Resurgence hu-5

by Charles Sheffield

  The time for philosophical speculations on the training of survival teams was past. Hans concentrated on the planet ahead. It was about fourteen thousand kilometers in diameter, which together with the readings of the mass detectors suggested a world possessing a metallic core beneath rocky outer layers. The substantial magnetic field confirmed that idea. Surface gravity was about fifteen percent more than standard, a bit high but well within the tolerable range. Surface temperature was another matter. There was an atmosphere, and it contained oxygen as well as nitrogen and argon. But the spectra revealed no hint of water vapor or carbon dioxide.

  Detailed maps of what lay below that frigid atmosphere would have to wait until they were in a parking orbit. However, the high albedo response to a remote laser probe, together with glints of specular reflection, suggested extensive ice cover—perhaps over the whole planet. If that implied worldwide glaciation, high-resolution radar measurements would be needed to probe its depth and learn what land or former oceans lay beneath.

  Those measurements could only be done on the surface, and that in turn implied their journey to Iceworld would be delayed by at least two extra days. Before the group left the Pride of Orion, Hans had suspected something like this might be necessary. With a warm world you could take high-resolution images from orbit. But if a world froze over and you wanted to know what it had been like before the freeze, you had to make measurements down on the ground. Also, Hans himself needed to visit the surface, no matter what the orbital measurements showed. You could never get a gut feel for a world from orbit.

  It was useless to try to explain this to the others. He stared at the frosted ball of the planet, enhanced in the ship’s display to gleam faintly with reflected starlight. With luck, maybe Darya and the rest would conclude for themselves the need for a trip all the way down.

  * * *

  The trouble was, the Savior’s instruments were almost too good. They represented the best technology available to the Fourth Alliance, and from an orbital altitude of no more than two hundred kilometers the imaging sensors and radar altimeters left little to the imagination.

  “Descend to the surface, to learn what?” Ben Blesh was watching on the display a revealing picture. It showed a succession of hills and valleys, all coated with a layer of blinding white. “It’s obvious what happened down there. The whole globe shows peaks and rifts and flat ocean surfaces, which the synthetic aperture radar confirms. There was no worldwide glaciation—no time for that. It’s clear that when the temperature dropped, all the water vapor and carbon dioxide precipitated out. You’d get one fall of water-snow and solid carbon dioxide. After that nothing would change. The air that remains still has some oxygen as well as nitrogen and argon, so things happened fast. There’s no doubt about the sequence of events. What can we possibly gain by going down to the surface?”

  He was asking a question that had occurred to Hans long ago. Before they achieved parking orbit, he had fired off a question to the Pride of Orion. Suppose that the internal energy source of a main sequence star were somehow turned off in a short time span (weeks or months). How long would it take to cool down by normal radiative cooling? I’m looking for an order of magnitude result: are we talking years, centuries, millennia, or millions of years?

  The first reply from Julian Graves was disappointing. I have consulted E.C. Tally, who is making his own calculations supplemented by the ship’s astrophysics library. Because the answer to your question depends on several other unknowns, in particular the star’s stage of progression along the main sequence, and the amount of gravitational potential energy contributed by the star’s own shrinkage during cooling, Tally is reluctant to provide a firm answer. He is, however, willing to provide a range of possibilities.

  Hans could imagine. The embodied computer would hum and mutter and hedge his bets until you were ready to scream. Luckily it was Julian Graves who had to sit and listen, rather than Hans himself. Did that mean E.C. Tally was still aboard the Pride of Orion? He should have been on his way days ago.

  Graves’s second answer was a bit better. At an absolute minimum, with limiting values of all variables, E.C. Tally indicates that radiative cooling would require twenty thousand years. A more likely value, including the gravitational energy provided by stellar shrinkage, would be between eight and eighteen million years. Any shorter value than twenty thousand years would prove that some external agent was employed to expedite cooling. One observational indicator is the ice fracture patterns, if any, on the planet’s surface. They will tell you if the cooling was rapid or slow. Here are the characteristic appearances associated with particular rates of cooling.

  Hans examined the images sent from E.C. Tally, and then those of the surface of the world that they were approaching. Ben Blesh’s comment was correct. There were visible cracks and fissures, but all were coated with a surface of white. The fusion process in the central star had not simply ceased, to be followed by a slow decline in stellar temperature. The sun had gone out, and its surface had cooled from around seven thousand degrees to a few hundred degrees in a very short period—a few decades, or even a few hours.

  What would that mean to any unfortunate creatures living on worlds circling the star? One final, rapid sunset, followed by endless night. The land animals would die off first, as rock and soil and sand lost heat in less than a day to the cold of space. Life would linger longest in the oceans, heat sinks protected by their own thermal inertia and by thickening shields of ice. It was not impossible that some living organisms would survive there even now, drawing chemical energy from hydrothermal vents in the deep ocean floor. But the experience of every known world said that intelligence had no chance of evolving in such locations.

  “Well? Did you hear me? What can we possibly gain by going all the way down to the surface?”

  Ben Blesh’s repeated question brought Hans out of his reverie. He should be asking himself the same thing, when the instruments were able to tell them almost everything.

  What was happening to him? A troubleshooter who indulged in the luxury of idle introspection was heading for real trouble.

  “If I could tell you what we would learn, Ben, we wouldn’t need to go down. I’m convinced that this world has something to tell us, but it won’t speak to us while we’re in orbit.”

  His answer sounded weak, and he knew it. He meant that the world would not speak to him until he set foot on the surface. There was a question to be answered of paramount importance, but it would not form itself clearly within his brain. What he had given Blesh was the instinctive reply of a ground hog, someone who needed to feel a planet’s ambience vibrating in his bones.

  It might be, of course, that instinct was wrong.

  * * *

  Until the ship touches down on Iceworld, I make the decisions.

  Hans clung to that thought as the shuttle plunged into the outer edges of the atmosphere. He couldn’t wait for the high-acceleration phase of descent, when for a few blessed minutes the others would be too weighed down in their seats to complain.

  It had been a tough half day, with even Darya turned against him. “Hans, you haven’t given us any real idea what you hope to learn. Why bother with this?”

  She was saying exactly what Ben Blesh had said. Everyone had asked the same question in a dozen different ways. “Because I’m right,” wouldn’t do for an answer. The entry from orbit came as a positive relief.

  Air was beginning to whistle and scream past the ship, while the gee forces within rose steadily. Hans had at his fingertips ample drive power to make their entry easier. One touch, and the autopilot would take over. They would ride easy and be feathered in to a gentle landing.

  He decided to do it the hard way. It was time to see if the “survival team” specialists were as tough and well prepared as they imagined.

  * * *

  Apparently they were.

  Hans was rustier than he had realized. There was never a moment of danger since the autopilot would take over i
n an emergency, but the landing was nothing to boast about. He had picked the final site with great care after inspection of hundreds of images, without discussing it with the others. Now he was within visual range, coming down too fast and overshooting. He corrected, but at a price. During the final two thousand meters the deceleration was enough to weld Hans to his seat.

  As the ship whomped down onto the icy surface, he felt his innards drive down into the bowl of his pelvis. Darya, sitting next to him, gasped in surprise or pain. It should have taken a minute or two before anyone was ready to move but while the ship was still skidding forward across the ice, Lara Quistner and Ben Blesh released their harnesses and stood up.

  Blesh said, quite casually, “Hull integrity maintained. Check monitors and confirm exit station.”

  “Check.” Lara Quistner was already by the main hatch and staring outside. “Clean landing and no external obstacles. All clear for exit.”

  Not a word from either of them about a botched landing, or why a manual landing had been performed. Hans moved his head from side to side—his cervical vertebrae would never be the same again—and struggled out of his harness. Next to him, Darya said feebly, “Check monitors? To see what? Before we left orbit you told us you were sure that the surface of this world was too cold for anything to survive.”

  “I did, and it is.”

  Even so, Blesh and Quistner were right. On a new planet you took nothing for granted. Darya was sprawled in her chair, breathing harshly. He made the effort and rose to his feet. He felt awkward and lumbering. Higher gravity, or poor physical condition? Maybe three weeks chained to an iron chair produced permanent effects. Whatever the reason, the heavy thermal suit needed to venture out onto the surface of this world would make him feel worse. The two survival specialists were slipping into theirs with an ease and efficiency that Hans would never match.

  “No exit for anyone until all the ship’s sensors report in.” His voice sounded hoarse and strained.

  “Of course not.” Ben’s perky tone, rather than his words, added what do you think we are? “There’s plenty of other things to do before we’re ready to go outside. Lara?”

  Fully suited, she moved again to the hatch and stared out. “I’m turning on external lights so we can add visuals to the sensor reports. When we go outside we can confirm the surface composition using chemical and physical tests.”

  “That’s good, but it’s not just our immediate surroundings that I’m interested in.” Hans was still climbing into his own thermal suit, and making hard work of it. “We’ll be heading for a place about four kilometers away, directly ahead of the ship. Does the surface seem as smooth as it did from orbit?”

  “Smooth, and firm enough to support our weight.” Lara Quistner was manipulating an external probe. “We can walk there if we want to.”

  “Quite feasible, from the look of it.” Ben Blesh was crouched at a bank of instruments duplicating those at the pilot’s console. “It’s level for a couple of kilometers, until it rises into some kind of low hills. It’s too cold for sleds, so if we don’t walk we’ll need a vehicle with wheels. The ship is provided with at least two, for all-purpose surface work. Want me to go ahead and give the instructions to prepare one?”

  “Not just yet.” Hans felt an irrational irritation. Ben Blesh and Lara Quistner were fast, efficient, cautious, cooperative, and doing everything right. Wasn’t that just what you hoped for from a survival team?

  It was. Unfortunately, their high-quality performance had another implication: Hans and Darya were not going to be particularly useful.

  But then, before that thought was complete, Hans understood why he had come to this world. His instincts were right after all. He hadn’t seen anything, but he knew what they were going to find.

  It was all psychological, of course, but suddenly his bones didn’t ache and he felt twenty percent lighter.

  “We take a vehicle,” he said. “Get one ready, Ben—and make sure that it comes equipped with a power digger.”

  CHAPTER ELEVEN

  On Deadworld

  The Savior was an all-purpose vehicle. Although its designers must have anticipated that its primary uses would be in space-based operations, the ship was well equipped to support surface work. Hans Rebka had a choice of two different types of wheeled vehicle. One was an open form, little more than a bare platform with seats, wheels, and a big cargo area. The other was a fully enclosed car complete with its own atmosphere, in which the riders did not need to wear suits and could eat, drink, or sleep in comfort.

  Hans Rebka chose the more primitive form. Even wearing a suit, he felt more in touch with the frozen world when its air was only a fraction of a centimeter away from his skin. Had it not been for the digging equipment—a mystery in its own right—he would have preferred to walk.

  If the others questioned his decision on choice of car, they did so in silence. No one spoke as they watched the digger, a hump-backed machine with the blue-black carapace of a gigantic spider, extrude multiple jointed legs and climb effortlessly onto the cargo rack at the back of the car. Rather less easily, Hans led the way to the front of the vehicle and they took their places on hard bucket seats. He engaged the engine and the car began to crawl across the frozen plain.

  Above, unfamiliar star patterns twinkled slightly. There was still enough heat in the lower atmosphere to permit small-scale turbulence. Hans glanced at the air temperature sensor. It hovered at a balmy hundred and fifty degrees above absolute zero, far warmer than open space. With no heat arriving from the central star, the planet’s metallic core must contain a good deal of slowly decaying radioactive materials. Some warmth continued to seep out from the interior. The air sniffers confirmed the temperature reading. All traces of radon, xenon, and chlorine had precipitated out onto the frozen surface. Oxygen and nitrogen remained, along with a greater-than-expected abundance of argon and traces of krypton. Hans assumed that was a characteristic of the Sag Arm, rather than of this particular planet.

  The car, its blue-white beams providing a narrow wedge of light on the surface ahead, trundled along at a sedate five kilometers an hour. The ship had landed close to the planetary equator, and the calm heavens wheeled steadily overhead. The pattern would repeat every twenty-nine hours, with no promise ever of returning day. Although the air felt perfectly still, at some time after the cold began there had been strong winds. The carbon dioxide snow had here and there blown into banks and deep drifts. Hans avoided them and kept his eyes fixed on the edge of the zone of visibility provided by the car’s lights. He could detect objects only to a distance of perhaps two hundred meters. After the three-kilometer mark he found himself impatiently trying to see beyond the narrow illuminated cone. He was filled with a combination of excitement and uneasiness. It was one thing to believe that you were right, and quite another to have proof to show to others.

  At last, he saw far ahead a change in the landscape. The frozen drifts rose higher and beyond them stood a regular, sawtoothed barrier. He had been waiting for this, but the others must have been keeping their own close watch. Before Hans was sure of what he saw, Lara Quistner said “What is that?” At the same moment Darya Lang put a hand on Rebka’s arm. “Hans, we should stop until we know what’s ahead.”

  “I know what it is.” Rebka kept the vehicle moving forward at the same slow pace. “I saw hundreds of these on the high-resolution orbital images. They were all partly covered by blown snow, but they are too regular in shape to be natural.”

  “Regular how?”

  “Nature often makes circles, but it seldom makes right angles. What we are seeing is a wall. I’d say it’s close to ten meters high, and it forms almost a perfect square.”

  “A walled town?” Ben Blesh had been perched on an uncomfortable rear seat. He pressed forward between Hans Rebka and Darya Lang, too interested to be either critical or argumentative. “Back in the Orion arm a fortification like this would mean at least a Level Two civilization.”

  Darya
added, “But no higher than a Level Three. Walled cities go away as soon as the means to destroy them are developed. So these people didn’t have explosives and artillery.”

  “Also, they didn’t expect attacks from the air.” Rebka halted the vehicle thirty meters short of the wall. “We’re talking pre-industrial here. No aircraft, so no spacecraft. An intelligent species—we’ll want to confirm that by looking inside the wall—but without the technology needed to escape. These people were in the worst possible situation. They knew what was happening to them, and they had plenty of time to worry about it. But without spaceflight, and pretty advanced spaceflight at that, there was no chance at all of their survival.”

  The others were silent for a while. At last Ben Blesh said, “Captain Rebka, how long do you think it took?”

  “I’ve been trying to answer that question. So far I’ve been unsuccessful. The Pride of Orion sent me a range of times, but without more information they couldn’t offer anything definite. When the fusion process was turned off in these people’s sun, the cooling began. I’d like to know if that cooling took place all at once, or over a period of thousands of years.” Rebka started the car moving again, but this time directed its course tangentially to the wall.

  Lara Quistner said softly, “Left to die slowly, in the cold and dark. It’s an awful tragedy. If only some spacefaring species in the Sag Arm had known about it, these people could have been helped.”