The Not-So-Near Miss - media coverage of asteroids - Brief Article

THE NEWSLETTER of the Central Bureau for Astronomical Telegrams in Cambridge, Massachusetts, doesn't reach many people. But it contained a brief announcement in March that grabbed the world's attention, at least for a few days, inspiring headlines like ASTEROID ZEROES IN ON EARTH.

Astronomers at the Cambridge, bureau reported that an asteroid discovered in December 1997 called 1997 [XF.sub.11] might come within 30,000 miles of us in late October 2028. "The chance of an actual collision is small," the astronomers wrote, "but one is not entirely out of the question."

Even as the ink was drying on the headlines, however, astronomers across the country were scrambling to double-check the calculations. And as predictions of the asteroid's path were refined, it turned out that 1997 [XF.sub.11] would miss us with 600,000 miles to spare--well outside the moon's orbit.

So what happened? Did someone forget to carry a 1 when making the initial calculation? Actually, nothing "went wrong." Instead this was an unusually public example of how astronomy works: observations lead to calculations that lead to new observations and refined calculations. "No scientific mistake was made," says Brian Marsden, whose March announcement touched off the controversy. "We simply reported that, based on the information that was available, this is what you get."

Marsden says he wanted to get the attention of astronomers who might inadvertently have photographed the asteroid in the past. (In fact, two groups had images from 1990 that helped pin down the asteroid's orbit.) And without this additional data, Marsden says, it would not have been possible to rule out a collision, if not in 2028, then sometime in the 2030s or 2040s.

The only problem was that much of the refining was done in the media spotlight, with developments and conflicts greatly exaggerated in the reporting. For example, while 1997 [XF.sub.11] is not going to hit Earth in 2028, it often goes unreported that it will get closer to us than any currently known large asteroid in the next 80 years. And although in the aftermath of all this publicity NASA played up the doubling of its funding for the search for near-Earth asteroids, the $3 million commitment scarcely seems sufficient to some astronomers. James Scotti, who discovered 1997 [XF.sub.11] while working on the University of Arizona's Project Spacewatch, says, "Our budget is about $1 million or $2 million a year. If everybody who went to see Armageddon and Deep Impact put a dime into a bin, we'd be able to complete our survey in no time flat."

If movies are any indication, death by asteroid would seem to have risen on the list of societal fears. Based on the number of ancient craters on Earth and on the moon, astronomers estimate that asteroids big enough to wipe out humanity probably hit Earth every few tens of millions of years.

Of course, just because 1997 [XF.sub.11] isn't going to smack Earth doesn't mean that another asteroid won't. Although there are believed to be some 2,000 objects a mile across or larger that intersect Earth's path, astronomers have charted the orbits of fewer than 200. Without a larger early-warning network of observers, Scotti warns, if we do have a date with destruction some time in the future, we may not find out until it's too late.

COPYRIGHT 1999 Discover
COPYRIGHT 2000 Gale Group