Threshold

  Chapter 45

  Blotched, pockmarked, scarred with orange-yellow blotches, Io's hostile surface streamed by Munin a scant hundred kilometers below. Bombarded by radiation so intense that it would be almost instantly lethal without shielding, shrouded in a sulfurous atmosphere just barely thicker than vacuum, with a surface constantly reshaped by stupendous eruptions of molten rock, the tortured moon's leprous face wrung an involuntary shudder from Horst. In a short time, Odin would meet its end—out of sight of Munin, as the lander would at that time be making its own Oberth Maneuver near the other side of Io. The orbital adjustment Munin had made to avoid hitting Io had sent her ahead of the doomed E.U. ship, passing some other debris along the way.

  "We are on course, Andy?"

  "All is ready. You just keep on with your design work."

  Horst studied the designs that he, Jackie, Mia, and Joe were working on.

  The fundamental challenges were really twofold. First, fastening the two vessels together so that the power of the Munin's rockets could be applied to both vessels. Second, determining where the Munin and Nebula Storm could be fastened together that wouldn't cause the thrust from the rockets to be applied off-center, thus turning what should be straight thrust into a spin.

  "The positive side is that we don't have to do most of it fast," Joe had pointed out. "We don't have to build these links to hold under ten Gs or anything."

  Mia shook her head. "There will be maneuvers that may well have significant peaks. Not ten gravities, but more than one."

  There were some points suitable for anchoring at least part of Munin on Nebula Storm. The most obvious were the attachment points that were originally used to suspend Nebula Storm in Ceres' gravity. Those had been heavily overengineered, and Joe was confident that they could take just about any strain that was likely to be encountered. Horst thought Joe was probably right. The obvious orientation to anchor the two vessels was one that placed their airlocks in as close proximity as possible. A couple of the tiedown locations were close, and if they could put a connecting tube between the vessels, they could use the internal supports of Nebula Storm as an anchor to the front landing gear of Munin.

  Jackie had come up with the best way to adjust the center of mass: extending two of the four habitat sections on Nebula Storm, the two which would be on either side of Munin when locked down, and putting as much heavy stuff—including water—in them as necessary to mostly balance the center of mass. The main rockets of Munin had some slight ability to deflect and adjust their angle of thrust, which would—they hoped—make up for minor deficiencies.

  To minimize vibration and movement during thrust, Mia wanted to use several tons of water. Freezing in place at the interface between Munin and Nebula Storm, the ice would probably help. How long it would last no one could tell, but they didn't have many alternatives.

  The real sticky point was exactly how to manage the connections and the landing itself. "I do not see how we can pull off this landing," Horst said finally. "Munin is designed to land. Nebula Storm is not, and together—especially in the configuration we will need to maneuver in—I cannot imagine even Miss Fathom bringing us down uninjured."

  Static crackled in his ear before Jackie answered. Even with the best selection of frequencies and top-notch signal enhancement, the storm of electromagnetic noise around Io made conversation difficult. "Yeah. I've got a possible fix for that, but then we can't do the welding we were talking about. We need to separate the ships just a few minutes before we come down."

  "Jackie, if we are separated, you are falling. We can land, yes, but what about you?"

  "Look, what we do is run a cable from your reactor to our engines. I get the accumulators partly charged, we'll have enough power to do another burn or two. Not big ones, but if we're slow enough—down at the hundred-meter-per-second range or so—then Nebula Storm will be able to land itself, if I retract the hab sections. It won't be pretty, and we'll probably get bumped around, but it's livable."

  "Yeah, that'd work!" Joe said. His enthusiasm dropped. "But that really throws a wrench in the works. First, we can't tie ourselves together through the airlock link—we don't want the airlock open. And . . . If we don't weld everything together . . ."

  "Cables," Horst said suddenly as he finally found what he'd been looking for in the Munin's extensive onboard manifest. "For exploring parts of Enceladus, or wherever we ended up going, as you had to on Mars. We had exploration vehicles with very strong cable to hold and lower large loads very long distances. These are combined metal-composite-carbonan cables, Jackie. If we use several of them at each connection point . . . ?"

  "Give me the specs." There was silence as she ran her models. "That . . . should work. How do we detach, though?"

  "Blow the cables," Joe answered promptly. "Have Maddie make appropriate demo charges. It's one of her specialties, remember. And we could rig something—a big cable, a rocket, whatever—to heat the connecting area where the ice is, weaken it so we can break free."

  Horst chuckled briefly. "This is going to be the most . . . what is that name—Goldberg? Yes, Rube Goldberg–inspired operation I have ever imagined. Are you sure that we do not need to trigger it all with a hamster on a wheel?"

  "I dunno," Jackie said. "Do you have a hamster on board?"

  "Let me check the medical supplies . . ."

  She laughed. "Oh, I needed that. Actually, the cables are a better idea if you guys can prepare most of that ahead of time. Welding in vacuum is a pain, and we will only have a few hours to get all this done."

  A roar of power thundered through Munin and shoved Horst down in his seat. "We are doing our Oberth now."

  A few moments later the rocket went silent. "Anthony?"

  "One moment . . . Yes, everything is good. We are catching up with Nebula Storm. In a few hours we will have to match up. Then we will have to work like demons."

  Horst signaled Jackie to shift frequencies. "Jackie . . . at least I will see you before—"

  "—before we might end up killing ourselves in this crazy stunt. Yeah. I'm glad." Her static-fuzzed image still was clear enough for him to see a hint of tears in her eyes. "But let's live through this, okay?"

  "I would much prefer that." He unstrapped and stood. "Now, I am sorry, but we all have to go and get the materials ready."

  "Yeah, I'm going to have to get everyone up soon to start prepping on our end. Especially A.J., since he's going to have to run our Locusts. They'll be invaluable for doing the outside work, even if the rest of us all do have suits."

  "Then I say good-bye for now."

  "See you soon!" She gave him a gleaming smile, and then disappeared.

  Horst turned to Anthony, Mia, and the others. "Okay, you can stop grinning at me. We have work to do."

  Anthony shook his head. "The things a man will do to get a date."

  "They're both engineers," said Mia. "What do you expect?"

  Io loomed before Hohenheim, now. It was no longer a disc but a monstrous wall, a wall of pustulant yellow touched with oranges and greens and whites, toward which Odin hurtled unstoppably. The general recalled that some had compared the surface of the Jovian moon—often imaged with a brighter orange shade—to that of a pizza. But the hideous surface before and below Odin looked more like decaying flesh, the peeling face of a horror-show zombie with a death-rictus grin and the stench of the grave.

  Uncertainty precludes answer.

  The simple phrase on the screen showed why he was staring as though enraptured. The combination of the damage done to the ship—the change in mass, in geometry, the failure of the nozzle which had not been performing per normal specifications, all of that and more—meant that there was still some element of uncertainty in the precise path of Odin around Io. Around Io—or into it.

  This was of course made worse by Odin's need for radiation shielding. Hohenheim had not dared tamper with those settings, and so wherever the system could maintain a shield, there one remained. But as Castillo had t
old him long ago, that meant there would be some small, and in this case unpredictable, forces exerted by the mighty magnetic and radiation fields of Jupiter on his smaller but concentrated shielding.

  And so Io grew, and grew, and was not even a planet with a curve easy to identify. He could see individual mountains now, one belching a cloud of yellow-black that, it seemed, would nearly reach Odin's current altitude.

  I should turn away. There is no need to see.

  But instead he stood. The surface of the moon was approaching rapidly. Coagulated sulfur and craggy, savage mountains seemed to cover everything. What would happen, would happen soon, and he would face it head-on.

  Odin screamed silently out of the black sky of the Jovian system, as though riding eight-legged Sleipnir down upon some inconceivably monstrous Jotun—or, no, a fire giant, great Surt himself. The drive-spines, three remaining, traveled before Odin like a three-pointed spear: Gugnir as a pitchfork. Ahead, Hohenheim saw a great ridge of mountains, higher than Everest, looming before his ship. He braced himself. There, in all likelihood, was his tombstone.

  One mountain in particular, a vapor-belching cone, lay directly in Odin's path. Hohenheim could not keep from sucking in his breath as Odin bore down on it at literally meteoric speeds.

  There was a sharp, shuddering snap that echoed high and low. Hohenheim was swept off the floor even with his boots and the grip he had had on his chair. He smashed into the ceiling, around and around, tumbling . . .

  Tumbling? He should have vaporized on impact!

  Even as that thought came to him, the spin began to reduce, the remaining laterals fighting the tumble. He glimpsed, weaving drunkenly by in the screen, the great ridge of mountains, receding now, the surface dropping away below him.

  Projected path clear blinked on the screen in front of the main engineering console. Hohenheim felt a great burst of relief, and wonder, and, yes, triumph.

  Whatever else, he would die on his own terms. And he would now have plenty of time to prepare those terms.

  Chapter 46

  Madeline strapped herself into the control seat. "Are all connections secure?"

  "As secure as we can make 'em," A.J. answered her. "Got Faerie Dust all over them to give me warnings if anything happens."

  Not that this would do me much good, Maddie thought but did not say. After all, once they committed to the landing, there would be really no chance to change their minds. If things started to come apart, they'd just have to do the best they could . . . which would probably be not enough, and they'd all die. But trying was a lot better than just waiting until something ran out. "Jackie, are the accumulators charged?"

  "Off the topic, do you realize how old-fashioned that name sounds? Accumulators, that is? Used to read it in like 1940s SF," A.J. said.

  "Shut up, A.J. Yes, Maddie, they're charged. Not nearly fully, but with our limited reaction mass, more than enough."

  "Disconnect power-cable connection, then, and seal the airlocks. A.J., all disconnect charges placed?"

  "Placed. They're under your control and codes. No one else can trigger them."

  "Good. Network?"

  Horst answered. "You have control of our rocket until disconnect, Madeline. The telemetry is triple-redundant to make sure we don't glitch during landing."

  "Balance?"

  "Got tons and tons of mass stuffed into the extended hab areas. We've modeled both ships, and the center of mass for acceleration is now pretty close. We can use the automated system on Nebula Storm to do some minor adjustments, and the main rockets on Munin have enough thrust-deflection capability."

  "What about our hull?"

  A.J. shook his head. "Don't worry about it. The part of our hull that might get hit by the rocket wash is all Vault alloy. Sure, keep the rocket on it long enough and we'd probably damage something, but we're not firing it that long."

  Maddie nodded. "Munin, are your reaction mass tanks fully loaded?"

  "Yes. Glad that where we are going there is a lot of ice, because otherwise we would all be very short of water when this is done."

  "Good. Everyone strapped in?" The others reported in. "Mia, I want you and Jackie to keep a really close eye on everything. We can't afford glitches."

  "Understood. We are watching."

  Madeline rubbed her eyes and took several deep breaths before putting her helmet on. This being a critical maneuver, she'd also taken a stimulant. She simply hadn't had enough sleep, and this was not the time to have slowed reflexes. There were only two good aspects to the situation. One, obviously, was the low gravity of Europa, less than one seventh of Earth's, which meant a gravity well of just slightly over two kilometers per second—within Munin's capacity to handle even with the added mass of Nebula Storm. That was critical, because not only did they need to land, they needed Munin to be able to lift them off of Europa eventually, because the nebula drive wasn't capable of lifting off from anything larger than a smallish asteroid.

  The second good thing was that Europa had no atmosphere to speak of. This jury-rigged double ship had the aerodynamics of a falling bridge, and were there any atmosphere—even one as thin as Mars'—the pressure variations during reentry would probably rip them apart. Aside from the gravity well itself, she'd be able to treat the maneuvers as being the same as in deep space. That gave them a chance. Not a great one . . . but I'd better make it good enough, she thought.

  "All right, everyone. We are almost there."

  Europa now loomed before them, eclipsing even Jupiter in size as the combined Munin/Nebula Storm overtook it in its orbit at a differential of less than a kilometer per second. Smallest of the Galilean moons, it was still immense, half again as wide as Luna, far more massive, far more complex. From their current altitude, it looked as smooth and polished as a billiard ball, an ivory cueball with multiple browned lines like cracks from age covering its surface. Somewhere below that surface, Maddie knew—depending on the scientist you asked, anywhere between two and fifty kilometers below—there was a dark ocean that covered the entire moon to a depth ten times greater than the deepest parts of Earth's ocean.

  The smoothness was deceptive. Europa might be the smoothest object in the solar system, but there were still plenty of ridges, blocks, edges, hills, and chasms, and they had only minimal control over their landing site. In the few hours they had, A.J. and Larry had gone over the available imagery and what they could make out with the onboard instruments and picked their best guess as to a landing trajectory that might offer decent landing topography . . . but it was still a crapshoot.

  "About to begin maneuvers. I'm going to ask everyone to either cut out radios or stay quiet unless they have something I need to hear. This is going to take all my concentration, and I don't need even a gasp, a curse, or a prayer distracting me."

  "Understood," A.J. acknowledged. She saw some people drop out of the network—mostly the former Odin crewmembers that she hadn't had time to get to know yet, and who weren't engineers involved in this maneuver. Helen and Larry also dropped out. Larry had done all he could, and Helen was not going to be able to do anything more, either, now that the gruntwork of putting the whole contraption together was over.

  "Here goes . . ."

  Munin's rockets coughed and then began a low, rumbling roar at minimal power. She wanted—needed—to get a feel for the clumsy dual ship before she kicked in full power. It was sluggish . . . wobbly . . . still some imbalance . . . but there, A.J. and Horst's programming was kicking in, automatic compensation based on the accelerometers all over the ships. The departure from projected optimal course was minimal. "Working so far. Full de-orbit burn coming up in three, two, one . . ."

  Now the rockets gave vent to full-bore thunder, sending a shudder of vibrations throughout Nebula Storm. "Ice seal under stress . . . holding, but I'm seeing cracks starting to build. Think it will hold, but be ready," A.J. said quietly.

  "Cables?"

  "All well within limits. No shifting yet. The torque on the hab sect
ion connecting tubes and supports is getting awfully near their design limits, but doesn't seem to be increasing any more."

  "Burn almost done . . . in five, four, three . . ."

  Just as the Munin ceased its rumbling, there was a reverberating crunch. "What was that?"

  "Ice seal shifted and broke. We're only held together with the string and duct tape now. On the positive side, we don't need to worry about making sure that part breaks when it comes to the time to separate."

  "Any advice?"

  Horst answered. "When we do the other burn for landing preparation, begin very slowly, as before, then taper slowly. This will let any slack be taken up and stress the cables least. Backing down slowly will let the strain off the cables evenly—I hope—so there will be no great shifts."

  "I understand." She leaned back. "It will be a while before we come to the landing decision. Larry, A.J., I want you to keep watch ahead of us and refine our landing site as much as possible. As we know from our little landing in John Carter, you don't have to hit at kilometers per second to ruin your day."

  "We're on it. Take it easy for now."

  She reached out and took Joe's hand. Even though the contact was just glove-to-glove, it felt good. "You okay?" he asked privately.

  "Scared to death. I practiced a lot after that crash, and Bruce said I was getting pretty good, but I'm not half as good as he is, and I think he'd find this a hell of a challenge."

  "You're my Supergirl. You'll do it."

  She giggled. "Yeah, I'll just fly out and catch us if something goes wrong."

  "I almost believe you could." He smiled at her fondly.

  "I'd try, anyway."

  "Maddie, all that matters is we're doing our best. And if anyone can get us down safe and sound, it's going to be you."

  Once more his words made all the difference. She stopped worrying. If the worst happened, it happened.