by Hal Clement
“Now what?” asked the man as the craft disappeared.
“The wind and current are both weaker, but they both still set toward The Cataract. The choices seem to be to keep on working or give up and drift back where we came from,” Janice replied. The man had nothing better to offer, even in his thoughts. The realization of how much better they would have done with a hull that didn’t catch wind or current had struck him long ago, but so had the futility of mentioning it.
They continued to follow instructions from The Module but routine changed somewhat for a while. Six more times in the next four hours a submarine appeared near them, remained for a minute or two while its crew, resembling six-winged dragonflies but too heavy in their armor to fly, looked them over, gestured in what appeared to be unsurprised and casual friendship, and went on its way. None of them appeared equipped to communicate with aliens. Both Erthumoi wondered why the first to find them had not broadcast the news, and how long it would take before someone really helpful would show up.
“I suppose,” Janice said at last, “that the first one did report. Probably no one working in The Pupil expects to run into visitors; these others have been just people who got the word and wanted a look. The help won’t get here until news reaches The Iris and someone who knows about our study group.”
“Maybe.” Hugh was a little doubtful. “Habras aren’t usually just curious about aliens; most of them have seen us by now—they fly, remember, and have one worldwide culture. I’d have expected these other subs to have come for some different reason, but I can’t guess what it was. I suspect we’ll just be waving to them until someone from Inex or higher hears the story and gets here.”
“They’ve all seen us, but they haven’t seen a boat like this,” his wife pointed out. “I’d want to look over something this odd in a lot of detail myself.”
“Well, maybe. The vector principle it uses should be obvious enough at a quick look, though. We’ll see.”
What they saw after the seventh visit was more hours of boredom. There were no more submarines, just travel. There were occasional—very rare, now, as they emerged into the least chaotic area of Habranha’s ocean—orders to change a wing setting, but increasingly frequent demands that one of them go overside to clear weed.
This, they knew, would get even worse as they approached the ring continent. Silt from its endlessly melting inner edge enriched the water and supported a gigantic food pyramid. The natives did their best to conserve the silicate, which they brought at great labor and expense from the ocean bottom to fertilize the relatively clean ice of The Iris and let them grow food for themselves; rivers of meltwater flowing into The Pupil encountered beautifully designed and built dams and sediment traps. Still, lots of the fine stuff got away, and the natives had to make the best of it by fishing the teeming waters of the central ocean. Presumably it was fishing submarines that the Erthumoi had seen.
But now these ceased to appear, and hour after hour went by with nothing to relieve the boredom but an occasional trip overside.
Even the thunder of The Cataract was gone, though not the higher-pitched rush of wind and wave, so when the helicopter did come the couple heard its rotor beat long before they saw it. When they did, it was not directly between them and The Iris, and not heading directly toward them.
They waved and even shouted, knowing that both actions were futile against a wave and spray background, and watched with mounting tension as the aircraft went on past.
Then it shifted course roughly toward them. Only roughly; it flew by again. Then it hovered, a kilometer away, and Hugh, rising as nearly to his feet as he dared, caught glimpses between the waves of the upper part of a native submarine below the flyer and heading directly toward them.
Then the crew of the helicopter seemed to see their boat, and the machine swelled in their vision. A few seconds later two heavy-duty slings were descending toward the Erthumoi.
Hugh reached for the nearer sling and started to hook it to his suit. A thunderously amplified voice, speaking his own language, stopped him.
“Around your hull! We’ve got to get that public nuisance out of the water!”
“Why?” asked the man, quite reasonably. Janice went silently overboard with the other sling and began to adjust it.
“Tell you later! Just do it! The Habras are polite people, but in their place I’d be working up an interstellar incident. Get moving!” Hugh was still inclined to stay where he was and try to figure out why his beautiful, well-planned, and successful vector boat was a public nuisance to anyone, but Janice added her voice to the one from above. Thirty seconds later the rotor hum rose in pitch and their hull lifted gently from the surface. The bottom wing followed, trailed by the several meters of weed that had accumulated since they had last cleared it. Habras on the submarine, which had also approached, gestured, and their craft settled out of sight.
The Erthumoi climbed a ladder that had been lowered from a hatch of the flyer, and found themselves surrounded by half a dozen of their own species. Hugh, quite able to put first things first when they were important, reported where, why, and in what condition they had left their Cephallonian companions. The aircraft commander nodded.
“We’ll pass that on to the natives. Their subs can probably tow the raft out, and we should certainly let them try first. If they can’t make it, someone can design and send in a better raft.”
The Cedars nodded. There was little risk of Habranha natives developing an inferiority complex from their alien visitors, both knew, but the policy was basically a good one. It sometimes kept starfarers from getting too arrogant.
“I suppose,” the aircraft commander went on, “you’ve figured out by now why we had to get your boat out of the water.” The fellow glared at him, and Hugh had a feeling that he himself should be blushing. A glance at his wife provided no help; she evidently didn’t get it either, which was some comfort. The pilot waited only a moment. “That thruster you had on the underwater fin or whatever you call it is made of metal, which is very rare on Habranha. It had gathered weed, much of it highly charged, so it’s—”
“It was broadcasting!” Hugh was just enough behind his wife to be slightly out of phase.
“It was, according to the Habras, howling. It was making conversation impossible for forty or fifty kilometers around, even under water. What it would have done if it had been producing the same waves above the surface I hate to think, but thank reason for impedance mismatching.”
“But why so far? Water doesn’t carry low-frequency electromagnetics very well,” Hugh objected.
“When the waves stimulate discharge in electrical organisms, simple attenuation formulae don’t work,” the captain pointed out gently. “But why was the driver mounted so far down? I can see it isn’t working now, but when it was, it must have tried to lift your front end right out of the water—or was that the idea?”
Janice smiled. Hugh could get some of his own back, here.
“Oh, no.” Her husband shook his head firmly. “The driver was never working at all.” Would he explain why? she wondered briefly. Of course not. At least, not completely. No one had figured out yet what had made the thrusters unreliable, unless Thrasher or Splasher had had an inspiration since the Erthumoi had left. Inspirations did sometimes happen to people. But Hugh was quite good at covering.
“We were just using it for its weight,” he went on. “We didn’t have anything else heavy enough that we could afford to risk—nothing at all except our robot and equipment, and we needed weight to keep the wings of our vector boat vertical. If the thruster had been pushing, as you say, we’d have wanted it right up under us. Besides”—he caught Janice’s eye briefly—“if we’d been using it that far below the hull we’d have had to rig a line to control it with. Can’t you imagine what would have happened when that began to pick up weed—at high speed? More drag on the line, more pull on the control; if pull meant more power, then more drag, more speed, more speed, more weed—you’ve heard of
feedback, haven’t you?” Janice kept a straight face, too.
1994
SORTIE
His Aitoff screen was offering one of its occasional, brief, random, views of Sergeant Gene Belvew’s real surroundings, cutting him off for half a second from those of Oceanus deep in Titan’s atmosphere, when the pipe stall occurred.
It would, he reflected at one level of his mind. He didn’t believe in an unqualified Murphy’s Law, which was strictly for civilians, but a scientist of any rank understood Murphy’ s Law of Selective Observation. If the jets had chosen any other time, he would have known it was coming, forestalled it easily without real thought, and forgotten it promptly as unimportant. As it was, his first warning was the waldo suit’s use of nonvisual input. It administered a sharp chill almost simultaneously in both of his elbows. By the time he could see Titan again, half a second later, thrust was gone and accelerometers showed that Oceanus was being slowed sharply by the dense atmosphere. His reflexes had already operated, of course, just a trifle later than they would have from a visual stimulus. The aircraft had practically no reaction mass in its tanks; he had been trying to replenish that at the time. The big satellite’s gravity, which his body in orbit couldn’t feel any more than it could the deceleration, was feeble; if the craft slowed too much now, even the vertical dive he was entering wouldn’t get him back to ram speed from his present altitude. Diving into the surface would not hurt him physically—the waldo’s feedback didn’t go that far—but would still be a bad tactical mistake. Ramjets could not be picked from trees, even if there had been trees this far from the sun. For increasingly scary moments the tension mounted as his elbows stayed cold; then ramflow resumed simultaneously in both pipes and the speed of his dive abruptly began rising with the restored thrust. Still reflexively he pulled out into horizontal flight with over a hundred meters to spare, put his nose—his own, not the ramjet’s—in the face cup and moved his head slightly to run the Aitoff screen through its half dozen most-likely-useful vision frequencies. He was already pretty sure what had caused the stall, but pilot’s common sense agreed with basic scientific procedure in demanding that he check.
Yes, he was still in the updraft; the screen displayed the appropriate false-color all around him, and the waldo—which doubled as an environment suit, and therefore did not interfere with his breathing system—was reporting the excess methane as a salty taste. As usual, there had been no one but himself to blame. He’d been driving just a little too slowly, trying to see below while filling the mass tanks, and a perfectly ordinary but random and quite unpredictable drop in the density of the rising current had raised the impact speed needed by the jets. If there’d been nothing backing up the interrupted visual sensors he’d have learned too late and had over a hundred meters less leeway.
No point thinking about that.
“What happened, Sarge? Or shouldn’t I ask?” Barn Inger, Belvew’s co-ranker and watch partner, didn’t bother to identify himself; only a few dozen people were anywhere near Saturn, and everyone knew the voice of everyone else who mattered. As Belvew’s “buddy” one of his jobs was to check with Gene vocally or in any other way possible whenever something unexpected occurred; the “shouldn’t I ask” was a standard courtesy. Not everyone enjoyed admitting mistakes, however important they might be as data, and the terminally ill people who formed an even larger fraction of the Titan exploration crew than of Earth’s remaining population were often touchy.
“I rode too close to stall. It’s all right now,” Belvew answered.
“Use anything from the tanks?”
“Nothing to use. There was enough room to dive-start.” Belvew did not mention just how little spare altitude he had had and Inger didn’t ask.
“You’re still over Carver, aren’t you? You could have put down and tanked up from the lake.” This was quite true, but neither speaker mentioned why the pilot had dodged that option without conscious thought. Both knew perfectly well; Inger’s stress on the “could” had been as close to being specific about it as either cared to go. He changed to a neutral subject.
“You seem to have the fourth leg about done.” Belvew made no answer for a moment; he was spiralling upward to start another pass through the raindrop-rich updraft—at a safer altitude this time. He wanted mass in his tanks as soon as possible, but was now prepared to accept the lower concentration to be found higher up. In standard light frequencies his target was indistinguishable from an Earthly thunderhead—there was even lightning, in spite of the nonpolar nature of the droplets, and Belvew faced the task of making several passes through it fast enough to avoid another ram stall but slow enough to escape turbulence damage to his airframe.
“Just about,” he answered at last. “I still have enough cans to finish Four and most of Five. I hope all the ones I’ve dropped so far work. I’d hate to have to go back just to make replacements. There’s too much else to do.” He fell silent again as the waldo began pressing his body at various points indicating that Oceanus was entering turbulence. His fingers, shoulders, knees, and toes exerted delicate pressure—now this way, now that—on the suit’s lining, answering the thumps he could feel and forestalling the ones the Aitoff screen was letting him anticipate by sight. For nearly two minutes the aircraft jounced its way through the vertical currents, and as the turbulence eased off and the air around his viewers cleared the pilot gave a happy grunt. He would have nodded his head in satisfaction, but that would have operated too many inappropriate controls.
“A respectable bite. Nine or ten more runs at this height should give me takeoff or orbit mass.”
“Or several dozen stall recoveries,” his official buddy couldn’t help adding. Belvew let the remark lie, and two or three minutes passed before anyone else spoke. The rest of the team had their own instruments and could read for themselves the rise of tank levels as the jet’s collection scoop gulped Titanian air, centrifuged the hydrocarbon fog droplets out of it, stored the liquid, and returned the nearly pure nitrogen to the atmosphere.
“There’s another odd surface patch a few kilos west of Carver,” Maria Collos’ voice came at length, as the main tanks neared the seven tenths mark. “It wouldn’t take you very far off plan to look at it before you start Leg Five.”
“Like the earlier ones, or something really new?” asked Belvew.
“Can’t tell for sure in long waves. It could be just another bit of melted tar. Even if that’s all, we’re getting enough of those to need explanation.”
“One would need explanation!” snapped Arthur Goodell, the least patient of the group usually, and excusably because of the endless pain of Synapse Amplification Syndrome. “I can see—so can you—how tars would settle out of the air as dust at this temperature. I can see dust getting piled into dunes even in the three kilo currents that pass for gales here. I can see it looking like obsidian if it gets melted and cooled again. What I don’t see is what on this iceball could ever melt it.”
“I’ve suggested methane rain, dissolving rather than melting the surface of a dune as it soaks in and forming a crust as it evaporates,” came the much milder and thinner voice of leukemia case Ginger Xalco.
“And I’ve suggested landing and finding out first hand whether those nice, smooth, glassy hilltops are the thin shells of evaporite over a dune, as you’re implying, or the tops of magma lenses,” snapped Goodell. “When do we do that? You’ve plenty in your tanks now. Gene. Why not take a good look at this new one—whether it turns out to be just another for Maria’s list or something really different? And don’t tell me it’s against policy; we’re here to find things out, and you know it. To quote the poetic character who wrote our original mission plan, ‘there’s no telling in advance which piece of a jigsaw puzzle will prove to be the key to the picture.’ ”
“It’s not a matter of set policy,” Belvew replied as mildly as he could—he had his own troubles, even if they didn’t include SAS. “Avoiding risk to the jets before the surface and weather gear are all
deployed is common sense, and you know it. Once they’re in action, long term studies can go on even if we lose transport. We’ve made one landing to deploy the factory, and a couple of others to restock from it, after all.”
“I know. Sorry.” Goodell didn’t sound very sorry, actually, but courtesy had very high priority. “It’d be nice to be around when some of the results crystallize, though. And you can’t count the later landings because they were in the same place and we knew what to expect.”
“Not exactly. The original shelf was gone.”
“The area was plain Titanian dirt, with no cliff to fall down this time. Even I could probably have set down safely.” No one contradicted this blatant exaggeration. “The old saw about dead heroes—”
“Doesn’t apply, Arthur.” Maria, somehow, was the only one of the group who could manage to interrupt people without sounding rude. “We’re already heroes. We’ve been told so.” There might or might not have been sarcasm in her tone. No one else, even Goodell, spoke for a moment. Then Belvew referred back to the landing question.
“There’s no reason I shouldn’t make a ground check after finishing the Leg Four, if Maria’s radar and my own eyesight can find me a landing and takeoff site. Actually, we’re all as curious as Art about the smooth stuff, and it’s good tactics to eliminate possibilities as early as we can. Let me top off these tanks just to play safe, and then you can put me back where I left Leg Four, Maria. After that’s done I’ll scout your new patch for landing risk.”
No one commented, much less objected, and Gene made his remaining passes through the thunderhead with no actual stalls. There were no remarks about his two close calls, either; everyone had flown the ramjets at one time or another except Goodell, whose own senses were drowned in pain too much of the time to let him use a body waldo, and Pete Martucci, whose reflexes, though he was the only one of the dozen not known to be dying of something, had never been good enough for piloting. All knew the ordinary problems of flying.
