by Ben Bova
“Rob, you moron, what were you trying to do? How are you going to get up here? Here-catch my stick!” She tried to hurl her alpenstock toward him, but her own spin betrayed her. He watched it whirl by a meter out of reach, strike the ice, and bury its sharp end in the surface.
“Relax, lady. I’ll get back down in a little while, and can jump again. Look-it’s not falling free; it must be sliding along the break. I’ll catch up.”
“When?”
“Hmmm…maybe ten or fifteen seconds.”
“How far down will the ice be by then? Will you still be able to jump that far?”
“Sure. We’ve all made bigger jumps here. The lovebirds did a forty-three-second one holding hands a couple of weeks ago, when they were celebrating their name anniversary:”
“What’s going on over there?” Bronwen’s voice came in. The Eiras didn’t really resent the geochemist’s frequent way of referring to them, since it was certainly not inaccurate, but her voice was a little sharp.
“Cliff edge broke under us. Still plenty of time to get back up,” Ling replied tersely.
“Chile! How did you-” Sheila’s voice cut in, and broke off as suddenly. Rob was facing the robot as she spoke, and saw nothing to motivate the question; there had been no visible motion by ZH50 since starting to lift. Then his body spin carried the man around to face toward cliff and woman, and the words made sense. Drifting through the vacuum only a few meters from her was a form which, in the dim light, seemed exactly like Chile.
The resemblance was mostly its black color, Rob realized almost at once; this was by far the best look he had had at the ghost. As far as general outline and size were concerned, it could have been any other member of the group. Each environment suit, however, bore a brilliant color pattern matching the team name, pale green for the Jengibres and orange for the Eiras, with black helmets for the men and white for the women. The pattern was for ease of seeing and instant recognition rather than any artistic consideration. For a moment, Ling’s bright hopes collapsed; it would have been quite possible for someone to send a group with only robots from Earth. In fact, that had been considered at some length. No ETI…
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 i
t 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.
The other two couples were equally in a hurry, and neither had as far to go, so they reached the ship first. The trouble was that, once there, no one could think of any really useful apparatus which could be carried, even on Miranda, and which promised to be more effective in communication with a robot than the lights and radios which they already had and the broader-spectrum equipment possessed by Chile. Dumbo was not portable. They had all gone inside, unsuited, and taken care of physical necessities; conversation had been almost continuous through all this, but no really promising suggestions had been made by anyone.
“Who’d have thought we’d need a language specialist?” Luis growled at last.
“How do you know we do?” asked Bronwen. “It may have been made on Earth, by some group we don’t know about.”
“Did you or Rob try ordering it to come back with you?” Chispa asked Sheila.
“Neither of us thought of it. Chile said he’d tried normal robot-to-robot signals with no response, and I guess we were both so convinced it was alien that ordinary speech seemed pointless.”
“You still should have tried.”
“Admitted. We still can, you know. Call Chile and have him order the thing to accompany him back here, in every symbol system he considers appropriate. “
“Will it obey orders from another robot?”
“Will it know Chile’s a robot?”
“Probably. It radiated infrared, and presumably senses it. It should know that he operates at local temperature, and we don’t. The inference would certainly be within Chile’s powers; we don’t know about this one’s, of course.”
“If it’s really alien, it might infer from that that we’re the robots, with inherently wasteful power equipment, and Chile is a native life-form. The trouble is, we don’t know its background,” Mike interjected.
“You’ve got your feet on the wrong pedestal, dear. If we’re trying to give it orders at all, the assumption is that it can understand us, and must be human made.” His wife didn’t dwell on the point, but went on. “We have to try, anyway.” She didn’t bother to check for open channels; there was always one through to the robot. “Chile.”
“Yes, Bronwen.”
“Any change?”
“None. It is standing facing me, presumably waiting for me to do something. It has now cooled down to ambient temperature; I would say that any doubt about its being a robot is gone.”
“You can’t sense an atomic power source?”
“I am not equipped to pick up such radiation directly.”
Bronwen had known that, but was feeling desperate.
“Try talking to it directly-”
“I have done so, every way I can.”
“This time, send your message as an order to approach you. If it responds, order it to follow you back to Dibrofiad. “ There was a brief pause.
“No action, Bronwen.”
“If you had received such an order from it, would you have obeyed?”
“Not without checking that the order had originated from a human being, or obtaining the approval of a human being. “
“So we haven’t proved anything. “ There was no response to this; Chile had no reason to interpret the remark as a question to him, and the human beings recognized its rhetorical nature. An uncomfortable silence ensued.
“Bronwen, let me try something?” Ling finally spoke, in doubtful tones. The commander nodded, not bothering to ask the nature of his idea.,
“Chile, the robot replaced that cube as nearly as possible to the place it was before the cliff broke off. It seems concerned with it. Without going to extremes if it interferes, approach the cube yourself as though you intended to pick it up again, and tell us how it-the robot-responds.”
There was another pause, while six people tried to imagine what was happening twenty kilometers away.
“It has interposed itself between me and the cube, and has been moving to stay so wherever I go.”
“Any body contact?”
“No. You said not to go to extremes. Shall I push it out of my way?” Ling looked thoughtfully first at Bronwen and then the others. The commander’s eyes also met theirs, in turn. Finally she nodded again.
“All right, Chile. No real force, just a suggestive shove.”
“Understood, Bronwen.” Imaginations fired up again.
“The response has been complex. It braced itself to resist my push, after I had made contact; naturally, it had to yield some distance to accomplish this. While it was setting its feet, it emitted a brief, very detailed burst of infrared, of the same general nature as we detected originally from the small cubes. This was immediately followed by a similar signal from elsewhere. It then ceased pushing against me and simultaneously seized my arm and pulled. This sent me over the cliff edge. I am now falling, and will be unable to do anything effective for the next fifty-five seconds.”
Ling blinked, and a grin spread over his face.
“Chile, did you determine the source
of that other signal?”
“Direction, not distance. I did not move enough for parallax while it lasted. However, its line touches ground just at the edge of Big Drop, in Block Twenty-five, seventy-one meters from the boundary between that one and Block Thirty-seven.”
“Great. Head for that spot as soon as you’re down. We’ll meet you there.”
“All right, Rob. You no longer want me to keep track of the other robot.” It was not a question.
“Don’t worry. It’ll be keeping track of you, I expect.”
“I see.” So did the others, and there was a general rush to get into armor. There was some delay, however, in going outside.
“Hold it,” Bronwen said firmly before helmets were donned. “We’re going to the Big Drop, and no one could stand a twenty-kilo fall; it would be about four hundred and fifty meters on Earth. I still don’t trust the chains, but we link up this time. “
“How close?” asked Mike.
“Fifty meters for the Gold team, twenty for the rest of us. If anyone but Chile has to get near the edge, Rob’s the best anchor, so Sheila can do it. Fifty meters will give him more room to catch the surface, and us more time to help, if she does go over; twenty is enough for us. I’ll carry the rest of the reel just in case.”
“It won’t reach five percent of the way down that cliff!”
“It would take a couple of minutes to fall five percent of the way. We’ll take the chain.”
Her husband nodded. Sheila had paled a trifle, but said nothing. It was true that Ling was the heaviest of the crew, while she herself was lightest except for Chispa. She had no intention of going nearer the edge than necessary, and certainly none of going over, but Bronwen was right to be foresighted.
The chain links were carbon-filament composite a millimeter thick, preformed in jointless loops half a centimeter long and already interlocked. Neither rope nor cable was practical; no known fiber, organic, metallic, or mineral, would remain flexible at Miranda’s temperature. The link material had a tensile strength of eight hundred kilograms as straight rod under Earth conditions, dropping to about five hundred at seventy Kelvins, with some remaining doubts about its elasticity in that range and more about the nontensile stresses and possible shock brittleness in its looped shape. No one had wanted to make the field test, but an armored person weighed only about two kilograms.