Still River

by Hal Clement

  “I can use parts of Molly’s and Charley’s samples. They’re picking up solids from the same sites.”

  “Or liquids. In this pressure and temperature range you could have ammonia oceans.”

  “My translator didn’t handle that last word. It gave me a new code. Can anyone clarify?”

  “How about lake or river?” asked Molly.

  “Neither one. Both new,” replied the Rimmore. The Human woman described the behavior of water and ammonia on planets whose temperature and pressure permitted large amounts of either liquid.

  “I see. That doesn’t happen on Hrimm. The biological liquid is ammonia, of course, but with a lot of free oxygen in the atmosphere that’s not stable—it exists at all only because life forms are constantly producing it. The same, of course, is true of the oxygen, as it must be on your world, Molly. We have ammonia bogs and swamps—did your translators handle those?—but no lakes or oceans.”

  “So there’d be no oxygen here, either,” suggested Carol. “No reason to expect life on a world this young, even with lots of ammonia.”

  “How about the clouds?” asked Carol.

  “Largely ammonium carbamate, which you’d expect to be produced from ammonia and carbon dioxide. Some water-ice crystals, some carbonates of ammonium and alkali metals. The difference between the clouds aloft and the dust down here seems to be a quibble. In connection with your other point, I found only a trace of oxygen, and with all the hard radiation from this sun, that was probably produced from the carbon dioxide,” replied Jenny.

  “Then we know what we’re doing,” Joe summed up. “We’ve picked twenty sites, symmetrically spaced around the planet, starting right here. We drop a drift robot at each and collect samples for analysis, then come back here to the tent, signal the robots to start all at once—not really necessary, but may simplify calculation later—and monitor them and their slaves, doing our analyses from here. By the time Classroom gets back, we should have enough data for all our needs—possibly even some that will support our various favorite hypotheses.”

  Molly felt herself blush at the last remark, and wondered what the equivalent reaction was with the others. The Rimmore watcbed with interest as the changing background color briefly hid her Human friend’s freckles. They both rather expected Charley to give some sort of retort, but it was Carol who made her feelings known, and these seemed unconnected with the Nethneen’s gentle gibe.

  “Assuming, of course, that the boat gets us back to the tent to work over our data—or is that inconsistent with a favorite hypothesis?”

  “Are you worried?” asked Charley. The Shervah turned her head so that both her side-placed eyes could cover the speaker at once; then she rolled them both away from him in opposite directions.

  “No.” The eye that had come to rest covering Molly winked. The Human wondered what that could mean; her translator had no way of handling gestures. Even with a private channel available, she decided, this was not a good lime to ask. She glanced toward Joe.

  “All that I need there is on the boat,” Joe responded.

  “Your robots, too? Everybody else ready to go?”

  “One drifter and its slaves are in the tent. I’ll set them out when we get back. I’m ready, yes.” The others spoke or gestured agreement, and Molly keyed the boat off the surface.

  Even without the wind, there was still precipitate; visibility in short waves—short enough for Molly—was only a kilometer or two. This was not dangerous, since the radar maps had shown very little relief on the planet’s surface and they were flying high enough to clear all of this, but it was boring. Molly shifted her pickup farther into the infrared, converting it at the screen to light that she could see but that was not short enough in wavelength to bother the others. It would have been possible to hood the screen and keep her face buried in it, but with only her own personal friends present she preferred to feel free to look around. The others, she saw, were also examining the surface flowing past below them. Not real work, by Joe’s standards.

  So far there was no sign of liquid, in spite of Jenny’s pressure report; they might have been over Enigma’s Arabian Desert. Dunes, easily recognized from above by their crescent shape, were numerous when they started, but before reaching the first vertex of Joe’s imaginary dodecahedron, the sand gave way to what looked more like bare rock. Molly was tempted to land for a sample, but decided against it; she would be busy enough with the scheduled stops, and more specimens could always be obtained if needed. She did not like to display impatience, especially before Joe. She knew he would understand, but didn’t want him to have to.

  The boat announced the approach to the first site, and a few seconds later came to a halt a few hundred meters above the ground. The five spent only seconds examining the surface, which was not very impressive: bare rock, very smooth on the finer scale, rippled and hummocked with larger irregularities averaging a few dozen meters across and one or two in height. Nothing showed any sign that liquid had ever flowed there, but the surface might well have been polished by wind-blown sand. Without waiting for suggestions from anyone else, Molly keyed the boat to slow descent. It settled to the rock half a minute later.

  Joe had already resumed his armor and was out of the conning room before they were down. Carol went with him. Three minutes later the robot—much taller than the one the Shervah had ridden to Joe’s rescue, since its slaves were now riding its top—was standing on the polished stone. Charley was outside cutting samples from the hard parts of the surface and scooping up bits of loose material that were lying in smaller hollows. Each went into a separate container, carefully labeled, and Molly recorded the whole procedure visually from on board. Carol was back inside before the Kantrick had finished, but Joe remained beside his machine, fussing with its various controls, until everything else scheduled for the site had been done.

  By the tenth landing, everything was both routine and, for some of the students, boring. Twice they had put down on lakes. Sampling was more interesting there; Jenny had gladly submerged and obtained liquid, solid, and mud specimens. Any of them could have done the same, as their armor was quite adequate for such an environment, but she was the only one used to a liquid environment, and the others felt the usual discomfort at not being able to see normally below the surface. Even Jenny was a little unhappy at so much clear liquid; she was used to the tangled vegetation of the swamps of Hrimm, where the combination of climbing and swimming for which her form was so well suited was the standard way to get around.

  The twelfth stop was desert again, this time with little evidence of wind. They were on the night side of Enigma now. As they descended, Molly wondered whether really different material would ever turn up. She was getting a little puzzled; the overall size and gravity of the world had matched her comet hypothesis, as had the atmosphere, but the specimens collected so far had not.

  The planet’s average density, from size and gravity, was about five thirds that of water, which by any reasonable standards suggested that a good deal of its makeup was ice—water, ammonia, carbon dioxide, or methane. The atmosphere strongly supported this notion, but the rocks, at nearly twice the planet’s average density, did not. Molly, very prematurely—before coming within sight of the place, in fact—had convinced herself and Charley that Enigma was simply a young ice-and-silicate body that any decently programmed translator would call a comet, but which was far too big and had far too high an escape velocity to show a tail even in Arc’s impressive stellar wind.

  The ice, it was beginning to appear, was already largely gone from much of the surface; it looked as though she would have to drill for it, and she had not come prepared to do any such thing.

  This was embarrassing. She had been given laboratory assignments at School obviously intended to remind her of the need to be prepared for the unexpected. Worse, her present companions had taken the assignments with her. Worse yet, she had done well on them, receiving even Joe’s commendation on the way she had gotten the group ou
t of trouble when it had looked for a time as though they had done a prematurely destructive test on a problem sample.

  The present situation was not only embarrassing but hard to believe. She had encountered plenty of ice bodies, small and large. There had been comets; there had been Pluto and Titan and Callisto in the Solar system, and Think and Sink in the School one. She knew what ice could do, given a set of temperature and pressure parameters.

  If it were all buried, it could not be contributing very rapidly to the atmosphere, and the latter had no business being anything like as dense as it was. At cloud-top temperature, methane and ammonia would escape in a few decades at the outside, even without bothering to consider Arc’s ultraviolet and the still faster loss of free hydrogen. The Human did not really enjoy mathematical modeling, but it looked as though she were going to have to play at it.

  After the present supply of data had been gathered and organized, of course. There might be easier explanations.

  “We’re coming down in a crater.” Joe’s quiet tones cut into Molly’s cogitation. Her fingers moved on the keys.

  “There don’t seem to be any real craters here,” objected Jenny. “Nothing suggesting them showed on the radar maps.”

  “Nothing suggesting impact features,” admitted Joe. “The hole we are just avoiding would look volcanic except that there is very little buildup around its edge, and the bottom is well below the surrounding ground level. There were many such on both the original map and the one we made during approach. If they had been mentioned in the original description we had of Enigma, we would certainly have been expected to offer an explanation for them.”

  “Shouldn’t we anyway?” asked Jenny.

  “If you can think of one, and the requisite work doesn’t interfere too greatly with what is already planned. Allowing oneself to become distracted by the unexpected is one of the more certain ways to keep from finishing any task, it seems to me.”

  “And ignoring the unexpected is one of the surest ways to have your solution outdated before you report it,” retorted Carol. “The explanation of these holes may have nothing to do with the official question of why Enigma has in atmosphere in spite of its small size, but I think a good, detailed map of a group of these things, and a close examination of a few of them, is in order.”

  “The map is available. Pick your area from the radar record and have it plotted at any scale you like. When do you want to do the examination?”

  “Well, I hate to delay the start of your own run. I don’t think there were any of these things near the tent…”

  “We can check that easily enough,” pointed out Charley.

  “And even if there aren’t we can get back here, or to some better site if the record shows one, quickly enough,” admitted Carol.

  “On the other hand, you could take a quick look right now, while Joe’s robot is being set out,” suggested Molly. You can see well enough even if it is night, can’t you?” “Certainly, with this sky glow.”

  Molly had been unaware of any sky glow and assumed it was too far in the infrared for her eyesight, but stuck to the main theme. “Do you have a pretty good idea of what you want to check?”

  “Yes, I think so.”

  “Then for goodness’ sake get outside and get your data. It won’t delay us worth mentioning. Can any of us help you?”

  “You might need a camera for what I can remember, but if you want to take one, I’d be glad of the material. Get sizes and especially inner slopes, and outer slopes if any, of all these holes you have time for. You take the left side of the ship, so you can start the moment you’re outside; I can move faster and will only have to look to remember, so I’ll go around to the other side.”

  “All right. We’re down; let’s go.” Molly seized a camera, thankful that there was some basic equipment aboard that no one had specifically had to arrange, and the two women headed for the exit lock that was already opening.

  Outside, the Human realized that she had forgotten an important point. She had been seeing the landscape on infrared pickup, converted on the screen to frequencies she could use. Now she was looking directly, and seeing was much harder. It was not totally dark; the sky produced some glow that even Human eyes could detect. Possibly Arc’s companion was above the horizon, though she would have been hard put to prove it at the moment, and a little of its radiation was getting through the dust. This was no time to theorize, however; there was work to do. The camera’s finder could be adjusted to convert to more comfortable light, though walking around with one eye glued to its small aperture was inconvenient and deprived her of depth perception.

  She walked slowly toward a low ridge fifty meters away, climbed it, and saw that it did indeed mark the rim of one of Carol’s craters. She took photos in both directions along the rim and toward the far side; these would be enough for the slope measurements, since the instrument was holographic.

  After some search through the finder, she thought she could see another feature some two hundred meters away. This proved to be an error; the ridge was simply a ridge, no more. The next two tries were successful, however.

  Then Joe’s voice sounded. “The robot is out and set. Have you recorded what you need, Molly and Carol?”

  “I have three sets of pictures,” replied the Human. “I’ll hope that’s enough for now. Carol has probably done a lot better.”

  Carol made no answer. Joe, being Joe, did not repeat his call at once; Molly, not being Joe, waited for scarcely ten seconds before she did.

  “Carol! Did you hear us?”

  Still no answer.

  “Joe, we’re not on private for some weird reason, are we? Can you others hear us?”

  Charley and Jenny both acknowledged at once. “Can either of you hear Carol? We can’t.” “Neither can we.”

  “Can anything go wrong with the translator channels? Joe, you’d know better than I—so would you other two. How about it?”

  “It is hard to believe. The receivers and transmitters that you carry yourselves, and the ones at the central translation computer in the boat, are extremely redundant; so are the internal works of the computers. The channels use achronic radiation, not electromagnetic, so they can’t be blocked by matter, though their range is only a few thousand kilometers, and of course they can’t be sensed directionally; that’s why I couldn’t use that system on these robots. Gross destruction of a translator would of course stop its transmission, but that would…”

  “Stop the lecture and let’s find Carol!” snapped Charley. Molly, come inside; you can’t possibly see well enough out there to be useful in a search. Jenny and I will come out. Joe, you stay there. Molly, come up to Con and guide us on the screens.”

  Before anyone could respond to these instructions, the Shervah’s voice came through to all of them. “You needn’t all come. Jenny, you’re the heaviest of the ones who can see well. Bring some rope, fifty meters at least. Don’t hurry; crawl. That was my mistake. I know this gravity is silly, but don’t let it fool you.”

  “Where are you?” asked Molly, making toward the boat, the only thing she could see reasonably well without the camera finder.

  “I am at the bottom of a hole about half a kilometer from the ship, two hundred grads from the bow direction to the right. I was in a hurry to get to it and jumped over the edge. I can’t jump out again.”

  “Why not?” asked Charley. “This gravity is weaker to you than it is to me, and I could do it.”

  “I’m tempted to suggest that you come and try,” said the Shervah bitterly. “If there were a knevreh at the bottom to eat you, I think I would.”

  Molly was inside now and able to move much faster. She didn’t know what a knevreh was, but the context suggested an answer.

  “I take it the sand inside is very loose, and at angle of repose,” she said.

  Carol was silent for a moment. “Your translator couldn’t have handled that!” she said at last. “Or have you been spending time studying our worlds, since t
he team was set up?”

  “Neither,” admitted Molly. “You said enough for inference. When we get back to Classroom try the main translator with ant-lion. Ecology is an interesting field, and a lot of Human information has been filed there by now, though I don’t suppose the boat’s unit carries it. Jenny has just passed me with a coil of rope; you’ll be with us in a few minutes.”

  “If she doesn’t make an equally big fool of herself. Watch the gravity, Jen; stopping isn’t easy, even on rock, and these holes are full of the loosest stuff you ever handled. I don’t think even eighteen pairs of legs, or whatever your count is, would give traction enough.”

  “Only fifteen for traveling. I’ll be careful,” promised the Rimmore.

  Conversation ceased for a minute or so, and Molly was able to reach the Con room and bring a vision screen to bear in the appropriate direction. She had not bothered to remove her armor, except for helmet and gloves. The centipedelike form of Jenny was easily located; the Rimmore might be traveling slowly by her own standards, but Molly felt uneasy as she watched. She tried to locate the hole, presumably somewhere ahead of Jenny, in which Carol was trapped, but even the highest of the boat’s pickups was too low to give her a good landscape. Designed primarily for use in space, the screens were not holographic.

  The Shervah had said half a kilometer—but that would have been a translation, and the translator did round to levels of accuracy implied by the speaker’s own choice of words. Two hundred meters more or less might easily have been meant, even though Carol’s highly precise distance judgment and incredible memory would have given her a far more exact knowledge of the real figure. There was no useful way for Molly to guide the rescuer, even though the boat’s sensors could tell her the latter’s distance to the centimeter.

  Jenny needed no guidance, however. Carol’s words had been enough—they might have come through in more helpful form to the Rimmore, Molly realized. Near the limit of vision set by the boat’s geometry and the local topography, Jenny stopped, quickly enough to prove she was in control and not speeding recklessly, and elevated the front half of her long body. After a moment she dropped back to the ground, crawled another ten meters in a direction slightly to the right of her original course, and stopped again.