Still River

by Hal Clement

  “Remember the hydrazoic acid!” came Jenny’s voice. Molly hesitated, then reassured herself.

  “I’ve already handled this thing pretty roughly. It was growing in soft mud and didn’t take much to pull up, but we dropped it on rock afterward. H-N-three would be liquid at this temperature, so there can’t be enough to matter, anyway.”

  “You could have dropped glyceryl nitrate safely on rock in this gravity. Maybe putting that thing in your armor isn’t such a good idea, Molly.” Carol did not actually draw away, but giving danger as much thought as she had just uttered, and allowing the matter to weigh for a moment against the importance of the research, was her equivalent to some people’s screaming and running. Molly was impressed.

  Still, she opened the appropriate panel and stowed the tangle away, not entirely without uneasiness. “It’s less likely to get jarred there than in one of the cans, after all,” she said firmly. “Now another temperature check of the water, and we’ll go on.” Carol helped without comment; she had not really expected her big friend to take such a chance, and felt a little guilty. Still, Molly was adult and entitled to take her own risks if she felt the potential gain was worth it; and of course the specimen was worth some risk—why were they here, after all?

  It was onward and downward again. For some time the river was just a river; then it fell for long, long minutes from top to bottom of what seemed to be the largest kame yet. The women outraced the drifting drops and found an extensive lake at the bottom. This had a few bits of floating detritus that might or might not have been alive. The edge of the body of water—it was water, according to a quick check—was nowhere in sight, and they set off at random, reaching a cavern wall with no sign of further passages in a few minutes. They followed this around to the left, as had become standard procedure with them, passing half a dozen tunnels but not stopping to investigate until they met one that was serving to drain the lake. They followed the new river without comment.

  There was no visible life in or beside it. Its current was slow, though it slanted downward at a steep angle and frequently slithered around rocks that might have fallen into its bed from above. Sometimes there were enough of these to dam it into a pool, whose exit often took several minutes to find in the rubble.

  At one of the smaller of these, Molly called for a stop.

  “Another temperature check? We did one only a few minutes ago!” Carol’s voice was definitely a complaint.

  “Another temperature check. I have my reasons.”

  “Which you won’t tell me.”

  “Which I’ll show you. Park this thing, please.” Carol stopped the robot, not quite happily, but at least curious.

  Molly made a reading, and smiled, invisibly since all the light was concentrated on the instrument. “Three hundred seventeen. It has to be water. There couldn’t be enough ammonia staying with it to smell at that temperature.”

  “You’re using it to replace what you used? Why worry? Surely your recycling equipment would handle that sort of impurity.”

  “Yes, it would. Probably I should top off my buffer tanks; thanks. I hadn’t thought of that.”

  “Then what are you going to do? Drink it? You’d be crazy. You can’t be that tired of reprocessed stuff.”

  “I certainly could be, but I’m not yet. Help me get this suit off.”

  “You are crazy—oh! Of course.”

  “Yes. Of course. Sorry you can’t join me, but you’d parboil in a few seconds.” Molly had undamped her helmet and now removed it carefully, keeping the mask and breathing connections tightly over her nose and mouth. Carol took the helmet and put it down for her, while the Human went to work on the body seals and presently opened and removed the waist-up section. Then she sat down and drew herself carefully out of the walking and recycling part, leaving it sitting on the bank of the pool.

  “Keep your light and at least one eye on that stuff, please. In this gravity I can’t help feeling it may blow away, and some of this mud seems soft enough to lose small pieces in. It all seems pretty wet, too; you’d think in this wind we’d find a dry surface occasionally.”

  “We didn’t have the ammonia drying, up at that level.”

  “True. Our reflux unit doesn’t get very far below saturation, does it?”

  Molly sat down again with air recycler beside her, mask still on her face and the connecting tubing carefully laid out to avoid tangles. The most important part of the suit was still to be removed.

  This was the “blubber,” the skin-tight layer some four millimeters thick in most places that covered her entire body except face and hands and contained the lining that absorbed perspiration and body wastes and the capillary system that pumped it to the actual recycling machinery. None of this contained moving parts larger than molecules, and in theory should last for years of use and even abuse; but Molly peeled it off with the utmost care and spread it out beside the rest of the armor.

  Then she entered the water and luxuriated for ten minutes. She climaxed the operation by holding her breath, removing the mask, and submerging completely for several seconds, rubbing the dried remains of sweat and, she admitted to herself, occasional tears from her cheeks. She stood up, accepted the mask handed to her by the Shervah, pressed it against her face, squeezed the tubing, and blew it clear around the edges; then she resumed normal breathing, only slightly afraid that she would detect the scent of ammonia.

  She didn’t. There was something else, very faint, that she failed to identify, but it did not worry her. The water could not be expected to be absolutely pure. She picked up the inner suit and immersed it in the pool, scrubbing its outer and especially its inner surfaces carefully and as completely as possible with her hands. Then, not worrying about drying—the suit would take care of that when repowered—she redonned the equipment, and presently stood fully accoutered in front of her small companion.

  “That was worth it. I’ve never wanted a bath so much in my life.”

  “I can sympathize, but I think you were perfectly insane, just the same” was the response.

  “Certainly I was, but that remark from someone who can pay more attention to a bunch of weeds than to the fact that her batteries are running down and the charger is out of action…”

  Joe interrupted again. His exact words were not important, but they served to change the subject. Molly wondered if he ever felt any real emotion; it was possible that the embarrassment he occasionally seemed to show was just to keep his listeners from feeling inferior. She was soon to form a more definite opinion.

  The journey was resumed, and they had been on the way for perhaps another two hours when the Nethneen’s voice came through again.

  “My computer seems to have failed.”

  “You have a backup, don’t you?” asked Charley.

  “Certainly, but it is behaving similarly. The diagram being relayed back is quite impossible.”

  “As impossible as the life on this planet?” asked Carol, perhaps too pointedly.

  “At least. The model has just plotted a cavern nearly spherical in shape and approximately twelve hundred seventy-four kilometers in diameter.”

  “That’s ridiculous, but not impossible.”

  “You’ve been computing, too, Charley?”

  The Kantrick evaded the question by ignoring it.

  “The biggest I’ve encountered so far was less than twenty, I admit, but even that means this gravity just doesn’t count. We’ve known that all along. What’s your record?”

  “So far, just over thirty-five in greatest dimension; it was not very spherical.”

  “Your lead mapper probably has something wrong with its radar. Wait until some others reach the same point. What does your program do when two of them disagree with each other?”

  “Checks against a third or a fourth, if necessary.”

  “Then wait a few minutes. The others will reach the same point, or points farther on, and straighten things out.”

  Joe made no answer, and everyone
waited, except possibly Jenny, who might have been too absorbed in work to hear. After about ten minutes, Charley made himself heard again.

  “Have any more mappers reached the area?”

  “I would assume so. There is no easy way to check their location except by the model sections they have completed. There has been no change in the model.”

  “Then either a lot of your mappers have the same fault, or you’ve lost a lot of mappers. What could happen to them? What would rivers like the ones we’ve been meeting do to them?”

  “Nothing, as far as I can judge.”

  “But there’s no way you can identify individual signals.”

  “No. It could have been done, and I thought of it, but the arrangements would have been complex and time consuming. I was worried about Carol and Molly and wanted the devices ready quickly.”

  “There is one possibility Charley didn’t mention,” Carol cut in.

  “What is that?” asked Joe.

  “That there really is a twelve hundred-kilometer cave below you. No one has really calculated the strength of this rock. We know the gravity is weak and the planet young. It may have started as an ice body, a sort of giant comet nucleus, and accreted silicates later.”

  “And more comets,” added Molly. “Consider the other caves. That would make the center just a super-kame.”

  “But how could such objects accrete without at least melting at the time?” Joe was more than doubtful; this was a worse blow than the life discovery.

  “I don’t know offhand; there’s a lot of information to be collected before we do much calculating, let alone genuine theorizing: The first job would seem to be getting that machine you’re riding down to where your model says the big cave is and checking for yourself whether it’s really there. Maybe, if it is, we can get together more quickly than any of us were expecting. I certainly hope so. Have you met any rivers yet?”

  “No. I don’t expect any. The air going in from the surface would be warmed both by compression and from the surrounding rock. If any liquid were filtering down, I would expect it to vaporize long before reaching my present depth.”

  “I hope you’re right. That’s a very firm conclusion, and another mistake would be quite a jolt, wouldn’t it?”

  “Yes, Carol. Facts can be most tactless at times. However, I am learning to put up with them—perhaps a little late in life. I am following what seems the best path that my model shows to the central hollow.”

  “Central?” asked Molly.

  “If real, yes. It commences eight hundred thirty-six kilometers below the surface and has a radius of six hundred thirty-seven. The planet, by our earlier measures, has a radius of fourteen hundred seventy-three. Unless the cavern is off-center on one of the axes at right angles to the rotation one, it is a hollow center to the planet.”

  “I don’t really believe in hollow planets,” Molly said thoughtfully.

  “Neither do I, yet,” replied Joe with what had to be genuine emotion, Molly was sure. “Suspend your judgment, young woman. I am trying to do the same. I am glad this machine can follow the indicated passage automatically; I am not sure I am in a state to guide it properly myself.”

  “How deep are you now?”

  “Six hundred fifteen kilometers from my entry point.”

  “Two hundred twenty-one to go.”

  “If it were a straight line, Charley. It is far from that. I suppose I could get the machine to tell me the integral, but I will simply say that it looks more like five hundred on the model.”

  “How fast are you going?”

  “Not nearly as fast as the little machines; this one is far less maneuverable, and as you must have noticed, many of these passages are rather tortuous. I would guess three and a half to four hours’ travel time.”

  “It will take us a lot longer,” Molly said thoughtfully. “At least, we know we only have to follow the river.”

  “If it lasts. Temperature may become too high even for water to stay liquid. Pardon me—I didn’t want to give you another matter for worry.”

  “We’d already thought of that one,” Carol assured him. “Don’t worry; we’ll face it if we have to. In the meantime, the river is here. You ride your car, we’ll ride ours. Your river any bigger, Charley?”

  “A lake, at the moment. I can’t find the outflow.”

  “Good. That happened to us not long ago. Maybe you are on our track.”

  “It’s the fourth time it’s happened to me.”

  “Oh. Well, downstream is still the way; keep looking.”

  “I am.”

  Molly wondered whether the Shervah were coming to tolerate Charley a little better, or whether the teasing had been meant to hurt. She herself might have used the same words, jocularly; she was not sure at all how Carol meant them.

  They went on, down the ever-slower stream. Gravity was weakening, too, though none of them had yet thought of this point, as more and more of Enigma’s mass was left overhead. Joe was aware of it; his travel was faster, and Enigma-normal was much closer to that of his natural environment. Carol and Molly weren’t, since from the beginning they had felt on the point of blowing away, and even their armor wasn’t much anchorage. The latter had, after all, been designed to be as light as possible, consistent with its other requirements. All the women really appreciated was the decreasing rate of flow of the water, and Carol was not sure whether that was an objective fact or that her time sense was getting out of order. Molly was more inclined by nature to trust her own senses, but near free fall put a severe strain on that inclination, space-trained though she was.

  She did not actually get sick, fortunately. This would have put a heavy strain, though probably not an excessive one, on her armor’s recycling capacity. She was, however, getting less and less comfortable. She was also beginning to itch again, in spite of the recent bath.

  Joe’s report was a relief to Molly, if not to the Nethneen; it took her mind off her mounting troubles.

  “The hollow center is real.” Once again his emotion seemed under control, but Molly felt quite sure that it was there. “It is not perfectly spherical, but very nearly so. The dimension is what I reported earlier. I am inside a hollow planet and am forced to believe it. I am grateful for your suggestion about its possible origin, Carol. I might not have been able to conceive one myself, and with none at all, I would have been most uncomfortable. I realize it is only a hypothesis, but at least it gives a foundation for more imagination and work planning. If someone could do the same for the existence of life here, which has been causing me acute discomfort ever since Carol first reported it—or at least, to be honest, after the later reports when I could not longer disbelieve it—I could be quite happy.”

  “You haven’t seen that?” asked Carol in surprise.

  “No. Have you?”

  “Of course. You have the data, too. You’ve had it for hours. You’ve had some of it for weeks.” “Well?”

  “The fact that this planet is a laboratory and has been for millennia. The bodies you found. Molly’s bath, for School’s sake! Obviously the life didn’t start here; the School brought it!”

  Chapter Twenty-Two

  Of Course Time’s Not Important Now

  “I have not felt more relieved, or more foolish, since Molly first reported life. Thanks a lot, Carol. We can check that suggestion very easily, too. The life we find should show a wide variety of underlying biochemistry. Usually a given planet has one particular chemical system reach the self-replication stage, and that usually takes over completely; others either never develop at all or are destroyed by the competition. Any reasonably careful study of a single world’s biology shows the evolutionary descent of all its life forms from a common molecule, and there are enough different ways to run life chemistry so that a particular basic commonly identifies a given world uniquely. Here we should find lots of different biochemistries competing with each other. It would be unlikely for any one to have eliminated the others, especially with frequent
reseeding by new visitors.”

  Carol added happily, “That the metallic growths Molly found were doing well enough, and the more obviously organic ones the rest of us have encountered were also in active ecologies as far as we could tell, would support that. Also Jenny has already reported two different basic biochemistries, I recall.”

  “Right. Lab work is needed, but its nature is clearly indicated. I wonder whether Jenny has been listening.”

  That was as close as Joe would come, of course, to addressing the Rimmore directly, since she was presumably at work. The answer was prompt.

  “I have been. Like you, Joe, I feel foolish. I got those two and didn’t see the implication; I just thought I wasn’t to the real basics yet. I am going to have to redo some of this work, because I was taking for granted that there would be some one common chemical theme here, like double helix with a small number of coding units, or the positive against negative paired-sheet arrangement, or that amusing one which duplicates using absorption versus emission microwave spectra, or…”

  “We get it, Jenny dear,” Carol cut in as courteously as she could; even with Joe listening, she did not consider this the time for a general biology lecture. “I think there was a suggestion of starting with microscope work first.”

  “I did. With only one specimen, but don’t—what’s Molly’s figure of speech, Charley?—don’t rub it in. We now know why we’re all students instead of Considered Words. Carol and Molly, the sooner you get back to this tent with what the two of you have collected, the better.”

  “I quite agree” was the Human’s emphatic response. “Joe, I suppose you can fly your horde of miniature mappers right across the hollow and set them to working upward on our side. If there are rivers actually reaching the center, it will be a big help.”