by Hal Clement
“First things first. Rek, shift to slow ahead, and turn—left is better. Good. Nose up a little; you’re starting a dive—not very steeply, but any is too much unless we really have to go down after Venz. That’s good. Hugh, I can’t sense very far now either; frost is forming on the lights, and charge on the body is confusing. Are you near him yet?”
“Here, holding wing—”
“I have the other,” Janice cut in. “Keep turning. There. Straight. Straight. A little right. Straight. Tiny down. We’re sinking. Almost—farther—there. I have hold of frame. Wings frozen open, further aft to get inside. Wait. Now. Safe.”
“You’re inside? All right. Rekchellet, work us upward, very slowly. With luck, which means if we aren’t too close to Solid Ocean, that will get rid of the frost. Just start the maneuver; I’ll be forward in a moment and will take over control.”
“Why up? What happened? Explain!” Hugh sounded emphatic even by code. Bill answered with apparent calm.
“I’m not sure I’m right. I said we’d need luck. There are several kinds of ice. I have control now, Rek. What we find on and near the surface is less dense than liquid water, so it floats. That’s ordinary land. I should say it floats if it doesn’t have too much mud in it, and it’s land if it has enough. At middle depths we find another kind, and very far down a third. The last kind is very hard to melt at the greatest depths, and both are denser than liquid water.
“We are near the depth boundary between the first two kinds, and I needed to know which was forming so I could tell whether we needed to go up or down. If it had been high ice and we had gone up, the decreasing pressure would have raised its melting point and we would have accumulated more and more, and finally reached the surface, or more likely hit the bottom of the surface pack, in the middle of a fair-sized iceberg with no way to get out, since we wouldn’t have been able to move. Us, not just the ship. If it had been middle ice, and we had gone down, the increase of pressure would have raised its melting point and again we would have formed the center of a large berg, this time on the bottom or on the deep ice shelf, if it exits. It ought to, since ice gets ‘way out toward the ring on the bottom. Before we got there, the change of the stuff around us to deep ice would have torn ship and us apart as the volume changed in different places at different times.
“When Venzeer said he was being dragged down, I judged it was middle ice, so I am sending us up. The decreasing pressure should lower the melting point and free us fairly soon.”
“Unless we overshoot,” Hugh suggested. “Phase boundary. Right?”
“Quite right,” Bill replied calmly. “I thought it was Janice who had all that information.”
“She has the numbers. I’m like Rek—just pictures.”
Janice’s code tone came in. “Ice seems to be going.”
Venzeer confirmed this with glee. “I can see my wing tips again.”
“Can you move wings?” Hugh asked, practically.
“Not yet. Better keep hold of me.” The Crotonite had a grip of sorts on a part of the ship with his handling nippers, which had not been as solidly immobilized as the great wings, but his rescuers had been carefully supporting him against the currents which rippled through the openwork hull of the Compromise.
“Don’t worry,” Janice assured him. “You’re thawing. Why no ice on Hugh and me?”
“Your armor’s at higher temperature,” Bill pointed out. “I don’t suppose you generate as much body heat as we flyers, but with no wings you have a lot less surface area for dumping it.”
Of course. Simple physics, thought Hugh to himself. Much simpler than the phase behavior of water. Aloud he coded, “Jan, how about solvents? Ammonia practically everywhere—”
“Not here,” Bill interrupted. “I’ve never known such pure water outside a lab. There’s some life, but even the microbes must be hungry. What do we do now? I’ve backtracked our course for a kilometer or so, and it’s a little warmer, so we should be rid of the ice pretty soon—I should think you could see out now, Rek.”
“There’s nothing to see but the rest of the ship, but you seem to be right. I never got a sight of Venz with his wings frozen. How do we get a record?”
“You could come out and take a look before he loosens up, if you think it’s that important. The Erthumoi were never bothered, so it’s safe enough.”
“I saw. I’ll make a sketch for you later,” tapped Janice.
Bill remained concerned with their main task. “If we can’t get any farther and still make measurements, what becomes of the mission?”
“Plenty of power,” Hugh pointed out. “Warm ship?”
“My first thought is that it would invalidate any measurements we made,” the Habra responded slowly.
“Not much more than our mere presence does. Our bodies were losing heat to the ocean, too,” Venzeer pointed out. “Mine, especially. We need use only just enough heat to keep the frost off.”
“But that will leave a trail of warmed water behind us as we go along. It takes very little temperature change to start convective instability. That’s why computing weather even in air is so hard.”
“In air,” Hugh emphasized. “PV small in liquid. Expansion a lot less. Density change—”
“You may be right, but we get more violent storms in the deeps than in atmosphere,” Bill pointed out. “And this might be just the thing to start them. I’m willing to try it if the rest of you are, though. Just be sure we keep track of how much energy goes into the heaters. Computing a storm pattern is hard enough even with all the data.”
“Computation impossible,” Janice keyed. “Situation chaotic.”
“Nothing’s basically impossible,” replied the native, “but I grant it’s far beyond our present abilities.”
“Impossible,” the woman repeated. “Meteorology should have given you folks chaos theory. Maybe bowling alleys needed too. But let’s go. Solid Ocean should be near.”
“Why?” asked Rekchellet. “We don’t have any surface data. The upper glacier extends a lot farther into Sunside than the Solid Ocean—after all, the latter’s just a theory we’re testing—but no one knows how much, and even if we did we don’t know how far we’ve come under the upper ice pack. I know there’s a sonic reflection from what seems to be a more or less vertical surface somewhere ahead, but I wouldn’t guarantee whether it’s one kilo or fifty, or even that it’s solid. What’s the basis of your guess?”
“Water purity. Bill said it. Should be fresh melt.”
“That sounds reasonable,” the native agreed. “We winged folk had better stay near or in the ship. You others don’t ice up so easily and can fly ahead, making measurements as you go. Don’t get very far, though. Instabilities may always be possible to calculate, whatever your chaos theory says, but I certainly can’t always do them in my head, and I’m not at all sure I’ll be able to sense them. I got caught only a few minutes ago, remember.”
“But you weren’t thinking about that!” objected Rekchellet.
“I should have been. The point is that this is research, and if we knew what was likely to happen there’d be no point in being here at all. Be very careful, wingless people. I know you can fly here but can’t believe those limbs are really efficient. I would advise using safety lines; we have them aboard, you know.”
“How long?” asked Hugh.
“About two hundred meters. You wouldn’t want to get even that far, since the ship’s light won’t suffice for clear sight at such a distance and that’s your only useful sense.”
“We have lights,” Hugh pointed out.
“By all means. Use them. But I’d still use the lines and let them dictate how far you got. Here—make fast.”
Man and wife obeyed, since they were sensible beings. The Compromise resumed her cruise away from Under the Sun at very low speed, the Erthumoi swimming ahead. Bill was still in the control cage guiding the vessel. Rekchellet carefully saved each sketch he made of the team members blurring out of sight ah
ead and slightly to each side—if they had gone straight ahead, the mud tanks forward of the living sphere and controls would have hidden them from everyone’s sight, though perhaps not from the Habra’s electrical senses. All the Crotonite could see were portions of the two safety lines, which had been made fast not to the bow but to frame members close to the pressure spheres.
The advance party stayed in code touch as well; sound, even the code, carried well through the water, and all the suits except Bill’s had impedance-matching coatings to handle the interface problem. The native had his own sound-to-radio transformer, and had learned the code during the weeks the Compromise was being rebuilt. For some time, the only words from the advance scouts were the routine “nothing new.” Bill stated with equal regularity that the water was still very pure.
Then Janice’s code came back off schedule. “Turbulence! Watch it, Hugh and Bill. Almost snapped my line.”
“Nothing here,” came her husband’s response. “You did—no. Just local I—” His code ceased.
“Why local?” came Janice.
“Don’t know. Maybe—” The Crotonites were irritated by the confused symbols, though they realized the cause. Bill forestalled any complaints they might have uttered.
“Not time to theorize yet!” called the native. “Come back toward the ship. Stay only ten meters or so ahead, so you can give me warning but will be able to come in quickly and hold on if something bigger hits.”
“Can’t you sense them?” asked Hugh. “No. The water’s too clean and featureless—I could spot something distorting the heat ripples of your suits when the eddies hit you, but no sooner. Stay close. I’m feeling turbulence with the ship, now.”
“Me, too,” asserted Rekchellet. “It’s good. I haven’t flown a cumulus cloud in months.”
“It won’t be good if it puts too much bending stress on the ship,” the native replied grimly. “I’m feeling it more now. You Erthumoi get aboard fast. I’ve been in lots worse storms than this seems to be so far, but not with crew outside—and then I could usually tell what was coming.” Janice and Hugh obeyed without question. The Habra went on, “I assume we still go ahead. Rek, get everything you can tell from your instruments on record. Never mind drawing, you can write. Just keep notes, and save them. We’re—”
“Jan! Slack!” the man’s code interrupted the pilot’s orders. “Bill! Sharp right!”
Hugh and his wife had obeyed the original command to pull back toward the Compromise, and had been some twenty meters ahead. The woman was about as far to the left of the vessel’s bow; Hugh on the other side. Something had suddenly become visible: a white, very thin and twisting tornadolike funnel reaching from the darkness ahead. Before this actually got to them, something snatched Janice forward, to the right, and somewhat downward. Hugh reached for her, but she passed a dozen meters beyond his grasp. Both had coiled their lines as they came in, but the woman had been slower, and had been startled by the sudden jerk of the current. Some loops of her coil escaped her grasp.
As her husband entered the eddy and was swept after her, he felt his own lifeline tighten, and let it slide gently through one gloved hand to avoid too sharp a jerk when the slack was used up. His swim fins sent him forward two meters—four—six, with his own line uncoiling again behind him; then he could reach hers. He seized it and began swinging his arm to wind the cord around it as many times as possible. She was still looping it up at the outer end.
The real jerk came first on the section between them, but both reacted properly, letting the arms which held the rope extend slowly to ease the shock. For the moment everything seemed safe; they were fast to each other, and both were attached to the Compromise.
They began drawing together, hand over hand, along Janice’s lifeline. This prevented Hugh from paying proper attention to his own, and before they reached each other the latter tightened abruptly. He instantly eased his grip on it, but in the momentary inattention it had wound about his left ankle. The polymer ridge around the joint—none of the armor was of metal, because of the Habranhan sensory problems—was not really sharp, but quite sharp enough. Now only Janice’s rope connected them to the ship.
She made contact with him seconds later, and played their remaining line as carefully as possible. Her husband concentrated on keeping hold of her armor and not interfering with her work. He would have liked to tie them together with his own length of rope but was unwilling to let go of her even with one hand. The eddy calmed briefly, and she hauled them closer to the sub. Bill could sense their location vaguely and helped, swinging the Compromise’s bow to the right and downward. They were almost in reach of a firm hold when another swirl hit the ship itself.
The bow lurched away again. Janice reacted quickly enough to save the line, and began hauling in once more. Then she realized that Hugh had lost his grip—actually, he had let go to grasp the hull himself—so she released her own coils of rope, and began kicking herself frantically toward him. Turbulence sent him out of reach time and again, sometimes one way, sometimes another; up, down, left, right, and all imaginable combinations. He too was swimming with all his strength, but the eddies seemed deliberately trying to keep them apart.
Bill was working, too, with all his piloting skill, to keep the Compromise near and bring it nearer. He uttered a burst of incomprehensible radio sounds at one point when chance brought the hull actually within reach of Hugh and the Habra thought the danger was over, only to see the man ignore the opportunity and continue trying to reach his wife. Intelligible words followed via Crotonite translator.
“You idiot! She’s still tied to the hull! She doesn’t need rescuing!”
But Hugh wasn’t completely out of his mind. A few seconds later he managed to grasp Janice’s safety line, and instead of hauling himself toward her, went hand over hand along it to the hull. Here he slipped inside between a couple of the stringers, hooked both legs around other sections of tubing, and only then began carefully taking up the line’s slack. This accomplished, he began playing her in carefully, never letting the cord suffer any sharp jerk. Bill helped by maneuvering the Compromise toward her until she was only a few meters away. Then, afraid of overrunning and colliding too hard, he neutralized his controls. The Erthuma couple drew toward each other along the last meters of line until hand-to-hand contact was possible. A moment later both were safely aboard, or as safely as the open hull structure permitted. Hugh didn’t really relax until both were inside the mud tank they considered their own.
William’s voice remained calm. “Go ahead, I take it?”
“Certainly, but no scouts,” Janice tapped. Her husband wondered whether he should add any remarks about speed, but decided to leave that to the Habra’s judgment. The Compromise got under way, trembling and shivering as she plowed into one region of turbulence after another. It might be a mild storm by the native’s standards, but Janice was wondering what motion sickness could do to a Erthuma body soaked in diving fluid. She and her husband, helmets just above their tank rim, looked ahead as well as they could. There was little to see but occasional swirls of white dust as ice formed briefly in higher or lower pressure parts of the eddies. Sometimes the whiteness vanished as quickly as it formed; sometimes growing clouds of whiteness drifted upward or downward depending on the density of the ice which had formed. Janice wondered if their native friend really thought this sort of thing could ever be calculated. She also wondered when they would reach the Solid Ocean—and how hard.
It was Rekchellet, looking out hopefully, who saw the bottom first an hour or more later, and might have sketched it before calling a warning if it had not been so featureless.
“Slow your descent, William,” he called. “The keel will touch in a few seconds.”
“We’re flying level, as far as I can tell,” returned the Habra. “I don’t see—oh. You’re right. I didn’t sense it. Too much static in the turbulence. We’re not going fast enough to hurt anything if—”
Technically the native was r
ight; the average speed of the Compromise was not great, though much greater than when Hugh and Janice had been swimming ahead. The turbulence, however, had fore-and-aft as well as vertical and lateral components, and as William spoke, the ship received a strong forward boost. The impact with the up-slanting bottom was not great enough to provide much of a jolt, especially as the bottom proved to be loose and powdery; the damage was indirect.
A vast cloud of white material billowed up around them, cutting off all sight and blocking even Bill’s senses with random static charges. Rekchellet, the only one not in near-zero buoyancy, felt his surroundings tilt as the Compromise came to a halt and then began gently rolling downhill toward what had been the left of their heading. Only the small size—eight meters internal diameter—of the pressure sphere allowed him to reach his controls as the ship went over on its back. The first roll dumped Hugh and Janice out of their tank, the second jarred Venzeer from his hold. He got another brief grip at an outer stringer, but let go as he realized he might be caught under the hull as it continued its slow and majestic downhill rolling. More white stuff swirled up as the frame members dug into the sloping bottom. The Crotonite, picking a moment when his flying senses told him that upward motion was changing to downward so he was presumably on top, slipped outside and flapped gently a few meters upward to get clear. The cloud around him darkened as the ship and its lights rolled away.
He started to follow the slowly fading luminosity. Then it occurred to him that going to one side might get him out of the stirred-up material and let him see better. This worked, after a fashion; he found himself able to see the cloud itself, and the brighter comet head that was presumably the Compromise, now well down the slope. Backtracking uphill by eye, he saw the hollow which might have been the point of impact. Near this he perceived two much smaller blurs of light, apparently revealed by currents which had swept the silt aside. He was an experienced explorer; he checked in before doing anything.
