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When Will an Asteroid Hit Earth? It's in the Stars

The possibility of a ruinous cosmic collision keeps space experts up at night. The means to protect us are available but problematic.

November 13, 2005|Marcia Dunn | Associated Press Writer

CAPE CANAVERAL, Fla. — Imagine last year's tsunami, last month's earthquake in Pakistan and hurricanes Katrina, Rita and Wilma all rolled into one -- and then some. If nations can't handle those calamities, what's going to happen when an asteroid collides with Earth?

In 30 years, there is a 1-in-5,500 chance that a specific smallish asteroid will hit a bull's-eye on our planet. At 360 yards wide, it could take out New York City and much of the surrounding area.

Fortunately, experts think further observation of the asteroid, 99942 Apophis, will almost certainly rule out an impact in 2036. Nevertheless, it's precisely that kind of predictable and preventable threat -- and the thought of being ill-prepared for it -- that alarms the world's normally intrepid spacefarers who are calling for action.

They issued an open letter at the Assn. of Space Explorers' annual congress last month in Salt Lake City, making a rare, united push for strategies and spacecraft to prevent a cosmic pileup.

Two of the astronauts -- Apollo 9's Rusty Schweickart and shuttle and space station veteran Ed Lu -- have helped establish a foundation on the issue.

"There are always natural disasters, and it always seems as though the preparation is somewhat less than adequate. But we have had a series of quite substantial ones here in the last year," Schweickart said in an interview with Associated Press.

Hollywood's depiction of cosmic collisions -- think "Armageddon" and "Deep Impact" -- has heightened public awareness, "but regrettably with the wrong solutions and over-dramatization," Schweickart said.

"You don't want to send up Bruce Willis and others to save us. That's Hollywood silliness," he said, chuckling. Instead, technology is far enough along that an asteroid could be deflected before hitting Earth, he said.

For now, the astronauts are being cautious in their approach.

"A lot of the folks working in this area are really attuned to not being Chicken Little, saying, 'Hey, this is going to kill us, it's going to kill us,' " Lu said. "That's not what we're saying. We're saying that you need to start thinking about it.

"The possible consequences are way worse than your run-of-the-mill natural disasters like earthquakes and tsunamis and hurricanes. As bad as they may be, this can dwarf them."

Astronauts know better than most just how small, fragile and vulnerable the planet is.

"When you go around it in an hour and a half, again and again and again and again, day after day, in some cases now, month after month after month, the Earth becomes a pretty small place," Schweickart said. "And then, of course ... most astronauts tend to be aware of things like asteroids and their impacts."

It's time, the space explorers say, for NASA to step up.

The association wants NASA to expand its Spaceguard Survey, a program that discovers and tracks near-Earth objects -- asteroids and comets -- that are at least two-thirds of a mile across. So far, 807 of an estimated 1,100 of these big, rocky asteroids have been discovered in the inner solar system along with 57 comets. NASA's Jet Propulsion Laboratory is plotting their future tracks.

An asteroid two-thirds of a mile wide, at impact, would be enough to take out a good-sized European country. By comparison, an asteroid or comet believed to be 6 to 7 miles across wiped out the dinosaurs 65 million years ago.

The space explorers want the many smaller, but still dangerous, asteroids tracked as well. Altogether, 3,611 near-Earth asteroids of all sizes have been discovered, with about 100,000 more capable of setting off a tsunami the size of the one in the Indian Ocean last December.

Scientists are carefully watching Apophis, which will whiz by Earth in 2029, passing within an unnerving 18,640 miles. That's a few thousand miles closer than many communications satellites and 220,000 miles closer than the moon. In 2036, the concern is that it will move in even closer, leading to the 1-in-5,500 chance it will strike.

For a few hundred million dollars, the astronauts say, NASA could launch a scouting mission to Apophis in the next decade or two to place a radio transponder on the surface and thereby plot its course. But Donald K. Yeomans, manager of NASA's near-Earth object program, contends that radar and telescope observations probably will rule out any risk of impact.

Schweickart agrees that based on the current odds, a deflection mission for Apophis would be a waste of money. "But the question is, do I agree with it when it's 1-in-100, when it's 1-in-50, if it's 1-in-20? That is a policy question. At what probability do you begin to spend hundreds of millions or billions of dollars in order to do something?"

That's not the only sticky policy question.

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