Wherever enough wall area could be seen, she checked carefully for evidence of faulting, hoping it would not appear. Sometimes she went to the length of sweeping mud out of the way to get a better look at underlying rock. She kept reminding herself that some of the laboratories on Think were over two hundred kilometers below the surface, and Think was an ice body, presumably less rigid than Enigma’s silicate structure, and unless the hollows weakened the latter ...
She put that possibility out of her mind, firmly. After all, Enigma had presumably had a million years or so to collapse in, if it were going to do any such thing; why should it pick the moment she was visiting the place?
“The last of the little mappers has arrived,” Joe finally reported. “I’m going underground to get as wide a search front as I can. Things aren’t going quite as fast as I hoped; apparently my machines aren’t spreading out as widely as I had planned. Don’t worry, though, the diagram is growing fast enough, and if it seems to slow too much, I’ll come out and hit the planet from your end.”
“I wasn’t worrying, and I’m sure Carol wasn’t,” replied Molly. “Keep your eye open for life forms; we’ll want to compare the two hemispheres.”
“Certainly. I have entered a cave that, according to my recorded diagram, provides a relatively quick path to the lowest level my machines have reached so far. I have seen no living organisms yet but am keeping lights on all around me. I’ve set my controller to follow the passage recorded and can devote full attention to observing. I will report anything worthy of note.”
Joe fell silent, and routine supervened. Molly, supposedly looking out for noteworthy material, was letting her mind wander once more; she was wondering who would be next to break the silence and trying to decide whether Charley deserved odds if she were to bet on the point. She hoped partly that it would be Jenny, with more details about the local life chemistry, and partly that it would be Joe.
She was also keeping rather close watch on her thermometer, since another thought had occurred to her. The local air was now well above the melting point of ice, but the last check had shown the river still to be somewhat below that temperature; it was evidently not yet pure water.
It was Joe who won, perhaps half an hour after he had started underground.
“There’s something strange about my diagram,” he reported. “It seems to be growing narrower at the lower end, as though the machines were finding fewer and fewer ways to go, and those were all funneling closer together. I find that both surprising and disturbing.”
“So do I,” admitted Molly. “If only the polar regions are porous, you’ll really have to go back out and come for us the other way.”
“And it will be necessary to rethink our ideas about planetary air circulation from the beginning. I shall investigate in person, of course, before committing us to any premature conclusions.”
“Of course.” Molly hoped she had kept sarcasm out of her voice; if she had not, she was sure now that the Nethneen would spot it. She maintained silence for more minutes, wondering what Joe’s investigation would disclose.
“This is a bit embarrassing,” the quiet voice resumed at length. “There seems to be no real change in the planetary structure. I made another thoughtless mistake in programming.”
“Do you care to be specific?” Molly wasn’t sure she should have asked even that much, but couldn’t resist.
“Of course; it will serve as a warning for all. I had, of course, equipped the machines to detect and home to free metal, since the search for you and your robot carries high priority.”
“Of course. That seems perfectly reasonable so far.”
“True. My mistake was in failing to provide for shutting off all the other metal sensors when one had responded. It appears that one of the machines has found a metal object, and all are now converging on it. I regret to admit that I am going to have to reset them individually when I get there. This will take some little time; I trust you will forgive me.”
“It seems a natural mistake. I wonder what metal they found? Offhand, I see no reason for there being anything of the sort—how far?—two hundred, nearly three hundred kilometers below Enigma’s surface.” Molly was not just being polite; even she was more curious about the discovery than amused or resentful at the Nethneen’s planning slip. Not even Charley sounded superior as all chimed in with comforting remarks.
“I will certainly examine what they have found, but will be some time getting to it. I suspect the approaching passages will be somewhat clogged with my robots.”
“Maybe it will be in a cave.”
“Maybe. I will let you know. I assume you are still traveling.”
“Yes. Nothing to report. You, too, Charley?”
“Nothing much. My river has joined a larger one; I am continuing to follow downstream.” None of them asked Jenny, presumably busy in her laboratory.
It was more than two hours before Joe reported again.
“It is in an open cave, but my machines are so clustered around whatever they found that I can’t see it yet.”
“Maybe it’s just as well they didn’t find us,” Carol remarked.
“Oh, they can’t be in actual contact; they were set to stop a few meters away and keep reporting position. I’ll have to reset a lot of them before I can see what’s there, though; if I merely push them out of the way, they go back as close as they can without interfering with each other. I’m starting to work now. Five or ten seconds will be enough on each—I’ll simply turn off the metal search.”
With five hundred—but he won’t have to do all of them before getting to the middle of the pile, Molly thought. Well, we’ve waited longer before. She kept the thought to herself; there are times when ordinary courtesy goes in line with mere decency.
The minutes passed, and the women resolutely kept their eyes and minds on the passing scenes revealed by their lights. There was still vegetation, if that’s what it really was. Neither of them had seen anything resembling animal life, in the sense that it could move around under its own power. Bushlike, grasslike, and totally strange growths showed both beside the river and in it. Again they stopped to check liquid temperature and, as far as they could, composition. It seemed fairly certain that the water percentage was now nearly total; there was nothing obvious to tell what the plants were doing about this. There was no point in collecting anything else; they would have had to discard something else, probably just as informative. They went on.
Then Joe’s voice sounded, with the near-whisper that indicated use of the private channel.
“Carol! Molly! There is a problem here. I am not sure what I should—no, I’ll have to face it and solve it myself.” He shifted to the general translator channel.
“I’ve found what attacked the robots, and it is a little disconcerting.” He paused, long enough for Charley to get in his inevitable question.
“What is it?”
“It seems to be two suits of environmental armor, designed for different species. One I do not recognize by name, though I have seen members at the School. The other, while its design is not just like any I have ever seen, would fit a Kantrick. You could get into it, Charley, except for one fact.”
“What’s that?”
“It is already occupied, I regret to report.”
“You mean there’s a—a…” Charley produced a choking sound that Molly had never heard from him. Before she could begin to speculate on what her translator was doing, and what sort of signal her fellow student was actually putting out, Joe responded.