Hooper sat down again, and stared into the middle distance for some moments. “Well it sure beats the hell out of Star Wars,” he said at last.
“Sam, it’s beautiful,” said Cannon. “The thing is undetectable, practically into our air space before we know what’s hitting us. When it does hit us, we’re obliterated. There’s no point in hitting back even if we could because, like you say, it’s just a freak natural disaster. Sam, you know I’m due to meet some senators from the Appropriations Committee in a couple of hours. I’m trying to get final approval for Bat-strike.”
“Which we’re selling on Middle East scenarios.”
“Fifty billion bucks down the tube, along with the new Grand Forks, our Navy, SAC, brilliant pebbles, C-cubed, all our surveillance systems, the whole BMDO. Everything we have, this thing beats it. And they don’t even have to worry about retaliation.”
“I don’t believe it,” repeated Hooper, grey-faced. “This is fantasy stuff.”
“And we reckon they set the whole thing up for a day’s defence budget.”
“What’s the timescale for this?” Hooper asked harshly.
“Heilbron thinks the Russians have pulled it off already,” said Cannon. “It’s somewhere out there now, on the way in.”
Downstairs, the shift was nearly over. The normally ebullient Pino had been unusually quiet, wrestling with some inner problem. Finally he said: “Colonel, do you know anything about astronomy?”
“Not much, Pino. What do you want to know?”
“Well, are we sure there are no men from Mars?”
“Relax, Pino, there are no Martians. Vince Spearman said it on TV.”
Pino seemed to be examining the arcane names on the screen in front of him. Then: “This guy Spearman — he’s okay?”
“AOK. He’s been checked out real good.”
The sergeant relaxed.
Eagle Peak, Tuesday Evening
Webb said, “If Nemesis is more fragile than a rock…”
Sacheverell groaned. “You’re not still on that comet crap. Ever heard of the asteroid belt?”
“Which fails to give us the periodicity in the extinction and cratering records.”
“What periodicity?” Sacheverell sneered. “There is none. And how come Toutatis, Mathilde, Eros and Gaspra are rock?”
“Mathilde has the density of water. It’s a friable sponge.” Webb turned to Noordhof. “Colonel, Herb will tell you to plan on diverting a solid rock. But if it’s a degassed comet and McNally fires an H-bomb at it, we’ll end up with a dust ball heading for us. When the ball comes in it will incinerate the upper atmosphere as it slows from cosmic speed to zero. It’ll remove all the ozone. Then it’ll take a year to sink through the stratosphere and during that year the Earth will be wrapped in a highly reflective dust blanket. Down here we’ll be in twilight. We’ll have a major climatic upset. Freezing gales will blow from sea to land. The continents will end up looking like Siberia. We might cut the thermohaline circulation in the Atlantic and switch off the Gulf Stream. If we do, that will feed through to a permanent snowfall in Eurasia. That will switch off the monsoon. Nobody in Asia will eat for a year or so. You’ll shift masses of water to the poles as ice and change the spin rate of the Earth. Maybe you’ll flip the geomagnetic field, and set off seismic faults and vulcanisms worldwide. Then when the dust clears you’ll be exposed to the full unshielded UV of the Sun, and you’ll have a global catastrophe on top of a global catastrophe. Herb’s certainties could do us in.”
“Maybe we want to get it right before we launch a bomb at it,” suggested Shafer.
Leclerc was looking puzzled. “I always thought comets had tails.”
“Not when they’ve degassed, André. They may crumble to dust but there are plenty of well-authenticated cases showing that they sometimes turn into asteroids.”
Leclerc said, “If we find Nemesis, could we tell its internal constitution by looking at it? Using Kenneth’s monster telescope? What do we actually know about the reflectivities of the Earth-crossing bodies?”
Sacheverell said, “We don’t. But the museums are stuffed with meteorites. They’re fragments of asteroids and they’re rocks.” He shot Webb a venomous look.
Webb said, “You don’t have comet debris in the museums because it breaks up in the atmosphere. Nemesis could be like Halley, with a crusty exterior and a fluffy inside.”
“Fluffy snowballs, right?” Shafer asked, narrowing his eyes. “Dust and ice in equal proportions?”
Webb nodded. “Give or take. Try to nuke it and you end up with a billion tons of dust. Look, if we get this wrong we could reduce the species to foraging bands.”
McNally’s face was a caricature of dismay. He said, “I go for Sacheverell’s theory.”
Noordhof spoke, in a thoughtful tone. “Ollie. Do you realize what you’ve just said? That if Nemesis is a comet, the interests of the world at large are best served by letting the USA take it? Are you saying we’re on opposite sides, Ollie?” Noordhof asked softly, playing with another cigar. Suddenly the air was electrically charged. Judy, at a terminal, stopped typing and swivelled on her chair to face them.
McNally broke the stunned silence. He gulped, “Hey, if the Russians changed its course without turning it to dust, so can we.”
Webb shook his head tensely, his eyes locked with Noordhof’s. “They probably had years of a start, letting them push it a few centimetres a second, without setting up big internal stresses.”
Judy Whaler turned back to the terminal. “A standoff burst! With neutron bombs!” she sang out over her shoulder, and carried on typing.
Webb blew out his cheeks with relief. “Thank you, Judy. Colonel, we just handle Nemesis with the utmost care. We use a standoff burst. Ablate a skin with neutrons.”
The relief was palpable. Shafer was scribbling. “Maybe yes, maybe no. Even a neutron bomb emits X-rays and they get to the asteroid first. If they create a sheath of plasma the neutrons might not get through. I don’t know that neutron bombs would help.”
She swivelled on her chair. “We do bombs at Sandia, Willy. We can handle the computational side. Neutron bombs are the ultimate capitalist weapon, remember? They’re designed to irradiate people, not destroy structures. Suppose instead of positioning a bomb on the surface of Nemesis we detonate it during a flyby, say a few hundred metres up. Instead of forming a crater, the top few centimetres are vaporized and blown off. The stresses are spread over a hemisphere instead of concentrating around a crater.”
Shafer said, “So we bathe the asteroid with neutrons and X-rays. And if it turns out to be a comet, we might still do it gently enough to preserve its structure.”
Noordhof asked, “Can we do it? Can we do it?”
Webb suggested, “Try a one-megaton burst at five hundred metres’ altitude and suppose the bomb energy is all in neutrons.”
Judy unconsciously swept her blonde hair back over her shoulder and said enthusiastically, “Neutrons get absorbed within twenty centimetres. If they just passed through you they wouldn’t do damage. It’s because they get absorbed within your body that they make such brilliant weapons. The energy will be deposited in a top layer of Nemesis around the thickness of a human body.” She turned back to her terminal.
You’re a bundle of fun, lady, Webb found himself thinking.
Shafer drew a circle and a point some way off, and tangent lines from point to circle. Webb saw what was coming and tried to keep up on a sheet of paper. Shafer said, “Give Nemesis a radius R and put the bomb a distance d from its centre. We need to know how much of the bomb’s energy is intercepted by Nemesis.” He scribbled rapidly and said, “Seen from the bomb Nemesis fills πR2/4πd2 or 1/4(R/d)2 of the sky.”