There are specific actionswe can take to watch and prepare for killer rocks from space.

Daniel Caton

Special to The Observer

Published: Tuesday, August 4, 1998

Section: VIEWPOINT

Page 11A

The students shuffled into the dome a little downbeat under the summer cloud cover. The two dozen 'freshmen preview' students were on campus early, getting a head start in July. A visit to the Observatory was squeezed into their schedule. Hoping for clear skies later, they sat on the floor and fired questions at me. And, for July 1998, the focus would be the killer asteroid movies. Were they realistic?

I explained my chagrin with those flicks, but perhaps not what they expected. The science was really not too bad, with the special effects in both being mostly realistic. For Deep Impact, that would be expected--the original celestial rock hounds Caroline and (the late) Gene Shoemaker were consultants. The exception was the first five minutes, where the astronomer computes an orbit based on a single measurement, which is impossible. Indeed, last spring's erroneous report of a threatening asteroid was based on insufficient data.

My real concern, I told the students, is that the public may relax after seeing NASA superheros successfully defend the planet with only a couple of weeks warning. I once did a 'worst case,' back-of-the-envelope calculation for a rock coming in on a direct-hit path at a typical velocity. How long would it take from naked-eye visibility to impact? Two weeks?

Try half an hour.

"Armageddon" has the announcer saying that 'fourteen brave souls' were trying to save the Earth. Actually, that is about right--there are about that many astronomers currently searching for killer rocks. It will be decades before they find them all, and it is not clear whether we need to sustain a search for new ones that drift in on very elliptical orbits.

Only a few weeks ago a whole new class of asteroids was discovered, that stay within the Earth's orbit but could just reach our celestial circle, giving us a gentle kiss of death. The Great Contractor left lots of construction debris in our Solar System, and we never know when we are going to stumble into a celestial cinder block.

The announcer also said that we finally have 'the technology to prevent extinction.' Correct, too, but not titanium covered Shuttles. Rather, aluminum coated mirrors in telescopes capable of detecting these bullets when they are far away.

What would it cost to find them all? We would need to set up perhaps ten new telescopes dedicated to the search. Current searches use 'scopes one to two meters in diameter--about a megabuck apiece. Operating the fleet would cost about ten million a year.

Sounds expensive? Compare that to the $15 billion contract Lockheed has to develop the 'Star Wars' system that would supposedly protect us from missiles from a cold war enemy who has thawed out and gone rancid. This is not to mention that the software is not likely to work if ever needed, and that Lockheed has had five straight test launch failures.

A student asks could we blast them apart? Maybe, maybe not. A recent computer simulation study had mixed results. Perhaps we should go out there and try it, ahead of time.

Another student asks if we could survive nuclear winter by growing crops under lights. I tell her that the African Violet on her table at home is used to growing in the shade on the forest floor. You need lots of photons for corn. We can't make that much electricity.

I tell them that they might get a sampling in November, during the annual Leonid meteor shower. About every 33 years the shower becomes a storm as we cross the debris path at the same time as the main clump of old comet. In 1833 and 1867 it was a downpour, with 100,000 shooting stars per hour, including some refrigerator-size boulders that could be heard hissing and popping as they burned up.

Or maybe we will get another meteorite like the one that hit Greenland last winter, lighting up the sky so brilliantly that people thought the end was near. Only now, after the winter ice has melted, is a team out there looking for the rock. But I think we'll need a bigger hit to serve as a wake up call

The sky would not clear that night so they left without looking through the 'scope. But I hope that a few of them had their minds opened to some new images. A picture of us living at the mercy of statistics. A realization that God gave us a brain to figure this out. And, to take measures.

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