Statistically, Earth is likely to be hit by an asteroid large enough to cause significant damage -- maybe not to the extent of wiping out most life on the planet, as was the case with the great extinction of some 250 million years ago, but it could wreak real havoc that mankind is unprepared to deal with.
It could happen tomorrow morning or not for another 250 million years, but the numbers say it's almost bound to happen and, as things stand, with little or no warning. A disturbing aspect of the spectacular explosion of a meteor over Russia last February was that no one saw it coming.
There are efforts underway to track near-Earth bodies whose orbits bring them close to our home planet, but they are uncoordinated and not a high priority with world space agencies.
Some may find this not altogether reassuring, but the United Nations is on the case. The General Assembly has approved formation of the International Asteroid Warning Group. So far it's an empty title, but we have to start somewhere.
The group's mission, according to accounts of the meeting that established it, is to act as a clearinghouse of information from nations or groups that have found potentially deadly asteroids or other space rocks.
Scientists really don't have a handle on the scope of the problem, but they know it's huge. The U.N., aided by private financing, hopes to launch an infrared asteroid-detecting space telescope in 2017. Former U.S. astronaut Fred Lu, a member of the warning group, noted: "There are 100 times more asteroids out there than we have found. There are about 1 million asteroids large enough to destroy New York City or larger."
Once discovered, there's the problem of what to do with a rogue asteroid. Given sufficient warning -- and, by that, scientists mean five to 10 years -- ramming it with a rocket or setting off a nuclear explosion should be enough to create a slight alteration in course that would cause it to miss Earth. Most recommendations so far similarly propose knocking the asteroid off course.
The most practical, detailed advice for dealing with a lethal and unavoidable impact, given the current state of the art, comes from former astronaut Rusty Schweikart: Make yourself a nice cocktail and go out and watch.
We hope the working group comes up with more practical plans for dealing with a killer asteroid than issuing endangered earthlings a bartender's guide.