Emergency protocol, item three: Survey your situation; ascertain your location and velocity relative to possible sources of assistance.
There were no possible sources of assistance. Still, his suit did have an inertial navigation unit; he could check his location and velocity. He verified that it was on, and brought up his position and velocity in the heads-up display. The dim red figures glowed in his faceplate, floating above the darkness. He was sliding down a slope at an angle just under twenty degrees, currently moving at eighteen meters per second relative to the ground. As he watched, the inertial guidance unit updated his speed. Eighteen point three meters per second. Eighteen point six meters per second.
He had no sense of his speed. Except for the slowly incrementing number in his display, it felt like he was motionless.
That wasn't doing him any good. He had the computer display a plot of his position as a function of time. His path across the surface of mirror was in the form of a perfect paraboloid. That made sense. Of course the mirror would be a paraboloid; it must be the reflector of an enormous telescope. He extrapolated the parabola forward, and plotted his motion as a tiny moving dot. He was moving faster and faster every minute, but his acceleration was slowing down as he headed toward the bottom. Extrapolating from the shape of the curve, he would reach bottom in about four minutes, or just a little over six minutes from when he had slipped off the edge. And then his momentum would carry him up the other side of the slope.
Emergency protocol, item four: Check consumables. Take action to minimize use of critical supplies until help is effected.
Lee checked the status of his suit. He didn't have consumables in any real sense of the word. His oxygen supply was a zero-buffer in-line rebreather; every breath he exhaled was stripped of carbon dioxide, which went through an electrolysis cycle that broke it down and immediately recycled it to his next breath. The whole thing was run from a solid-state battery, the same battery that also powered his suit heaters. So it was the batteries that were his ultimate consumable. He checked his battery status: green, at 76 percent full charge. The batteries were sized to run for two full mining shifts plus a little margin, so that gave him a bit over twelve hours of remaining power for life support. Was there any chance somebody would deduce where he was and assemble a rescue before he ran out of power? Unlikely. Nobody would even notice that he was missing until the start of his next shift, which was—he checked the time—another thirteen hours. And even then, it would wait until the end of the shift before somebody would check his quarters to find out why he'd missed work.
Item five: Appraise resources. Apply the resources available in the most efficient way to effect rescue.
Fine. His resources were his suit, and—and nothing else, really. Everything else he carried had been in the toolpack he'd lost, or was left with the snowcat. If he'd been wearing a suit for free-space operation, he would have no problem; the maneuvering thrusters would be enough to push him across the slope in any direction he wanted. But the surface suit he wore had no thrusters.
Item six: When the emergency is over, contact Spacewatch to cancel emergency call for assistance.
He figured he could ignore that part of the emergency protocol.
Running through the emergency protocols hadn't shown him any way out of this problem, but it had at least damped down his panic. He was now a minute away from the bottom, moving at a hundred and sixty meters a second. He converted that in his head. Vesta, where he had been raised, had been originally settled by Americans, and had stubbornly refused to switch to metric, even after America itself had joined the European Union. He was sliding along at just under a hundred miles an hour. He checked his display again, and noticed that his path wasn't actually taking him quite to the bottom. He would miss it slightly to the left. Right, he thought. He'd been swinging when the clip holding the tether had snapped, and the lateral velocity meant that his actual path was an ellipse—in fact, a Lissajous figure—that wouldn't quite pass through the center. The actual bottom of the mirror would be passing slightly to his right. He inched himself around to look, knowing that it was a pointless move, since there would be nothing to see.
But there was something to see, something gliding silently past. He couldn't quite make it out, until he realized his image intensifier was off, and turned it on.
He was racing past a landscape of dark sand and rocks and a few enormous boulders. It seemed to be just meters away from him, but a glance at his rangefinder told him that this was an illusion, and the rubble field was nearly fifty meters off. The bottom of the mirror was not empty, but was filled with a million years of debris that had fallen into the crater and slid to the bottom.
The suit thermostat was working fine, but he felt suddenly cold. Hitting that debris field at a hundred miles an hour would have been an abrupt end to all his problems.
The rubble slid past him—or rather, he slid past it—and dwindled behind him. He had reached the lowest point on his trajectory and was rising now, sliding up the slope toward the opposite rim.
He turned the image intensifier off again, to conserve the tiny amount of power it drew. He was now sliding feet first up the slope. He checked his data. At the lowest point of his slide, his maximum speed had not quite hit a hundred and seventy meters a second, and now he was decelerating as the slope steepened and he slid up toward the opposite rim. He leaned back to think, and caught a glimpse of the sky.
Even with no enhancement, the sky was spectacular. There were stars below him, and stars above him, and it seemed as if he were gliding on a perfectly transparent sheet of ice through endless space. The sun was a speck of fire, so bright that it almost hurt his dark-adapted eyes, and yet so small it shed nearly no light. When he averted his vision, he could see that it was surrounded by a ghostly disk, so faint as to be little more than the memory of a glow, the zodiacal light. And surrounding that were stars in their millions, fragments of diamond scattered across the velvet of night, glinting in colors from electric blue to a deep brick red.
Lee stared at the stars, running through the emergency procedure list again in his mind. Stop ongoing damage, squawk for help, check location, conserve consumables, survey resources and solve problem, call home.
Step five, that was the hard one: survey available resources and solve the problem. But he still had no resources to survey. His surface suit had no attachments, not even a spare tank of oxygen he might have been able to use as a cold-gas thruster. It protected him from the cold and vacuum, gave him something to breathe, and that was it. Life support and batteries were integral to the suit; he couldn't take them out even if he wanted to. And everything else was in the miner's toolkit.
Stop, squawk, site, safeguard, survey and solve, and finally call your mother to tell her you're safe.
Survey resources. What about the toolkit? It was sliding across the same surface that he was, with a head start of only a few seconds. It had the tools that might solve his problem—a radio beacon, for one. And, if nothing else, he could use it for reaction mass. If he could hurl it away from him fast enough, he would gain a little bit of momentum to get him to coast over the rim. It was on the mirror with him, maybe only a few meters away.
Lee twisted himself around until he was sitting upright and snapped his image intensifier on to full. Toolpacks were distinctly colored, to make sure one miner didn't accidentally grab the wrong one, and his was a bright lime green. It took him only a few seconds to spot it. There it was, no more than twenty meters ahead of him, spinning slightly as it slid.
In fact, since it was ahead of him, it would reach the far lip of the bowl before he did, turn around, and come right back to him.
According to the graph he had made in his display, the rim was about a minute away. He fixed his gaze on the toolpack sliding ahead of him, ready to grab it as it slid back toward him. Yes. There it was, right up at the edge—was it actually going to fly up over the edge and out of the bowl? It just kissed the edge, slid toward the left, and th
en started gliding back down toward him.
He was slowing down as he rose toward the edge, and the toolpack was speeding up as it fell. He stretched toward it, spread-eagled across the mirror, but the toolpack slid past well outside the reach of his outstretched fingers.
But he had no time to cry out over missed chances. In another moment the edge of the mirror approached, and he clambered across the mirror's surface on all fours, stroking like a swimmer. If he could just gain even a single meter of altitude...
To no effect. The edge hovered ahead of him, tantalizingly close, tantalizingly out of range. All his effort hadn't gotten him a millimeter closer.
The rim disappeared in the distance, as he gained speed back downward.
Why hadn't the pack come back to him? It was that elliptical motion, he realized. The toolpack was orbiting the center of the mirror, just as he was, sliding in an ellipse that didn't intersect his trajectory.
He was sliding back down now. Six more minutes to the bottom, twelve to the other side. And then another twelve minutes down again, and back, and back ... until his battery died and he froze and suffocated. And after that, how long would his body continue oscillating? Days? Years? The mirror couldn't be perfectly frictionless; nothing in the universe was perfect. If it was perfect, the rubble wouldn't be there in the center; the rocks that fell in would still be oscillating.
He was the bob on a pendulum, he thought, with a frictionless surface instead of a rope. For a moment his thoughts took him back to his childhood, growing up on Vesta. He and his brother had competed with each other on the swings, seeing who could go higher. They must have tried a hundred times to swing so hard as to go all the way around, over the bar. They never succeeded, even with Vesta's low gravity making it easy; when they barely got higher than the pivot point, the rope would go slack, and the swing would fall with a jerk.
Thinking about the past wasn't going to help him, and he forced his thinking back to his present situation. In a few minutes he would be back to his starting point. What about the safety rope? If it was still dangling down—but it wouldn't be. He replayed his fall in his mind. The safety rope had snapped back like an elastic band when the clip broke, and disappeared over the edge. He would try to grab it, if it was in reach, but he wouldn't count on it.
It wasn't. He slid up, frustratingly close to the rim, and for a moment he seemed to hover with the rim just out of reach, and then slid away. The toolpack hadn't come any closer to him this time than it had on the opposite rim, and the rope was nowhere in sight.
But here was something else to think about. Sedna rotated once every ten hours. In—he checked the time—two hours, the sun would be overhead. In the cold dark a hundred astronomical units from Earth, the intensity of the Sun was dim, but what would happen when it was focused by a mirror twenty kilometers in diameter? In fact, that was very likely the purpose of the mirror, he realized. It wasn't a telescope; it was an enormous solar furnace.
But he wasn't thinking. The mirror might focus sunlight to a high concentration indeed, but that would be miles overhead, at the focal point of the mirror. On the surface of the mirror itself, the sunlight would be no brighter, and no less bright, than any other time. It was freezing he had to worry about, not frying.
Passing the bottom of the mirror. Lee clicked his image intensifier on again, watching the rubble in the center, trying to think of a way to make use of it. But it was still fifty meters away. Nothing useful there.
He clicked it off, and he was surrounded again by a world of stars and darkness.
Should he go back to reflecting on his life? Swinging with his brother, that was a good time, even if they never did make it over the bar. He could spend the remaining few hours remembering good times. The thing about being a prospector, he thought, is that you see a lot of places, but you only see the backsides, the seedy sides, the places in town near the dockyards. And they all look the same. He knew miners with a girl on each rock-town they visited, but no matter whether the deal was explicit or implicit, one way or another they were strictly pay propositions. He made good money, when he was employed, but somehow he never really managed to save any of it. It wasn't that he was wasting his life, not exactly, he thought, but there had been enough of it already. It was time for him to move on. He needed to study, finish a degree, make something of himself.
Well, he had plenty of time to study, if that was what he wanted to do. Not that it would do him much good—he was trapped in a bowl. But that reminded him, he did have one resource that he hadn't though of. His personal databot had a load of study materials, and one of his subjects was physics. What if his problem had a solution somewhere in the physics texts? It was a long shot, but why not try?
He booted up his study material, and put in search text: “PROBLEM, SLIDING ACROSS AN ENORMOUS MIRROR.” He had no real hope that anything would come out, but the search gave him one hit.
Astonishingly, the hit was in literature, not physics. The link was to the twentieth century, an ancient science fiction story that had two men sliding on the surface of a frictionless mirror. He'd always hated classic science fiction. He'd read enough of it in school, before he'd dropped out. The teachers all seemed to love it. But the old authors had always gotten everything so wrong. The characters did amazingly dangerous things, with no safety backups; they were uniformly too stupid to live.
Things like stealing a snowcat to drive across an alien planet, without telling anybody where they were going? Well, it has seemed like a good idea at the time.
The databot didn't have the text of the story, only a brief summary in a survey on twentieth-century literature. He scanned through it. It wasn't quite his situation, he realized with mounting disappointment: the characters in the story had far more resources at their disposal. In the story, the two characters were roped together, and they used that fact to pump up rotational speed to allow them to fly apart. The discussion went on to say how the solution in the story wouldn't work; the author had ignored conservation of angular momentum. No help! Lee would have thrown the book away in disgust, if it had been a physical book and not just a glow in his heads-up display.
If only he had a book to throw away! Or anything at all. He could have used the momentum. It was exactly like being adrift in space without a pack. He had no control over his motion.
See related terms, the summary said. Simple harmonic oscillator. Frictionless motion.
He queried simple harmonic oscillator, saw that it seemed to be a tutorial about sines and cosines, with no obvious application to him, and then flicked over to frictionless motion and scanned the tutorial. Superfluid helium, it said, was the only substance known to support frictionless motion. Well, that was interesting. Could the aliens have found some way to solidify superfluid helium? No, that was ridiculous. But, still, the surface of the mirror was desperately cold, cold enough to make even God shiver. Maybe the mirror was made of some substance that had a thin film of superfluid helium on the surface? Could he possibly heat the mirror and destroy the effect?
But no, that was a dead end. Even if it weren't frictionless, the surface would still be far too smooth for him to be able to climb the slope to the rim. He'd have to carve steps into the slope, and he had no tools to do that. Did the material have any give at all? He kicked at it as hard as he could, but it was like kicking solid granite. His toe hurt, even through the boot, but there had been not the slightest give to the surface. Whatever material it was made of, it was hard.
A frictionless surface probably had commercial value, even if it only worked when it was cooled nearly to absolute zero. If that bastard Kellerman just knew that one of his workers was slipping along the surface of a material more valuable than any ammonia on the planetoid, rescue would be here soon enough.
That line of thought didn't bring him any closer to rescue.
The rim approached, or rather, he approached the rim. He slid toward it, slowed, hovered frustratingly short of the edge, and then dropped away. Lee checked th
at his radio was still broadcasting the useless call for help; verified that the toolpack was still out of reach, checked his battery status. No help, no help, no help.
He was sliding down the slope on his stomach, like riding a sled. He twisted around and then carefully pushed himself up onto his hands and knees. He pushed upright, balancing on his knees, with one hand on the slippery mirror for balance. Wobbly, but after a while he could keep his balance. That wasn't too hard. He tried getting up onto to his feet, and made it for a moment, his arms windmilling desperately to keep his balance before his feet shot out from under him.
It was like trying to stand on ice. He worked at it and eventually found his balance. It was a lot like snowboarding on the hills of Callisto, he realized, or skiing the polar caps of Mars, something he'd tried once on shore leave. The carbon dioxide snow of Mars was nearly frictionless, too, but if you stayed loose and alert, you could stay vertical. The trick was to keep his center of gravity above his feet. It was a matter of holding his arms out, keeping his knees bent, and making continuous sliding adjustments. The low gravity worked in his favor, giving him time to correct.
He stood, surfing down the slope. If only his brother could see him now!
It did nothing to help his situation, but just being able to stand gave him a tremendous feeling of accomplishment, as if he were now in control of his environment. He imagined himself an Olympic ski champion, gliding down the run of artificial snow on the slopes of Olympus Mons. He checked his display: almost to the bottom and heading uphill again, he was racing at 150 meters per second. That must certainly be breaking all ski records! He raised his hands in triumph to the imagined cheers of thousands—and skittered backward, landing on his butt.
Analog SFF, January-February 2008 Page 18
