Bisesa said, They could just kill us. Turn off the power. The air recycling. Wed be helpless.

They could. But they wont, Alexei said. They want to know what we know. Where were going. So theyll be patient, and hope to get hold of us later.

I hope youre right. As if in response, the softscreen turned green again. Alexeis grin broadened. So much for that.

Okay, whos for beans?

12: MOUNT WEATHER.

Bella had expected Bob Paxtons briefing to take place in her offices in the old NASA headquarters building on E Street in Washington, a block of concrete and glass repaired and refurbished since weathering the sunstorm.

But Paxton met her outside the building. He stood by the open door of a limousine. Bella. The car was one of a convoy, complete with uniformed naval officers and blue-suited FBI agents.

She thought he looked comical, an elderly man rigid in his much-cherished uniform, standing there like a bellboy. His face was twisted in the morning light. He was, she had learned, a man who distrusted the sun, even more than most of his bruised generation.

Morning, Bob. Going for a ride, are we?

His smile was disciplined. We should relocate to a more secure situation. We have issues of global importance, of significance for the future of the species. I recommend we convene at Mount Weather. I took the liberty of making the arrangements. But its your call. He eyed her, and the tension that had existed since the day she took the job crackled between them.

Shed never heard of Mount Weather. But she couldnt see any harm in indulging him. She climbed into the car, and he followed; they would be alone together.

They pulled out. The convoy took Route 66 and met Highway 50, heading west. The road was full of traffic, but their speed was high.

How far are we going?

Be there in half an hour. Paxton sat there and glowered, visibly irritated.

I know whats bugging you, Bob. Its Professor Carel, isnt it?

The muscles in his grizzled cheeks worked, as if he longed to be chewing gum. I dont know anything about this old English guy.

No doubt you had him vetted.

As best we could. He doesnt have anything to do with this. Not part of the team.

Hes coming at my invitation, she said firmly. In fact, in a sense, to her this elderly British scientist was part of the team, a deeper and older team-up than anything she was involved in with Paxton.

Professor Bill Carel had once been a graduate student working with Siobhan McGorran, another British astronomer who had become involved in the grand effort to build the sunstorm shieldand who had, in its aftermath, married Bud Tooke, and then nursed him through his cancer, a cruel legacy of that astounding day. That personal link was in fact the channel through which Carel had contacted her, and had tried to persuade her that he had a contribution to make regarding the presence of the object in the solar system, which he had heard of in whispers and leaks.

She tried to express some of this to Paxton, but he just waved it away. Hes a cosmologist, for Christs sake. Hes spent his life staring into deep space. What use is he going to be today?

Lets keep an open mind, Bob, she said firmly.

He fell into a silence that lasted all through the rest of the drive. Bella had raised a child, she was used to sulks, and she just ignored him.

After eighty kilometers they pulled off onto Route 101, a narrow two-lane rural road that clambered up a ridge. At the crest of the ridge they came to a line of razor-wired fencing. A faded sign read: U.S. PROPERTY NO TRESPASSING.

Beyond that Bisesa could make out a few battered aluminum huts, and beyond them, a glassy wall.

They had to wait while their cars interfaced with the bases security systems. Bella was aware of a faint speckle of laser light as she was probed.

So, Mount Weather, she prompted Paxton.

Five hundred acres of Blue Ridge real estate. In the nineteen-fifties they set up a bunker here, a place to shelter government officials from D.C. in the event of a nuclear exchange. It fell into disuse, but was revived after 9/11 in 2001, and again after 2042. Although now its essentially a loan from the U.S. government to the World Space Council.

Bella tried not to grimace. A bunker from the Cold War, the War on Terror, and now the War with the Sky. Appropriate, I suppose.

Manned by navy officers mostly. Used to confinement and canned air. Mount Weather is a good neighbor, Im told. They keep up the roads, and send out the snow plows in winter. Not that theres much snow nowadays...

She had been expecting the convoy to pass on to a gate in that shining impenetrable wall. She was shocked when, with a rip of foliage, the whole chunk of land beneath the car turned into an elevator and dropped her into darkness.

Bob Paxton laughed as they descended. I feel like Im coming home.

As smiling young naval officers security-processed the party and escorted it to its conference room, Bella glimpsed a little of Mount Weather.

The ceilings were low, paneled with grimy tiles, the corridors narrow. But these unprepossessing corridors enclosed a small, old-fashioned town. There were television and radio studios, cafeterias, a tiny civilian police station, even a little row of shops, all underground, all contained within a hum of air conditioning. It was like a museum, she thought, a relic of the mindset of the mid-twentieth century.

At least the conference room was modern, big and bright and fitted with softwalls and table screens.

And here Bill Carel was waiting for her. In a room full of heavy, rumbling figures, mostly men, mostly about Paxtons age, mostly in one uniform or another, Carel in his shabby old jacket was standing alone beside a coffee percolator.

Bella ignored Paxtons cronies and made straight for Carel. Professor. Its good of you to come. She shook his hand; it was flimsy, bony.

He was a little younger than she was, she recalled from his file, somewhere in his fifties, but he looked frail, gaunt, his face liver-spotted, his stance awkward and uncomfortable. The sunstorm had blighted many lives; perhaps he had been battling illness. But the eyes in his cadaverous face were bright. He said, I hope the contribution I have to make is a valid one, and useful.

Youre not sure? She felt obscurely disappointed at his diffidence. An unworthy part of her had been looking forward to using him to tweak Bob Paxtons tail.

Well, how can one be sure? The whole situation is unprecedented. But my colleagues urged me to contact youto contact somebody.

She nodded. However this turns out, Im grateful you tried. Cradling a coffee, Bella led Carel to a seat. Ill make sure you get your say, she whispered. And later we must talk of the Tookes.

After that she made a hasty circuit of the room, meeting and greeting. As well as the Patriots Committee types there were representatives of the various multinational armed forces and governments that supported the World Space Council.

She didnt get a good first impression of the quality of these delegates. The Council had been engaged in nothing but preparatory and advisory activities for decades; since the sunstorm the War with the Sky had been cold. So working for the Council had not been a prized assignment for a career officer. Maybe this was a room full of Bob Paxtons, steely-eyed fanatic types, or else dead-enders.

But she told herself not to rush to judgment; after all if there were a new threat approaching the Earth, these men and women would be her prime resource in dealing with it.

Standing at the head of the table, Bob Paxton, self-appointed chair, flicked his finger against a glass to call the meeting to order. The rest of the panel, perhaps starstruck to be in the presence of the first man on Mars, submitted their attention immediately.

Paxton said the purpose of the meeting was twofold. First to give Chair Fingal an overview of the assets she has at her disposal. Second to focus specifically on the anomaly currently approaching Jovian orbit And at that point, Bella put in, I will invite Professor Carel to make his contribution. Paxton rumbled a grudging assent.

They began to speak of the defense of the solar system.

13: FORTRESS SOL.

Paxtons presentation was a carnival of bullet-points, graphs, and images, some of them three-dimensional and animated; the holograms hovered over the middle of the table like ads for fantastic toys. But the subject matter was grim.

Since sunstorm day, we have devoted considerable assets on Earth and beyond to watching the skies....

Bella got the impression that Earth was plastered with electronic eyes, peering at the sky in all wavelengths. This included NASA assets like the venerable Deep Space Network chain of tracking arrays in Spain, Australia, and the Mojave, a near-Earth asteroid watching facility in New Mexico called LINEAR, and other Spaceguard facilities. The giant radio telescope at Arecibo likewise now gave over much of its time, not to astronomy, but to seeking unnatural signals from the stars.

The visual astronomers too had suddenly found money coming their way to realize previously unaffordable dreams. Bella studied images of the unimaginatively named Very Large Telescope in Chile, an Extremely Large Telescope in Morocco, and a monster called the Owl, the Overwhelmingly Large Telescope at a site called Dome C in Antarctica, where enough steel to build a second Eiffel Tower supported a monstrous mirror a hundred meters across. The Owl was busy photographing the birth of the first stars in the universeand, more significantly, was mapping the surfaces of planets of nearby stars.

Facilities off-Earth were no less impressive. The most successful of the new space observatories was Cyclops Station, which trailed the Earth in its orbit at a stable Lagrange point. At Cyclops there had been assembled a telescope with a single, very large Fresnel lensnot a mirror, but a diffracting lens.

As for what all these automated eyes were looking for, a century of theoretical studies by the old SETI enthusiasts had been plundered. Strategies were being devised to detect signals of all types down to very brief burstsstray flashes of tight-beam laser signals, perhaps, detectable down to a billionth of a second long.

Paxton also spoke of lesser eyes, a whole fleet of them scattered right through the solar system out as far as the orbit of Neptune. He brought up a three-dimensional image of Deep Space Monitor X7-6102-016, which had been posted into orbit around Saturn.

These are our robot sentries, our picket line, Paxton boomed. DSM X7-6102-016 was typical, the most advanced scientific gear but robust, hardened and shrouded. These little critters patrol the skies all the way out to the fringe of OutSys. And they watch each other just as keenly.

Thats true, Professor Carel put in hesitantly. In fact it was the other probes observation of the destruction of X7-6102-016 that was brought to my attention, rather than anything that the probe transmitted itself. Bella said, So we live in a heavily surveilled solar system. What else do you have, Bill? Weapons. Paxton waved a hand, and the image of DSM X7-6102-016 broke up.

We call the concept Fortress Sol, Paxton said grimly. Were establishing layers of deep defense from the outer solar system to the inner, all of it centering on the home of humanity, the Earth. You know yourself, maam, that we have established facilities as far out as the Trojan asteroids.

The Trojans were a rich concentration of asteroids trailing Jupiter around its orbit at a Lagrange stable point. Right now Bellas daughter Edna was out at Trojan Station, working on a new generation of spacecraft, the A-ships. All heavily classified.

Next in we have the asteroids. For military planning purposes we use the A-line, the central belt, as the boundary between InSys and OutSysthat is, the inner and outer systems. After that we have stations at the Lagrange points of Mars and Earth...

In the EarthMoon system itself there were weapons platforms on the Moon and at the lunar Lagrange points and in Earth orbit: killer satellites that could pepper any interloper with projectiles, or fry it with X-ray lasers, or simply ram it. There were ground-based systems too, heavy lasers, particle beams, and reconditioned Cold War ICBMs still capable of hurling their lethal payloads away from the Earth. Even in Earths upper atmosphere huge aircraft patrolled continually, bearing weapons that could knock out incoming missiles. And so on. The whole of cislunar space seemed to be bristling with weaponry, from Earths surface up through what Paxton barked out as LEO, HEO, GEO, and super-GEOlow, high, geosynchronous Earth orbit and beyond.

And the overt hardware of war was just the start. Everything that could be weaponized was. Even space-based weather control systems, like the kilometers-wide space lenses and mirrors, could easily be redirected. Every plowshare could be turned to a sword.

Bellas imagination quailed when she tried to imagine the sort of last-ditch defensive battle that might depend on the use of such weapons. And the fact that these weapons, built to fight a War in the Sky, could just as easily be turned against an enemy on the ground was lost on nobody.

Paxton said, Were well aware of course that these facilities could have done nothing to stop the sunstorm. Therefore we have fallbacks. We dont know what these Firstborn might hit us with next. So for planning purposes we have looked back at other disasters, natural ones, that have hit us in the past, and how we coped with them...

He moved into a new chart, a dismal classification of catastrophe.

There were local disasters that killed a few percent of the worlds population, like major volcanic eruptions and the twentieth-century world wars, and global disasters killing a significant fraction of the population, such as would follow the strike of a small asteroid, and extinction level events, so devastating that a significant proportion of all species would be eliminated, and life on Earth itself threatened. If not for the shield, Paxton said crisply, the sunstorm would have inflicted the mother of all extinction level events on us, since it would have melted Earths surface down to the basement rock. As it was the shield reduced the event to a mere global disaster.

And the sunstorm, he said, had inspired the approach being taken to make the Earth resilient in case of any future attacks.

Were trying to rework our industrial base so we can reconfigure to recovery mode as rapidly as possible in the face of any of these major disaster types. So, for instance, if we had to build another shield, we could do it more effectively. Of course some would argue that as a species we ought to be making this kind of preparation even if the Firstborn didnt exist.

We have some advantages. A space-based infrastructure could help reboot a terrestrial civilization. Weather control systems to stabilize a damaged climate, as after the sunstorm. Orbital stations to restring any downed elevators. Space-based energy systems and comms links. You could store medical facilities up there. Maybe you could even feed the world, from orbiting farms, or lunar agriculture, say. The children of the Earth turning back to help their wounded mother. He grimaced. If the fucking Spacers cooperate.

However we have to go beyond all this, and consider the worst case. He said sternly, looking them all in the eye one by one, We must plan against extermination.

Of course we have populations off-Earth now. But Im told theres still some doubt that the off-world colonies could survive if Earth were lost altogether. So we have further backups.

He spoke of vaults, on Earth and off it; there was one dug into a lunar mountain called Pico, for instance, in the Mare Imbrium. Copies of the wisdom of mankind, on gold leaf and stored electronically. DNA stores. Frozen zygotes. Caches to be retrieved by whoever might come this way, if mankind were exterminated. The Earthmail, a desperate firing-off of a fragment of human culture to the stars on the eve of the sunstorm, was another sort of cache.

All right, Bill. Do you think this is going to be enough?

Paxton said with a hard face, Do any of you know what space opera was? Fiction of the far future, of wars fought across galaxies, of spaceships the size of worlds. Were only a century on from World War Twoonly a hundred and fifty years since the main transport mechanism for warfare was the horse. And yet were faced with a space opera threat. In another thousand years, say, well be scattered so far that nothing short of a Galaxy core explosion could kill us all. But for now, were still vulnerable.

Bill Carel dared to raise a hand. Which is actually a logic that suggests a second strike is more likely now, than later.

Yeah, Paxton growled.

And, despite your fine presentation, Admiral, there are obvious flaws in these strategies. There was an intake of breath, but Carel seemed oblivious. May I?

Go on, Bella said quickly.

First there is the sparseness of your resources, Admiral. Just because you have a station in the orbit of Jupiter doesnt mean you can counter a threat coming at the same radius but from the far side of the sun.

Were aware of that And you seem to be thinking in two dimensions, as if this was a land war of the old sort. What if an attack were to come at us out of the eclipticI mean, away from the plane of the sun and planets?

I walked on Mars, Paxton said dangerously. I know what the ecliptic is. As it happens the present bogey has come sailing in along the plane of the ecliptic. For the future were considering out-of-plane options. But you know as well as I do that the energy costs of getting up there are prohibitive. Yes, Professor Carel, the solar system is a mighty big place. Yes, we cant cover it all. What else can we do but try?

Carel almost laughed. But these efforts are so thinly based its virtually futile Paxton glowered, and Bella held her hand up. Please, Bill.

Im sorry, said Carel. And then there is the question of the efficacy of all these preparations against the threat we actually face Fine. Angrily Paxton cleared down his displays. So lets talk about the anomaly. Bella longed for fresh coffee.

After his long and detailed discussion of Fortress Sol, Paxtons presentation on the anomaly was brief.

He briskly reviewed the principal evidence for the bogeys existence. Right now this thing is passing through the J-line, the orbit of Jupiter. In fact we have a window to intercept it, because its fortuitously passing close to the Trojan base, and were working on mission options. And then it will sail on through the asteroids, past the orbit of Mars, to Earth, where it seems to be precisely targeted. But we still have no idea what it is, or what it might do if and when it gets here.

When he sat down there was a brief silence.

Bill Carel looked at Paxton, and around the room, as if expecting another contribution. Is that all?

Thats all we got, Paxton said.

Carel said softly, I did not dream you would have so littleit is as well that I came. If I may, Admiral?

Bob Paxton glared at Bella, but she gave him a discreet nod, and he gave the floor to Carel.

In a way, Carel said, my involvement with this bogey began in the years before the sunstorm, when I worked with an astronomer called Siobhan McGorran on a probe we called QAP. He pronounced it cap. The Quintessence Anisotropy Probe...

Paxton and his Patriots shifted and grumbled.

The Quintessence Anisotropy Probe was a follow-up to a craft called the Wilkinson Microwave Anisotropy Probe, which in 2003 had studied the faint echoes of the Big Bang, and had established for the first time the proportions of the basic components of the universebaryonic matter, dark matter, and dark energy. It was dark energy, called by some quintessence, that fueled the expansion of the universe. Now the purpose of the QAP was to measure the effects of that cosmic inflation by seeking the echoes of primordial sound waves.

It was really a very elegant concept, Carel said. The primordial universe, small, dense, and ferociously hot, was an echo chamber full of sound waves propagating through a turbulent medium. But then came the expansion. He spread his delicate hands. Poom. Suddenly there was room for things to cool down, and more interesting physics.

As the expansion cut in those ancient sound waves were dissipated. But they left an imprint, their pattern of compression influencing the formation of the first galaxies. And so by mapping the galactic distribution we hoped to reconstruct the primordial sounds. This in turn would provide clues as to the physics of the quintessence, the dark energy, which at that time As the uniforms got more restless, Bella said gently, Perhaps you should get to the point, Bill.

He smiled at her. He had a softscreen of his own that he spread out over the table; it quickly interfaced with the tables subsystems. Here is a profile of the cosmic expansion. It was a spiky graph, plotted on logarithmic scales, an upward curve. He spoke of how this curve had been established by analyzing old light seeping from the deepest sky, and by taking correlations of the structures to be observed on a variety of scales. The frequency of the patterns of galactic formation mapped back to the frequencies of those lost sound waves.

This time Paxton cut him off. Jesus Christ, Poindexter, put me out of my misery. Where are you going with this?

Carel tapped his softscreen. It was one of my own students who fortuitously came across an animation of the destruction of DSM X7-6102-016.