Resurgence hu-5

by Charles Sheffield

  “All non-structural interior bulkheads are expendable. All food refrigeration systems, together with all food that would spoil. All but an absolute minimum of other foods. All water recycling equipment may be dispensed with, since present water supplies will suffice for a trip back to the Orion Arm. All drinks but water. All storage lockers, all furniture except for control chairs, all sleeping accommodations, all soft furnishings, all carpets and drapes. All clothing beyond what people are wearing at the time we leave. All spare suits. Most lighting fixtures. All exercise and recreational equipment. All toilet and bathroom fixtures, unless you feel it necessary to keep one working toilet.”

  Nenda said, “That would be nice.” Hans Rebka added, “Keep going, E.C. This is beginning to sound familiar—just like it was where I grew up.”

  “All air quality monitoring and air purification equipment. This introduces a slight risk, which the councilor believes to be tolerable.”

  Julian Graves nodded. “Compared to the risk if we stay on Marglot, it’s negligible.”

  “Most communication and navigation equipment, beyond a bare minimum. All cosmetics. All personal computing equipment. I volunteer to upload their contents into my own internal storage, and will download them again into new equipment if and when the opportunity arises. All interior temperature control and air circulation systems. Individuals must seek their own comfort zones. There are also many smaller potential savings. For example, Kallik assures me that a Hymenopt can go months without food or water, and she is quite willing to do so. My own body can be left behind, and only my brain retained. Should we survive, a new embodiment will present no problem. Though I cringe at the prospect of Sue Harbeson Ando’s indignation if I return to her yet again for a replacement.”

  “I cringe at the prospect of somethin’ a lot worse than that. Suppose we do the list, every one?”

  “We will achieve a further mass reduction of 7.44 percent. Making the same assumptions as before as to engine efficiency, that provides us a final velocity of 8.27 kilometers a second.”

  “And we need 9.43 or better. It won’t do. We’re still more than twelve percent short.”

  “I don’t understand something.” Darya Lang had been sitting silent. “Seems to me we’re missing out on something huge. What about all the equipment associated with atmospheric flight? There are the air-breathing engines, the extensible wings, the stabilizers, and the landing gear.”

  E.C. Tally was nodding. “Most of the landing gear is also needed for an air-breathing power takeoff. However, if we were to dispense with the rest, we would achieve a further mass reduction of two percent of our original. This would bring us to a final velocity of 8.44 kilometers a second. However, the consensus seems to be that we should not readily abandon a capability for atmospheric travel. Captain Rebka is worried that we may need to fly atmospheric for other reasons.”

  “I am. Keep going, E.C. You still haven’t mentioned the beetlebacks.”

  “They are on my list of relevant facts. They move slowly, perhaps because the snow is hindering their progress. But they do move, and groups of them are still converging on our location. Given their possible role in the destruction of Marglot, it is difficult to believe that they come to do us anything but harm.”

  “So we may have to take a short hop. After that, maybe we burn our bridges and get rid of the Have-It-All’s engines for air travel. There’s one more thing we need to sort out, an’ maybe it’s the main reason I wanted us to meet.” Nenda looked around at the others. “This isn’t a deal where we all get to pick, an’ everyone has their personal preference. We’re in one ship. Somebody has to make the call: if we fly, when we fly, how we fly. Some of you have been in trouble as often as I have—maybe more. You know you don’t run emergencies by committee.”

  Darya said at once, “Take me out of the decision-making loop. I like to sit and think for a year before I make up my mind.”

  “You made your mind up about that quick enough. But all right.”

  Hans Rebka said, “I’m not like Darya, I can make up my mind fast. But I don’t know this ship the way you do, Nenda. I don’t know what it will and won’t do, when you can change your mind, how you can cut corners. This one has to be yours. The rest of us can listen, and maybe make suggestions. But calling the shots must be your job.”

  “I was afraid you would say that. I don’t like it much, but I know I’d like anythin’ else a whole lot less.” Nenda stood up. “All right. I’ll say when. Meanwhile, we hold on to the equipment to fly atmospheric. Everythin’ else goes.”

  He paused. The door of the conference room was history, ripped off its hinges and thrown overboard by Archimedes. Now Torran Veck and Teri Dahl stood in the opening, the lower part of their suits still caked with frozen snow.

  “You got problems? We’re busy here.”

  “No problems with the runway and the engines.” Torran Veck took a step forward. “They’re not perfect, but we’ll have a hard time doing better. There’s something else going on that we don’t understand.”

  “Join the club.”

  “When we arrived at Marglot, we thought it was tidally locked to the gas-giant M-2.”

  “It was. It still is. This just isn’t a Hot Pole anymore, because everywhere is cold.”

  “You don’t need to tell us that. It’s seventy below outside. And Marglot isn’t tidally locked to M-2. Its rotation rate is changing.”

  * * *

  Nenda didn’t believe it. Hans Rebka didn’t believe it, Darya didn’t believe it. Nobody believed it, until they saw the evidence.

  That came from above, and it was not obvious at once to human senses. Outside the ship it was night, the sky was clear, and stars were visible. The sensors of the Have-It-All—those few that remained—made a series of observations and fed them to the ship’s computer. Within microseconds, a precise calculation was completed. The computer reported:

  The rotational period of Marglot when the Have-It-All arrived at this system was measured to be 39.36142 standard hours, with a variation of one unit in the final digit probably caused by planetary internal activity. The rotational period as measured in the sequence of observations that was just completed is 14.388 standard hours.

  “Marglot ain’t tidally locked any more?”

  That is correct.

  “It’s in free rotation relative to M-2. How the hell can that happen?”

  Nenda was talking to the group around him, but the computer answered: There is no mechanism described in our data banks which can account for such a thing.

  E.C. Tally added, “Nor in mine.”

  The computer had not finished. The same sequence of observations that provides a new value for the rotation period also shows that the rotation rate is still increasing, by 0.0644 radians per hour per hour.

  Tally shook his head in a human gesture of bewilderment. “I do not understand that, either.”

  “I don’t understand it, an’ I sure as hell don’t like it. But I’m forced to believe it. Tally, we need to dump out all the items on your list, fast as we can do it. Everybody helps. If you’re in doubt, don’t come back an’ ask. Chuck it.” He waved his arm. “Go on, go on. Get outa here.”

  It was Nenda’s ship, and his control cabin. Everyone moved out—reluctantly—except Hans Rebka and Atvar H’sial. The two men stared at each other.

  “You realize it won’t be enough, no matter what you tell people to throw out. We still can’t reach orbit.”

  “ ’Course I do. I’m not a dummy. I just didn’t see any point advertisin’ disaster. Suppose you were me, and had to act. What would you do?”

  “Clean off the engines, reduce mass as far as I could—exactly the same as you are doing. Then I’d cross my fingers and fly. Don’t worry, I’m not trying to second-guess you. I just want to be sure we’re on the same wavelength.”

  “I think we are. Let’s go and dump somethin’ expendable—or maybe not so expendable. When in doubt, throw it out.”

 
Hans Rebka left, leaving only Louis and Atvar H’sial in the room.

  “How about you, At? What’s the problem, too proud to work?”

  “When my personal existence is at stake? Not at all. I wish to draw to your attention a factor which seems to have been overlooked. But first, a question. In terms of the rotational axis of Marglot, what is the Have-It-All’s current location?”

  “We’re almost at what used to be the Hot Pole, which puts us just about smack on the rotational equator. What’s your point, At? It’s a bit late for a geography lesson.”

  “But not, perhaps, for one in elementary mechanics. The acceleration due to gravity on the rotational equator of Marglot is 8.411 meters per second per second. With a rotational period of 39.36 hours, as it was when we first arrived here, and a radius of 5,286 kilometers, the centripetal acceleration on the equator was 0.01 meters per second per second. That is negligible when compared with the acceleration of gravity, little more than a thousandth of it. With a shorter period of rotation, equal to its present value of about 14.4 hours, the centripetal acceleration has increased to 0.08 meters per second squared. This is still a small value, an outward force equal to only about one percent of the gravitational force. It is insignificant when compared to the large reduction of mass needed by the Have-It-All in order to achieve orbit. However, the rotation rate is still increasing. Let us suppose, as a theoretical exercise, that it continues to increase at its current rate. This will have three effects, two of them undesirable and one desirable. The first undesirable effect will result from atmospheric inertia. The air of Marglot will resist being dragged around with the body of the planet. We must anticipate huge winds from the east, which I note are already arising. Second, the balance of forces on the planet will force it to assume a different shape. Marglot will become increasingly oblate, bulging more at the equator. That will undoubtedly induce major structural changes. We must expect great earthquakes, of unknown magnitude.”

  “Wonderful. Just one more reason to get the hell out of here—if only we could.”

  “We already had reasons enough to leave. But the undesirable consequences are perhaps outweighed by the desirable effect of more rapid rotation. As the planet continues to spin faster and faster, the centripetal acceleration at the equator will increase. Furthermore, that acceleration increases quadratically, proportional to the square of the angular rate. Eighteen hours from now, the outward centripetal force at the equator will equal 12.3 percent of the inward gravitational force. The total downward force on an object on the surface at that time will equal the difference of those gravitational and centripetal forces. If the Have-It-All still exists then, and if there is a surface that permits a take-off, and if the thrustors perform at their estimated levels when we are in the air, we should be able to leave the surface and ascend to orbit.”

  “That’s a whole lot of ifs you got there.”

  “True. But which would you prefer, Louis Nenda?” Atvar H’sial rose from her crouched position. “A substantial set of contingent possibilities, or a single unpleasant certainty?”

  CHAPTER THIRTY-THREE

  The end of Marglot

  Darya Lang normally worked alone. She did not like to be in charge of others, even when her own safety was involved. Today she was particularly happy to let someone else make the decisions.

  On the other hand, those decisions had so far practically made themselves. In order to take maximum advantage of Marglot’s rotation, the Have-It-All had to be launched to the east, and from as close to the equator as possible. It also had to be launched soon. The speeded-up planetary rotation was producing ground tremors that shook the ship, and bigger earthquakes were clearly on the way.

  Darya was standing up, although that was never the way you prepared for a lift-off. It was not a matter of choice. Every chair in the cabin had been removed except the one at the controls where Louis Nenda was sitting. Lacking the service of his usual automatic sensor systems, Nenda had assigned Darya and everyone else on board to monitor some aspect of navigation or signals. The only exception was Claudius, off his radiation high and once again a stone-cold corkscrew of green misery.

  Nenda might have the only seat, but he was not a happy man. Darya saw him take a last look around at his ship. The Have-It-All had been stripped to the bones. With all interior bulkheads gone the entire interior length was visible. Darya could see them all—Julian Graves, Teri Dahl, Sinara Bellstock, Kallik, Atvar H’sial, everyone, in what had once been luxurious cabins and were now ragged metal frames. The aliens were as inscrutable as ever. The humans looked pale as ghosts. No one had slept for more than thirty-six hours.

  The ship’s intercom had been stripped out. Nenda had to shout to be heard above the howl of wind on the hull. His voice echoed along the bare walls. “We’re all inside, and the hatches are closed. Hold on to somethin’. It’s gonna be bumpy as hell ’til we’re high enough to be above the worst of these winds.”

  Tally had been assigned to the display that looked aft from the ship. He said, “Beetlebacks. I see silvery reflections from a group of them. They are heading for the ship, but the winds severely inhibit their movements. Some are being swept off their feet and carried backwards.”

  “My heart bleeds. I wish we had a few in front, then I could run over ’em.”

  “But if we could capture one—any one. They share data, and our information gain could be enormous. A delay of a few minutes, until the nearest one reaches the Have-It-All—”

  “—would be a lousy idea. Sorry, E.C. Say bye-bye to beetlebacks, and hello to a bump or two.”

  Nenda initiated the sequence for atmospheric take-off. Bump wasn’t the word for it. Hans Rebka clung to a metal stanchion, while Darya hung on to him. First there was the bone-rattling run over hard ice. That ended at the moment of lift-off, but a few meters up the winds hit the ship with full force. The retractable wings fluttered and shook and seemed ready to break off. The ship tilted, and Darya thought one of the wingtips was going to hit the snowy surface. For a horrible moment there was no space at all between the wingtip and its own shadow on the ground.

  The Have-It-All shivered and righted itself. As it gained altitude, Darya had a view of a bigger area of the changing planet. Patterns of dark lines crisscrossed the snow. The ground was already fracturing, breaking open into fissures that widened as she watched. Subterranean stresses were growing faster than anyone had expected.

  A little higher, and they reached a region where the winds were less affected by local ground contours. The Have-It-All steadied. Nenda said, “I’m takin’ us to three thousand meters, an’ I’m goin’ to hold it there for a while. We’re not shakin’ to bits anymore, but we want to gain all the speed we can as the planet spins faster. The air gets dragged around with everythin’ else, so it will boost us.” He was inspecting read-outs. “I hate to say this too soon, but you know what? We may make it. If I turned on the orbital thrustors right now, we have enough speed to take us to space. No hurry, though. Let’s build up a good margin before we move.”

  Hans Rebka left Darya behind at the stanchion and dived forward to stand behind Louis Nenda. He said, “I’m not sure there’s no hurry. Suppose that the rotation speed of Marglot goes on increasing?”

  “It will. That’s good. It helps us.”

  “To a point it does. But suppose it goes too far?” Rebka turned toward E.C. Tally, who was still staring at the aft display—probably longing for his lost beetlebacks. “E.C., would you do me a calculation? Suppose that the spin rate of Marglot goes on increasing. How long before the centripetal acceleration at the equator is equal to the surface gravity?”

  “The calculation is rendered more complicated than you might expect, because the change of spin rate of Marglot continues to accelerate. The reason for that, I presume, is the planet’s rapidly spinning inner core—which, as I noted at the time of my first arrival in orbit around Marglot, is the source of the planet’s anomalously high magnetic field. That core is coupling now t
o the planetary mantle, and that in turn to the outer crust. To estimate the coupling constants—”

  “Could we have a number, E.C., rather than a dissertation?”

  “Certainly. The purpose of my comments is to explain that there must be uncertainty in my answer, since the future spin rate is itself uncertain. However, my best estimate is that centripetal and gravitational forces at the equator will be equal fifteen hours from now.”

  “So in fifteen hours, and probably a lot less because of the internal deformations, Marglot will come apart. Lumps of the planet will be thrown out into space. That will start in the plane of the equator. And Nenda, you are flying this ship—”

  “—smack on the equator. Wrong place to be if there’s fireworks.”

  Darya had been watching her own assigned display, one that looked out and down from the ship. She said, “There will be fireworks, and in a lot less than fifteen hours. It has started. Look ahead.” They were approaching the night side of the planet. Beyond and beneath the ship the darkness was illuminated by a orange glare. “Volcanoes, and lava flows.”

  Nenda said calmly, “Maybe I should take us outta here right now.” As he spoke, a long tongue of flame leaped skyward in front of the ship. A smoking juggernaut of rock ten times the size of the Have-It-All shot past, still glowing bright red.

  “Maybe you should.” Hans Rebka was equally casual. They spoke so softly that probably no one but Darya could hear either man. “There’s already large-scale planetary deformation. It can only become worse, and the equatorial region is absolutely the wrong place to be.”

  “So we wanna be outta here. I hear you.” Nenda turned and shouted, “Grab a hold of somethin’ firm again. Orbital thrustors comin’ on—now.”

  He did something that Darya could not see, but she felt the upward surge. The ship shook with its worst spasm yet. Vibrations seemed ready to tear it apart. Her knees buckled, and she clung for her life to the metal post.