“Of course. I’d gotten so committed to the value of keeping going that I’d forgotten we didn’t have to!” exclaimed Molly. “We’ll just wait! When you find the river, Charley, you can follow it down to the fall and over, and we can’t possibly be very far from its foot. If we let ourselves sink to the bottom, we can probably stay put; and when you and Jenny get down here, you’ll be able to see our lights even if we are underwater—I mean…”
“Sorry.” The Shervah’s voice was softer and more apologetic than any of them had ever heard it. “We can’t wait here.”
Chapter Eighteen
Of Course There’s Inflow
“I don’t think I can take the temperature,” the Shervah explained. “I waded in that first brook for a while, and my feet were freezing even through the armor. If temperature gets too low, my air starts to condense.”
“That’s right; nitrosyl chloride has an awfully steep vapor pressure curve. Ail right, we’ll have to find shore somehow, or think of a way to dry out the inside of the robot and get it going again while we’re still swimming—that doesn’t seem awfully practical, somehow. But wait a minute—the temperature is a lot colder for me than for you, and your armor should insulate as well as mine. I’m perfectly comfortable—well, as far as that’s concerned, anyway. I’d give a lot to get out of this suit and wallow in hot water. Are you really getting cold?”
“Not yet. I’m reporting what happened earlier. My feet nearly froze while I was wading.”
“Did you measure the actual temperature of the brook?” “No.”
“Then the temperature of this puddle won’t tell us whether you’re really in trouble, but we’d better get it on general principles.”
Molly was somewhat mystified by the situation. As she had said, the ambient temperature was much worse for Human than for Shervah, and the small humanoid’s suit protection should be at least as good as Molly’s. Indeed, it must be; a vivid picture from fairly recent memory and more recent conversation preempted her thoughts for a moment. It was of a black, airless sky, dominated by half a dozen blazing O-type suns all within three or four parsecs. Much less impressive, though bright by Solar system standards at some seven hundred astronomical units, hung Fire and Smoke, the binary dwarves that formed the main mass of the School planetary system. None of their individual planets was noticeable at this distance. The foreground was a landscape of grayish, dirty methane ice, like the surface of Pluto. Molly and Carol had been together, just as they were now, with an assigned experiment. They had just reached Sink, the outermost common planet of the School suns, with its ten-Kelvin environment that was needed for their work, and this time it had been Molly who was uneasy. “Come on!” Carol had been saying. “It’s safe enough. There’s no gas to conduct; you can only lose heat to the ground, and there isn’t much contact area even for you. Don’t worry; I’ve been here before!”
Here on Enigma they did not have vacuum around them; maybe that made the difference in the Shervah’s mind. Molly would have to be the support.
She attempted to bring her set of wrist instruments in front of her helmet while swimming hard enough to keep from being sunk any further by the robot. She was not very successful and was a couple of meters below the surface by the time she had a reading. Its value surprised her enough to take all her attention, and the two went down even further as she called the others.
“Joe! Charley! The temperature is up about ten Kelvins from the value I reported in that upper cavern. Either we’ve come down an awfully long way, or something is carrying heat to this liquid. Do you check with that, Carrie?”
“Yes. I still don’t know whether it’s warm enough so I can stop worrying, though.”
“I’d think you’d be feeling cold already if your armor’s heaters weren’t handling the situation. I know ammonia doesn’t have the heat capacity of water, but…”
“But if this were liquid water, I wouldn’t be worried about the cold.”
“Is your armor refrigerating or heating right now?” “Heating.”
“Which was it doing when you were freezing your feet?”
“I don’t remember—didn’t notice. I suppose it was heating, but now that I think of it, maybe it was just trying to hold an average. I don’t know much about its heat distribution system or its internal sensing…”
“You should have made the armor yourself,” pointed out Charley. Carol, for once, had no answer; the criticism was completely right, and she knew it. The suit was part of her field equipment, and she should have known all there was to be known about it.
“Tell the rest of us if you feel the slightest bit cold or your air pressure seems to be dropping,” advised Molly. “We’ll look for dry land, but maybe we needn’t be as frantic about it as we thought. Let’s get back to the surface and try to see if we’re getting anywhere.”
But the surface came back to them. They might have been falling for several seconds—perhaps half a minute—before either of them realized that surface was all around them; they were once more inside a large drop rather than a whole river. They must have gone over another fall. Molly reported the fact, resignedly, to the three so far above.
“We’re trying to swim out of it, but the stuff is wet and sticks to us. It’s huge, too—the biggest by far of any we’ve seen yet.”
“Are your heads through the surface so you can see out?” asked Joe.
“We’re sticking out,” Carol replied, “but there’s too much stuff on our helmets to let us see. Why is it important? There’d be nothing but more drops of river floating down around us.”
“Different size drops, and different density objects like you and the robot, should fall at different rates—there is air, remember. I was wondering whether you were in front of most of the stream or behind it.”
“I don’t see how we could be anywhere but middle” was Molly’s contribution. “What we need is to get to one side and dry out this piece of hardware. That’s worth the effort of getting out of the drop for, though. Come on, Carrie—we’ll give some momentum to the robot as long as it’s in the liquid, and as it’s about to emerge we’ll try to get out ourselves. With luck, we’ll be clear long enough for me to dry off your helmet again, and you’ll have a chance to tell whether there is any direction that will get us clear of this stuff. I suppose we’re in another cave.”
“That’s what I was taking for granted,” agreed Joe.
“All right.” Charley was practically authoritative. “You two try to get dry, and Jenny and I will get back to mapping. Now we look for any river, I’d say, and follow it down. Sooner or later we get to the same lake, or ocean, or something.”
“One more delay,” Joe said firmly.
“What?” grated the Rimmore.
“One more piece of apparatus for your mappers, and never mind remarks about whether I should have thought of it earlier. Come back here while we install radar units in your machines. Right now you have to explore any cavern you find visually and might still miss some connecting passages. This way you’ll get every open space you enter, logged in detail the moment you’re into it, and your computers will maintain a complete three-dimensional image set that you can display for your own convenience to help you see where you’ve been, how to get back, or where other things are—if you get a broad enough total picture. Head back here; I’ll have the units ready for you when you arrive.”
Not even Charley argued.
Twenty hours later, Molly woke. There had been no particular stimulus; there was still darkness except for her lights and Carol’s, and at the moment not even translator voices. They were far enough from the river, for the moment, so that it was nearly inaudible, not that it made much noise anyway. The hours they had spent trying to win free of the falling drops when they were falling and to work their way out of eddies and other currents when they were flowing had been the main reason she had had to sleep. They had finally struggled to the bank at a point where the stream was practically horizontal, and carried themselves and the robot far enough from the weirdly writhing current to feel safe from it; there, even Carol had collapsed. The Shervah was still lying motionless; for the first time in Molly’s recollection, her eyes were actually closed. For a moment the Human heart almost stopped as she missed the robot; then she saw it parked on the rock a couple of meters away. Was it dry yet and the energy converter that was their life usable?