Читать книгу Titan - Stephen Baxter - Страница 6

After seven years of flight, after travelling a billion miles from Earth, the human spacecraft Cassini reached Saturn.

Cassini was about the size of a school bus. Thick, multi-layer insulation blankets covered most of the craft’s structure and radiation-hardened equipment. The blankets’ outermost layer was translucent amber-coloured Kevlar, with shiny aluminum beneath; the two layers together made it look as if the spacecraft had been sewn into gold.

But Cassini looked its age.

The blankets were yellowed, and showed pits and scars from micrometeorite impacts. The brave red, white and blue flags and logos of the US, NASA, ESA and the contributing European countries, fixed as decals on the insulation, had faded badly in the years since launch. Cassini’s close approach to the sun, with the intense heat and solar wind there, had done most of the damage.

A fat pie-dish shape, ten feet across, clung to the side of the Cassini stack, so that the craft looked like a robot warrior going to battle, clutching a shield. In fact, the shield was a combined aeroshell and heat shield for a separate spacecraft, called Huygens, which was designed to land on Saturn’s largest moon Titan. The results Huygens gathered would serve as ‘ground truth’, confirmation and calibration for the more extensive orbital surveys Cassini would perform of the moon.

Now Cassini reached a point in space almost four million miles from Saturn’s cloud tops.

From here, the planet looked the size of a quarter-inch ball bearing held at arm’s length. Spinning in just ten hours, the planet was visibly flattened. A telescope might have shown its yellowish cloud tops, with their streaky shading and complex, anti-cyclonally rotating cloud systems. The sun was off to the right, with its close cluster of inner planets, so Saturn, seen from the probe, was half in shadow. The ring system, tight around the planet, was almost edge-on to the spacecraft, all but invisible, and it cast sharp shadows on the cloud tops.

Titan – the largest of the moons, orbiting twenty Saturn radii from its parent – was a reddish-orange pinprick, well outside the ring system.

Titan appeared to lie directly ahead of the spacecraft.

It was time.

Pyrotechnic bolts fired, silently, releasing puffs of vapour that immediately crystallized and dispersed. Three springs pushed Huygens away from Cassini, and a curved track and roller made the released probe spin, at seven revolutions per minute.

The path of Huygens and its parent probe diverged, at half a mile per hour.

Two days after the release, with the two craft about thirty miles apart – each clearly visible from the other, as a bright, complex star – Cassini fired its main engine once more, to deflect its orbit. Now Cassini and Huygens parted more rapidly.

Cassini’s nominal mission was a four-year orbital tour of the Saturn system. Its objectives were to study Saturn’s atmosphere, the atmosphere and surface of Titan, the smaller icy satellites, the rings, and the structure and physical dynamics of the magnetosphere.

And while Cassini flew on, Huygens – dormant, unpowered, a mere ten feet across, spinning slowly for stability – fell directly towards the burnt-orange face of Titan.

It was November 6, 2004.

… It would be a second-generation star.

It formed from a spinning cloud, of primordial hydrogen and helium, polluted by silicon, carbon and oxygen: rock and snow, manufactured by the first stars, the oldest in the Universe.

The cloud was a hundred times the width of the Solar System, to which it would give birth.

The cloud collapsed, and spun faster. It heated up. At last, the cloud became unstable, and broke up into successively smaller fragments.

It shrank. The cloud became opaque, and the heat it generated as it collapsed could no longer escape.

The core imploded suddenly.

The collapse made the core, a protostar, shine brilliantly, ten thousand times as bright as the sun that would shine on mankind.

Eventually the core was so hot that hydrogen nuclei began to fuse to helium. The thermonuclear energy generated balanced the inward gravitational force. The protostar stopped contracting.

It was a star. The sun.

The remaining nebula cloud condensed into dust particles and snowflakes. The orbiting particles collided with each other, and – because of the stickiness of the ice, and the organic tars coating the dust – they formed a flat disc of swarming planetesimals, objects ranging in size from a few yards across to several miles.

The planetesimals collided; some grew in size, forming planets, and others fragmented.

Most of the nebula’s mass was lost in the process.

Earth formed in a million years. Earth was dominated by rock, its snow boiled away by the young sun’s heat, its surface pounded by planetesimals.

Further out, it was different.

Further out, everything was moving more slowly, and the nebula was less dense. It was cold enough for water, carbon dioxide, ammonia and methane to condense into ice. So while the inner planets were dominated by rock, the accreting planetesimals at Jupiter’s orbit and beyond swept up dirty snow.

Hundreds of millions of years after Earth, Saturn formed, gigantic, gaseous. It radiated heat as it collapsed, warming the orbiting fragments of nebula gas and dust.

Around Saturn, an accretion disc formed. Moons coalesced, from a mixture of water ice, silicates, ammonia, methane and other trace elements.

One of them was massive.

It was half rock, half ice. It heated as it collapsed, because of its huge mass; the primordial ices melted and vaporized. The rock settled to the center, because of its greater density. At last, at the core of the moon, a ball of silicate formed, overlaid by a shell of ice, six hundred miles thick.

An ocean gathered. It was a mixture of ammonia and methane. A dense atmosphere was raised over it. The new world was a cauldron, with pressures hundreds of times that of Earth’s sea level in human times, and temperatures measured in hundreds of degrees.

The high pressure and temperature were sustained, for millions of years. And in the organic soup of the ammonia-water ocean, complex chemistry seethed.

But the new ocean and atmosphere were not stable. Ultra-violet flux from the young sun beat down; planetesimals continued to fall, blasting away swathes of the air; the atmospheric gases dissolved in the ocean.

The atmosphere cooled and thinned. The pressure dropped.

The ocean froze over.

New methane lakes formed, which converted slowly to ethane. Sunlight broke up atmospheric ammonia, to release a new atmosphere of nitrogen.

The moon settled into its long freeze.

But it was not inert. Ultraviolet photons from the sun and charged particles trapped in Saturn’s magnetic field beat down on the thick layer of air. Chemistry continued in the new atmosphere, and complex organic deposits rained down on the frozen surface …

Thus, for billions of years, Titan waited.

An object looking a little like a comet streaked across the sky of Titan, battering atmospheric gases to a plasma twice as hot as the surface of the sun itself.

Cooling, it fell towards the surface slush.

A parachute blossomed above it.

Huygens was built like a shellfish, with a tough outer cover shielding a softer kernel, with its fragile load of instrumentation. When its job was done, the outer aeroshell broke open, like the two halves of a clam shell, and the main chute unfolded.

So, after being carried across a billion miles, the aeroshell was discarded. It had absorbed nearly a third of the probe’s entire mass.

The descent module, exposed, was built around a disc-shaped platform of thick aluminum. Experiments and probe systems were bolted to the platform. The equipment was shrouded by a shell of aluminum, with a spherical cap for a nose and a truncated cone for a tail. It looked something like an inverted clam. Now cutouts in the shell opened, and booms unfolded from the main body. Instruments peered through the cutouts, or were held mounted on the booms, away from the main body.

Tentatively, the lander sought contact with the orbiter.

Fifteen minutes after its unpackaging, the main chute was cut away, and a smaller stabilizer chute opened.

The probe began to fall faster, into the deep ocean of air. Vanes around its rim made it rotate in the thickening air.

Diaphragms slid back. A series of small portals opened in the protective shell of the craft, and sensors peered out.

At the base of Titan’s stratosphere, some thirty miles above the surface, the temperature began to rise a little. Gradually, the surface became visible. Downward-pointing imagers peered, in visible and infra-red light, and as the probe slowly rotated, mosaic panoramas were built up.

At last, the probe crashed into the slush. Slowed by Titan’s low surface gravity, and the density of the lower air – half as dense again as Earth’s – the impact was slow, as gentle as an apple falling from a tree.

The probe continued its battery of experiments, pumping telemetry up to the orbiter, which sailed onwards towards Saturn.

Huygens was primarily an atmospheric probe. It had not been certain that the probe would survive the impact. And the probe had actually been designed to float if need be, for none of its mission planners had been sure whether oceans or lakes existed here, or if they did how extensive they were, or whether the chosen landing site would be covered by liquid or not.

Just six minutes after landing, the probe’s internal batteries were exhausted.

Melted slush frosted over the buried portals of the inert, cooling lander. And a thin rain of light brown organic material began to settle on the upper casing.

The chatter of telemetry to Cassini fell silent. The orbiter passed beneath the horizon, and then turned its high gain antenna away from Titan, to Earth. Patiently, Cassini began to download everything the lander had observed.

Some of the results were unexpected.

Paula Benacerraf worked through her EVA suit checklist.

She connected her Snoopy hat comms carrier to the suit’s umbilical. She set the sliding oxygen control on her chest pack to PRESS. She put on her gloves and snapped home the connecting rings. Then she lifted her helmet over her head. The suit built up to an overpressure, and she tested it for leaks.

The ritual of checks was oddly comforting. It took her mind off what she was about to do.

Tom Lamb rapped on her backpack.

Paula Benacerraf turned, awkwardly. Foot restraints held them both in standing positions, packed in head-to-toe. In her EMU – her suit, her EVA mobility unit – she felt ludicrously bulky, awkward in the confines of Columbia’s airlock, which was just a cramped, cylindrical chamber in the orbiter’s mid deck.

‘That’s it, Paula. I think we’re go.’

She said, ‘Already?’

‘Already.’ Lamb grinned out of his helmet at her, and she could see silvery stubble in the creases of his leathery cheeks. ‘You’re an independent spacecraft now.’

Her heart was hammering under the tough surface of her HUT, her hard upper torso unit. ‘Spaceship Paula. It feels good.’

Tom Lamb had once been the youngest Moonwalker. Now, at sixty-two, he was one of the oldest humans to have flown in space.

And Benacerraf, forty-five, a grandmother, was one of the oldest rookies.

Benacerraf disconnected her suit from the wall mount.

Lamb said, ‘Houston, we’ve got the hatch closed and we’re waiting for a go for depress on time.’ His native Iowan twang was overlaid with a Texan drawl acquired over long years at Houston.

‘Affirmative, EV1; you have a go for depress.’

Lamb turned to the control panel and turned the depress switch to position 5. Then, with the pressure down to five psi, Lamb turned the switch to its second position. ‘Depress valve to zero.’

Benacerraf heard a distant hiss. She moved the oxygen control on her chest pack to its EVA position.

‘Pressure down to point two,’ Lamb said now. ‘Let’s motor.’ He kicked his feet out of their restraints. With a confident motion he twisted the handle of the outer airlock hatch. Benacerraf thought the hinges and handle looked old, like bits of a school bus, with the polish of long use.

Lamb pushed the hatch outward, and Paula Benacerraf gazed into space.

She was looking along the length of the orbiter’s payload bay. The big bay doors were gaping open, the silvered Teflon surfaces of their radiator panels gleaming, and the bay itself was a complex trench, crammed with equipment, stretching sixty feet ahead of her. There was no direct sunlight; the bay was in the shadow of a wing, and the light in the bay was like a diffuse daylight.

Tom Lamb moved out through the airlock’s round hatchway, and drifted over to the left payload bay door hinge. There was a handrail and two slide wires that ran the length of the big hinge, and Lamb tethered himself to the wires. She could see his bright EV1 armbands.

He turned and waited for her.

‘Houston, the hatch is open and EV1 is out.’

‘We see you, Tom.’

‘EV2 is halfway out, getting ready.’

Benacerraf, with her hands on the doorway, felt as if she was frozen in place, as if she really couldn’t step out there.

Lamb lifted up his big gold visor, so she could see his face. ‘Just stay with it, kid. One step at a time.’

She grunted. ‘Some kid,’ she said.

Somehow, though, Lamb’s gravelly words punctured her tension.

She kept her eyes down on the floor of the payload bay and drifted through the hatch, just as she had done a hundred times in training, in the big swimming pool in the Sonny Carter Facility at Ellington Field. She fixed her own tether in place. Now, at least, she wouldn’t go drifting off into space.

For the first time she looked up.

Columbia was flying with her instrument-laden payload bay pointing at Earth, so that the planet was a ceiling of light above Benacerraf, a belly of ocean strewn with white, shadowed clouds.

Earth flooded the orbiter with light.

When he saw she was tethered, Lamb pulled himself along the length of the payload bay with practised ease. He reached the far end, and, diminished, he performed a simple pirouette, his tether flailing around him slowly.

‘Hey, Paula,’ Lamb said now. ‘Look at your hands.’

She lifted up a gloved hand before her face. There was grease on the glove, from the payload bay door hinge.

When she’d first joined the astronaut corps six years ago Benacerraf had been in complete awe of Tom Lamb.

He was the last Apollo veteran still working in the program, all of thirty-two years since the last Lunar Module had lifted off that remote surface. Tom Lamb still called himself an aviator, Navy style. She knew he had some kind of antique aeronautics degree from some technology institute in Georgia. But as far as he was concerned, Lamb was primarily a graduate of the Naval Pilot Test School at Patuxent River, in Maryland. She knew he had been known as a superb stick-and-rudder man, and his specialism had been night carrier landings, the hairiest flying in the Navy.

And as a young teenager Paula Benacerraf had watched Lamb and his commander Marcus White bounce like sun-drenched beach balls over the rubble-strewn floor of Copernicus.

How could you meet, how could you work with, a man like that?

But the awe had soon worn off, for Benacerraf.

Benacerraf was an engineering specialist – her discipline was orbital construction techniques – and she’d come into NASA with a hatful of qualifications, awards and degrees. She’d worked as a ground-based contractor on a number of Space Station construction missions. It was only when, because of Shuttle launch wave-offs and Russian construction delays, the Station assembly sequence had started to fall drastically behind its timeline that the need had been identified to draft the right experience directly into the program.

So – against the advice of her daughter Jackie, against the resistance of her employers – Benacerraf had given up her fancy consultant’s salary and her nice apartment in Seattle, and moved down to the humid stink of Houston, on Government pay.

At first she’d worked as a specialist in the backrooms behind the Mission Control rooms, in Building 30 of JSC, the Johnson Space Center. Then she’d been promoted to work as a Mission Controller, in the FCR – the Flight Control Room – itself.

But it still wasn’t enough. It was pretty obvious that this construction project – if it was ever going to get back on schedule – needed foremen in space.

Benacerraf had been a space nut since watching Lamb and his buddies on the Moon, all those years ago. But the thought of actually going up there herself, in a dinged-up old Space Shuttle, pretty much appalled her.

Tom Lamb himself had been deputed to talk her round. He’d used all the grizzled charm at his disposal.

… But I’ve got two grandchildren, Tom.

Hell, so have I. And if I can still cut it, a couple of years off my pension, why not you?

She was given promises of cooperation, special provisions, fast-tracks through the training. Even bonuses, to compensate her for her dropped salary. You’ll be treated with respect, drawled Tom Lamb. We need you, kid.

The training maybe hadn’t been quite as smooth as she’d been led to believe – too much resistance from the Spaceflight Training Division for that, who had insisted she had to work her way through their hierarchy of trainers and simulators, fast-track or no fast-track. But the pumped-up pay had come in as promised.

She just hadn’t bargained for the respect.

As an ascan, an astronaut candidate, she was royalty – at the rank of princess, at any rate, until she flew. People around the JSC campus were truthfully in awe of her, and the deference with which she was suddenly treated embarrassed her deeply.

But if she was a princess, Tom Lamb was a king among kings. And he loved it. She would watch him stroll through the Public Affairs Office or the clinic or the Crew Systems Lab, and people come running to serve him. And Lamb just lapped it up. It was as if Lamb had spent the whole of his adult life preparing for this role. Which, in a sense, he had.

Her opinion about Tom Lamb had evolved rapidly.

She pulled herself tentatively along the slide wire.

The orbiter was like a splayed-open aircraft. Before her she could see the big delta wings, spreading out to either side of the payload bay. Straight ahead, at the far end of the bay, was the bulky, rounded propulsion system housing, with its tanks and the engine bells for the main engines and the orbital manoeuvring system. Behind her was the flat rear bulkhead of the cabin section, like the wall of a big roomy shack, which contained the rest of the crew.

The curve of the wings was elegant. But for her, the design was spoiled by the softscreen mission sponsors’ logos displayed there: the US Alliance, Boeing, Lockheed, Disney-Coke. She knew that stuff brought in a lot of money to NASA, but for her it was a step too far.

At the back of the bay she could see the EDO wafer, the extended-duration pallet with its supplement of lox and liquid hydrogen for the orbiter’s fuel cells, which would allow Columbia to stretch out this mission to sixteen days. One objective of this flight had been to test the new EDO wafer in extremes of temperature, so the orbiter had been aligned to keep the payload bay in shadow for hours at a time, longer periods than on most flights.

Tom Lamb approached her, along the starboard fuselage longerons. ‘You ready for the MMU?’

‘Sure.’

‘Houston, EV2 preparing to deploy MMU.’

‘Copy that, Tom.’

Benacerraf made her way to the MMU station. The Manned Manoeuvring Unit was a big backpack shaped like the back and arms of an armchair. Since launch it had been stored in its station in the payload bay against the rear cabin bulkhead, on the starboard side.

Lamb had got there first, and he ran a quick check of the MMU’s systems.

‘You ready?’

‘Let’s do it.’

Lamb held her arms. He turned her around, and she backed into the MMU. She felt latches clasp her suit’s backpack.

‘Houston, EV2,’ she said. ‘EMU latches closed.’

‘Copy that.’

She pulled the MMU’s arms out around her. She closed her gloved hands around the controllers, which were simple hand-controllers on the end of the arms. A fibre optic data cable plugged into her suit from the MMU.

Lamb released the tethers which still clipped her to the payload bay slide wires, and reached around her. ‘Captive latches released.’

‘Copy.’

He shoved her gently in the back, and she floated away from the bulkhead. ‘Don’t even think about it,’ he said calmly. ‘It’s just like the sims.’

… Suddenly she didn’t have hold of anything, and she was falling.

‘Oh, shit.’

‘We didn’t copy that, EV2,’ the capcom said humourlessly.

Lamb ignored him. ‘Come on, Paula. Turn around.’

She had two big nitrogen-filled fuel tanks on her back now, and there were twenty-four small reaction control system nozzles. She grasped her right-hand controller, and pushed it left. There was a soft tone in her helmet as the thruster worked; she saw a faint sparkle of nitrogen crystals, to her right. In response to the thrust, she tipped a little to the left.

The controller was intuitive; moving it up or down made her pitch, her feet tipping up; left or right gave her a yaw, a sideways tilt. She twisted the handle, and made herself roll about an axis through her head to her feet.

The payload bay rotated around her.

‘It’s heavy,’ she said. ‘I can feel the unit’s inertia as I roll.’

‘You mass more than seven hundred pounds, suit and all, Paula.’

She blipped the RCS thrusters again, and slowed her roll. She finished up facing Lamb, where he clung to the aft cabin bulkhead. She pushed her left-hand controller, which drove her forward and back. There was a gentle shove, and her drifting slowed.

The MMU seemed to be working well, but its scuffs and scorch marks showed its age. And things most definitely did not feel the same, up here, as in the tethered sims on the ground. When she started moving, she just kept on going, until she stopped herself. She was in a frictionless, three-dimensional environment, like a huge ice-rink, where Newton’s laws held sway in their bare simplicity.

No wonder the Station assembly has proceeded so slowly, she thought. We just aren’t evolved for this environment.

‘Okay, Paula,’ Lamb called. ‘You ready for your one small step?’

No, she thought.

‘Let’s do it.’

‘Houston, EV2 is preparing to leave the payload bay.’

‘We copy, Tom.’

Benacerraf tipped herself up so she was facing Earth, with the orbiter behind her.

Earth, before her, was immense, overwhelming. The overall impression was of blue sea and white clouds, the white of an intensity that hurt her eyes. When she looked towards the horizon she could see the atmosphere, a thin blue shell around the planet.

She gave herself a single, firm thrust with the RCS. She felt a small, definite shove in the small of her back.

She rose out of the bay towards the face of Earth; she saw the big silvered doors to either side of her recede.

A tone sounded softly in her helmet, startling her.

‘Oh-two alarm, EV2.,’ the capcom reported.

An oxygen leak. Holed fabric, maybe. ‘Houston, EV2.. Should I come back? I—’

‘Belay that, EV2,’ Lamb said. ‘Paula, just take a couple of deep breaths. Relax. You’re safe and snug in there.’

She became aware of her breathing, which was shallow and rapid. Her suit monitors had misinterpreted her high oxygen consumption as a leak.

Deliberately, she slowed her breathing; she tried to unclench her muscles, to relax in the warm cocoon of the suit.

‘Just look at the view, kid.’

She looked at the view.

She was flying up towards Africa. The clouds piled over the equator seemed to reach down towards her, clearly three-dimensional and casting long shadows. She could see the Nile, and the ribbon development along it, surrounded by the baked-hard surface of the desert; the dependence of the people on the Nile’s water was clear.

She was extraordinarily comfortable. The suit was quiet, warm, safe. She could hear the whir of her backpack’s twenty-thousand rpm fan – it sounded like a pc fan. She heard squeaks and pops on the radio, as she drifted over UHF stations on the ground. In her bubble helmet she had a hundred and eighty degree vision, and she had a great sense of freedom. She knew that when she returned to the cabin, after the EVA, it would seem constricting, absurdly confining.

As she gazed at Earth – at all of humanity, save for the six on orbit with her on Columbia and a handful on Station – she felt some of the tension drain out of her, as if it was being drawn up to the planet. She felt lifted out of the web of concerns that dominated her life: the difficulties of her career, the frustrating pace of the space program, her unsatisfactory relationship with Jackie, her daughter, the blizzard of hassles that made up every day, mail and balky technology and her car and her apartment and accounts she had to pay and …

No wonder people get hooked on this, she thought.

‘Okay, EV2, Houston. Coming up to your three hundred feet limit.’

‘Copy that.’ Three hundred feet was as far as she could allow herself to travel. Moving away from Columbia, Benacerraf was actually entering a slightly different orbit. If she went much further, return to the orbiter would become a full-scale rendezvous, a matter of complex course correction manoeuvres.

She passed out of the shadow of the wing, and into sunlight; her EMU seemed to glow.

‘I see your light, Paula,’ Lamb called.

‘I’m pleased to hear it, Tom.’

‘EV2, Houston. Confirming your ground-to-MMU direct link is operational.’

‘Thank you.’

‘And your transponder beacon is functioning.’

‘Copy that.’

‘EV2, Houston. You have a lot of green-eyed people watching you; looks like you’re having a lot of fun.’

‘Sure. This is working very nicely. Ah, I’m glad I’ve got old Brer Rabbit out here with me, out in the briar patch where he belongs.’

She heard Lamb chuckle at that, back in the payload bay. She was aping the first words he’d spoken on the Moon.

Most astronauts got off the active list after four or five flights. They moved out into industry, or up into some kind of program management position within NASA. What kind of man was it who would keep on subjecting himself – and his family – to the grind of training, two years for every Shuttle mission, the enormous dangers of the missions themselves, flight after flight, year after year, logging up the spaceflight hours well into his sixties, endlessly defying the survival odds?

She’d even formulated the thought that maybe Lamb wasn’t actually good for anything else. To stay in the office you had to resist promotion, after all. You had to demonstrate sustained mediocrity. John Young, the other great surviving Moonwalker, had been taken off the active roster when he’d been so vocal in criticizing NASA safety procedures after Challenger.

Besides, all that ancient astronaut-as-Cold Warrior garbage from the 1960s, which still clung around NASA, just did not cut any ice with Benacerraf. It had nothing to do with the future of space travel as she saw it, which could only be about a steady, logical and gradual expansion of the space frontier, beyond Earth. Or even with the actions required of NASA, the space agency, to survive in a future of decreasing funding, increasing irrationality, a growing sense of military threat from China and elsewhere which was causing the ancient Cold Warriors to come rearing from their bunkers once more …

It might take all of her career to build the Space Station; she might never get to see another human being walk on the Moon. Well, that was fine by her. Space was a damn difficult place to work.

But as long as Lamb, and one or two others, still hung around, you still had the hero-centered distortion of the whole organization. As if everything that had happened after 1972 had been a long, dull coda. Even the Mission Controllers and their backroom staff were mostly aviation people of some kind, she was finding; and a startling number of the controllers – who were supposed to be there as specialist engineers or scientists – would apply to join the astronaut office at every recruitment round, regular as clockwork.

… But all that was before she’d begun to train with Lamb for this flight, STS-143. Before she’d sat with him through hours of sims, observed his prowess at the antique complexities of the Shuttle system, seen him demonstrate his calm control in the abort options. Tom Lamb could handle things, she’d come to realize. His old-fashioned jock bull hid a central, deep-rooted competence.

As she’d been strapped into Columbia’s flight deck for her first launch, she’d been grateful for Lamb’s calm voice, responding to the ground. If anyone could get her home alive, it would be Tom Lamb.

And anyhow, now she was up here, she started to see his point of view.

She swung herself around, and faced back down into the payload bay. She blipped her left-hand controller to slow her rotation.

Columbia’s cabin was above her head, the tail section below her feet. The starboard wing was in the shadow of the sun; the big Stars and Stripes on the port wing was obscured by the open bay doors. Her eyes were dark-adapted to Earthlight, so she could see no stars beyond the orbiter. Columbia was like a complex toy, brilliant white and silver, set against complete blackness.

At first glance Columbia looked faintly ridiculous: that fat, boxy body, the patchy coloration of the thermal protection system, the snub nose, those thick wings and that huge tail: Columbia was like an airliner stranded in space, its aerodynamic surfaces useless in vacuum. Columbia, the first of the five Shuttle orbiters built – and so the most primitive – weighed all of a hundred and eighty thousand pounds dry. You had to haul all that mass up into orbit, and back down again, every flight, to deliver just fifty thousand pounds of payload to orbit.

And after thirty flights Columbia was showing her age. She could see how the white-painted hull was scarred and battered, the slight discolorations between the tiles, the scuffs on the windows that sparkled in the sunlight, the stains on the thermal fabric lining the payload bay.

But all of that seemed to fade from her awareness, as she saw the orbiter drifting serenely against the blackness of space. Bizarrely, Columbia looked as if she belonged up here.

The Shuttle system was the technology of the 1970s, still flying in the ’oos, with the hard wisdom of the intervening years built into it. And, realistically, no replacement system in sight. Columbia was fresh paint over rusty, obsolescent technology. But somehow, up here, she was able to make out the 1960s von Braun dream of spaceplanes which the orbiter embodied.

Her throat hurt. Damn it, she felt as if she was going to cry.

The light around her changed. The shadow of the starboard wing was growing longer. Columbia was passing into another forty-five minute night.

‘… Hey, Paula,’ Tom Lamb said now. ‘Scuttlebutt from home. Some double-dome from JPL is saying he’s found life on Titan.’

‘Really?’

‘So they say. Nice place to hear about it, huh.’

‘Yes,’ she said.

… She turned again, to face Earth.

At the rim of the planet she could see the airglow layer, a bright layer of oxygen radiating at the top of the atmosphere, like a false horizon. The lights of cities, strung along the coasts of the land, looked like streetlights scattered along a road. There was a thunderstorm over central Africa, and she could see lightning sparking constantly, over cloud systems spanning thousands of miles. The lightning propagated through the clouds like a living thing, growing and spreading; its glow shone from beneath the layer of cloud, and she could see three-dimensional structure within the cloud, edges and swirls of purple.

The leading edges of Columbia glowed, a faint orange, in an aura a few inches thick. The glow came from a thin hail of atoms of atomic oxygen, interacting with the orbiter’s surfaces.

Even here, she thought, they were not truly free of Earth.

She thought about the news from Titan, wondering vaguely what it might mean for her.

The low-level arc floodlights in the payload bay glowed like a captive constellation.

The suit technician removed the protective cover from Jiang Ling’s helmet. Jiang sat down on the lip of the hatch and hauled herself into the orbital module, head first. Another technician pulled off her outer boots, and she swung her legs inside the module.

She was alone, here in this orbital compartment, this elongated sphere within which she would spend a week in low Earth orbit. The compartment was like a miniature space station, crammed with storage lockers, provisions, scientific equipment and literature. Everything was gleaming white, new and shiny.

The technicians were framed in the hatchway. They were both Han Chinese: military officers, with their brown uniforms visible under their white coats. They grinned at her. But, she thought, their eyes were hard.

One of them passed her a small brass bell. She took it in her gloved hand. It was inscribed with the face of Mao Zedong, in comfortable, corpulent middle age.

The technician grinned at her. ‘Maybe ta laorenjia will bring you luck.’

She raised her hand in thanks.

The technicians stepped back into the white room beyond the doorway, and hauled the hatch closed. It shut with finality. Even the quality of the sound changed. She was aware of a sense of enclosure, almost of claustrophobia.

Clutching the brass bell, she put such thoughts aside as irrelevant.

Beneath her was an inner hatch. She twisted around and lowered herself through this. Now she was entering the second of her craft’s three modules, called the command compartment, which she would ride to orbit – and home to Earth again, to her planned soft landing in the Gobi Desert.

Below her, inaccessible now, was the third part of her craft: an equipment module, containing fuel tanks, oxygen, water supplies, life support, and the mass of equipment that ran the on-board systems. The equipment module would be used to manoeuvre the craft in orbit, and when Jiang finally returned to Earth this stage would be used as a retro-rocket, before being jettisoned along with the orbital module.

She settled into her couch. The command compartment was a compact half-sphere, its walls curving up before her. There were bulky compartments and packs all around her, strapped to the walls and floor, most of them containing equipment that would be needed for the return to Earth: parachutes, flotation gear, emergency rations, blankets and thick clothes. The spacecraft’s main controls were set out before her: an artificial horizon, handsets for attitude controls, communications and monitoring gear.

She was hemmed in, embedded in this solid mass of equipment like a wrapped-up porcelain doll.

The astronaut trainees, morbidly, called the command compartment the xiaohao, after the small isolation cells which were still operated within Qincheng Prison in Beijing. But her brief feeling of confinement had passed, for the capsule was already alive: the cabin floodlights glowed cheerfully, complex graphics scrolled through the softscreens embedded in the walls, and green lights shone all over the instrument panels.

There were two small circular windows, one to either side of her. Now there was only darkness within them, because the spacecraft – perched here a hundred and seventy feet above the ground at the tip of the Long March booster – was enclosed within its protective fairing. But there was a small periscope, its eyepiece set in the center of the instrument panel before her, whose extension poked out beyond the fairing.

Seen through the periscope, the sky was a vast blue dome, devoid of moisture.

This was Inner Mongolia, the north-east of China. The desert was a vast, tan brown expanse, as flat as a table-top, stretching to the horizon in every direction. Beijing was hundreds of miles east of here. To the north, beyond the shadow of the Great Wall, camel trains still worked across the Mongolian Gobi.

The Jiuquan launch center itself was modest. There were just three launch pads set in a rough triangle a few hundred yards apart. The pads were concrete tables, a hundred feet across, with minimal equipment at each; there was a single gantry almost as tall as the Long March booster itself, which was moved on rails between the pads. She could see the railway spurs which brought booster stages here. There was no surrounding industrial complex, as at Cape Canaveral or Tyuratam. There was only an igloo-like blockhouse close to each pad, buried partly underground, containing the firing rooms; further away there were gleaming tanks and snaking pipelines for propellant storage and delivery, and a small power station.

The launch complex, in fact, was dwarfed by the thousand-mile hugeness of the Gobi.

To Jiang, the elemental simplicity of this facility was its power. Here in the mouth of the desert it was as if her booster had barely any connection with the Earth it was soon to shake off. To Jiang, Jiuquan was the reality of spaceflight, reduced to its core …

The flight was still to come, of course. But already, she sensed, the worst of her mission was over: the public tours, the attention from TV and net correspondents, the speeches to thousands of Party cadres in Tiananmen Square, even the meeting with the Great Helmsman himself. Of course there would be many more such chores after the flight, but that was far from her mind.

For now she was alone in here, contained within the xiaohao – in this environment she had come to know so well. Here, she was in command, and she was ready to confront destiny: to become the first Chinese, in five thousand years of history, to break the bonds of Earth itself.

A voice crackled in the small speakers on her headset. ‘Lei Feng Number One from the firing room. Are you ready to begin your checklist?’

She was still clutching the brass bell. She reached up, and fixed it to the handle of the hatch above her with a twist of wire. She touched Mao’s face with a spacesuited finger. The bell rang gently. She smiled. Now, ta laorenjia could protect her as he did millions of Chinese; Mao Zedong, three decades after his death, had become the most popular household folk god.

She settled back in her couch. ‘This is Jiang Ling in Lei Feng Number One. Yes, I can confirm I am ready to proceed with the checklist. Today is a good day to fly!’

The work seemed to come in waves, with clusters of switches to throw and settings to check in a short time. In addition she had to record measurements in her log book. And she had to work to reduce the condensation inside the cramped compartment. In orbit this would be done automatically, but on the ground the light pumps were overwhelmed by Earth’s gravity, and she had to open and close valves at set times, and she had a little hand-pump she used to move condensate from one part of the cabin to another.

There were several long holds in the countdown, when malfunctions were encountered. During these periods she had literally nothing to do, and she found them difficult times.

She was aware of continual movement and noise. She could feel the rocket swaying as the thin desert wind hit its flanks; and there was a succession of thumps, bangs and shudders, as ancillary equipment was moved to and from the booster. She was very aware that she was suspended at the top of a thin, fragile steel tower housing thousands of tons of highly explosive propellant.

There were cameras all over the cabin, focused on her face behind its open visor, their black lenses glinting in the floods. She tried to keep her expression clear, her movements calm and assured.

She felt a deep nervousness gnaw at her, more worrying even than the prospect that some catastrophe might claim her life, today. If something went wrong, if the mission was aborted, was it possible that she would somehow be blamed?

Jiang was not Han Chinese. She was a Turkic Uighur, a Muslim minority which emanated from the westernmost province of Xinjiang. Jiang’s family came from the desert capital Urumqi; her family had moved to Beijing when she was a child when Jiang’s father, a mid-ranking Party cadre, was posted to the Minorities Institute in the capital in the 1970s. Since her father was both an official and a Uighur, the family had been treated with a special deference reserved for select representatives of minority groups who served as symbols for the Party’s efforts to build ‘socialist solidarity’ between central China and the non-Han regions. In Beijing, Jiang had attended a special ‘experimental’ school reserved for the children of the Party élite.

Among the Han astronaut trainees there had been some resentment at her promotion – sometimes suppressed, sometimes not. And there had been genuine surprise when she had been selected for the honour of this first flight, ahead of the Han candidates.

Jiang believed that it was on the basis of her superior abilities. Perhaps that was true. But she knew that she could not help but accrue rivals and enemies, now, as she moved into national, even international prominence.

Meanwhile the xiaodao xiaoxi – the back-alley scuttlebutt – was that the Chinese space program, in its thirty-year history, had already killed five hundred people. Even worse, it was said, one astronaut had already lost his – or her – life, in a clandestine suborbital test of the Lei Feng-Long March system.

Jiang Ling believed some of this, but not all. She would be a fool to try to deny that she was exposing herself to enormous risks, here in the Lei Feng. Perhaps more risks than any other astronaut from East or West since the first pioneers themselves.

But for Jiang it was worth it. And not for the glory – for being what the People’s Daily called a jianghu haojie, a modern-day knight errant – and certainly not for the ‘iron rice bowl’ which her status afforded her. To Jiang, it was simply this moment, the hours and days to come: to be thrust into orbit, to look down on the Earth like a glowing carpet below. To Jiang, that was worth any risk.

As she’d come to the pad, a technician had told her the Americans were claiming to have found life on Titan, moon of Saturn.

Lying here now, Jiang tried to absorb the news. What could it mean? Could it be true?

In the end she dismissed the speculation. What value was a mission to Saturn? What use was life on Titan, even if it existed? Perhaps the stars were for America, but Earth was for China.

And now the holds started to clear up, and her mood lifted.

Jackie Benacerraf didn’t know what to expect of JPL. She certainly didn’t rely on the descriptions from her mother, the famous spacewoman.

She drove her hired car out along the Glendale Freeway, out of downtown LA, along tree-lined roads. She drove through swank suburbs, following the softscreen map in the car, and was surprised when she rounded a turn, and came upon JPL.

At first glance JPL could have been any reasonably modern corporate or college site, maybe a hospital: it was spread over two hundred acres, nestling in the eroded, green-clad shoulders of the San Gabriel Mountains, the blocky office buildings interspersed with Southern California palms. She caught glimpses of some kind of campus inside the security fences, fountains and trees.

But the roads here were called Mariner Road, and Surveyor Road, and Ranger Road. For the Jet Propulsion Laboratory had built and run spacecraft which had reached every planet in the Solar System, save only Pluto. And, right now, the scientists here were gathering information from the moons of Saturn.

She parked her car. Isaac Rosenberg was there to meet her at the visitors’ reception. ‘Jackie. Thanks for coming in.’

‘Isaac, it’s good to meet you again.’

He pushed his John Lennon spectacles a little further back up his nose. ‘Rosenberg. Everybody calls me Rosenberg.’

‘Rosenberg, then.’

He was somewhere in his mid-twenties, she figured, maybe a couple of years older than she was. He didn’t look as if he lived too well; his face was pale and badly shaved, and his prematurely thinning black hair, none too clean, was tied back in a pony tail.

But none of that mattered, compared to the look in his brown eyes.

He said, ‘Thanks for coming out. Listen, you want me to get you a coffee? A doughnut, maybe?’

‘No, thanks, Rosenberg. I want you to tell me about your results. At the party the other night, you were so –’

‘Out of it.’

‘Were you serious? Are the press reports true? How come the official spokesmen won’t answer questions on it?’

‘Come see the results for yourself.’

He led her through the reception area and across the campus, to a long, low building he called the SFOF, for Space Flight Operations Facility. He took her up to the second floor, to a big windowless loft of a room, painted grey, with grey carpeting. It was divided up into rows of cubicles, within which worked – Rosenberg said – the engineers and scientists who controlled Cassini’s systems. So this is a spacecraft control center, she thought. It was about as lively as a bank’s back office.

They crossed the engineering room, and then passed through a hall to a science area, and entered a new warren of cubicles, the science back room. Rosenberg took her to his own cubicle, which was cluttered up with papers and rolled-up softscreens and an old-fashioned hard-key calculator. There were reproductions of the covers of antique science fiction magazines taped to the cubicle walls, she saw: By Spaceship to Saturn, and Raiders of Saturn’s Rings, and Missing Men of Saturn.

He showed her a Packard Bell softscreen, stuck to one wall, which was cycling through displays of what turned out to be a thermal profile through Titan’s atmosphere, as sampled by the descending Huygens lander. Grabbing a mouse, he cleared down the screen and pulled up data from a fresh database.

She’d met him a few days before at a party at her old fraternity at Caltech, where he was getting steadily drunk on ice beer and talking too much, loud and fast and humourlessly, about his work here at JPL on the Cassini/Huygens mission. He’d attracted a rotating audience of student types, some intrigued, some argumentative; as the group cycled, Rosenberg would happily launch into his obsessive monologue again, as far as Jackie could tell pretty much from the beginning.

He was talking about biochemistry – the chemistry of life – on Saturn’s moon, Titan.

Jackie was intrigued. Here was a classic loser magnet, but with a story of such compelling intensity that it was attracting a crowd, if a transient one. And she got even more interested, when the sensational claims about life on Titan had started appearing in the press and the net.

She was in the middle of a new effort to revive her once-promising career in journalism, which had been pretty much dormant since her second kid was born. If she was going to progress, she knew, she was going to have to develop a nose for a story, her own story, something dramatic and compelling – but out of the way, far from the attention span of the big boys.

And maybe – she’d thought, listening to this skinny monomaniac mouthing off to a bunch of strangers about weird chemistry results from Titan, and with his eyes shining – maybe, she’d found it.

Before the end of that party she’d buttonholed Rosenberg and arranged to meet him here, at JPL. She’d figured it was a better than evens chance that he would have forgotten all about her, in which case she would have driven all this way out here to the arroyo for nothing. But when she’d arrived at the security gate, she found he’d left a media pass for her to collect.

Soon the softscreen was covered by chemical notation and complex molecular structure charts.

He said, ‘How much biochemistry do you know?’

Actually, she’d picked up a little in her graduate days. But she said, ‘Nothing.’

‘All right. I’m working in the group responsible for the GCMS results.’

‘GCMS?’

‘Gas chromatograph and mass spectrometer. In-situ measurements of the chemical composition of gases and aerosols in Titan’s atmosphere, and at the end of Huygens’s descent, a direct sample of the surface. The lead scientist is a guy at Goddard. On the lander, a slug sample was drawn in through filters and into an oven furnace, which –’

‘Enough. Tell me what you do.’

‘I’m working on high atomic number results. Complex molecules. Look – what do you know about conditions on the surface of Titan?’

‘Only what I’ve seen in the pop press the last few weeks.’

‘All right. Titan is an ice moon, with a thick layer of atmosphere. The only moon with a significant layer of air, anywhere. In a lot of ways, Titan right now is like primeval Earth – say, four and a half billion years ago. Its chemistry is mostly based around carbon, hydrogen and nitrogen. And chemistry like that produces a lot of the key molecules of prebiotic chemistry.’

‘Prebiotic?’

‘The components of life. But there’s a crucial difference. Titan has no liquid water. It’s too cold for that. The importance of water on primitive Earth is that it was a solvent. It allowed the polymerization of volatile reactive organics and the hydrolysis of prebiotic oligomers into biomolecules … I’m sorry. Look, you need water as a solution medium, so that the components, the building blocks, can assemble themselves into proteins and nucleic acids, the main macromolecules of our form of life.’

Our form of life. That phrase made her shiver. ‘But maybe there are other solvents.’

‘Correct. Maybe there are other solvents. In particular, ammonia. And we knew before Huygens that there is ammonia on Titan. Now. Look here. Look what the Huygens GCMS found.’ He pointed to a diagram of a molecule shaped like a figure eight on its side, with some of its edges highlighted in blue for double covalent bonds.

‘What is it?’

‘Ammono-guanine. That is, guanine with the water chemistry systematically replaced by ammonia.’ He looked up at her, the multicoloured diagram reflected in his glasses. ‘Do you get it? Exactly what we’d have expected to have found, if some ammonia-based analogue of terrestrial life processes was going on down there. Look at these ratios.’ He pulled up another image. ‘See that? Here, close to the surface, you have a depletion of methane and gaseous nitrogen, and a surplus of ammonia and cyanogen, compared to the atmosphere’s average. The analogy is clear. Methane and nitrogen are being used in place of monose sugars and oxygen, and you have ammonia and cyanogen instead of water and carbon dioxide –’

‘What are you saying, Rosenberg?’

‘Respiration,’ he said. ‘Don’t you get it? Something down there has been breathing nitrogen, and exhaling ammonia.’

‘So, could it mean life?’

He looked puzzled by the question. ‘Yes. That’s the point. Of course it could.’

She frowned, staring at the molecular imagery. It was exciting, yes, but it was hardly the electric thrill she’d been hoping for. Even those blurred images of the microfossils in that meteorite from Mars had had more sex appeal than this obscure stuff.

‘What do you think we should do about this?’

‘Send another probe, of course,’ he said, staring into the screen. ‘It ought to be a sample-return. We’ve just got to follow this up. Look at this.’

He studied his results, and Jackie studied him.

Right now, her own mother was on orbit, in Columbia.

In the long months of her mother’s work absences, Jackie had often wondered why it was always people with no life of their own on this planet – Rosenberg, her own mother after her lawyer husband walked out with his secretary – who became obsessive about finding life on others.

Anyhow it was academic. The funding just wasn’t there. Maybe not for the rest of your working life, Rosenberg, she thought sadly. This data, here, might be all you’ll ever see.

Rosenberg flexed his fingers, as if itching to thrust them into the ammonia-soaked slush of Titan.

‘Lei Feng Number One, there are five minutes to go. Please close the mask of your helmet.’

Jiang obeyed, locking the heavy visor in place with a click of aluminum. ‘My helmet is shut. I am in the preparation regime.’

‘Four minutes and thirty seconds to go.’

As her helmet enclosed her she was aware of a change in the ambient sound; she was shut in with the sound of her own voice, the soft words of the launch controllers in the firing room, the hiss of oxygen and the scratch of her own breathing.

Impatience overwhelmed her. Let the count proceed, let her fly to orbit, or die in the attempt!

Still the holds kept off: still she waited for the final, devastating malfunction which might abort the flight completely.

But the holds did not come; the counting continued.

The voices of the firing room controllers fell silent. There was a moment of stillness.

Jiang lay in the warm, ticking comfort of her xiaohao, the little Mao bell motionless above her, the couch a comfortable pressure beneath her, no sound but the soft hiss of static in the speakers pressed against her ear.

She closed her eyes.

And so the countdown reached its climax, as it had for Gagarin, Glenn and Armstrong before her.