this object is headed and whether it poses any threat of collision with the earth?' Laura looked at Gray, whose face betrayed nothing.
'There are too many unknown variables. The observatory at Mount Palomar picked it up at extreme range by random chance. They were calibrating a new camera, and one of the astronomers noticed that a star was missing from the field. That's the way many of the dark objects in our solar system are discovered — by obscuring a known star — and so they set about looking for another such event in the vicinity. When another star was obscured earlier today, their rough calculations indicated a close pass to the earth, which is all we know right now.'
'And just how close will this pass be? Is there a chance that this thing could hit us?'
'That's obviously everyone's concern, but it's too early to tell yet. All we know is that there is some object of considerable mass — a comet or an asteroid, probably the latter — that is in roughly the same orbit as the earth. What we would need to know before we could accurately predict its course is its mass, shape, rotation, and material composition.'
'When will you know all that?'
'Well… we'll never know all of it. We're trying to get some shots with the Hubble, but it's still about ten million miles away and it's no more than a few miles in diameter. There's not too much data you can get out of a dark, cool object like an asteroid at that range.'
'I'm sending them the data now,' Gray said without taking his eyes off the screen.
'Let's assume that it strikes the earth,' the reporter said. 'What effects could it have?'
'Oh, my,' the scientist said nervously, rocking from heel to toe and shoving his hands deep in his pockets. 'Well, that's… I think it's a bit premature to be speculating about that right now.'
'But let's just suppose for a moment the worst-case scenario — that this object is on a collision course with the earth. What would be the type of things that might happen if it hits us?'
The scientist shrugged and smiled in discomfort. 'It could, of course, be catastrophic. But we'd need more data before even preliminary conclusions could be drawn.'
'I hate to belabor the point,' the reporter pressed, 'but it's the question that's on the minds of most of our viewers tonight, I'm sure. If that asteroid or whatever it is were to strike the earth — understanding that we don't know right now whether that's even remotely likely — what kinds of damage could it do?'
The scientist again struggled with the question. 'We have only geological records of strikes of this magnitude, and extraterrestrial observations of such events like Shoemaker-Levy 9. The earth is constantly bombarded with debris, but objects smaller than about a hundred and fifty feet in diameter explode or burn up in the upper atmosphere. Our current predictions put the chances of an object one mile in diameter striking the earth at about one every three hundred thousand years. That size strike would probably raise enough dust to lower world temperatures for two to three months, which would have climatic effects. We should also, on average, get hit by an object that's five miles in diameter once every ten million years or so. Its impact would boil significant volumes of our oceans, vaporize hundreds of cubic miles of crust, fill the air with burning sulfur, and trigger forest fires with falling cinders all across the planet.'
'And how does the size of the object you're now tracking compare to that,'
'Oh, it's considerably larger, in all likelihood.'
'It's eight by twelve by six miles,' Gray supplied matter-of-factly.
Laura opened her mouth to ask Gray how he knew, but her attention was drawn back to the screen.
'And what would an object of that size do if it struck the earth, Professor?' the reporter asked.
'Well, purely theoretically, I suppose, if a dense object ten or more miles in diameter were to strike the earth head-on — not skipping back off into space in a glancing blow with our atmosphere — at a relative velocity of some tens of miles per second…' He hesitated. 'Of course it might break up in the tidal forces of the earth's gravitational field while still some distance away, which is not necessarily a good thing. Then it might pepper a very wide area with large meteorites, some of which would surely impact on populated regions.'
'But what if it didn't break up?'
The scientist arched his eyebrows. 'Well, we would be talking about a multigigaton event.' Laura's gaze shot over to Gray. She'd never even heard the word gigaton before. Gray stared fixedly at the screen.
'Force, as everyone knows, is mass times velocity squared. With a velocity of forty to eighty miles per second…' Again he faltered. 'It would be unprecedented, at least on rocky planets like earth which preserve a record of geologic events in the form of craters.'
'What are you saying, Dr. Summers? If an intact asteroid of that size were to strike the earth squarely, what would that do?'
His pursed lips protruded cherry-red from his beard. 'It would certainly cause tidal waves along virtually every shoreline on the planet. But the wave effects wouldn't be limited to the oceans. With forces like the ones we'd be dealing with, liquefaction of the upper crust would occur. The ground would behave like a liquid, and a series of shockwaves would ripple outward from the point of impact. Those waves of solid earth could be a hundred feet or more high, and they would radiate outward like the ripples on a pond at thousands of miles per hour. Buildings can't withstand even a few inches of movement, and no structures ever built by man could survive those waves.'
'Could it possibly crack the earth open?' the interviewer asked.
The scientist shook his head but said, 'A large segment of the crust would probably be tossed up from the point of impact into low earth orbit, but most of that should then rain back down to earth over the next days and weeks. And the shock would clearly set off nearly simultaneous earthquakes along every fault line on the planet, plus produce a multitude of new fault lines like the starring around a crack on a windshield. It might even fracture the crust straight through and create a brand-new plate, which would change the course of continental drift.'
The reporter pressed his earpiece closer. 'I'm… I'm being asked by CNN studios to inquire whether that would be the worst of it.'
Another shrug. 'Climatic change is a certain. Temperatures would fall, ice would form, water tables would rise, crops would fail as previously fertile zones became less temperate. I would anticipate catastrophic extinctions of species on the order last experienced sixty-five million years ago with the Yucatan strike — the one that killed the dinosaurs. 'The fact of the matter is, though, nobody really knows.'
'Could it… could we be dealing with the possibility of… of extinction?'
The scientist's gaze shot up. 'Human extinction? As a species? Oh, good Lord, no!' He shook his head vigorously. 'Life is very stubborn. In even the most extreme scenarios human life would survive in numerous pockets all around the earth. No, no. I wouldn't worry at all about human extinction.' He smiled reassuringly.
The looks of dread on the faces of the newspeople summed the story up best. It was only when the anchorwoman's lips began to move that Laura realized the television was now muted.
Laura turned to Gray. 'Is that why you have those nuclear devices? To blow that thing up?'
'No. You wouldn't want to do that. Our calculations show there's a greater danger from getting hit with a bunch of little pieces than with one big blow. Plus, our planet would plow back through the debris year after year, orbit after orbit for generations. That shrapnel would not only increase the threat from meteorites, it would make spaceflight from this planet dangerous virtually forever.'
'Joseph,' Laura whispered, a chill rising up her spine, 'what's going on?'
'That object detected by Mount Palomar's an asteroid. Solid iron, shaped like a peanut. No rotation whatsoever. Its velocity relative to the earth is a positive sixty-two miles per second.'
'How do you know all that when even the Hubble space telescope can't give them a good enough picture to make those calculations?'
'Because it's mine.'
Laura wasn't sure she'd heard him correctly. 'What's yours?'
'That asteroid.'
Her lips curled, but the laugh didn't quite materialize. 'What?'
'I sent a probe out a couple of years ago and began deceleration the winter before last.'
Laura looked from his face, to the pictures on the hundreds of special bulletins from all around the world, then back. 'You mean you brought that thing here?' she asked with a growing sense of outrage.
Gray nodded.
He was completely insane. She'd known he was eccentric, possibly even dangerous, but she had never presumed that his actions could threaten a level of destruction so vast. She spoke in a low and quivering voice. 'What have you done?' Laura bolted from the sofa to pace the room in anger. 'My God, Joseph! Who do you think
