At last hatches swung open. They walked through an airlock and clambered into a roomy interior. There was even a small medical area, complete with robotic arms capable of manipulating a set of surgical instruments.

Paula said, Well cover around a quarter of the planets circumference, traveling twenty hours a day at a nominal fifty klicks per hour. Five days should see us home.

Twenty hours a day? Myra and Bisesa exchanged glances. They had already been cooped up for weeks on the elevator and aboard the Maxwell. But these Spacers were used to lengthy confinement in small places. The Discovery will do the driving itself, of course. Its done the route a dozen times already, and probably knows every boulder and ice field. Its a smooth ride once were underway...

Paula briefly spoke to a traffic control center, and then the rover briskly popped itself loose of the dome airlock.

Once they were sealed in Alexei sat and blew air through pursed lips. Well, thats that. What a relief.

Myra glanced back at the Lowell domes. Couldnt we be chased?

Alexei said, The other rovers are out in the field. Mars is still very sparsely populated, Myra, sparsely equipped. Not a good place to mount a car chase. And its unlikely that Astropol and the other agencies have any assets at the polar base. Bisesa had learned that Astropol was a federation of terrestrial police agencies dedicated to offworld operations. Oh, they could come after us, Alexei murmured. But it would take something drastic to do it. They may not be ready to show their hand just yet.

The rover swung itself around and set off to the north.

Bisesa and Myra sat up front behind a big observation window, and watched the view unfold. It was about midday, and the sun was to the south behind them; the rovers shadow stretched ahead.

The domes of Lowell soon slipped behind the rear horizon, obscured by the rovers immense rooster-tails of dust. The road was metaled at first, glassy; then it was hard-pressed dirt, a scar in the faded dust, and before long nothing but a rutted track. Away from the base there was no sign of human activity, save for the odd weather station, and those endless rutted tracks peeling off to the north. Bisesa could make out the remnants of the Ares flood in the scoured landscape, the teardrop islands, the huge scattered boulders. But everything was old, worn down with age, every rock surface rubbed smooth, every slope draped with thick dust.

With nothing to see but rocks, Myra soon went to join Alexei and Paula, who had a common interest in an exotic form of poker.

Bisesa sat alone in the bubble rovers blister window, riding smoothly over Mars. As the sun wheeled through the sky, Mars began to work a kind of spell on her. It was like Earth, with some of the furniture of an earthly landscape: the land below, the sky above, the dust and the scattered rocks. But the horizon was too close, the sun too small, too pale. A corner of her hindbrain kept asking: how can the world be like this?

It was in this mood of strangeness that she saw the arch.

The rover never brought them close. But it loomed over the horizon, tall, impossibly slender. She was sure that that immense crosspiece could not have been supported on Earth; it was Martian architecture.

The day wore away. The sunset was long and elaborate, with bands of diminishing color following the small sun toward the horizon. The night sky was oddly disappointing, though, with only a scattering of stars; there must be too much dust suspended in the air. Bisesa looked for Earth, but either it wasnt up or she didnt recognize it.

Paula brought her a plate of food, a piping-hot risotto with mushrooms and green beans, and a mug of coffee fitted with a lid. She leaned down and peered straight ahead, through the window.

Bisesa asked, What are you looking for? The north celestial pole. People generally ask. Tourists like me, you mean.

Paula wasnt fazed. Mars doesnt have a bright pole star, like Polaris. Butlook, can you see Cygnus, the swan? The brightest star is Deneb, Alpha Cygni. Follow the spine of the swan, up through Deneb, and the celestial pole is about halfway between Deneb and the next distinct constellation, Cepheus.

Thank you. But the dust everywherethe seeing isnt as good as I expected.

Well, Mars is a museum of dust, the climatologists say, Paula said. Its not like Earth. We have no rain to wash the dust out, no sedimentary processes to bake it all into rock. So it stays in the air.

Mars as a snow globe, Bisesa thought. I saw an arch.

Paula nodded. Erected by the Chinese. They put up a monument like that every place one of their arks came down.

So that tremendous structure was a memorial to hundreds of Chinese who had died on Mars on sunstorm day.

Bisesa ventured, Paula, I was a little surprised you came along with us.

Surprised?

And that youre mixed up with this secretive business at the pole of Mars. Alexei, yes, I can see it in his personality.

He is a bit furtive, isnt he?

They shared a laugh. Bisesa said, But you seem more Conformist? That pretty airline-stewardess smile was still in place, illuminated by the dash lights. I dont mind if thats said of me. Maybe its true.

Its just that youre so good at your job.

Paula said without resentment, I was probably born to it. My mother is the person most people remember of the Aurora crew, after Bob Paxtonthe only one, probably.

And so visitors respond to you.

It could have been a handicap. Why not turn it into an asset?

Okay. But that doesnt extend to hauling your backside all the way to the north pole for us. She paused. You admire your mother, dont you?

Paula shrugged. I never met her. But how could I not admire her? Bob Paxton came to Mars and sort of conquered it, and then went home again. But my mother loved Mars. You can tell that from her journals. Bob Paxton is a hero on Earth, she said. But my mother is a hero here on Mars, our first hero of all. The stewardess smile flicked back on. More risotto?

In the murky Martian dark, in the warmth of the cabin, Bisesa fell asleep in her seat.

She woke to a tap on her shoulder. She found she was swathed by a blanket.

Myra was sitting with her, gazing out of the window into dawn light. Bisesa saw they were driving through a landscape of rolling dunes, some of them tens of meters high, frozen waves a kilometer or two apart. Some kind of frost gathered in their lee.

My, I slept the night through.

Are you okay?

Bisesa shifted, exploring. A little stiff. But I guess even a chair like this is comfortable in low gravity. Ill stretch and have a wash shortly.

Youll have to wait for Alexei. Hes shaving his head again. I guess I got hypnotized by the view. White line fever. Or something. Myra sounded irritable. Myra? Is something wrong?

Wrong? Christ, Mother, look at that view. Nothing. And yet here you are, sitting up here for hour after hour, just drinking it in.

Whats wrong with that?

Its you. If theres something strange, youre drawn to it. You revel in it.

Bisesa glanced around. The others were asleep. She realized that this was the first time she and Myra had effectively been alone since the washed-out days after her waking at the Hibernaculumthere had never been real privacy even on the Maxwell, and certainly not in the elevator spider cabin.

Weve never had a chance to talk, she said.

Myra made to stand up. Not here.

Bisesa put her hand on her arm. Come on. Who cares if the police are listening in? Please, Myra. I dont feel I know you anymore.

Myra sat back. Maybe thats the trouble. I dont know you. Since you came out of the tankI think Id got used to living without you, Mum. As if you had died, perhaps. And when you did come out, you arent how I remember you. Youre like a sister Ive suddenly discovered, not my mother. Does that make sense?

No. But we havent evolved for Hibernacula time-slips, have we?

What do you want to talk about? I mean, where am I supposed to start? Its been nineteen years, half my life.

Give me one headline.

Okay. Myra hesitated, and looked away. You have a granddaughter.

Her name was Charlie, for Charlotte, Myras daughter by Eugene Mangles. Now aged fifteen, she had been born four years after Bisesa went into the tank.

Good God. Im a grannie.

When we broke up, Eugene fought me for custody. And he won, Mum. He had the clout to do it. Eugene is powerful and hes famous.

Bisesa said, But he was never very human, was he?

Of course I had access. But that was never enough. Im not like you. I dont want strangeness. I wanted to build a home, for me and Charlie. I wantedstability. I never got close to that. And in the end he cut me out altogether. It wasnt hard. Theyre hardly ever even on the Earth.

Bisesa reached for her hand; it was cold and unresponsive. Why didnt you tell me this before?

Well, for one thing you didnt ask. And, look, here we are on Mars! And were here because youre the famous Bisesa Dutt. You have much more important issues to worry about than a lost granddaughter.

Myra, Im sorry. When this is all over Oh, dont be ridiculous, Mum. It never is over, with you. But Ill support you even so. I always will. Look, forget about it. You had a right to know. Well, now you do. Her face was intent, her mouth pinched. Green light was reflected in her eyes.

Green?

Bisesa sat up with a jolt, and looked out of the blister window.

Under a salmon-pink dawn sky, the rutted tracks snaked across a plain that was painted a deep dull green.

Paula joined them. Discovery. Slow down so we can see. The truck obligingly slowed, with a distant grinding of gears.

Myra and Bisesa sat uncomfortably; Bisesa wondered how much Paula had heard of their conversation.

Now Bisesa could see that the green was a carpet of tiny plants, each no larger than her thumb. Each plant looked like a leather-skinned cactus, but it had translucent sectionswindows to catch the sunlight, Bisesa supposed, without losing a precious drop of moisture. There were other plants too. She picked out small black spheresround to retain heat, black to soak it up during the day? She wondered if they turned white, chameleon-like, to avoid dissipating heat at night. But the cacti predominated.

Myra said, The cacti are what Helena discovered, in the wake of the sunstorm. Life on Mars.

Yes, Paula said. The most common multicelled organism weve found yet on Mars. The subsurface bacterial mats and the stromatolites in Hellas are more widespreada lot more biomass. But the window cacti are still the stars of the show. The species has been named for my mother.

Each window cactus was a survivor from deep ages past, Paula said.

When the solar system was young, the three sister worlds were briefly similar: Venus, Earth, Mars, all warm, wet, geologically active. It was impossible to say on which of them life spawned first. Mars was certainly the first to accumulate an oxygen atmosphere, the fuel for complex, multicelled life-forms, billions of years before the Earth. But Mars was also the first to cool and dry.

Paula said, But this took time, hundreds of millions of years. You can achieve a lot in hundreds of millions of yearswhy, the mammals filled out an ecology vacated by the dinosaurs in less than sixty-five million years. The Martians were able to evolve survival strategies.

The roots of the cacti were buried deep in the cold rock of Mars. They didnt need oxygen, but fueled their glacial metabolism with hydrogen released by the slow reaction of the volcanic rocks with traces of water ice. Thus they and their ancestors had survived aeons.

There were always volcanic episodes, Paula said. The Tharsis calderas thicken the air every ten to a hundred million years. The cacti grow, propagate, grow dormant again, surviving as spores until the next episode. And then the sunstorm caused rain, water rain. The air has stayed thick and wet enough to keep them out of their dormant stages right through the year.

And, the biologists say, they are related to our sort of life. Its a different sort of DNA here, Paula said. Using a different set of basessix, not fourand a different kind of coding. The same with Martian RNA and proteins, not quite like ours. Its thought the amino acid set thats used here is subtly different too, but thats still controversial. But it is DNA and RNA and proteins, the same toolbox as on Earth.

Mars was young in an age of continuing massive bombardment, as the relics of the solar systems violent formation smashed into the new worlds. But that battering ensured that an immense amount of material, blasted off the roiling surfaces, was transferred between the planets. And that material contained life.

Bisesa gazed out at the patient cacti. So these are our cousins.

But more distantly related than we are to any other life-forms from Earth. The last significant biomass transfer must have been so early that the final form of DNA coding wasnt yet settled on either world. But the relationship is close enough to be useful.

Useful? How?

Paula tapped a softscreen on the Discoverys dashboard, and produced images showing how Lowell scientists were finding ways to splice Martian genes into terrestrial plants. And that was how a new breed of plant was being developed, neither purely terrestrial nor purely Martian, able to grow outside the pressurized domes of the colonies, and yet capable of providing food for humansand of injecting oxygen into the air. Some of the biologists thought it was a route to terraforming, a first step toward making Mars like Earth. An informal grouping of them even had a slogan: All These Worlds Are Ours.

In fact, Paula said, Im glad we happened on the cacti. Its important you know about this, Bisesa. Why? So you can understand what theyve found at the pole. I cant wait, Myra said dryly.

And I cant wait for the bathroom, Bisesa said. She pushed her way out of her chair, letting the blanket drop. Alexei? Are you done in there yet?

The Discovery rolled on, patient, silent, for kilometer after kilometer, a cybernetic Stakhanovite. By the middle of that day they were through the green, and rolled across a dull, undulating plain.

After that, each day of the journey the sun climbed lower. At last it panned around the horizon, and there was no full daylight, only a kind of twilight glow that washed around the obscured sky.

Bisesa understood. Mars was tilted on its axis, just as was Earth; in northern winter the pole pointed away from the sun, and as she headed north she was driving into a twelve-month-long Arctic night. What was different about Mars was how quickly the changes came; here, the lines of latitude clicked away rapidly. She had a very clear sense that she was driving over the surface of a small round world, an ant crawling over an orange.

One sunset they saw a bank of clouds on the northern horizon.

By dawn they were under it. The polar hood was thick enough to obscure all but the brightest stars; Deneb and the celestial pole were lost.

By midday it had begun to snow.

20: LIBERATOR.

Its taken us under five days to cross the solar system, Thea. Think of that. And now theres only a few hours to go before Q-hour, our rendezvous with the bomb...

The Liberator had the mass and rough dimensions of the old Saturn V launchers. But whereas most of a Saturns mass would have burned itself up and been discarded in minutes, leaving its payload to coast unpowered most of the way to its destination, the Liberators mighty engine could maintain a thrust of a full gravity or more for days, even weeks. That had enabled the ship to cut a straight-line trajectory from one point on the J-line to another, from the Trojan base to the position of the bomb. Its path was a rectilinear oddity in a solar system of circles and ellipses.

And Edna had crossed half the distance between Jupiter and the distant sun in a hundred hours.

Were actually slowing down now. Were approaching the Q-bomb tail-first, our exhaust blasting out...

Most of the officers serving in space have been transferred from the U.S. Navy, because most spacecraft are more like submarines than anything else. But the Liberator is different. Weve so much energy to burn that we have more room on this ship than on any spacecraft since Skylab. If youve never heard of that, look it up. John Metternes and I share a kind of big apartment, with bedrooms, showers, and a stateroom with softscreens and coffee-makers. When we go to the ports and look down at the flank of the ship, its like looking out of the window of a high-rise hotel on Earth. But most hotels dont have antennae and sensor booms. Or gun ports.

I need to go, love. The drives about to be cut, and it would be embarrassing to meet the bogey with me stranded in midair!...

How do I feel? Im frightened. Excited. I have confidence in my abilities, and Johns, and in the Liberator, which has already proven herself a fine ship. I just hope thats enough to carry the day. II guess thats all, Libby. Close file.

Yes, Edna. It is time. I know. Call John, would you?

Bisesa couldnt see a thing.