Titan n-2

by Stephen Baxter

  And there was her theme.

  She said: “It is precisely three thousand, nine hundred and sixty-seven years since Chinese astronomers witnessed an extraordinary heavenly event.

  “The motions of all five naked-eye-visible planets brought them together in the sky. Above the crescent Moon at the horizon, Venus, Mercury, Mars, Saturn and Jupiter were strung out like lights on some celestial road, near the great square of Pegasus. That unique conjunction must have been a transfixing event. It was the beginning of the planetary cycles of our ancient astronomers.

  “There has been no other time in the last four thousand years, and there will not be in the next four thousand, when such a spectacle will be visible again. But I am reminded of it now, as I study the Earth, Moon and sun framed together in the window of my capsule. How appropriate it is that a Chinese person should be here, to witness this unique conjunction!”

  The joy in her voice was unfeigned. Jiang Ling was happy and proud to be here. She said that in her broadcasts, and she meant it.

  The habitable compartments of Tianming were small, confining. The craft was improvised, of course, and much of its mass besides was given over to the weapon and its support systems, rather than to her comforts. But she was comfortable here, in this little spinning metal shell in space, and she was not given to claustrophobia.

  Her mother told her she was happy in space, and nowhere else. It was true.

  Sometimes it struck her as remarkable, however, how everything in the Universe had become separated into two distinct categories, characterized around herself: within a few feet of her body, contained in this compact craft, or else they were millions of miles away.

  She continued with her broadcast, and other duties.

  Her shelter in space consisted of cylindrical compartments, strung together along a common axis, like a collapsible telescope. Its curved hull was swathed with a powder-white insulating blanket, which shone brightly in the sun. Three huge solar panels were fixed around the module’s widest section; they could be swivelled, like the faces of flowers, to trap the sunlight, and they were covered with cells, big black squares neatly aligned.

  The smaller cylinders were used for docking with ferry craft and experimental work, and they were crammed with storage lockers, science equipment and control panels. The main body of the craft was called the working compartment, some fourteen feet wide.

  There was a small table at which she could sit, by wrapping her legs around a rudimentary T-shaped chair. There were control and instrument panels, and command and signal equipment of the type used in Lei Feng spaceships. There were a number of work positions, where she could take measurements of such items of scientific interest as the interplanetary plasma environment surrounding the ship. There was a single, rather small porthole. During the cruise, the Tianming was rolled, continually, to ensure a uniform heating by the sun’s rays; this had the effect of limiting her useful observations.

  To the left and right of the workstations there were controls for the craft’s basic systems: air regulation filters and pumps, temperature and humidity controllers, as well as more equipment and bio-medical research apparatus.

  There was a small galley area, with enough supplies, she was told, for a mission of one hundred days, with a small margin. There was an exercise cycle into which she could strap herself. Her orders were to use this for no less than three hours a day, in order to reduce the risk of muscle wastage and bone erosion.

  Beyond the working chamber, inaccessible to Jiang, was a small hemispherical module containing rocket motors and propellant tanks.

  Her home in space was brightly lit, compact and cheerful. She felt liberated, after the confines of the Lei Feng capsule, within which it had been barely possible to move. Everything was new and clean, even the lavatory section, the drawers full of neatly folded coveralls and underwear. The fans and pumps hummed comfortingly, and there was a smell of freshness — not a natural smell, but like a new carpet, she thought.

  She slept in a cupboard, a box little larger than she was. Inside, however, tucked into her sleeping bag with the folding door drawn to, she was secure.

  She had brought with her the small brass bell that had accompanied her on her first flight, in Lei Feng Number One — how long ago that seemed! As she prepared for sleep, she watched it drift in stray currents in the circulating air, on its curling length of vermilion ribbon, occasionally ringing. The inscribed face of Mao was intermittently visible, like the Moon hidden by clouds.

  During her hundred-day flight, she performed science experiments with her space aquarium.

  It looked like a suitcase containing two carousels from a compact disc player; but the walls of the carousels were clear, and murky water was visible within. The aquarium contained one thousand mussel larvae, thirty thousand sea urchin eggs and six thousand starfish embryos. One carousel spun up, imitating the Earth’s gravity, and the other provided a gravity-free environment. The experiment had begun three hours after departing Earth orbit, when Jiang had injected a sperm concentrate into a container full of sea urchin eggs.

  She had used a microscope to observe the effects of spaceflight on urchin embryo development. The study was designed to provide insight into the causes and cures of osteoporosis and muscular dystrophy. And she followed the calcium formation of a mussel’s shell, to shed light on the bone depletion suffered by humans in space. The creatures’ unusual swimming and feeding patterns, carefully recorded on video, were studied to provide pointers on how the oceans’ fish populations might better be managed. Jiang also spent much time studying the embryos of starfish. The purpose was to learn how to predict and control early birth defects in humans. The embryo of a starfish, in early stages of development, was remarkably similar to that of a human…

  The bioscience program was genuine work. But it was essentially a blind: a misdirection, intended to confuse anyone following her mission suspiciously.

  In some senses she was lying, and she felt obscure shame about that: to come all the way out here, fifteen times as far as the Moon was from Earth — an astounding technical feat, especially for a country which a century ago had been an agricultural backwater — and lie!

  And yet, she felt, on another level she was telling a greater truth, a truth that transcended the exigencies of her mission.

  Earth was not alone. Earth and Moon swam together through a sea of objects, of varying sizes, called NEOs: near-Earth objects, also called Earth-crossing asteroids.

  The object of Jiang’s mission was known as NEO 2002OA, discovered in 2002. It was a mountain-sized rock, covered with impact craters and a regolith — a pulverized surface layer — like the Moon’s. It was on a course which would bring it within a million miles of Earth: just four times the distance from Earth to Moon, only some one hundredth of the distance from Earth to sun.

  There were three hundred thousand NEOs a hundred yards across or bigger, and some two thousand half a mile across or bigger. Some were rocky, some metallic, others rich in organics.

  Earth sat at the bottom of the deepest gravity well between sun and Jupiter. Over billions of years, twenty percent of all the NEOs would impact the planet.

  It was undoubtedly true, she had learned, that if humanity was to have a long-term future, leaving the planet and dispersing was the only option. Space travel was no leisure luxury for a rich world, but essential for the survival of the species.

  Perhaps, she comforted herself, her mission — successful or otherwise — might spur a greater awareness of the hazardous environment within which humanity had, perforce, made its home; perhaps, in some ultimate long term, she might actually prove the savior of humanity.

  Perhaps she might be remembered as mankind’s greatest hero.

  Rather than as its supreme villain.

  Three days from her closest approach, with the asteroid grown massive in her window, she saw the flashes of the drone warheads which had preceded her.

  The weapons had emplaced themselves close to the
asteroid, though away from its surface. The flashes looked like miniature dawns. They were immediately surrounded by surges of debris from the asteroid’s pulverized surface, which rocketed out in well-defined jets, some fragments glowing white-hot.

  There was, of course, no heat, no sound, no concussion wave transmitted from the massive explosions — though her heart quailed as she looked into the fusion light.

  She carefully observed the explosions, and prepared to compute their consequences.

  The mission philosophy was simple. The smallest impulse required to deflect that rocky body was more than could feasibly be delivered by a single weapon. Too large an explosion, besides, could shatter the object, removing its usefulness.

  Therefore a string of automated weapons had been launched by Long March boosters over the days preceding Jiang’s own launch. The necessary impulse would be applied, not by one large detonation, but by a series of smaller ones. Tianming was distinguished only in carrying the last — albeit the largest — of the weapon set, to deliver the final tweak to the asteroid’s new trajectory.

  The mission design offered a chance for more accuracy, besides. The asteroid still had to travel many millions of miles along its new path. The successive explosions could be used to herd the asteroid closer towards the required final trajectory. The last detonation was, of course, the final opportunity for adjustment.

  It was explained to Jiang, carefully, that China lacked the facility for sufficiently precise deep space tracking of either the asteroid or an unmanned spacecraft, and the robotic expertise to enable such a craft to navigate itself, sufficiently precisely. Only a human navigator — such as herself — using optical techniques on the spot could make the precise measurements of the deflection achieved of the asteroid by the unmanned probes, and then emplace the final weapon sufficiently precisely to achieve the last elements of the required deflection.

  Such was her purpose.

  It was also explained, equally carefully, that time, resource deficiencies and mission constraints were such that it had not been possible to provide a separable delivery system for the weapon itself. Nor any return or reentry provisions for the crew. That is, it was necessary for Tianming to remain in place during the explosion.

  This was a factor which she took into account, in the course of her decision to accept the mission.

  To fly in space:to venture once again beyond the atmosphere, to become the first Chinese to venture beyond low Earth orbit, the first Chinese to spend a hundred days in space — for that, she had, to her own surprise, been willing to exchange everything. Her life.

  Even her place in history.

  Jiang Ling was a spaceflight junkie.

  It was even possible, she mused, that had this flight been offered even to some of the one hundred frustrated American astronauts, dispersing slowly from Houston, some of them may have accepted, so great was the lure of returning to the secret place, to space.

  And having made her bargain, she would, of course, complete her mission.

  It was conceivable that the detonations would be observed from the United States itself, and elsewhere. If they were, the Party had a further plausible cover story, she knew: that the explosions were being used in a scientific analysis of the asteroid’s structure.

  The light faded rapidly. The debris cloud dispersed quickly — or rather, the asteroid’s new orbit took it away from the fragments blown out of it by the weapons.

  The dosimeter aboard Tianming indicated that the radiation dose she had already taken exceeded nominal safety limits.

  Jiang Ling smiled.

  She picked up her optical navigation gear — a sextant with a simple telescope — and began to study the new position of the asteroid.

  On the last day before closest approach, she found it more difficult than before to comply with the order to complete her three hours’ cycling.

  For her final broadcast she chose to feature the aquarium. She positioned the camera so that it focused on the apparatus, and then moved so that her own face was in the shot, close to the aquarium. For the benefit of the video camera, she made a show of peering into the microscope; her vision filled with blue water light. She spoke in her broadcast about these little creatures being her fellow passengers aboard Tianming.

  It was a little corny, but it contained the essential truth. Somewhere in the milky-blue images of squirming sea urchins and eerily human starfish embryos, somewhere in this drop of the primeval sea which she had carried with her, so far from Earth, there was a sense of unity with all life, a hope of salvation.

  She was not alone, even here, so far from the planet which had spawned her; she was still as one with all the creatures of the world.

  Her greatest regret, in fact — which grew as 2002OA loomed — was that the thousands of creatures in this aquarium could not hope to survive the events to come.

  Jiang Ling could no longer see Earth, Moon or sun.

  On this, the hundredth day, the dark hide of 2002OA slid past the small window of Tianming.

  It was as if she was flying over some miniature Moon, she thought. The surface was so pierced and broken by craters of all sizes that it was impossible to tell, by eye, how far away it was; she might have been in an Apollo spacecraft sailing over the surface of the Moon, sixty miles below, or peering through some camera at a plaster mockup, just out of arm’s reach.

  The spacecraft was in the shadow of the asteroid now, and only the spotlights of Tianming illuminated the surface, less than a mile from the craft: she fired her camera through the window, and the digitized photographs of churned regolith were sent immediately to the ground stations.

  She heard the clatter of solenoids, felt the judder of the craft as it was pushed by squirts of the automatic reaction control system.

  She was beyond the useful reach of her optical navigation; now, the automatic systems of the spacecraft had come into their own — particularly the radar, which would determine Tianming’s distance from the asteroid surface, and match it to the ground-based calculations using her astronomical observations of the asteroid’s new path.

  For optimal yield, the warhead required a standoff detonation, with the warhead placed forty percent of the object’s radius above the surface. There, the weapon could irradiate an ideal thirty percent of the surface of 2002OA.

  The weapon had been engineered to maximize its production of neutrons, which would be absorbed by the top few inches of the crust. The irradiated shell would heat, expand and spill away, thus imparting a rocket-like stress wave impulse to the asteroid.

  From now on, until the mission reached its conclusion, Jiang Ling was a passenger.

  She found the thought oddly restful.

  She went to her sleeping cupboard, and retrieved the small brass bell. She rattled it, and the small clapper rang against the wall of the bell, and she stared into the corpulent, smiling face of ta laorenjia.

  She ate a final breakfast. She found the ground crew had packed a special, final meal: duck, pork with rice, and even a small bulb of ckemshu, a rice liqueur.

  She ate with relish. Then she carefully tidied away the plate and cutlery and enclosed microgravity cups.

  It was hard to imagine that in a few minutes none of this familiar cabin and environment would exist; it was right to behave as if that were not so.

  According to her mission clock, the final moment was mere seconds away. She had requested that the cabin camera be disabled, and that the radio link be kept silent.

  She didn’t want a countdown. And she had said her good-byes.

  The last person she had embraced, on Earth, was her mother.

  A little before detonation, Jiang Ling pressed her fists into the sockets of her eyes.

  She saw the complete bone structure of her hands, like an X-ray, drenched in pink light.

  There was a moment of heat—

  * * *

  It was Benacerraf who found the methane vent.

  As, despite her mountain-top adventure, she cont
inued to ban any EVA beyond the walk-back limit, Rosenberg had set up a systematic program to take atmospheric and surface samples from the area around Tartarus they could reach in a couple of hours. So he sent Benacerraf in her snowshoes striking across the featureless, dull ground to the north-west. After a couple of miles, as he had instructed, she filled up her little sample bottles and started to return.

  As she returned — taking a sighting on the white crest of Mount Othrys, visible as a hulking silhouette through the haze — she came upon a place where the gumbo appeared to have a different consistency, a lighter color.

  She stopped, right in the middle of the discoloration patch.

  She dug at the gumbo with her snowshoe, and bent down to take a closer look. The light was even worse than usual; they were coming to the end of one of the eight-day-long Titan “days,” and the methane overcast was heavy. But even in the dim, dried-blood light, she could see there was something unusual about the gumbo here. It was peppered by big, flattened bubbles. And as she watched, a fresh bubble emerged from under the tholin, spreading and flattening, streaks of color swimming in its surface.

  She must have walked right over this patch on the way out. Whatever this was, it was out of the ordinary, surely the kind of thing Rosenberg had them out here looking for.

  She bent, awkwardly, and took fresh sample bottles from her EMU pockets. She took a scraping of the gumbo itself, the air above the gumbo, and — with reasonable skill, she thought — managed to insert the plastic needle of a syringe into a bubble without breaking the sticky meniscus, and was able to draw out the uncontaminated gases within.

  She straightened up, labelled the bottles, noted her location and walked on.

  Back at Tartarus, inside the scuffed, patched-up, shack-like interior of the hab module, Rosenberg was distracted. He was busy trying to rebuild a balky nutrient pump from the CELSS farm, and he told her to store her sample bottles and he’d check them when he had time.