by Hal Clement
For just a moment, she allowed her memory to flash pictures of her six-year-old holding his own with flying Parkemm children in that soupy-aired, low-gravity colony; with Nethneen in their nearly airless environment; even with Jenny’s people—the child had learned quickly enough that gravity was no real problem if one stayed submerged, though ammonia furnished less support than water. She had quickly gotten over a mother’s natural worry; the child care centers on the School planets were as good as Human ones, even when it came to teaching the very young about environments and environmental equipment.
For another second, Molly wondered whether she would do as well, in the next few days, as her son had in the last few years. Would she ever see him and his father again?
She buried the question firmly. One could only do one’s best.
“Thanks, Carrie.” Molly shifted back to the common translator channel and went on. “If that sand spout, or whatever it is, has been mapped, Charley, I’d go on with the surface search for the time being at least. It seems to me more and more important that we get an idea of air flow out to the surface and, if there is any, in from it. Joe, is your map far enough along to give us any hints at all on that point? Could this cavern circulation be enough of the total to show on the planetary scale?”
“I have no basis for a guess, since I had not considered the possibility and haven’t seen the map itself for some time. It occurs to me that it would be better for Charley to continue his search with the new mapping robot so that I can take the boat, with the shop, back to the tent. Will you please come back here, Charley? I think the matter important.”
“All right, if you’re sure the latest machine is really ready.”
“As ready as the one Jenny is using. Controllable by any of us, electromagnetic location interlock with the boat and, through the computer, with all the other robots in touch; collecting equipment; power…”
“All right. I’m on my way to the shop. I’ve started the boat back toward the tent.”
Many kilometers below, traveling at unknown speed in unknown direction, the two women listened to this conversation without expecting much new to come from it. Both were tired and getting heartily sick of darkness and recycled nourishment. Both knew that their armor was slightly less than perfectly efficient at the recycling process and that eventually it would not keep them alive, but neither was worried about this yet. Both were far too intelligent to let their minds dwell on the point. With work, they could also have kept their minds off simple discomforts, but only at rare intervals was there a chance to work.
Twice, as the hours passed, they stopped and made a close examination of the rock and pseudovegetation that formed the bank of their alien Styx, but neither study proved interesting. As far as either could tell, the former was a finegrained, possibly amorphous matrix, possibly but not certainly silicate, possibly but not certainly modified both thermally and chemically, possibly but not certainly cemented by hydrates or ammates or both. Their eyes simply couldn’t tell enough. Four times during the hours Jenny reported discovery of a cave from which wind was blowing; twice more Charley, now surveying with the new mapper, did the same. No sign of inflow had been detected. Joe, back at his map, had described verbally in great detail what was appearing, but neither he nor any of the others could recognize anything useful. It seemed like an ordinary planetary circulation, to those whose home planets had significant atmospheres, except for the presence of extraheavy dust clouds at the summer pole and relatively clear air at the other. If the clouds had been water or ammonia condensate, even that would not have been startling.
Maybe, Molly thought, when enough detail had been added—maybe, when they could see it themselves ...
But if they could see it themselves, the main problem would be solved.
Even Charley was saying less and less as the hours wore on and Enigma crawled along its vast orbit. He had decided that Molly was not going to end this underworld Odyssey until someone else made an effective move; he remained emotionally certain that she could do so whenever she wanted. He was growing more and more afraid that he himself was the one who was expected to take the effective step—he remembered what Jenny had said, days earlier back on Classroom, about originality and his own failure to display it. This had to be a part of the test.
Should he take his robot into one of the caves he had found and start mapping the passages inside? Mathematically, this seemed poor policy; the women were traveling in more or less a straight line—at least, along one line—and only wild coincidence could bring him in touch with them that way.
Was there some painfully obvious step that he should have thought of and taken? Was the Human losing patience with him?
Should he—?
“The river’s GONE!” came Carol’s voice, in a near-shriek.
He should have. He couldn’t now. Molly was taking new action herself. He’d failed, of course.
Chapter Seventeen
Of Course We’ll Wait
“You mean you moved away from it without noticing? How could that happen?” asked Jenny.
“We mean the river is gone,” stated Carol. “So is the only wall we could see, and so is the ground under us.”
“Stop and backtrack,” said Joe quietly.
“Right. We are. I’m driving much more slowly just to play safe, but—yes. There it is again. The way we were following simply opened into a much larger cave, like the one above. The river is tumbling in through the ceiling; it looks really weird in this gravity.”
“It could still pack momentum,” remarked the Nethneen. “Be careful.”
“Don’t worry. The wind around it is plenty of warning, slow as the waterfall looks.”
“Which way is the wind? Any guidance?” asked Charley.
" ’Fraid not,” replied the Human. “Random stuff; eddies set up by the moving water. We’re holding motionless, if the inertial guidance can be trusted, and can feel this-way-that-way gusts trying to knock us off the robot.”
“Then what will you do? Come back the same way you’ve been traveling?”
“Where would that get us? And when?”
“Closer to the surface, at least.”
“Not good enough. All we know about the area around the original cave is your information that there seem to be no other surface openings near it. At least it seems sensible to be heading somewhere else—maybe toward one of the places you or Jenny have found. Heading down a river has something to be said for it, by itself; if any of you find one, doing the same is probably the best remaining chance of getting us together.”
“If rivers tend to converge underground the way they do on a surface,” Charley remarked.
“Do your own theorizing about that; I don’t want to!” snapped the Shervah.
“You could be heading straight away from the region we’re mapping.”
“Maybe,” agreed Molly. “This robot knows somewhere inside its crystal cerebrum, I suppose, but we can’t ask it. Or maybe—Carrie, you’ve been using the inertial system telling this thing which way to go. It must have some reference direction of its own. If we let it sit quietly on a solid surface, how long would it take to tell itself, if it doesn’t know already, which way and how fast this planet is rotating? Personally I’d guess about five minutes, but you know better than I do, probably.”
“I’m not sure I do, but that seems a reasonable guess. Joe, I never knew—did you build the sensors in Classroom’s shop, or use standard ready-made ones?”
“Oh, I built them, of course. Slowly as Enigma rotates, five minutes will change attitude quite enough to measure. A good thought, Molly.”
“Then we’ll land beside the waterfall and let this thing decide which way is north, and then head in that general direction; that’s where you two have been finding your wind vents, isn’t it?”
“Yes,” replied the Rimmore. “Should we bother to look for more?”
“Of course. Keep on mapping toward us, if the storm will let you.”
&nb
sp; “I have another suggestion” came Charley’s voice.
“What is it, Charley?” Molly answered quickly, gesturing her small companion to silence.
“I propose to go underground at the nearest entrance I’ve found; perhaps Jenny might do the same thing, but if she wants to do that she should use one of the places near where I do.”
“Why?” asked Carol impatiently, ignoring Molly’s obvious wishes.
“You can program the robot to stop after it has gone a certain distance in a certain direction—it can keep track of all components of its travel, no matter how irregular its actual path. Even if it won’t give any other signal, you can find out when you’re close to this area, which is…” he paused to interpret instruments “—three hundred fifty-one kilometers distant and twenty grads right of north from the hole you two went inside by. Just arrange for it to go that far in that direction and stop. It won’t be exact, obviously, but it will put you somewhere in this neighborhood. While you’re making that trip, I, and Jenny if she wants, can be mapping the caverns under this area, within whatever radius seems smart, and as deep as we have time for. We will, of course, file the map in the boat’s computer—no, we’ll be out of electromagnetic touch once we’re very far underground, but our own machines have enough capacity to record the planet, probably.
“Once you two know you’re in the area, you can start examining it in detail, moving around as seems good to you, and describing it carefully. Sooner or later we’ll find a match with one of our maps.”
“Beautiful!” Molly made no attempt to hide her enthusiasm.
Carol didn’t feel as happy, considering the source of the idea, but could not deny that it seemed a good one. “I’m not sure it’s better than staying with the river, but it has possibilities,” she admitted.
“There was a good windy cave only fifteen kilometers from here,” Charley resumed. “That will make it three hundred sixty kilometers and almost exactly north for your robot setting, Carol. Are you going to come over and map, too, Jenny?”
“Yes, by all means. Let’s see—my unit has copied from yours, so the maps are joined—there’s another vent only a dozen kilometers from yours, just about east—that will make its distance about the same for Carol and Molly, and we’ll be a broader target laterally. I’ll start at that one, and we’ll try to make our underground maps join up as quickly as possible at as many depths as we can.”
“Fine.” The Kantrick was in top spirits again. “I’m at the vent, and going underground. At least I’ll be out of the glare of this murderous star.” He shifted to private channel. “Was that the right idea, Molly?”
The Human couldn’t quite see the point, either of the question itself or of his making it private, but she followed his lead. “There are probably hundreds, almost certainly dozens, of workable ideas. This seems a good one. There’s only one thing that would make one ’right’.”
“Is it the one one of us was supposed to have?”
“Supposed by whom? I was hoping someone would think of something to get us out of this mess, and I’m happier than I’ve been for—it seems like weeks. Thanks, Charley.”
“Molly.” It was Carol, on general channel. The larger woman looked inquiringly at her. “I’d like to go fast, once we know which way to go, but I don’t want to sail at full clip through an empty cave with no idea of when the far wall may come up. Shouldn’t we find the bottom, if only to keep ourselves conscious of how fast we’re going and a little more alert to what may be ahead?”
“Probably we should. But how fast do we dare go down?”
“That’s no problem. The robot can sense its own height even if it can’t tell us, and I can key it to stop on a downward trip before it hits anything.” Carol refrained from mentioning how nice it would have been had the machine possessed similar horizontal sensing capacities. “As soon as we’re oriented we’ll move out far enough from the fall to feel safe, and I’ll set up a fastest-downward.”
“What if we’re over another lake? This waterfall—excuse me, you know what I mean—must stop somewhere, and…”
“It will read that as a surface. Don’t worry. Even if we splash, we’re in armor.”
Minutes later, the two were once more descending through Enigma’s darkness. Molly had set her light to the narrowest, brightest beam possible without hurting Carol’s eyes and was keeping track of the falling liquid a couple of hundred meters away, while the Shervah swept hers in the opposite direction and occasionally downward, using a broader focus.
“We’ll have to be ready to move farther from the fall,” the Human reported after a minute or two. “I suppose this is what happens to real water under decent gravity, too, but I’ve just never observed the detail. The fall reaches terminal velocity for this gravity and air density, which is pretty slow, and starts to break up into big drops, and those are blowing around randomly. I suppose they correspond to the spray under a real waterfall.”
“How big are the drops?” Joe asked with interest.
“The smallest I see from here are a centimeter or two. They range up to blobs of a couple of meters, changing shape and orientation as they fall—if you can call that drift a fall. We’re going down faster than all but the very biggest, so I haven’t been able to follow any one of them for very long. They’re pretty, Carol; have a look. I’ll cut my light for a moment; yours should reach that far, with your eyesight.”
The Shervah, unfortunately, followed the suggestion, and like her friend found the sight interesting. The drifting, shimmering, writhing blobs of fluid were indeed beautiful. Lacking cameras, they alternated with each other trying to describe what they saw to Jenny and the others. Not quite all their attention was thus employed—both were conscious that the “drops” were spreading farther and farther from the original fall and closer and closer to the robot, in their random wanderings—but neither was thinking of danger for the moment. Probably neither would have been able to foresee its details even with full attention.
Quite abruptly, the robot’s descent stopped, or seemed to. Carol reached for the control keys, while Molly swept her light around to see whether they had reached a solid cave floor or a lake. She saw neither, and before Carol could finish her key work the descent resumed. The Human began to report the event to the others, while her companion swiftly considered possibilities. A likely one occurred to her immediately. A large drop might have drifted below them temporarily and been interpreted by the robot’s sensor as ground. She suggested this to Molly, who interrupted her partially completed report with a brief “Wait a minute,” and both turned their lights downward to check the possibility.
It seemed likely enough; there was a blob of ammonia only a meter or two below, whose motion suggested that it might have been right under them a few seconds earlier. Molly nodded and was about to resume her call to the others when Carol called her attention to another.
“Hold it; we’ll check. There’s one that should drift under us in a few seconds—half a minute, maybe. We’ll be nearly down to it by then; let’s see if the robot does the same thing. If it does, we’ll know, and can move out farther from this—would you call it ’spray’?”
“All right. Are you following, up there?”
“More or less,” Joe replied. “Update us when you can; I get the impression you’re busy.”
“Thanks. A minute or so,” replied Carol. “We have a check to make on what your height sensor responds to—yes. There. We are stopping again, Molly. Shall we get away from here right away, or—we’d better move; staying won’t tell us anything more.” She reached again for the keys but was too late.
Ammonia is less polar than water. It therefore has a lower surface tension and tends to wet a given surface less readily. The latter quality should have helped when a smallish, half-meter mass of the liquid touched Carol’s shoulder, but the former was enough. The drop did not hold its shape but spread out, covering her helmet almost at once. She was not using her sight on the keys, naturally, but havin
g that sense blocked was quite enough to distract her. She failed to key the new command.
She knew what had happened, of course.
“Molly! Get this thing off me!”
The Human was equally quick at seeing the trouble, but this was not quite the same as knowing what to do about it. Nothing remotely resembling a large sponge was on hand. Gloves, Human or Shervah, were quite inadequate wiping tools. The laser sampling cutters were as likely to boil the armor as the ammonia. It was several seconds before Molly thought of using the heat output from her armor’s refrigerating system, and many more before she could get herself into a position to apply this usefully. By this time, Charley was asking frantically what the trouble was.
Molly was too busy at what amounted to a free-fall dance to be able to tell him, but Carol, who could do nothing but hang onto the robot and keep as motionless as possible, made it clear. Before she was finished, Joe made one of his rare interruptions.
“Carol or Molly! Close the access door to the robot’s keyboard, if you haven’t already!”
“Gravdh! M’Kevvitch!” No one asked for translation as Carol’s glove slapped at the small panel. “Got it. But won’t ammonia leak in through those pressure-sensing openings all over it?”
“I didn’t overlook quite everything. They seal against liquids. I’ve heard of rain. If you have the port shut, it will be liquid-tight.”
“But we’re still in the spray area. More drops could hit us any moment. With the port shut, I can’t move us out.”
“When Molly gets you dry, you’ll have to look around and try to spot a moment when nothing is going to get to you, and do a quick job of…”
