the issue, hoping that it would just go away or people would lose interest in it. We couldn't just turn off our TV sets and think about our golf games. It wouldn't be a communist plot. We couldn't exercise our normal foreign policy solution of bombing the asteroid back to the dark ages -- any attempt to blow it up would cause it to shatter, and Earth would be subjected to a devastating solid rock hailstorm.

Nope, somehow the human race would have to sit down together and work out a plan that would save all of us -- not just our friends and ideological allies -- not just the rich -- not just the Christians -- not just the white race -- from a virtually certain collision that might well send us all off to the same happy hunting ground in which the dinosaurs found themselves 65 million years ago.

Who knows? The experience might cause a spiritual revolution. After experiencing success working together to save ourselves and all our diversity of cultures from common annihilation, we just might all be able to sit down and work together to solve other, lesser problems in the future.

But don't bet the family store on it.