Encounter With Tiber

by Buzz Aldrin

  Kekox moved to sit between Otuz and me, and then asked, very gently, “So, Otuz, what was the energy problem, if you understand it?”

  She sighed in the big dramatic way she always did when some grownup asked her to prove she understood something. “Our world, and Kahrekeif, are both going around planets that go around stars that go around each other. That’s a lot of motion. To go from here to Kahrekeif you have to change your speed and direction—and your position—by enough so that you go from moving like one of them to moving like the other. That’s a huge difference in speed, and it’s a very long distance, and changing speed, position, and direction that much takes a lot of energy.”

  “Not bad at all,” Kekox said, grinning at her, and then did the thing I was dreading—he looked at me and said, “So what’s the energy associated with a trajectory?”

  “Some ways of getting from one place to another require you to speed up more or slow down more at one end or the other, and like that,” I said. I was babbling; if I pretended not to know, Kekox would pick on me and Poiparesis and Soikenn would be shamed, but if I admitted that I did know, Mejox might sulk, or even give me a beating later. For the moment my trust in Kekox won out over my fear of Mejox, so I went right on babbling. “When Zoiroy and the Sun are close together, and Sosahy and Sahmahkouy are between them, that’s called a close approach, and at that time there are a bunch of low-energy trajectories, because the two gas giant planets are close together and moving pretty much in the same direction at the same speed. But during most of the orbit the directions and speeds are very different and the distances are much bigger.”

  Kekox’s eyes were warm and friendly, and I felt better than I usually did when I was forced to excel Mejox in public. Then he turned to Mejox and said, “Now, see, you do understand all about the energy for trajectories, and you understand that it’s an important part of the story, right?”

  “Oh, yes, sure,” Mejox said, looking at the floor.

  “Well, as I was saying,” Kekox went on, “we had no idea what we’d find, and we didn’t realize that Kahrekeif’s inclined, highly elliptical orbit meant trouble. We didn’t even realize until we were on our way and got data from the last few fast flybys that Kahrekeif had been captured by Sahmahkouy so recently that it was still spinning.”

  “Recently?” Priekahm asked. “Like the year before?”

  “Like ten million years before,” Kekox said, smiling at her as if he were going to pat her on the head. “A short time in astronomy and geology.”

  “And wasn’t it very hard to land on it if it was spinning?” she asked. Every so often I wanted to pinch or slap her; she wasn’t nearly as dumb as she acted, but she loved the attention she got from our teachers by playing stupid.

  “The spin is not a big problem for landing—coming down from orbit you’re moving so much faster than the surface is that the little bit of motion of the surface doesn’t really matter. It had better not be a problem, Priekahm, because Setepos is rotating.” Setepos was the new world we were going to; we all leaned in to hear better, because whenever an adult would talk about it, it was the most interesting possible subject to us.

  But Kekox didn’t take the hint, and continued his story. “We had landed on Kahrekeif near its equator, still knowing nothing. Pretty clearly at one time it had had liquid water—there were channels, dry riverbeds, and lake basins filled with icy slush. Kahrekeif still had enormous deposits of ice, some just below the surface or covered with dust. There was a lot of frozen carbon dioxide at the poles, but the air was very thin, only about five percent as thick as what we need to breathe, and since it was almost all carbon dioxide, even if it had been thick enough we couldn’t have breathed there. And the strangest thing of all was that Kahrekeif—they think this is because it was spinning—was one big magnet.”

  “Why didn’t the ship stick to it?” Priekahm asked.

  “One big, not very strong magnet,” Kekox said, sounding amused. If I had asked such a question, he’d have glared at me for being silly; if Otuz had, he’d have told her he was disappointed in her.

  “All those were clues to what was going to happen. Another clue that we really should have noticed was that although the air was very thin, there were no impact craters anywhere; that should have told us something was resurfacing Kahrekeif regularly. Maybe if we’d managed to get an orbiting probe there first we’d have realized.

  “But we didn’t, and we wouldn’t find out how all of the clues fit together until much later. We were climbing over a raw basalt scarp, about a day’s hike from the lander—”

  “What’s a scarp?” Otuz asked.

  “A long straight cliff wall, between one plain and another,” he said. “Like the Great Barrier Cliff of Palath, though that’s much more eroded than this was. Scarps are made when a world shrinks as it cools—they’re like cracks in a cooling pastry—and since these were new and raw they were pretty good evidence that Kahrekeif was a relatively new world. Anyway, we had climbed halfway up the cliff face and were resting on a wide flat spot. We had wanted to get up onto the higher plain to take some observations as Kahrekeif began its close approach to Sahmahkouy.

  “Because its orbit was so highly elliptical, Kahrekeif’s orbit around Sahmahkouy was more like a comet’s than anything else—it swung in much closer than we ever get to Sosahy, and swung back out to fifty times as far. And because, you know, the speed in orbit depends on the mass of the central body, Kahrekeif actually takes longer to go around Sahmahkouy than Sahmahkouy takes to go around Zoiroy; the planet goes around the sun in two years, but the moon goes around the planet in about two and four-fifths years. So once every fourteen years, it happens that Kahrekeif first makes a close pass at Sahmahkouy—it seems like it almost grazes the cloud tops—and then swings way, way in toward Zoiroy, toward its star.

  “What we didn’t know was that the huge electric charges in Sahmahkouy’s cloud tops actually discharge to Kahrekeif; the little moon gets hit by lightning for about half a day at its nearest approach. Fortunately for us—or I wouldn’t be here to tell you the story—the magnetic field of Kahrekeif guides those gigantic lightning bolts down to the poles, so that none were hitting where we were, or through the orbit of our ship. But it was a near enough thing anyway.

  “The first part happened in less than a twentieth of a day. We had pitched a normal camp up there on the ledge, halfway up the scarp, and we were getting ready for bed. The next day we were to go up to the top to observe the eclipse that happens at that point in the orbit.

  “Just at sunset, the northern sky flashed bright blinding white, over and over, and the radios stopped working. We couldn’t raise the ship or the base on the radio. Even the helmet sets were unreliable within a few armslengths of each other, so we had no idea what was going on. Electric shocks came right through the ground, not enough to burn, but enough to make your legs kick, and all the freestanding metal was suddenly a shock hazard.

  “We had barely begun to figure out what must be causing it when the air pressure started to rise, fast. Tutretz, the expedition’s meteorologist, made a brilliant guess, which is why we’re alive. He realized that the big electric currents caused by the lightning strikes must be flowing through the slurry of water ice and frozen carbon dioxide that made up the polar caps, and in the low pressure it was heating them enough to vaporize them. The whole atmosphere was re-forming around us, and as Kahrekeif swung in toward the sun for the next half-year, it would cause a rapid greenhouse effect; there was going to be a lot more air, and liquid water, and it would be a lot warmer. So even though the winds were rising with every breath, he made us strike camp, pile all the gear we could onto our packs, strap on respirator packs, rope ourselves together, and start climbing, up and off that shelf, to a place he’d spotted earlier that day.

  “So much dust had been whipped into the air that it was black as Shulathian night. We climbed by the light of our helmet lamps, staggering, falling, dragging each other, but by the Creator, with Tutre
tz pushing us, we climbed, even as the winds rose to hurricane force. We got up to the small place he’d spotted—a long, long way above, and it would have been a hard climb even in daylight. It was really no more than a deep overhang, and how he found it in the pitch dark and the howling wind, I have no idea.

  “We set up and sealed shelters in there. So many radio parts had burned out that there was no hope of contacting base, or the ship, that night—between fifteen personal radios we weren’t sure we had the parts to make one working radio. We were all hopelessly exhausted, so as soon as the shelters were up we all went to sleep—it wasn’t completely safe and it violated a lot of tradition, but there wasn’t much point in setting a watch—the alarms would wake us if anything went wrong, and besides no one could have stayed awake. We’d had a day’s climb before the storm started, and the better part of a day afterwards in the dark and the wind.

  “We had reached the overhang far into the night, with a dark storm howling outside, dark enough to hide the giant lightning flashes from our direct view, though some light did flicker through the thick clouds of dust and water, lighting the shelter walls with sudden bright flashes. If there was dawn, none of us saw it; shortly after, the eclipse started, and that lasted for many hours, so it was dark and stormy for a long time. I have memories of looking out the viewport of my sleeping bag—we were in the shelters, but we all pressurized our bags that night because we weren’t sure the shelters would hold—and seeing the wall of the shelter shaking in the howling wind, even in the protection of the overhang, and lights flashing on the shelter walls, probably more reflected light from where the bolts of lightning were entering the upper atmosphere, over the poles, half a world away. At least we were on reasonably insulating rock now, and the electric currents flowing through the soil didn’t bother us.

  “We all slept more than half a day by the clock.

  “Most of us seemed to wake at the same moment in mid-afternoon, or maybe the first people to get up made so much noise when they saw all the light shining through the shelter walls that they woke the rest of us up. The shelters hadn’t breached, so we were able to get out of the sleeping bags to put on pressure suits. As soon as we could we ran out of the shelter airlocks to see what had happened.

  “We looked from the lip of the overhang back down toward the broad shelf where we’d been before the chaos started. Falling down onto it was the biggest waterfall I’ve ever seen in my life, and where our camp had been there was a big cold blue mountain lake shining in the sunlight—yes, the sunlight. The sky was blue and held big fluffy clouds, and out beyond the scarp we could see lakes and rivers. Tutretz checked his instruments and found that we had gone from a pressure of five percent of what is normal here on our world to just about twice normal—forty times as much air as there had been the day before. The air was almost entirely carbon dioxide and water vapor—greenhouse gases—so that as we swung inward toward the sun for the next ten eightdays or so, temperature and pressure would continue to rise rapidly.

  “We tore apart four radios to make one working one, and then hailed the ship with no problem at all; their electronics had taken hits the previous day, but they were all right. There was no trace of the base. We never even found any remains of the four crewmen who died there.

  “For another eightday, while the orbiting ship’s crew got the uncrewed cargo lander modified so that it could haul us up, we explored the high plateau. The sudden injection of all that C02 had created a runaway greenhouse, and so much of the ice was bound in weak structures that there had been a lot of explosive melting and sublimation. The ship photographed all kinds of places where wet soil was erupting upward in cold mud volcanoes.

  “Tutretz worked it all out later: during the times when Kahrekeif is swinging outward from Sahmahkouy, and away from its sun, there’s not enough greenhouse effect to keep the atmosphere unfrozen. So it slowly freezes into a slush of water and C02 mixed with dust—we called it ‘fizzy frozen mud’ so often that that became the recognized scientific term. Every two and four-fifths years, Kahrekeif makes a close pass at Sahmahkouy and is blasted with lightning, and the ground currents evaporate the fizzy frozen mud explosively, but usually the cold mud volcanoes just erupt for an eightday or so, and then freeze again, and the bulk of the fizzy frozen mud stays solid. But every fourteen years it happens that the orbital positions line up so that Kahrekeif gets a long period of warming, then gets zapped, and then gets another long period of warming—so that the ices are much more ready-to-go when the lightning hits, and then the thicker atmosphere goes right into runaway greenhouse. Five years later there’s another period of sustained cold, and the process starts over again. So it wasn’t surprising that so much of the surface looked new; it was getting resurfaced every fourteen years.

  “The expedition wasn’t wasted at all. We learned a great deal about geology—but we also learned that Kahrekeif was a terribly dangerous place, and one where the dangers would change all the time. Probably someone will try to settle there, but it isn’t likely to be the place that saves our civilization.” He sighed. “And here I just meant to tell you about the adventure on the scarp. Well, bedtime, all of you, tomorrow you start your history tour.”

  2

  AS I WAS PUTTING my clothes into my box that night, I heard voices from Mejox’s chamber next door. I put my ear to the wall and listened.

  Kekox was saying, “Mejox, I don’t want to hear one more word from anyone about your bullying Zahmekoses. Especially not when he does something better than you do. He’s the most loyal friend you could want. More than you deserve. Do you understand that? He is worth five thousand times as much to you as your loyal friend than whatever satisfaction you get out of making up games that you win against him. He’s not going to complain, but I’ll know and you’ll be sorry.”

  Mejox’s voice was whiny in a way I hated. “I just like it to be fair. And I like to win.”

  “Learn to like people,” Kekox said bluntly. “People are what an emperor has to know and like. When you’re rich and powerful—if you last that long and we don’t all die on this trip—the only friends you will be able to trust are the ones you make now. And a brilliant kid like Zahmekoses is the kind of friend you should be making. Now, treat him like an equal and remember that your friend’s success is your own—or answer to me.”

  Mejox said something I didn’t quite hear; his tone was whiny and unpleasant. There was a sharp, flat crack and a shriek through clenched teeth. The old Guard had slapped Mejox, who cried out in pain. My blood froze.

  “Now listen here,” Kekox said. “I know you’re a Roupox and I know your family has a lock on the Imperium. But for the next twenty-four years, you’re my charge, and you’re going to grow up decent. You have to lead, Mejox, and if you don’t know the difference between leading and throwing your weight around, or getting someone’s loyalty and bullying him into submission, learn it. Or I’ll hit you again.” His voice became gentler. “Don’t you see? Isn’t Zahmekoses your best friend? Don’t you want him to be happy?”

  Mejox was crying—I could hear the low, keening noise. He must have said yes, because then Kekox added, “Then be his friend. He adores you, Mejox, he’d do anything for you. That won’t last if you keep making him take second place. He’s Shulathian, for the Creator’s sake, it’s in his nature to be smart and creative and artistic, but of course he’s also flighty and irresponsible. It’s just the way those people are. Now, a lot of the Shulathians I know are wonderful people and some of them are great friends of mine, people I’m always glad to see. We had three Shulathians on Kahrekeif with us and I have nothing but good to say about them. I’ve said for years we ought to let them into the Imperial Guard. Shulathians will do things out of personal loyalty that us practical Palathians would never dream of. If you make him your good friend, you’ll always have someone smart and loyal at your back, ready to die for you if he has to. But if you keep hurting his feelings and bullying him, he’ll fester and brood until you won’t b
e able to get a thing out of him. Never forget that the Shulathians did govern themselves—even if they did it very badly—for thousands of years before we conquered them, and as much as they need us, we have to earn their loyalty.”

  “Zahmekoses is my best friend,” Mejox said. I felt a small glow of happiness inside. Mejox went on to demand, “Why do you say those things about Shulathians? If they’re so bad—”

  “Not bad,” Kekox said emphatically. “Don’t even let yourself start thinking that. We have enough bigots and troublemakers out there as it is. But they are flighty, excitable, and irresponsible. That’s why they make great scientists and lousy engineers, and great lawyers but they’re terrible leaders. But you need everyone’s skills, Mejox. On this expedition we had to have a couple of first-rate scientists, for one thing, which is why we have Soikenn and Poiparesis. And then … well, you’re not too young to know there was political pressure, too. There’s been a lot of pressure ever since your grandfather’s uncle gave Shulath home rule. There was pressure on us from all those Egalitarian maniacs.

  “But that’s neither here nor there; these are the people you have to work with, and Zahmekoses is the best friend you’ll ever have. I’m telling you how to make sure he stays your best friend. I suppose I can’t make you listen—but I know you’ll listen to this. If you abuse or exploit that boy again, or force him to lose at things where he’s better than you—wham. You get hit. Learning to bear pain is another part of leadership, and I don’t think I’ve taught you enough about it.”

  “Zahmekoses is my best friend, and I like him better than anybody,” Mejox insisted.

  “Good, then it won’t be hard for you. Now get some sleep. Tomorrow is going to be a very long day.” I heard the door close on Mejox’s room, and slipped silently onto the bed and made myself relax and become still.