Enigma

by Michael P. Kube-Mcdowell

  “What kind of artifacts?” Thackery asked, more from reflex than real curiosity. “Metal. Little things, the size of your palm or smaller. Pieces from some kind of machinery.”

  Koi asked, “Can we go down in the pit?”

  “Sure. There’s some footholds cut in the wall at the far end.”

  “I’ll pass,” Thackery said, and sat down where he had been standing.

  When the others reached the bottom, Koi went first to the nose and examined the joint there, then stood and walked toward the back, running her gloved fingers along the spine-like center rib until it was too high for her to reach. “Why did they stop digging?” she wanted to know when she straightened up.

  Jankowski frowned. “They went all the way down to the A level. You can see by the ash layers in the wall of the pit all the episodes of volcanism. Ash, pyroclastic flow, tuff breccia, ash again, basaltic lava—we’re standing on what was the valley floor when the Wynea lived here.”

  “So we’re looking at the whole thing? There’s nothing buried?”

  “No.”

  “And no other structures in the area?”

  “No.”

  “Anything else like this on the whole planet?”

  “Not that we’ve found.”

  “So what do your bosses think it is?”

  “A range shelter.”

  Koi regarded him dubiously. “Really?”

  “They modeled the prevailing wind patterns in the valley prior to the volcanism and found that the small end faces upwind. If you span the area between the center rib—think of it as a ridge pole—and the ground ribs with fabric, like they do with the arches inside their buildings, you’d have a good-sized protected volume inside.”

  Thackery called down into the pit, “You almost finished, Amy?”

  “Almost,” Koi answered. “Why aren’t you sure?” she asked Jankowski.

  “Mostly the fact that we haven’t found any more of them yet—though Dr. Essinger expects to, eventually. ‘Find one, it’s an oddity—find two, it’s a commodity’ is how he says it.”

  “And that’s why it hasn’t been included in the Annex’s reports?”

  “You have to understand that everything we find spends some time on the Interim list before any report is filed. This one’s just been there a little longer than usual.”

  “Because you can’t find another?”

  “I guess. And because of the way this one was found. It was solid pyroclastics and lava right down to the spine—and then nothing, right down to the original valley floor. The other artifacts were just lying on the A level, on the floor of the shelter, as it were.”

  “There was a cavity in the deposits?”

  Jankowski nodded. “The center rib was part of the roof of the cavity. Whatever the fabric was, it was apparently strong enough to hold out the lava until it cooled—which the other fabrics we’ve found indoors wouldn’t have. Dr. Essinger would like to find a sample of it before he closes the books.”

  Koi looked up to where Thackery sat on the lip of the pit. “What do you think?”

  His face devoid of interest, Thackery clambered to his feet. “If you folks can get out the way you got in, I think it’s time we headed back.”

  “You are disappointed, no matter what you told Kevin,” Koi whispered to Thackery when they were alone that night, squeezed together onto a one-person foldaway in a test of both agility and companionability.

  “I’m just afraid you’re right—that the colony failed without any help from the D’shanna.”

  “Did you ever really expect anything different?”

  “All the way over to Site 241,1 was thinking that Sputnik followed Kitty Hawk by only about fifty years. If the Wenlock had achieved flight, then the D’shanna would have had reason to come here.”

  “Kevin tried to tell us it wasn’t a plane.”

  “And I wouldn’t listen, I know. Well—there’s two new colonies waiting for us. Essinger says we could probably beat the followup mission to 16 Herculis. Or we could go all the way across to the Perseus octant and drop in on the Shinn.”

  “Or we could always just get into Munin and go out to the rim of the Galaxy, and come back a few thousand years from now when somebody else has sorted it all out.”

  “Don’t think the thought hasn’t crossed my mind.”

  “I was joking,” Koi said, pulling away from him. “Besides 16 Herculis, there’s still Ross 128 and 2 Triangulum Australis. And I’m not ready to write off this planet yet.”

  “Oh, we’ll stay a while yet. But I can’t see much reason to hope for anything.”

  “Do me a favor?”

  “What’s that?”

  “Don’t be with us like Neale was with you at Sennifi. Let me tell you when I’m finished, and not the other way around.” His smile was rueful. “Sorry.”

  “You haven’t done it yet,” she said, and kissed him. “I just want to make sure you don’t.”

  A night’s sleep seemed to restore Thackery to his former state of enthusiasm and optimism. He was the first up of the Munin team, and had cleaned and inspected all four E-suits by the time the others dragged themselves down to breakfast. “I’ve asked Kevin to take us out to the Werno dig,” Thackery told Koi when they settled at a table.

  Her face wrinkled unhappily. “Why don’t you take Derrel, or Barbrice?”

  “Why, what are you going to do?”

  “I want to look a little more into this business of the 241 artifact. Besides, we don’t want the others to think that the only way to get to go on a field trip is to sleep with the boss.”

  “You think they might think that, eh? Then I guess I’ll take Barbrice.” Koi glowered threateningly, then relaxed into a smile. “That’s all right. She’s gay.”

  “Figures. Listen—there’s no need to get hung up on the 241 artifact just because I was for a while.”

  “No danger,” she said cheerfully. “We’ll see you in a few hours.”

  Now that she knew it was there, Koi had no trouble extracting the data on the 241 artifact from the Annex’s Interim files. The abstract contained a variety of information which Jankowski had not provided, including one intriguing fact: an assay showing that the ribs were made of tantalum-niobium alloy.

  That one discovery made the range shelter idea fallacious on its face. Tantalum and niobium were both refractory metals, relatively rare in the crust of 7 Herculis-5—in fact, the orbital assays suggested that the source minerals, tantalite and samarskite, were even less common on 7 Herculis-5 than they were on Earth. Abundance aside, together tantalum and niobium made an alloy with outstanding corrosion resistance, high-temperature stability, and tensile strength—hardly the alloy of choice for something as mundane as a shelter.

  This wasn’t part of their working technology, she thought triumphantly. And Essinger must realize it too. That’s why they haven’t said anything. He’s in no hurry to look stupid.

  After a few minutes of further checking, Koi confirmed that except for Site 241, no tantalum-niobium artifacts had been uncovered anywhere on the planet. That might have been of minor significance, except for the level of skill the Wenlock had evinced as chemists.

  For tantalum was resistant not only to ordinary atmospheric corrosion, but to acids and alkalis as well, even to highly reactive fluorine. Had tantalum been available in quantity from some local deposit or ore, now hidden from the surveyors by layers of ash and lava, the Wenlock would surely have found a variety of uses for it. But even in those applications where its properties would have been valuable—surgical instruments and implants, cutting tools, chemical equipment—the Wenlock had employed more conventional alloys, such as iron-chromium steels.

  This isn’t proof, she told herself sternly, trying to constrain her deductive leaps. But there was no resisting the central conclusion: Whatever the 241 artifact is, it wasn’t made on this planet.

  Koi turned next to the photographic records of the artifact.

  “Model,” she instr
ucted the netlink, and a three-dimensional solid graphic replaced the actual image. “Hold foreground and abstract,” she instructed, and the pit vanished from the display.

  “Rotate left and down. Stop. Draw,” she said, and touched a stylus to the screen to trace a line closing the double-S base and another vertically from the back end of the center rib. That looks good—

  “Fill, using Class A aerodynamic parameters,” she said, and the skeleton acquired flesh.

  “Rotate right and up.”

  The modeling program obediently complied, and Koi sat back in her chair and steepled her fingers against her lips. On the display before her was a persuasive side view of a hightailed, delta-winged aircraft.

  Aircraft? High tensile strength—high melting point—high corrosion resistance—just like you’d need for—“Evaluate: atmospheric entry, multiple-skip aerodynamic braking, unpowered descent to flight-normal altitude.”

  NOT POSSIBLE UNDER CURRENT PARAMETERS.

  “Modify.”

  As she watched, the trailing edge of the wing lengthened,. the fuselage tapered to a point at the base of the tail, and the vertical stabilizer grew larger. The changes affected only the portion of the shape which the modeling routine had created; the three tantalum-niobium ribs remained unchanged.

  MODIFICATION COMPLETE.

  No, not an aircraft—a goddamn spacecraft. A winged reentry vehicle. These people found the skeleton of a goddamn transonic spaceplane sitting under eighteen metres of pyroclastics in the middle of nowhere on a colony planet and didn’t even know what they’d found.

  “Save model,” she said grimly, and folded the netlink’s display flat against the controls. There’s one big problem, Amy dear. The Wenlock couldn’t have built it. The D’shanna, at least Merritt’s D’shanna, wouldn’t have needed it.

  As far as Koi knew, that left only one possibility. And that one was so fantastic that she could scarcely bear to entertain it.

  Guerrieri did not share her enthusiasm, and was loathe to share her conclusion.

  “That’s not a spacecraft—it’s a shell,” he complained when Koi showed him the model.

  “That’s what I want your help with—filling it.”

  He shook his head. “You’re as bad as the paleontologists who reconstruct an entire skeleton from half a jawbone.”

  “This ‘jawbone’ has a melting point of over 1600 degrees Celsius, a perfect airframe profile, and an extremely suspect genealogy.”

  “But it’s still just a jawbone. Don’t you realize how complex even a dead-stick glider is? Where’s the load-bearing stringers and truss spars? Where’re the control surfaces? Where’re the avionics and navigation packages?”

  “Some of those may be in the Annex warehouses. That’s why I want you to go out there with me and look at the rest of the Site 241 artifacts.”

  Guerrieri sighed expressively. “You won’t let me rest until I say yes, will you?”

  “Nope. Best you surrender now.”

  Guerrieri raised his hands over his head. “I’ll get my E-suit.”

  The 241 artifacts were together in one storage crib, the smaller ones individually bagged and filed, the larger ones individually boxed and stacked. Each object and container bore a glittery scanstrip, on which its file number and the location in which it had been found were encoded.

  Inside the containers, Guerrieri and Koi found an array of metallic objects which might have come from an exotic hardware shop. Nearly all had moving parts—bits of tubing with integral flutter valves, variable-angle Y-connectors, pinless shear hinges, interlocking mushroom-shaped anchors. Yet the artifacts bore little evidence of use or wear, and their surfaces gleamed the same burnished blue-silver as the larger pieces still at Site 241. Guerrieri shook his head as he turned one over in his hand.

  “Barbrice would be a lot more use to you with these than me,” he said, wearing an almost comic expression of befuddlement.

  “She’s with the boss,” Koi said with calculated offhandness. But her mind was busy. You know Thackery in a way she doesn’t—better maybe even than I do. You share a survivors’ bond, from Descartes and Gnivi—it’s why you came on this tour, whether you realize it or not. You knew him before the D’shanna took hold. You may be the only one who knows whether he’ll be able to give them up.

  “Lucky her,” Guerrieri said, returning the object he held to its envelope and reaching for another. With Koi looking on but saying little, he continued that process for more than an hour, even to uncrating the larger objects, though they proved no more illuminating than the small ones.

  “I’ve seen enough if you have,” Guerrieri said when he had repacked the last case.

  “I’m done,” she said agreeably. She did not mention that she had visited the storage crib electronically that morning, using the archival recordings of each object which Jankowski had mentioned. It’s different when you hold them in your hand. More real—more convincing—I hope.

  “Can we head back now?” Guerrieri asked.

  “Sure, if you promise to spill your thoughts on the way.”

  “I was afraid you’d expect that.”

  “Why?”

  Guerrieri closed the warehouse door behind them, then stopped to turn up his suit ventilation and thereby dispel the fog that had formed on the inside of his faceplate. “There’s not much question that they go with the big artifact, and with each other,” he said as they started off down the street toward the Annex. “And they’re mechanical, structural—they were clearly meant to do things. But they don’t make anything. I don’t know what else I can say.”

  “That may be enough.”

  Guerrieri shook his head. “Don’t you understand? It’s still just bits and pieces. Where’s the rest of it? Unless your picture of what happened here includes street thieves and chop shops?”

  “Hardly.”

  “Then what happened to the structural material? The control surfaces, the spars, the stringers, the skin?”

  Inwardly, Koi smiled. That’s the first step—now you want to know what happened to something that two hours ago you said didn’t exist. “It’s gone.”

  “Gone where?”

  “Into the ground.”

  “What are you talking about?”

  “The artifact was buried in basaltic lava. Even three miles from the nearest vent, that lava had to be a thousand degrees Celsius. The heat destroyed everything except what we’ve seen—everything that wasn’t made of tantalum-niobium.”

  “You’re saying it survived the heat of a free-fall reentry and then was destroyed by the lava? That’s nuts.”

  “Not at all. The nose cap and wing leading edges are the only areas which experience temperatures in the thousand to fifteen hundred degree range. All the other surfaces see less than a thousand degrees—most less then five hundred, and that only for a few minutes. But the lava would have taken days to cool. I ran the numbers.”

  “And by the time it does, the rest of the spacecraft is gone—leaving the cavity the dig crew found,” Guerrieri said slowly. “So what did they use, then? What was the magic material?”

  For an answer, Koi bent down, picked up a fragment of plaz, and handed it to him.

  He ignored it and stared at her. “A glass spacecraft?”

  “I wish it were that simple,” she said with a shake of her head. “That isn’t glass. It isn’t even almost-glass. There’s almost no silicon, almost no calcium, almost no sodium.”

  “So what is in it?”.

  “Oxygen and hydrogen, in a ratio of 8 to 1 by molecular weight and 1 to 2 by molecular count. And a few minor impurities—”

  “Oxygen and hydrogen—that’s water.”

  “Arranged in a long-chain tetrahedal crystal structure, with each oxygen atom bound to four hydrogen atoms.”

  “Crystal structure—,” Guerrieri gaped at her. “That’s ice, goddamnit. What the hell are you trying to tell me? That’s ice, goddamnit all.”

  “That’s what I’m trying to tell
you.”

  Guerrieri’s protests ceased then, and he took a seat in the doorway of a ruined Wenlock home. “You choreographed this all very nicely,” he said in a subdued voice.

  “Thank you.”

  He looked hard at the piece of plaz in his hand. “I assume you ran through all my immediate objections yourself.”

  “I went through a lot. I probably have you covered.”

  “Not conventional Ice-1, of course. You’re talking about a metastable polymorphic form.”

  She nodded. “Just like diamond is a metastable form of carbon—and as unlike the parent material as you could ask for. I’m glad I don’t have to give you a course in chemical polymorphism.”

  “Oh, no—I spent a long night sweating over the phase diagram for water back in my Institute days.” He turned the plaz over and over in his hand slowly. “I can tell you this, nothing like this was on it.”

  “Call it Ice X. Or maybe the impurities are important, and we should call it an alloy instead. We need to put a good X-ray crystallographer to work finding out.”

  “It’s just possible. Just barely possible. Which means that maybe the Wenlock did build spacecraft after all—at least one.”

  “No,” she said firmly. “This is not a Wenlock artifact.”

  “Then what?”

  “You know what it has to be.”

  Guerrieri let the plaz slide from his hand to the pavement, and cocked his head to stare at her. “Please be gentle with me. My head hurts already.”

  She smiled at his joke. “I’m trying, but it isn’t easy.”

  “You’re going to make me say it, aren’t you? That this is an FC spacecraft?”

  She came and crouched before him, at his eye level. “What if Mannheim were just just a little bit wrong? What if the FC civilization existed not during an interglacial stade, but during one of the glaciations? Couldn’t an inventive culture deprived of what we consider the crucial metals develop an entire technology based on what was available to them?”.

  “A technology of ice?”

  “That’s one pretty remarkable product of it lying there by your feet.”

  “It’s a long way from a city dome to a starship.”