Bella crossed straight to a glass-walled elevator, and rose quickly and silently up through the interior of the VAB. She stared down over rockets clustered like pale trees. Once the rocket stacks of Saturns and space shuttles had been assembled in this building. Now a century old and still one of the largest enclosed volumes in the world, the VAB had been turned into a museum for the launchers of the first heroic age of American manned space exploration, from the Atlas to the shuttle and the Ares. And now the building was operational again. A corner had been cleared for the assembly of an ApolloSaturn stack: a new Apollo 14, ready for its centennial launch in February.

Bella loved this immense temple of technology, still astonishing in its scale. But today she was more interested in who was waiting for her on the roof.

Edna met her as she stepped out of the elevator car. Mum.

Hello, love. Bella embraced her.

As Bella and Edna walked the security guard shadowed them, and a news robot rolled after them, a neat sphere glistening with lenses. Bella had to expect that; she did her best to ignore the silent, all-encompassing scrutiny. It was an historic day, after all. By scheduling the Bimini switch-on today, she had meant to turn Q-day into one of celebration, and so it was turning out to beeven if, she sensed, the mood was edgy rather than celebratory right now.

The tremendous roof of the VAB had long since been made over as a viewing platform. Today it was crowded, with marquees, a podium where Bella would be expected to make a speech, people swirling around. There was even a small park, a mock-up of the local flora and fauna.

Two oddly dressed men, spindly, tall, in blue-black robes marked with golden sunbursts, stared at a baby alligator as if it were the most remarkable creature they had ever seen, and perhaps it was. Looking a little uncertain on their feet, their faces heavily creamed with sunscreen, they were monks of the new church of Sol Invictus: missionaries to Earth from space.

Edna walked with the caution of a space worker restored to a full gravity, and she winced a bit in the brilliant light, the breeze, the uncontrolled climate of a living world. She looked tired, Bella thought with her mothers solicitude, older than her twenty-four years.

You arent sleeping well, are you, love?

Mum, I know we cant talk about this right now. But I got my subpoenas yesterday. For your hearing and my own.

Bella sighed. She had fought to keep Edna from having to face a tribunal. Well get through it.

You mustnt think you need to protect me, Edna said, a bit stiffly. I did my duty, Mum. Id do the same again, if ordered. When I get my day in court Ill tell the truth. She forced a smile. Anyway the hell with it all. Theas longing to see you. Weve made camp, a bit away from the marquees and the bars...

Edna had colonized an area of the VAB roof close to the edge. It was perfectly safe, blocked in by a tall, inward-curving wall of glass. Edna had spread out picnic blankets and fold-out tables and chairs, and had opened up a couple of hampers. Cassie Duflot was already here, with her two kids, Toby and Candida. They were playing with Thea, Ednas daughter, Bellas four-year-old granddaughter.

In this corner of the VAB roof it was Christmas, Bella saw to her surprise. The kids, playing with toys, were surrounded by wrapping paper and ribbons. There was even a little pine tree in a pot. An older man in a Santa suit sat with them, a bit awkwardly, but with a grin plastered over his tired face.

Thea came running. Grannie!

Hello, Thea. Bella submitted to having her knees hugged, and then she bent down and cuddled her granddaughter properly. The other kids ran to her too, perhaps vaguely remembering the nice old lady who had come with a memento to their fathers funeral. But the kids soon broke away and went back to their presents.

Santa Claus shook Bellas hand. John Metternes, Madam Chair, he said. I flew with your daughter on the Liberator.

Yes, of course. Im very glad to meet you, John. You did good work up there.

He grunted. Lets hope the judge agrees. Look, I hope you dont think Im butting inI can see theres a family thing going on here I forced him down for some shore leave, Edna said, a bit acidly. This weird old obsessive would sleep on the Liberator if the maintenance crew would let him.

Dont let her bug you, John. Its good of you to do this. ButChristmas, Edna? Its only the fifteenth of December.

Actually it was my idea. Cassie Duflot approached Bella. It was just that, you know, we still arent sure how today is going to turn out, are we? She glanced at the sky, as if seeking the Q-bomb. I mean, not really sure. And if things were to go wrong, badly wrong You wanted to give the kids their Christmas anyway.

Do you think thats odd?

No. Bella smiled. I understand, Cassie.

It does make it a hell of a day, Edna said. And whats worse, if the world doesnt get blown up today, well have to do it all again in ten days time.

You attracted quite a crowd for your launch, Bella, Cassie said.

Looks like it Mum, you havent seen the half of it yet, Edna said. She took her mothers arm again and walked her toward the glass-walled lip of the building.

At the roof edge Bella was able to see the ocean to the east, where the low sun hung like a lamp, and the coast to north and south, her view stretching for kilometers in either direction. Canaveral was crowded. The cars clustered along the shoreline, and were parked up as far as the Beach Road to the north, and to the south on Merritt Island and the Cape itself, carpeting the old industrial facilities and the abandoned Air Force base. Everywhere, flags fluttered in the strong breeze.

And out at sea she saw the gray, blocky form of a reused oil rig. Rising from it was a double thread, dead straight, visible when it caught the light.

They came for the switch-on, Edna said. You always were a showman, Mum. Maybe politicians have to be. And reopening Americas elevator today is a good stunt. People feel like a party, I guess.

Oh, its more than just another space elevator. Youll see.

New ways forward, Mum? Ive just come down from a conference with Bob Paxton and others on new deep-defense concepts.

Big concepts. Terraforming programs, for instance.

Youre kidding.

No. Just thinking big. Thats what cutting your teeth on the shield does for you, I guess. And I must talk to Myra Dutt sometime. She glanced at the sky. We have to do something about Mirthis other place Myras mother went to. Theyre humans in there too. If we can speak to them, as Alexei Carel claims they have been able to on Mars, surely we can find a way to bring them home...

There was a stir. Bella was aware of people approaching her, hundreds of eyes on her on this roof alone, and that cam robot whirled and glistened at her feet, puppylike. Even those monks by the alligator pond were staring at her, grinning from ear to ear.

She looked at her watch. I think its time.

Mum, youre going to have to say something.

I know. Just a minute more. She looked out to sea, to the shining vertical track of the elevator. Edna, call the kids so they can see.

The children came to join them, clutching their presents, with Cassie and John Metternes, who hoisted Thea up onto his shoulders.

A flare went up from that oil rig, a pink spark arcing and trailing smoke. Then there was motion along the track of the elevator, shining droplets rising up one of the pair of threads. A ragged cheer broke out around them, soon echoed among the wider throngs scattered across Canaveral.

Its working, Bella breathed.

But whats it carrying? Edna murmured, squinting. Magnify...Damn, I keep forgetting Im in EVA.

Water, Bella said. Sacks of seawater. Its a bucket chain, love. The pods will be lifted to the top of the tower, and thrown off.

Thrown where?

The Moon, initially. Later Venus.

Edna stared at the elevator stack. So wheres the power coming from? I dont see any laser mounts on that rig.

There arent any. There is no power sourcenothing but the Earths rotation. Edna, this isnt really an elevator. Its a siphon.

Ednas eyes lit up with wonder.

The orbital siphon was an extension of the space-elevator concept that derived from the elevators peculiar mechanics. Beyond the point of geosynchronous orbit, centripetal forces tended to throw masses away from the Earth. The trick with the siphon was to harness this tendency, to allow payloads to escape but in the process to draw more masses up from Earths surface. Essentially, the energy of Earths rotation was being transferred to an escaping stream of payload pellets.

So you dont need any external energy input at all, Edna said. I studied this concept at USNGS. The big problem was always thought to be keeping the damn thing fedyoud need a fleet of trucks working day and night to maintain the payload flow. But if all youre throwing up there is seawater We call it Bimini, Bella said. Its appropriate enough. The native Americans told Ponce de Leon about a fountain of youth on an island called Bimini. He never found it, but he stumbled on Florida...

A fountain of youth?

A fountain of Earths water to make worlds young again. The Moon first, then Venus. Look, Edna, I wanted this as a demonstration to the Spacers that were serious. It will still take centuries, but with resource outputs like this, terraforming becomes a practical possibility for the first time. And if Earth lowers its oceans just a fraction and slows its rotation an invisible amount to turn the other worlds blue again, I think thats a sacrifice worth making, dont you?

I think youre crazy, Mum. But its magnificent. Edna grabbed her and kissed her.

Thales spoke. This is a secure channel. Bella, Ednathe Q-bombs closest approach is a minute away.

Secure line or not, the news soon seemed to ripple out. Silence spread through the rooftop marquees, and the massed crowds around Canaveral. Suddenly the mood was soured, fretful. Edna took Thea from John Metternes and clutched her close. Bella grabbed her daughters free hand and gripped it hard.

They looked up into the brilliant sky.

55: Q-BOMB.

The choice had been made. The bomb was already looking ahead, to the terminus of its new trajectory.

The blue, teeming world and all its peoples receded behind it.

Like any sufficiently advanced machine the Q-bomb was sentient to some degree. And its frozen soul was touched by regret when, six months after passing Earth, it slammed into the sands of Mars, and thought ended forever.

56: MARS 2.

November 2071 The dust was extraordinary here in Hellespontus, even for Mars, dust museum of the solar system.

Myra sat in her blister cockpit with Ellie von Devender as the rover plunged over the banks and low dunes. This was the southern hemisphere of Mars, and they were driving through the Hellespontus mountains, a range of low hills not far from the western rim of the Hellas basin. But the rovers wheels threw up immense rooster-tails, and the stuff just flew up at the windscreens, wiping out any kind of visibility. The infrared scanners, even the radar, were useless in these conditions.

Myra had been around space technology long enough to know that she had to put her faith in the machinery that protected her. The rover knew where it was going, in theory, and was finding its way by sheer dead reckoning. But it violated all her instincts to go charging blindly ahead like this.

But we cant slow down, Ellie said absently. We dont have time. She was paging her way through astronomical datanot even looking out the window, as Myra was. But then her primary task was much more significant, the ongoing effort to understand what precisely the Q-bomb had done to Mars since its impact five months ago, an impact that had done little harm in itself, but which had planted a seed of quintessence that would soon shatter Mars altogether.

Its just all this dust, Myra said. I didnt expect these kind of conditions, even on Mars.

Ellie raised her eyebrows. Myra, this area is notorious. This is where a lot of the big global dust storms seem to be born. You didnt know that? Welcome to Dust Central. Anyhow you know were in a rush. If we dont find that old lady on its hundredth birthday were going to let down the sentimental populations of whole worlds. She grinned at Myra, quite relaxed.

She was right. As everybody waited for the full extent of the bad news about the planets future, the electronic gaze of all mankind had been fixed on Mars and the Martians. It was sympathetic or morbid, depending on your point of view. And of all the frantic activities in advance of the final evacuation of a world, none had caught the public imagination as much as what cynical old hands like Yuri called treasure hunting.

Mars was littered with the relics of the pioneering days of the robot exploration of the solar system, some seventy years of triumph and bitter disappointment that had come to a definitive end when Bob Paxton planted the first human footprint in the red sands. Most of those inert probes and stalled rovers and bits of scattered wreckage still lay in the dust where they had come to rest. The early colonists of Mars had had no energy to spare to go trophy hunting, or a great deal of interest; they had looked to the future, not the past. But now that it appeared that Mars might have no future after all, there had been a clamor to retrieve as many of those old mechanical pioneers as possible.

It wasnt a job that required a great deal of specialist skill in Martian conditions, and so it was an ideal assignment for Myra, a Martian by recent circumstance. For safety reasons she couldnt travel alone on these cross-planet rover jaunts, however, and so she had been assigned Ellie as a companion, a physicist rather than a Mars specialist who might be better employed elsewhere. Ellie had been quite happy to go along with her; she could continue her own work just as well in a moving rover as in a station like Lowell or Wellsbetter, she said, for there were fewer distractions.

Of course, Ellies work was far more important than any trophy-hunting. Ellie was working with a system-wide community of physicists and cosmologists on predictions of what was to become of Mars. Right now she was looking at deep-sky images of star fields. As far as Myra understood, their best data came not from Mars itself but from studies of the sky: though it was hard to grasp, the distant stars no longer looked the same from Mars as they did from the Earth. It defeated Myras imagination how that could possibly be so.

Anyhow the retrieval program had been successful in terms of its own goals. With the help of orbital mapping Myra and others had reached the Vikings, tonnes of heavy, clunky, big-budget Cold War engineering, where they still sat in the dry, rocky deserts to which cautious mission planners had consigned them. The famous, plucky Pathfinder craft with its tiny robot car had been retrieved from its rock garden in the Ares Vallisthat one had been easy; it wasnt far from Port Lowell, site of the first manned landing. Myra knew that British eyes had been on the retrieval of fragments of the Beagle 2, an intricate, ingenious, toylike probe that had not survived its journey to the Isidis Planitia. And then there had been the recovery of the exploration rovers, Spirit and Opportunity, worn out by journeys that far exceeded their design capabilities. All these antique artifacts were destined for Smithsonian establishments on the Earth and Moon.

The retrieval expeditions had had scientific goals too. There was some interest in how man-made materials had withstood up to a century of exposure to Martian conditions. And the landing sites were of interest in themselvesotherwise the probes would not have been sent there. So Myra and Ellie had worked through a crash last-minute science program of sampling, mapping, and coring.

There had even been efforts to retrieve some of the elderly orbiters, still spinning around Mars, long silent. There was universal disappointment when it was discovered that Mariner 9, the very first orbiter, was gone; if it had survived into the 2040s it was surely swallowed up when sunstorm heat caused a general expansion of the Martian atmosphere.

Myra was glad to have something constructive to do. But she hadnt expected such intense public scrutiny of her treasure-hunting, with every move being followed by a system-wide audience. The crews had been promised that no images would be returned from the rover cabin itself. But Myra tried never to forget that the rovers systems could easily be hacked; she could be watched at any moment.

The day wore on, and the daylight, already murky under the rovers artificial dust storm, began to fade. Myra began to fret that they would not after all find the wreck of Mars 2, as the light ran out on this anniversary day.

Then Ellie sat back, staring at a complex graph on her softscreen.

Myra studied her. She had gotten to know this edgy physicist well enough to understand that she wasnt given to extravagant displays of any emotion save irritation. This sitting-back and staring was, for Ellie, a major outburst.

What is it? Well, there it is. Ellie tapped her screen. The destiny of Mars. Weve figured it out. All right. So can you say what it means, in simple terms?

Im going to have to. According to this message Im to take part in a three-world press conference on it in a couple of hours. Of course the math is always easier. More precise. She squinted out at the dust, thinking. Put it this way. If we could see the sky, and if we had a powerful enough telescope, we would see the most distant stars recede. As if the expansion of the universe had suddenly accelerated. But we would not see the same thing from Earth.

Myra pondered that. So what does that mean?

The Q-bomb is a cosmological weapon. We always knew that. A weapon derived from the Firstborns technology of universe creation. Yes?

Yes. And so So what it has done is to project Mars into its own little cosmos. A kind of budding-off. Right now the baby Mars universe is connected smoothly to the mother. But the baby will come adrift, leaving Mars isolated.

Myra struggled to take this in. Isolated in its own universe?

Thats it. No sun, no Earth. Just Mars. You can see that this weapon was just supposed to, umm, detach a chunk of the Earth. Which would have caused global devastation, but left the planet itself more or less intact. Its too powerful for Mars. It will take out this little world altogether. She grinned, but her eyes were mirthless. It will be lonely, in that new universe. Chilly, too. But it wont last long. The baby universe will implode. Although from the inside it will feel like an explosion. Its a scale model of the Big Rip that will some day tear our universe apart. A Little Rip, I suppose.

Myra pondered this, and didnt try to pursue the paradox of implosions and explosions. How can you tell all this?

Ellie pointed to the obscured sky. From the recession of the stars weve observed with telescopes on Mars, a recession you wouldnt see from Earth. Its an illusion, of course. Actually the Mars universe is beginning to recede from the mother. Or, equivalently, vice versa.

But we can still get off the surface. Get to space, back to Earth.

Oh, yes. For now. There is a smooth interface between the universes. She peered at her screen and scrolled through more results. In fact its going to be a fascinating process. A baby universe being born in the middle of our solar system! Well learn more about cosmology than we have in a century. I wonder if the Firstborn are aware of how much theyre teaching us...

Myra glanced uneasily about the cockpit. If they were being hack-watched, this display of academic coldness wasnt going to play too well. Ellie. Just rejoin the human race for a minute.

Ellie looked at her sharply. But she backed off. Sorry.

How long?

Ellie glanced again at her screen and scrolled through her results. The data is still settling down. Its a little hard to say. Ballparkthree more months before the detachment.

Then Mars must be evacuated by, what, February?

Thats it. And after that, maybe a further three months before the implosion of the baby cosmos.

And the end of Mars. Just six more months grace, then, for a world nearly five billion years old. What a crime, she said.

Yeah. Hey, look. Ellie was pointing to a crumpled, dust-stained sheet protruding from the crimson ground. Do you think thats a parachute?

Rover, full stop. The vehicle jolted to a halt, and Myra peered. Magnify...I think youre right. Maybe the twisters whip it up, and keep it from being buried. What does the sonar show?