Donald Moffitt - Genesis 02

Even if they came together at the apex of an ispceles triangle twenty-odd thousand miles up, the slight lean from the true vertical wouldn’t have mattered that much. Not with the materials they had available.”
    “Okay, you’ve got your twelve moons, bobbing up there like captive balloons, and connected to make a dodecagon—”
    “To make a circle, Bram. The line bellies outward.”
    “Okay, a circle. What next?”
    “Next they started spinning the world. Faster and faster. At the same time, they began playing out more of their superfilament. They must have fed it out in a liquid form that instantly hardened—”
    “There was a terrestrial animal called a spider that did that biologically,” Ame put in.
    “Yah, I wouldn’t know about that. Anyway, they probably fed in the raw materials at the poles, from a couple of big gas clouds they had parked out in space. The oxygen and carbon could’ve come from carbon dioxide they siphoned off a hothouse-type planet—there’s one of those in almost every G-star system, same as gas giants. That must’ve been a sight to see—the two big vortices whirling from the poles millions of miles into space, while the tethered moons spun out farther and farther weaving a gossamer web between them.”
    “You don’t think small, I’ll give you that.” Bram laughed.
    “ Now you start extruding your foam—mountains of it, oceans of it, following the network of filaments into orbit, the trapped bubbles of gases blowing the material up to two or three thousand times its volume before the molecules cross-link and become rigid. It maintains the disk shape, reaching a predetermined orbit at the limit of the spin force, with an excess material falling back to the surface. Foam that squeezes laterally through the web shears off, making a nice smooth face. Depending on the altitude, the excess stuff either slides outward or falls back to the hub. It’s exactly like the preliminary stages of the formation of a protostar… or… or a galaxy! The material settles more and more into a flat rotating disk! But now, with the growth of the disk, angular momentum is transferred and the spin slows down! So you get the stable situation we see here, with the moons traveling just a little faster—or lower—than they ought to be for synchronous orbit and maintaining the tension that helps hold the whole structure together.”
    He stopped, out of breath.
    “What’s happened to your rocky world at the center?” Bram asked.
    “Oh, that? It’s smeared all over the faces of the disk. Some of it’s been flung out beyond the rim and fallen back, and we’re standing on it. And the rest of it’s a plug in the hole at the center of the disk, where the gravity is perpendicular to the disk surface. “It’s heavy there, that close to the center of gravity, I promise you!”
    “What about it, Enry?” Bram said.
    “It could be.” The geologist’s voice was muffled; he must have turned his head away from the helmet mike to check data. “I’ve got samples that could have come from the rocky core of a gas giant that broke up. Silicates that show signs of once having been under tremendous pressure. Millions of atmospheres worth—the kind of pressure that turns molecular hydrogen into metallic hydrogen. The paleomagnetism’s interesting. The orientation’s every which way. As if the samples originated elsewhere and were scattered all over the place.”
    “What did I tell you?” Jao sounded smug.
    “There’s something else,” Enry drawled.
    “What?”
    “The rocks show that there’s a steady leakage of gases from the interior of this … world. Oxygen, and carbon dioxide, and lighter gases like nitrogen and helium. The rim can’t hold on to an atmosphere, of course. But there could be a considerable amount of gas still trapped in the … cavities that Jao postulates.” There was a moment of silence with an unmistakable frown in it. “More than there ought to be, from the rate of leakage, after seventy million years.”
    “The gases are subliming off the foamed surfaces,” Jao said quickly. “And maybe off the superfilament as well. Nitrogen, did you say? I’m going to have to rethink the chemistry of it. Plenty of oxygen, that’s for sure. Hey, we might be able to tap into it during our stay—take some of the load off Yggdrasil!”
    “How far down would we have to drill to tap atmosphere?” Bram asked.
    “I don’t know. It would take some pretty fancy mathematics to