Kitabı oku: «The Complete Mars Trilogy», sayfa 7

PART THREE The Crucible

It formed with the rest of the solar system, around five billion years ago. That’s fifteen million human generations. Rocks banging together in space and then coming back and holding together, all because of the mysterious force we call gravity. That same mysterious warp in the weft of things caused the pile of rocks, when it was big enough, to crush in on its center until the heat of the pressure melted the rock. Mars is small but heavy, with a nickel-iron core. It is small enough that the interior has cooled faster than Earth’s: the core no longer spins inside the crust at a different speed and so Mars has practically no magnetic field. No dynamo left. But one of the last internal flows of the molten core and mantle was in the form of a huge anomalous lumping outward on one side, a shove against the crust wall that formed a continent-sized bulge, eleven kilometers high: three times as high as the Tibetan plateau is above its surroundings. This bulge caused many other features to appear: a system of radial fractures covering an entire hemisphere, including the largest cracks of all, the Valles Marineris, a lace of canyons that would cover the United States coast to coast. The bulge also caused a number of volcanoes, including three straddling its spine, Ascraeus Mons, Pavonis Mons and Arsia Mons; and off on its northwest edge, Olympus Mons, the tallest mountain in the solar system, three times the height of Everest, one hundred times the mass of Mauna Loa, the Earth’s largest volcano.

So the Tharsis Bulge was the most important factor in shaping the surface of Mars. The other major factor was meteor fall. In the Noachian Age, three to four billion years ago, millions of meteors were falling on Mars at a tremendous rate, and thousands of them were planetesimals, rocks as big as Vega or Phobos. One of the impacts left behind Hellas Basin, 2000 kilometers in diameter, the largest obvious crater in the solar system; although Daedalia Planum appears to be the remains of an impact basin 4500 kilometers across. Those are big; but then there are areologists who believe that the entire northern hemisphere of Mars is an ancient impact basin.

These big impacts created explosions so cataclysmic that it is hard to imagine them; ejecta from them ended up on the Earth and the Moon, and as asteroids in Trojan orbits; some areologists think that the Tharsis Bulge started because of the Hellas impact; others believe that Phobos and Deimos are ejecta. And these were only the largest impacts. Smaller stones fell every day, so that the oldest surfaces on Mars are saturated with cratering, the landscape a palimpsest of newer rings obscuring older ones, with no patch of land untouched. And each of these impacts released explosions of heat that melted rock: elements were broken out of their matrix and fired away in the form of hot gases, liquids, new minerals. This and the outgassing from the core produced an atmosphere, and lots of water; there were clouds, storms, rain and snow, glaciers, streams, rivers, lakes, all scouring the land, all leaving unmistakable marks of their passage – flood channels, stream beds, shorelines, every kind of hydrologic hieroglyphic.

But all that went away. The planet was too small, too far from the sun. The atmosphere froze and fell to the ground. Carbon dioxide sublimed to form a thin new atmosphere, while oxygen bonded to rock and turned it red. The water froze, and over the ages seeped down through the kilometers of meteor-broken rock. Eventually this layer of regolith became permeated with ice, and the deepest parts were hot enough to melt the ice; so there were underground seas on Mars. And water always flows downhill; so these aquifers migrated down, slowly seeping, until they pooled behind some stoppage or another, a rib of high bedrock or a frozen soil barrier. Sometimes intense artesian pressures built against these dams; and sometimes a meteor would hit, or a volcano appear, and the dam would burst apart and a whole underground sea would spew over the landscape in enormous floods, floods ten thousand times the flow of the Mississippi. Eventually, however, the water on the surface would freeze and sublime away in the ceaseless dry winds, and fall on the poles in every winter’s fog hood. The polar caps therefore thickened, and their weight drove the ice underground until the visible ice was only the tip of two world-topping lenses of underground permafrost, lenses ten and then a hundred times the visible caps’ volume. While back down toward the equator, new aquifers were being filled from below, by outgassing from the core; and some of the old aquifers were refilling.

And so this slowest of cycles approached its second round. But as the planet was cooling, all of it happened more and more slowly, in a long ritard like a clock winding down. The planet settled into the shape we see. But change never stops; the ceaseless winds carved the land, with dust that grew finer and finer; and the eccentricities of Mars’s orbit meant that the southern and northern hemispheres traded the cold and warm winters in a 51,000 year cycle, so that the dry ice cap and the water ice cap reversed poles. Each swing of this pendulum laid down a new stratum of sand, and the troughs of new dunes cut through older layers at an angle, until the sand around the poles lay in a stippled cross-hatching, in geometrical patterns like Navajo sand paintings, banding the whole top of the world.

The colored sands in their patterns, the fluted and scalloped canyon walls, the volcanoes rising right through the sky, the rubbled rock of the chaotic terrain, the infinity of craters, ringed emblems of the planet’s beginning … Beautiful, or harsher than that: spare, austere, stripped down, silent, stoic, rocky, changeless. Sublime. The visible language of nature’s mineral existence.

Mineral; not animal, nor vegetable, nor viral. It could have happened but it didn’t. There was never any spontaneous generation out of the clays or the sulphuric hot springs; no spore falling out of space, no touch of a god; whatever starts life (for we do not know), it did not happen on Mars. Mars rolled, proof of the otherness of the world, of its stony vitality.

And then, one day …

She hit the ground with both feet solid, nothing tricky about it, the g familiar from nine months in the Ares; and with the suit’s weight, not that much different from walking on Earth, as far as she could remember. The sky was a pink shaded with sandy tans, a color richer and more subtle than any in the photos. “Look at the sky,” Ann was saying, “look at the sky.” Maya was chattering away, Sax and Vlad spun like rotating statues. Nadezhda Francine Cherneshevsky took a few more steps, felt her boots crunch the surface. It was salt-hardened sand a couple of centimeters thick, which cracked when you walked on it; the geologists called it duricrust or caliche. Her boot tracks were surrounded by small systems of radial fractures.

She was out away from the lander. The ground was a dark rusty orange, covered with an even litter of rocks the same color, although some of the rocks showed tints of red or black or yellow. To the east stood a number of rocket landing vehicles, each one a different shape and size, with the tops of more sticking over the eastern horizon. All of them were crusted the same red-orange as the ground: it was an odd, thrilling sight, as if they had stumbled upon a long-abandoned alien spaceport. Parts of Baikonur would look like this, in a million years.

She walked to one of the nearest landing vehicles, a freight container the size of a small house, set on a skeletal four-legged rocket assembly. It looked like it had been there for decades. The sun was overhead, too bright to look at even through her faceplate; it was hard to judge through the polarization and other filters, but it seemed to her that the daylight was much like that on Earth, as far as she could remember. A bright winter’s day.

She looked around again, trying to take it in. They stood on a gently bumpy plain, covered with small sharp-edged rocks, all half-buried in dust. Back to the west the horizon was marked by a small flat-topped hill. It might be a crater rim, it was hard to say. Ann was already halfway there, still quite a large figure; the horizon was closer than seemed right, and Nadia paused to take note of that, suspecting that she would soon become accustomed to it, and never notice. But it was not Earthlike, that strangely close horizon, she saw that clearly now. They stood on a smaller planet.

She made a concerted effort to recall Earth’s gravity, wondering that it should be so hard. Walking in the woods, over tundra, on the river ice in winter … and now: step, step. The ground was flat, but one had to thread a course between the ubiquitous rocks; there was no place on Earth that she knew of where they were distributed so copiously and evenly. Take a jump! She did, and laughed; even with her suit on she could tell she was lighter. She was just as strong as ever, but weighed only thirty kilos! And the forty kilos of the suit … well, it threw her off balance, that was true. It made her feel that she had gone hollow. That was it: her center of gravity was gone, her weight had been shifted out to her skin, to the outside of her muscles rather than the inside. That was the effect of the suit, of course. Inside the habitats it would be as it had been in the Ares. But out here in a suit, she was the hollow woman. With the aid of that image she could suddenly move more easily, hop over a boulder, come down and take a turn, dance! Simply pop in the air, dance, land on top of a flat rock – watch out—

She tumbled, landed on a knee and both hands. Her gloves broke through the duricrust. It felt like a layer of caked sand at the beach, only harder and more brittle. Like hardened mud. And cold! Their gloves weren’t heated the way their boot soles were, and there wasn’t enough insulation when actually touching the ground. It was like touching ice with the bare fingers, wow! Around 215° Kelvin, she recalled, or –90° Centigrade; colder than Antarctica, colder than Siberia at its worst. Her fingertips were numb. They would need better gloves to be able to work, gloves fitted with heating elements, like their boot soles. That would make the gloves thicker and less flexible. She’d have to get her finger muscles back into shape.

She had been laughing. She stood and walked to another freight drop, humming “Royal Garden Blues.” She climbed the leg of the next drop and rubbed the crust of red dirt off an engraved manifest on the side of the big metal crate. One John Deere/Volvo Martian bulldozer, hydrazine-powered, thermally protected, semi-autonomous, fully programmable. Prostheses and spare parts included.

She felt her face stretched in a big grin. Backhoes, front loaders, bulldozers, tractors, graders, dump trucks; construction supplies and materials of every kind; air miners to filter and collect chemicals from the atmosphere; little factories to render these chemicals into other chemicals; other factories to combine those chemicals; a whole commissary, everything they were going to need, all at hand in scores of crates scattered over the plain. She began to hop from one lander to the next, taking stock. Some of them had obviously hit hard, some had their spider legs collapsed, others their bodies cracked, one was even flattened into a pile of smashed boxes, half-buried in dust; but these were just another kind of opportunity, the salvage and repair game, one of her favorites! She laughed aloud, she was a bit giddy, she noticed the comm light on her wrist console blinking; she switched to the common band and was startled by Maya and Vlad and Sax all talking at once, “Where’s Ann, you women get back here, hey Nadia, come help us get this damned habitat online, we can’t even get the door open!”

She laughed.

The habitats were scattered like everything else, but they had landed near one that they knew was functional; it had been turned on from orbit some days before, and run through a complete check. Unfortunately the outer lock door could not be included in the check, and it was stuck. Nadia went to work on it, grinning; it was odd to see what looked like a derelict trailer home sporting a space station lock door. It only took a minute for her to get it open, by tapping out the emergency open code while pulling out on the door. Stuck with cold, differential shrinking perhaps. They were going to have a lot of little problems like that.

Then she and Vlad were into the lock, and then inside the habitat. It still looked like a trailer home, but with the latest in kitchen fixtures. All the lights were on. The air was warm, and circulating well. The control panel looked like a nuclear power plant’s.

While the others came inside, Nadia walked down a row of small rooms, through door after door, and the oddest feeling suddenly came over her: things seemed out of place. The lights were on, some of them blinking; and down at the far end of the hall, a door was swinging slightly back and forth on its hinges.

Obviously the ventilation. And the shock of the habitat’s landing probably had disarranged things slightly. She shook off the feeling and went back to greet the others.

By the time everyone had landed and walked across the stony plain (stopping, stumbling, running, staring off at the horizon, spinning slowly, walking again), and had entered into the three functioning habitats, and gotten out of their EVA suits, and put them away, and checked out the habitats, and eaten a bit, talking it all over the whole while, night had fallen. They continued working on the habitats and talking through most of that night, too excited to fall asleep; then most of them slept in snatches until dawn, when they woke and suited up and went out again, looking around and checking manifests and running machines through checks. Eventually they noticed they were famished, and went back in to jam down a quick meal; and then it was night again!

And that was what it was like, for several days; a wild swirl of time passing. Nadia would wake to the bip of her wrist console and eat a quick breakfast looking out of the habitat’s little east window: dawn stained the sky rich berry colors for a few minutes, before shifting rapidly through a series of rosy tones to the thick pink-orange of daytime. All over the floor of the habitat her companions slept, on mattresses that would fold up against the wall during the day. The walls were beige, tinted orange by the dawn. The kitchen and living room were tiny, the four toilet rooms no more than closets. Ann would stir as the room lightened and go to one of the four toilets. John was already in the kitchen, moving around quietly. Conditions were so much more crowded and public than they had been on the Ares that some of them were having trouble adjusting; every night Maya complained she couldn’t sleep in such a crowd, but there she was, mouth open girlishly. She would be the last to rise, snoozing through the noise and bustle of the others’ morning routines.

Then the sun would crack the horizon, and Nadia would be done with her cereal and milk, the milk made of powder mixed with water mined from the atmosphere (it tasted just the same); and it was time to get into her walker, and out to work.

The walkers were designed for the Martian surface, and were not pressurized like spacesuits, but were rather made of an elastic mesh, which held in the body at about the same pressure that the Terran atmosphere would have. This prevented the severe expansion bruising that would result if skin were exposed to Mars’s minimal atmosphere, but it gave the wearer a lot more freedom of movement than a pressurized spacesuit would have. Walkers also had the very significant advantage of being fail-operational; only the hard helmet was airtight, so if you ripped a hole at knee or elbow you would have a badly bruised and frozen patch of skin, but would not suffocate and die within minutes.

Getting into a walker, however, was a workout in itself. Nadia wriggled the pants over her long underwear, then the jacket, and zipped the two sections of the suit together. After that she jammed into big thermal boots, and locked their toprings to the suit’s ankle rings; pulled on gloves, and locked the wrist rings; put on a fairly standard hard helmet, and locked it to the suit’s neck ring; then shouldered into an airtank backpack, and linked its air tubes to her helmet. She breathed hard a few times, tasting the cool oxygen-nitrogen in her face. The walker’s wristpad indicated that all the seals were good; and she followed John and Samantha into the lock. They closed the inner door; the air was sucked back into containers; John unlocked the outer door. The three of them stepped outside.

It was a thrill every morning to step out onto that rocky plain, with the early morning sun casting long black shadows to the west, and the various small knolls and hollows revealed clearly. There was usually a wind from the south, and loose fines moved in a sinuous flow over the ground, so that the rocks sometimes seemed to creep. Even the strongest of these winds could scarcely be felt against an outstretched hand, but they hadn’t yet experienced one of the storm winds; at five hundred kilometers per hour they were pretty sure to feel something. At twenty, nearly nothing.

Nadia and Samantha walked over to one of the little rovers they had uncrated and climbed in. Nadia drove the rover across the plain to a tractor they had found the day before about a kilometer to the west. The morning cold cut through her walker in a diamond pattern, as the result of the X weave of the heating filaments in the suit material. A strange sensation, but she had been colder in Siberia many a time and she had no complaints.

They came to the big lander and got out. Nadia picked up a drill with a Phillips screwdriver bit, and started dismantling the crate on top of the vehicle. The tractor inside the lander’s crate was a Mercedes-Benz. She poked the drill into the head of a screw, pulled the trigger and watched the screw spin out. She moved to the next, grinning. Innumerable times in her youth she had gone out in cold like this, with numb white chopped-up hands, and fought titanic battles to unscrew frozen or stripped screws … but here it was ziiip, another one out. And really with the walker it was warmer than it had been in Siberia, and freer than in space, the walker no more restrictive than a thin stiff wetsuit. Red rocks were scattered all around in their uncanny regularity; voices chattered on the common band: “Hey, I found those solar panels!” “You think that’s something, I just found the goddamn nuclear reactor.” Yes, it was a great morning on Mars.

The stacked crate walls made a ramp to drive the tractor off the lander; they didn’t look strong enough, but that was the gravity again. Nadia had turned on the tractor’s heating system as soon as she could reach it, and now she climbed into the cab and tapped a command into its autopilot, feeling that it would be best to let the thing descend the ramp on its own, with her and Samantha watching from the side, just in case the ramp was more brittle in the cold than expected, or otherwise unreliable. She still found it almost impossible to think in terms of Martian g, to trust the designs that took it into account. The ramp just looked too flimsy!

But the tractor rolled down without incident, and stopped on the ground: eight meters long, royal blue, with wire mesh wheels taller than they were. They had to climb a short ladder into the cab. The crane prosthesis was already attached to the mount on the front end, and that made it easy to load the tractor with the winch, the sandbagger, the boxes of spare parts, and finally the crate walls. When they were done, the tractor looked as overloaded and topheavy as a steam calliope; but the g made it only a matter of balance. The tractor itself was a real pig, with six hundred horsepower, a wide wheelbase, and wheels big as tracks. The hydrazine motor had pick-up even worse than diesel, but it was like the ultimate first gear, completely inexorable. They took off and rolled slowly toward the trailer park – and there she was, Nadezhda Cherneshevsky, driving a Mercedes-Benz across Mars! She followed Samantha to the sorting lot, feeling like a queen.

And that was the morning. Back into the habitat, helmet and tank off, a quick bite in walker and boots. With all that running around they were famished.

After lunch they went back out in the Mercedes-Benz, and used it to haul a Boeing air miner to an area east of the habitats, where they were going to gather all the factories. The air miners were big metal cylinders, somewhat resembling 737 fuselages except that they had eight massive sets of landing gear, and rocket engines attached vertically to their sides, and two jet engines mounted above the fuselage fore and aft. Five of these miners had been dropped in the area some two years before. In the time since, their jet engines had been sucking in the thin air and ramming it through a sequence of separating mechanisms, to divide it into its component gases. The gases had been compressed and stored in big tanks, and were now available for use. So the Boeings each now held 5,000 liters of water ice, 3,000 liters of liquid oxygen, 3,000 liters of liquid nitrogen, 500 liters of argon, and 400 liters of carbon dioxide.