Tuesday, August 30, 2005
Astronomers are debating what to do about Earth's close encounter with an asteroid in 2029 and again in 2036 - passages that might be too close for comfort.
Apophis, a 1,059-foot-wide asteroid, has excited astronomers since it was spotted last year. After observing it for a while, scientists concluded that it has only a 1-in-8,000 chance of ever smacking into Earth. But even that slim chance has them talking and NASA pondering how to keep track of it - just in case.
"The most likely turn of events is that it will miss us," says Steve Chesley of NASA's Jet Propulsion Laboratory in Pasadena, Calif., which has monitored the asteroid since December as part of its normal watch over "near-Earth" asteroids. "We are prepared for the worst but certainly don't want to act too hastily."
Precisely how are they "prepared for the worst"? Actually, they aren't. They are full of horse pucky. They are merely proposing to put a transmitter on Apophis so that they can keep tabs on whether the odds of it hitting Earth go up.
The key question about Apophis is whether its 2029 trajectory will go through a roughly 2,000-foot-wide region called a "keyhole," says astronomer Clark Chapman of Southwest Research Institute in Boulder, Colo. If it passes through that region - that one-in-8,000 chance - its course would be deflected to make an impact with Earth in 2036 very likely, he says.
This asteroid passes near Earth every seven or eight years, but the 2029 trajectory is expected to be its closest approach. In the petition, Schweickart warned that waiting for better estimates of Apophis' likely path in 2020, after another flyby of Earth, would leave little time to deflect the asteroid away from the keyhole.
Don't worry, though. An asteroid of this size will leave a crater of only two miles in diameter. Of course, the collateral damage from the impact could have global consequences, but hey, there's only a 1 in 8,000 chance.