PLATINUM POHL

by Frederik Pohl

  I wonder sometimes what they wanted. Escaping a dying planet? Political refugees? Tourists that had a breakdown between somewhere and somewhere, and hung around just long enough to make whatever they had to make to get themselves going again? I used to think that they’d maybe come by to watch human beings evolving on Earth, sort of stepfathers beaming over the growing young race; but we couldn’t have been much to watch at that time, halfway between the Australopithecines and the Cro-Magnards.

  But, though they packed up nearly everything when they left, leaving behind only empty tunnels and chambers, there were a few scraps here and there that either weren’t worth taking along or were overlooked: all those “prayer fans,” enough empty containers of one kind or another to look like a picnic ground at the end of a hard summer, some trinkets and trifles. I guess the best known of the “trifles” is the anisokinetic punch, the carbon crystal that transmits a blow at a ninety-degree angle; that made somebody a few billion just by being lucky enough to find one, and smart enough to analyze and duplicate it. But all we’ve ever found is junk. There must have been good stuff worth a million times as much as those sweepings.

  Did they take all the good stuff with them?

  Nobody knew. I didn’t know, either, but I thought I knew something that had a bearing on it.

  I thought I knew where the last Heechee ship had taken off from; and it wasn’t near any of the explored diggings.

  I didn’t kid myself. I knew that wasn’t a guarantee of anything.

  But it was something to go on. Maybe when that last ship left they were getting impatient, and maybe not as thorough in cleaning up behind themselves.

  And that was what being on Venus was all about. What other possible reason was there for being there? The life of a maze rat was marginal at best. It took fifty thousand a year to stay alive. If you had less than that you couldn’t pay air tax, capitation tax, water assessment, or even a subsistence-level bill for food. If you wanted to eat meat more than once a week, and demanded a cubicle of your own to sleep in, it cost more than that.

  Guide’s papers cost a week’s life; when any of us bought them, we were gambling that week’s cost of living against the chance of a big enough strike, either from the Terry tourists or from what we might find, to make it possible to get back to Earth—where no one starved, no one died for lack of air, no one was thrust out into the high-pressure incinerator that was Venus’s atmosphere. Not just to get back to Earth. To get back in the style every maze rat had set himself as a goal when he headed sunward in the first place: with money enough to live the full life of a human being on Full Medical.

  That was what I wanted. The big score.

  4

  Not by accident, the last thing I did that night was to visit the Hall of Discoveries.

  The third of Vastra’s house winked at me over her flirtation veil and turned to her companion, who looked around and nodded.

  I joined them. “Hello, Mr. Walthers,” she said.

  “I thought I might find you here,” I said, which was no more than the truth, since Vastra’s third had promised to guide her this way. I didn’t know what to call her. “Miss Keefer” was accurate, “Mrs. Cochenour” was diplomatic; I got around it by saying, “Since we’ll be seeing a lot of each other, how about getting on to first names?”

  “Audee, is it?”

  I gave her a twelve-tooth smile. “Swede on my mother’s side, old Texan on my father’s. Name’s been in his family a long time, I guess.”

  The Hall of Discoveries is meant to get Terry prospects hotted up, there’s a little of everything in it, from charts of the worked diggings and a full-scale Mercator map of Venus to samples of all the principal finds. I showed her the copy of the anisokinetic punch, and the original solid-state piezophone that had made its discoverer almost as permanently rich as the guy who found the punch. There were about a dozen fire-pearls, quarter-inch jobbies, behind armor glass, on cushions, blazing away with their cold milky light.

  “They’re pretty,” she said. “But why all the protection? I saw bigger ones lying on a counter in the Spindle without anybody even watching them.”

  “That’s a little different, Dorotha,” I told her. “These are real.”

  She laughed out loud. It was a very nice laugh. No girl looks beautiful when she’s laughing hard, and girls who worry about looking beautiful don’t do it. Dorotha Keefer looked like a healthy, pretty girl having a good time, which when you come down to it is about the best way for a girl to look.

  She did not, however, look good enough to come between me and a new liver, so I took my mind off that aspect of her and put it on business. “The little red marbles over there are blood-diamonds,” I told her. “They’re radioactive and stay warm. Which is one way you can tell the real one from a fake: Anything over about three centimeters is a fake. A real one that big generates too much heat—square-cube law, you know—and melts.”

  “So the ones your friend was trying to sell me—”

  “—are fakes. Right.”

  She nodded, still smiling. “What about what you were trying to sell us, Audee? Real or fake?”

  The third of Vastra’s house had discreetly vanished, and there was nobody else in the Hall of Discoveries but me and the girl. I took a deep breath and told her the truth. Not the whole truth, maybe; but nothing but the truth.

  “All this stuff,” I said, “is what came out of a hundred years of digging. And it’s not much. The punch, the piezophone, and two or three other gadgets that we can make work; a few busted pieces of things that they’re still studying; and some trinkets. That’s all.”

  She said, “That’s the way I heard it. And one more thing. None of the discovery dates on these things is less than fifty years old.”

  She was smart and better informed than I had expected. “And the conclusion,” I agreed, “is that the planet has been mined dry. You’re right, on the evidence. The first diggers found everything there was to be found … so far.”

  “You think there’s more?”

  “I hope there’s more. Look. Item. The tunnels. You see they’re all alike—the blue walls, perfectly smooth; the light coming from them that never varies; the hardness. How do you suppose they were made?”

  “Why, I don’t know—”

  “Neither do I. Or anybody else. But every Heechee tunnel is the same, and if you dig into them from the outside you find the basic substrate rock, then a boundary layer that’s sort of half wall-stuff and half substrate, then the wall. Conclusion: The Heechees didn’t dig the tunnels and then line them, they had something that crawled around underground like an earthworm, leaving these tunnels behind. And one other thing: They overdug. That’s to say they dug tunnels they didn’t need, lots of them, going nowhere, never used for anything. Does that suggest anything to you?”

  “It must have been cheap and easy?” she guessed.

  I nodded. “So it was probably a machine, and there really ought to be at least one of them, somewhere on this planet, to find. Next item. The air: They breathed oxygen like we do, and they must have got it from somewhere. Where?”

  “Why, there’s oxygen in the atmosphere—”

  “Sure. About a half of one percent. And better than 95 percent carbon dioxide; and somehow they managed to get that half of one percent out of the mixture, cheaply and easily—remember those extra tunnels they filled!—along with enough nitrogen or some other inert gas—and they’re present in only trace amounts—to make a breathing mixture. How? Why, I don’t know, but if there’s a machine that did it, I’d like to find that machine. Next item: Aircraft. The Heechee flew around the surface of Venus at will.”

  “So do you, Audee! Aren’t you a pilot?”

  “Sure, but look at what it takes. Surface temperature of two-seventy C. and not enough oxygen to keep a cigarette going. So my airbody has two fuel tanks, one for hydrocarbons, one for oxidants. And—did you ever hear of a fellow named Carnot?”

  “Old-time scientist, was he
? The Carnot cycle?”

  “Right again.” That was the third time she’d surprised me, I noted cautiously. “The Carnot efficiency of an engine is expressed by its maximum temperature—the heat of combustion, let’s say—over the temperature of its exhaust. Well, but the temperature of the exhaust can’t be less than the temperature of what it flows into—otherwise you’re not running an engine, you’re running a refrigerator. And you’ve got that two-seventy ambient air temperature; so you have basically a lousy engine. Any heat engine on Venus is lousy. Did you ever wonder why there are so few airbodies around? I don’t mind; it helps to have something close to a monopoly. But the reason is they’re so damn expensive to run.”

  “And the Heechees did it better?”

  “I think they did.”

  She laughed again, unexpectedly and once more very attractively. “Why, you poor fellow,” she said in good humor, “you’re hooked on the stuff you sell, aren’t you? You think that some day you’re going to find the mother tunnel and pick up all this stuff.”

  Well, I wasn’t too pleased with the way things were going; I’d arranged with Vastra’s third to bring the girl here, away from her boyfriend, so I could pick her brains in private. It hadn’t worked out that way. The way it was working out, she was making me aware of her as a person, which was a bad development in itself, and worse than that, making me take a good look at myself.

  I said after a minute, “You may be right. But I’m sure going to give it a good try.”

  “You’re angry, aren’t you?”

  “No,” I said, lying, “but maybe a little tired. And we’ve got a long trip tomorrow, so I’d better take you home, Miss Keefer.”

  5

  My airbody lay by the spacepad and was reached the same way the spacepad was reached. Elevator to the surface lock, a tractor-cab to carry us across the dry, tortured surface of Venus, peeling under the three-hundred-kilometer-an-hour wind. Normally I kept it under a foam housing, of course. You don’t leave anything free and exposed on the surface of Venus if you want to keep it intact, not even if it’s made of chrome steel. I’d had the foam stripped free when I checked it out and loaded supplies that morning. Now it was ready. I could see it from the bull’s-eye ports of the crawler, through the green-yellow murk outside. Cochenour and the girl could have seen it too, if they’d known where to look, but they might not have recognized it.

  Cochenour screamed in my ear, “You and Dorrie have a fight?”

  “No fight,” I screamed back.

  “Don’t care if you did. You don’t have to like each other, just do what I want you to do.” He was silent a moment, resting his throat. “Jesus. What a wind.”

  “Zephyr,” I told him. I didn’t say any more, he would find out for himself. The area around the spacepad is a sort of natural calm area, by Venusian standards. Orographic lift throws the meanest winds up over the pad and all we get is a sort of confused back eddy. The good part is that taking off and landing are relatively easy. The bad part is that some of the heavy metal compounds in the atmosphere settle out on the pad. What passes for air on Venus has layers of red mercuric sulfide and mercurous chloride in the lower reaches, and when you get above them to those pretty fluffy clouds you find some of them are hydrochloric and hydrofluoric acid.

  But there are tricks to that, too. Navigation over Venus is 3-D. It’s easy enough to proceed from point to point; your transponders will link you to the radio range and map your position continuously on to the charts. What’s hard is to find the right altitude, and that’s why my airbody and I were worth a million dollars to Cochenour.

  We were at the airbody, and the telescoping snout from the crawler was poking out to its lock. Cochenour was staring out the bull’s eye. “No wings!” he shouted, as though I was cheating him.

  “No sails or snow chains, either,” I shouted back. “Get aboard if you want to talk! It’s easier in the airbody.”

  We climbed through the little snout, I unlocked the entrance, and we got aboard without much trouble.

  We didn’t even have the kind of trouble that I might have made myself. You see, an airbody is a big thing on Venus. I was damn lucky to have been able to acquire it and, well, I won’t beat around the bush, you could say I loved it. Mine could have held ten people, without equipment. With what Sub Vastra’s purchasing department had sold us and Local 88 had certified as essential aboard, it was crowded with just the three of us. I was prepared for sarcasm, at least. But Cochenour merely looked around long enough to find the best bunk, strode over to it and declared it his. The girl was a good sport, and there I was, left with my glands all charged up for an argument and no argument.

  It was a lot quieter inside the airbody. You could hear the noise of the wind right enough, but it was only annoying. I passed out earplugs, and with them in place the noise was hardly even annoying.

  “Sit down and strap up,” I ordered, and when they were stowed away I took off.

  At twenty thousand millibars wings aren’t just useless, they’re poison. My airbody had all the lift it needed built into the seashell-shaped hull. I fed the double fuels into the thermojets, we bounced across the reasonably flat ground around the spacepad (it was bulldozed once a week, which is how come it stayed reasonably flat) and we were zooming off into the wild yellow-green yonder, a moment later the wild brown-gray yonder, after a run of no more than fifty meters.

  Cochenour had fastened his harness loosely for comfort. I enjoyed hearing him yell as he was thrown about. It didn’t last. At the thousand-meter level I found Venus’s semipermanent atmospheric inversion, and the turbulence dropped to where I could take off my belt and stand.

  I took the plugs out of my ears and motioned to Cochenour and the girl to do the same.

  He was rubbing his head where he’d bounced into an overhead chart rack, but grinning a little. “Pretty exciting,” he admitted, fumbling in his pocket. Then he remembered to ask. “Is it all right if I smoke?”

  “They’re your lungs.”

  He grinned more widely. “They are now,” he agreed, and lit up. “Say. Why didn’t you give us those plugs while we were in the tractor?”

  There is, as you might say, a tide in the affairs of guides, where you either let them flood you with questions and spend the whole time explaining what that funny little dial means or you go on to do your work and make your fortune. What it came down to was, was I going to come out of this liking Cochenour and his girlfriend or not?

  If I was, I should try to be civil to them. More than civil. Living, the three of us, for three weeks in a space about as big as an apartment kitchenette meant everybody would have to work real hard at being nice to everybody else, and as I was the one who was being paid to be nice, I should be the one to set an example. On the other hand, the Cochenours of the worlds are sometimes just not likeable. If that was going to be the case, the less talk the better; I should slide questions like that off with something like “I forgot.”

  But he hadn’t actually been unpleasant, and the girlfriend had actually tried to be friendly. I said, “Well, that’s an interesting thing. You see, you hear by differences in pressure. While we were taking off the plugs filtered out part of the sound—the pressure waves—but when I yelled at you to belt up, the plugs passed the overpressure of my voice, and you understood it. However, there’s a limit. Past about a hundred and twenty decibels—that’s a unit of sound—”

  Cochenour growled, “I know what a decibel is.”

  “Right. Past a hundred and twenty the eardrum just doesn’t respond anymore. So in the crawler it was too loud; with the plugs, you wouldn’t have heard anything.”

  Dorotha had been listening while she repaired her eye makeup. “What was to hear?”

  “Oh,” I said, “nothing, really. Except, well—” Then I voted to think of them as friends, at least for the time being. “Except in the case of an accident. If we’d had a gust, you know, that crawler could have flipped right over. Or sometimes solid objects come fly
ing over the hills and into you before you know it. Or-”

  She was shaking her head. “I understand. Lovely place we’re visiting, Boyce.”

  “Yeah. Look,” he said. “Who’s flying this thing?”

  I got up and activated the virtual globe. “That’s what I was just coming to. Right now it’s on autopilot, heading in the general direction of this quadrant down here. We have to pick out a specific destination.”

  “That’s Venus?” the girl asked. “It doesn’t look like much.”

  “Those lines are just radio range markers; you won’t see them looking out of the window. Venus doesn’t have any oceans, and it isn’t cut up into nations, so making a map of it isn’t quite like what you’d expect on Earth. That bright spot is us. Now look.” I overlaid the radio-range grid and the contour colors with mascon markings. “Those blobby circles are mascons. You know what a mascon is?”

  “A concentration of mass. A lump of heavy stuff,” offered the girl.

  “Fine. Now look at the known Heechee digs.” I phased them in as golden patterns.

  “They’re all in the mascons,” Dorotha said at once. Cochenour gave her a look of tolerant approval.

  “Not all. Look over here; this little one isn’t, and this one. But damn near all. Why? I don’t know. Nobody knows. The mass concentrations are mostly older, denser rock—basalt and so on—and maybe the Heechee found it easier to dig in. Or maybe they just liked it.” In my correspondence with Professor Hegramet back on Earth, in the days when I didn’t have a dying liver in my gut and took an interest in abstract knowledge, we had kicked around the possibility that the Heechee digging machines would only work in dense rock, or rock of a certain chemical composition. But I wasn’t prepared to discuss that with them.