Shafer shook his head again. “No way can you guys be hiding an array more than ten kilometres across, not even in the New Mexico desert.
Ergo
, if you’re beaming centimetre waves the angular spread is at least one part in a million.”
Noordhof spread his hands. “So? Nothing!”
“Nothing at five thousand miles. But if you catch Nemesis a million kilometres away the centimetre wave beam is spread out over one kilometre, the whole size of the asteroid. With attenuation like that you couldn’t boil an egg. Uncertainties
in thermal conductivity or internal temperature will make no difference. I’m sorry Mark, but your top secret, Darth Vader, gigabuck, Space Dominance, missile-zapping Star Wars supermaser is as useful as a peashooter. We’re back to nukes.”
Webb couldn’t resist it: “I told you it wouldn’t work.”
“Where the hell do you think you’re going, Webb? Are you looking for Nemesis in the woods?”
“I’m looking for inspiration, Colonel. From the performance I’ve seen here, I’m more likely to find it with the squirrels.”
Noordhof opened the microwave door angrily. “Well, you might take the friggin’ rock out with you.”
Shafer was still laughing when Webb left the building.
At the far end of the little car park there was a gap in the trees which, on closer examination, turned out to be the beginning of a natural path. It was close to a cluster of garbage bins and Webb suspected that it might be a raiding route for some animals. He took off along it, and found that the path skirted the foot of Eagle Peak, rising gently as it went, with the cliff easily visible to the left through the heavy ponderosa trees. After about twenty minutes, far beyond Noordhof’s hundred-metre limit, he turned off to the base of the cliff, brushed the powdery snow off a broad boulder and sat down on it. There was the merest hint of cable rising above the trees about a mile back; otherwise there were no signs of human artefact. For the first time since he had been snatched from another snow-covered mountain, halfway round the planet, Webb had time to stop and think.
A last-minute asteroid deflection was a crass thing, a hefty punch with a barely controllable outcome. A punch on the nose, slowing Nemesis down long enough for the Earth to slip past, was more effective than a sideways swipe. But as the warning time dwindled so the punch became increasingly desperate, to the point where either you risked breaking the asteroid into a lethal swarm or you could do nothing to ward
it off. Just which side of the threshold they were on they wouldn’t know until they had identified Nemesis.
The Russians, however, had had a different problem: that of precision. Probably, Webb thought, they had used a standoff explosion of a few megatons to give a crude impulse of a metre a second or thereabouts. The bigger the bomb the more potential asteroid weapons were available, and the Russians had hundred-megatonners in their arsenal. For every asteroid liable to hit the Earth they would have a hundred or more potential weapons in the form of near-missers.
But after that they would have had to finesse. A hit within a few hundred miles—or even a thousand miles—of Kansas would be adequate to obliterate the States. But a thousand miles is
precision
! After the initial big explosion, possibly years in the past, they would have required a series of small shepherding explosions, maybe little more than Hiroshimas, to guide the asteroid in.
All of which implied a fair amount of clandestine space activity, maybe using the Phobos or Venera series as a cover. Leclerc’s knowledge of past Russian space trips was the key.
There was a movement in the woods. A couple of crows were cautiously dropping from branch to branch about fifty yards away. And something small was scurrying through the trees. A white fox popped its head up and looked at Webb curiously. In a flash of inspiration, Webb suddenly realized that there was another key. He jumped up and the fox and crows disappeared.
In passing he looked in the kitchen and the common room, and knocked on Leclerc’s door. He threw off the hat and jumper. Back down to the conference room. “Where’s André?” he asked. Judy looked up briefly from a terminal and shrugged.
Webb picked up a pile of blank paper and made his way to the common room. It was empty. Warm afternoon sunlight was streaming in through the panoramic window. A green leather chair had a worn, comfortable look about it.
He settled in. The sun was warm on his thighs and a light scented breeze was coming in through the window.
In some anonymous galaxy near the boundaries of space and time, two neutron stars had collided. With collision velocities close to the speed of light, the stars had annihilated their own matter, transforming it into a flash of radiation of incomprehensible intensity. Before even the Sun and Earth had formed, the radiation was spreading out through the Universe as a thin, expanding spherical shell. And then came the Sun and planets, and life evolved in the oceans, and then the reptiles had crawled on to land and the big archosaurs had ruled the Earth until the solar system entered a spiral arm, whence they had died in a massive bombardment of dust and impacts. It was an episode which had left the mammals and the insects, in their turn, to inherit the Earth. By the time the first primates had appeared the gamma rays were invading the Local Supercluster of galaxies; when
homo sapiens
was learning to carve on rocks the radiation was sweeping through the cave man’s own galaxy; and finally, at the very instant the apes had learned how to throw little metal machines around the Earth, the shell had momentarily rushed through the solar system, on its endless voyage to other stars and other galaxies.
But as the energetic photons swept past, a tiny handful had been picked up by the satellites which the apes had just developed; a millisecond gamma ray burst was duly recorded; theoreticians speculated; papers were written and debated; and arriving from cataclysms scattered through the cosmic wilderness, other gamma ray bursts were being picked up, recorded, discussed and debated, and catalogued.
And this was Webb’s problem. The Universe snaps and crackles across the whole electromagnetic spectrum. Neutron stars collide; massive stars run out of thermonuclear fuel, collapse and then destroy themselves in a gigantic thermonuclear explosion; red dwarfs dump their atmospheres on to white dwarf companions; relativistic jets squirt from the
nuclei of galaxies and stars. Somewhere in this tremendous background of noise was a local event. A sprinkling of X-rays, perhaps, from an illegal nuclear explosion; or a brief flash of light in the sky. An explosion on Nemesis would throw hundreds of thousands of tons of debris into space. Maybe ice, maybe boulders, but surely dust. A cone of dust, fanning out into space and sparkling in the sunlight; a beacon in the dark interplanetary void.
Amongst the thousands of X-ray flashes picked up by CHANDRA, there might just be a signature of a different sort. Or maybe even the wide-angle camera on SPITZER had picked up a fading infrared glow as the debris from the crater dispersed into the zodiacal dust cloud. Or the Hubble had picked up something.
The first thing was to calculate the signatures that would discriminate between natural astrophysical processes and the effects of a bomb. He would have to investigate a wide range of physical processes. Maybe the hefty thump of 14 MeV neutrons from the thermonuclear fireball yielded a characteristic signature; or the timescale for dispersal of the dust yielded a light curve unlike that from any eclipsing binary. Webb sighed and pulled over a coffee table with a dish of Liquorice Allsorts and jelly babies. It was going to be a long session.
Lunch came and went unnoticed. Colleagues came and went through the common room; Webb was not disturbed. The level of the sweets in the dish next to Webb slowly declined. Around six in the evening Judy went into the kitchen and the smell of curry soon wafted around the common room. Kowalski appeared shortly afterwards, dressed in his Eskimo suit, and then Shafer and Noordhof emerged from the conference room, arguing about something; their voices changed to a low murmur but Webb appeared not to notice. Someone handed Webb a coffee and switched on a lamp. The sun set. Papers scrawled with formulae piled up on the coffee table. The sweets disappeared.
Around midnight Webb completed his calculations: he had his electromagnetic signatures. The best bet had turned out to be the simplest: an unexplained flash of light, seen in the telescope of some amateur comet hunter somewhere on the planet. It might just have been recorded in the IAU Circulars, the electronic clearing house for transient and unexpected astronomical phenomena.
He looked at his watch in surprise, and realized that he hadn’t eaten. There was a plate of chicken curry, boiled rice and a Nan bread in the microwave oven. He fired it up, was tempted by the can of Red Stripe on the kitchen table but decided against it. He gulped the food down and then went straight through to the conference room along the now darkened corridor. The room too was dark apart from the light from the terminals. Judy and Sacheverell were sitting at terminals. Starfields were drifting across their vision.
“How did the briefing go, Herb?” Webb asked.
“No sweat,” Sacheverell said without looking up.
“We’re filtering out the main belters automatically,” Shafer said, “otherwise we’d snarl up.”
“And between Spacewatch, Flagstaff and ourselves we’ve found thirty Earth-crossers already,” Judy said. “Thirty-one,” she added as the terminal beeped.
“How are you handling them?” Webb asked.
“No sweat.” Sacheverell again. “The Teraflop is coping with everything we throw at it. We come back to the new ones after an hour or two. Look.” He pressed a terminal key and the single picture was replaced with a dozen small squares, each centred on a bright spot. The little pictures, like frames from a movie, showed clearly that the spot was drifting against the stellar background. “Usually they’ve moved several pixels, sometimes dozens. We might not get an orbit but if it has a strong tangential drift we know it’s not an immediate hazard.”
“Where are you searching?” Webb asked Shafer.
“Where you expect to find them,” Sacheverell interrupted.
“In and around the ecliptic plane. I hope you’re not going to start on crap about high inclination dark Halleys.”
“They’re not practical weapons, Herb. Anyway it doesn’t matter where you look, you haven’t a hope.”
Sacheverell looked up from the screen. “Hey, we finally agree on something.”
“But don’t tell the Colonel what we’re agreed on. He’s already had a bad day.” Webb sat down at a spare terminal and quickly typed into the Internet. Once into the IAU Circulars, he began to read every one, starting from the most recent and going back through time. Each unexplained flash of light, each gamma ray burst, each surge of X-rays reported in the sky, had to be matched against the theoretical expectations he now carried in his head. It was a slow, painstaking, tedious grind.
Around 3 a.m. Judy disappeared, and half an hour thereafter Webb too felt he had to take a break. He wandered across the darkened hallway to the dimly lit common room and flopped down in an armchair. The urge to sleep was almost irresistible. There was a smell of perfume. “Hey, Mister!” Judy said in a soft voice. “Not even Superman could keep that up.” Startled, he saw that Judy was in the armchair opposite. In the dim light he could just make out that she was wearing a long green dressing gown; her hair was tousled and her blue eyes were strained with tiredness.
Without thinking, he said, “What’s a nice girl like you doing in nuclear weapons? You should be having babies.”
She bristled, but then burst out laughing when she detected Webb’s sly grin. “Webb the sexist! I’m sure. I’m in nukes for the same reason you’re in astrophysics, Oliver. I love the subject.”
He felt unable to think. When he spoke, the words were slurred with exhaustion. “So the lady loves nukes. I still can’t think why.”
In spite of her exhaustion, enthusiasm came through in her voice. “Think of a nuclear fireball in the first microsecond of its formation. The power to devastate a small country in something the size of a beachball. There’s a wonderful purity about a nuke, Ollie. It sweeps away everything; even elements are transmuted. It’s as near as we can get on Earth to the Creation.”
“You make getting nuked sound like a religious experience,” Webb replied, hardly caring what he said. “But you want to destroy things, and I want to understand them. I happen to think we were created from something like your fireball.”
“The Big Bang?” she asked.
Webb shook his head. “The nucleus of the Galaxy. This is something that nobody in their right mind believes. But I still say women are for childbearing. They’re supposed to create, not destroy.”
“All females defend their young. Having had our babies we need to protect them. I do create, Oliver, I create peace. Is that not a noble pursuit in a barbaric world? You have the nerve to sit there and bask in the purity of your subject, with Nemesis on the way in? We can only manage miserable ten-megaton firecrackers, but you? You go cosmic.”
“I also love dogs,” said Webb.
“I prefer cats. And cars. I can strip a Pontiac to its gudgeon pins and reassemble it in a day.”
Webb said, “You can strip me to my gudgeon pins any day. I’m a fair cook, and I climb mountains.” He thought, This conversation is getting surreal.
She shook her head. “I’d rather fly over them in my Piper. But maybe you can cook me a dinner some time.”
Webb’s skin tingled at the invitation and he thought, hell I must still be alive. “Which brings me to boyfriends. Got any?”
“Lots of them, all strictly platonic. So far I find nukes more interesting.”
“Are all nuclear physicists as beautiful as you?”
“Only the females.” She stretched her slim legs out on the coffee table between them, nudging papers aside with her bare feet. “What about you?”
“The ladies? I have an effect on them. But haven’t had time to explore the subject. I notice you paint your toenails, ma’am.”
“I hope you paint yours, Oliver. Otherwise we have nothing in common.”
Noordhof marched in and switched on a light. He took one look at the exhausted scientists, blinking in the light, and said, “You two. Get to bed before you collapse, and that’s an order. You’re no damn use in that state.”