Then he was facing Chile again, just in time to see the robot’s feet and legs suddenly crush through the surface.
A robot’s reaction time is electronic as far as perception goes, but mechanical response is another matter, especially for one built to work in Uranus system temperatures. Chile’s legs sank for their full length, and what in a human being would have been his seat struck the ice sharply. About two cubic meters of the spur’s tip broke away under the blow, carrying robot and cube along. Ling watched helplessly as they began to sink slowly beyond the edge of the larger block, which unlike them was not yet falling completely free. Then his attention shifted again at a cry-a real shriek this time-from Sheila.
“What are you doing?”
By the time the man had turned far enough to see, it had been done. The ghost had almost collided with her and seized her arm; for a moment the two had formed another spinning two-body system. Then, using its legs, it had thrust itself off violently in a dive toward the edge, the reaction removing any doubt that Sheila would reach safe ground. Ling wondered for a moment whether it would strike him too; maybe it was a real robot acting under First Law. Then he saw it was aiming at Chile.
He himself was catching up with the main sliding mass, which must still be affected by friction. In a few more seconds he could jump, if he wanted to. A dozen meters up by then, and as far toward his own shadow-no problem. Plenty of time. As he touched the surface about three meters from Sheila’s stick, he even considered for a moment whether he should ride the mass down and get a closer look at the newcomer.
Then he realized that this might not be a good idea. The block was starting to tilt outward as friction continued to delay its inner part. He had no way of deciding how much spin it would acquire, but the Idea of being underneath when it reached bottom was as unattractive as the technique of climbing around it to stay on top was impractical. A blot of quick-frozen crimson glass under a mass of ice might make the day for some future archaeologist, but Ling was not feeling that altruistic. Chile could take care of things below; the new arrival had to be a robot. Surely no human being would make a deliberate dive into a hundred-and-fifty-meter gulf-though come to think of it such a drop wouldn’t have to be lethal-and maybe it was nonhuman in quite a different way-just tougher-why had it made the leap, apparently using Sheila merely as a convenient reaction mass for orbit correction?
“Rob! What are you doing? Don’t stay with that thing-get back up here, idiot!” The man returned to reality with a start which almost separated him from the surface again. He tapped the ground gently with a boot toe to swing himself onto the proper line, and kicked off hard. Again much harder than necessary; he was still rising as he passed over the new cliff edge, and another half minute elapsed before he landed not quite flat on his back. By this time, the detached fragment he had left was nearly halfway down the cliff, and Chile presumably even lower.
“Chile! Report!” Ling didn’t wait even to get to his feet to snap out the order.
“I no longer have the cube,” was the prompt response. “What is clearly another robot passed me in fall, and snatched it away. I saw it approach, but did not foresee its intentions. It has a somewhat greater downward component than I, and will land first, about eight seconds from now. I question the likelihood of my catching it, unless it turns out to be very much less agile than I. This is poor country for maneuvering. Do you wish me to try?”
“Keep it in sight,” Ling ordered without hesitation. “We want to figure out its origin if we can, and what it wants to do with the cube. Observe, and report at your own judgment. “
“Yes, Rob.”
“Can you talk to it?” asked Sheila.
“It has not responded to any standard signal impulses. If it was made by U.S. Robots, it is of a series unknown to me.”
“Does it emit anything?” Mike Eira’s voice came across the kilometers.
“Yes, it-pardon, Mike. Rob, it has just reached the ground, and immediately leaped back toward the cliff top. It should be near you and Sheila in fifty-five seconds. Mike, it has emitted many infrared bursts similar to those of the small cubes.”
“You’re recording them for Dumbo.”
“Of course. I have now reached the ground, and also leaped.”
“Maybe you should stay below, in case-”
“Too late, Bronwen. Rob said to keep it in sight, and I am now out of touch with the ground.”
“All right. It wasn’t much of an idea anyway.”
Silence supervened, while the robots orbited back toward the cliff top. The stranger just cleared the edge with a near zero vertical component; Chile had made more allowance for error and was three or four seconds longer getting his feet on the ground. By this time the ghost had settled to its knees-it was even more humanoid than had been obvious at first-and bent almost over the edge to put the cube down. A hemisphere which might have been dust, smoke, or ice fog expanded around the point of contact, spreading and thinning radially except where the ghost’s body blocked it, without the puffing and billowing which an atmosphere would have caused. After a few more seconds this ceased to form, and its remnants quickly dispersed to invisibility.
“The cube appears to have been replaced in essentially its original orientation,” Chile stated. Sheila and Ling were still too far back to see clearly, and were not approaching at all rapidly; there would be no loose mass to jump back from if they went over the edge on their own.
“Then we’ll stop worrying about it for now, and concentrate on the other robot,” Rob replied. “Chile, I’m afraid to ask this, but what can you tell us about the origin-the manufacture-of this thing?”
“As I said, it is not a make familiar to me. Like me, it appears designed to operate at the local temperature. It has no obviously nonstandard engineering.”
“You mean it could have been made by an appropriately skilled designer to simulate the motions and actions of a human or similar being.”
“Yes.”
None of the listeners bothered to ask whether there was any evidence of nonhuman origin; Chile didn’t have that kind of imagination, and certainly lacked appropriate experience. Ling and probably Mike Eira would have been afraid to ask anyway, though they could certainly think of sufficiently specific questions. For some seconds, ZH50 and his companions looked the ghost over silently, while it finished its work and slowly stood up. The human beings could now see some differences between it and their own robot; it was a few centimeters shorter, about Sheila’s height, its legs were shorter and its arms much longer for its size, and there was no neck. The head seemed fixed directly and immovably on top of the trunk.
“It is slightly above ambient temperature,” Chile reported, “but no more so than I. Heat generated by its recent action could explain it. It is certainly not producing low-grade energy at anything like the human rate. “
“Then there is no real doubt it’s a robot.”
“I see no cause for any.”
“Or a life-form that operates at Uranian temperatures,” suggested another voice.
“I have no way to judge that.”
“Get conscious, Luis. A hundred-and-fifty-meter jump? Humanoid shape like Chile’s-”
“I haven’t seen it yet, Rob; you’re thirty kilos or so away. What’s unreasonable about a human shape?”
“It just doesn’t seem likely in this gravity, and with no air.”
“You mean it has a nose? Even Chile”
“No, no, I meant-”
“Clear the channels, everyone,” came Bronwen’s voice. “Sheila and Rob, get back to Dibrofiad as quickly as you can. The rest of us will do the same. On the way, think of anything portable and possibly useful in communication; we’ll pick it up and get back out to Barco,’ if that thing stays. Chile, you stay with it. If it moves, follow it. Do your best to record and analyze anything it does and especially anything it radiates-I know analysis is more Dumbo’s and Sheila’s line, and I’d like to get what you already have back to Dumbo right now, but if that thing can jump up Barco, you ‘re the only one we can count on staying with it. We’ll have to wait for your data dump. Let’s go, people; Chile, observe, follow, and record, at any risk short of loss of data already secured.”
“Very well, Bronwen.”
Once out of Chile’s sight, Rob and Sheila traveled in rather dangerous fashion, taking much longer leaps than were really justified. Both felt that they remembered their former route well enough to avoid any really perilous drops. Even without walking sticks, the time lost recovering footing after a bad landing was more than made up by that saved in the jumps themselves. The sun had moved a little to their right since the start of the walk, but still formed a good guide to the Dibrofiad’s direction. Ling was again uncharacteristically silent during the hour of the return trip, and Sheila made no effort to learn his thoughts.