Rama 2 by Arthur C. Clarke and Gentry Lee

It was a weird sound, like dozens of unshod baby feet on a linoleum floor, and it was definitely coming in her direction. Nicole didn’t have much time to wonder. Seconds later the head and antennae of a centipede biot appeared at the edge of her pit and, without slowing down in any way, proceeded directly down the wall at the opposite end.

Altogether the biot was four meters long. It clambered down the wall without difficulty, placing each of its sixty legs directly against the smooth surface and holding on by some kind of suction. Nicole put on her backpack and watched for her opportunity. She was not that surprised by the appear­ance of the biot. After what she had seen in her vision, she was certain that she was going to be rescued by some means.

The centipede biot consisted of fifteen attached, jointed segments, each with four legs, and an insectlike head with a bizarre array of sensors, two of which were long and thin and resembled antennae. The jumbled pile of metal at the other end of the pit was apparently its spare parts. While Nicole was watching, the biot replaced three of its legs, the carapace for one of its segments, and two knobby protruberances on the side of its head. The entire process took no more than five minutes. When it was finished, the biot started again up the wall.

Nicole jumped on the centipede biot’s back when three-fourths of its body was heading upward. The sudden extra weight was too much. The biot lost its grasp and fell, along with Nicole, back into the pit. Moments later it tried again to scale the wall. This time Nicole waited until the entire length of the centipede was heading up the wall, hoping that the strength of the extra segments would make the difference. It was to no avail. The biot and Nicole collapsed into a heap.

One of its front legs had been severely injured during the second fall, so the biot made the necessary repairs before trying to ascend the wall a third time. Nicole, meanwhile, pulled all her strongest suture material out of her medical pack and tied one end of a long octuple thickness around the three back sections of the biot. In the other end of the suture thread she made a loop. After she first put on gloves to protect her hands and then fashioned a waistband to keep the thread from cutting, Nicole tied the loop around her waist.

This could be a disaster, Nicole realized as she imagined all the possible outcomes of her scheme. // the thread does not hold, I could fall. The second time I might not be so lucky.

The centipede inched its way up the wall as before. Several small steps after it was completely elongated, the biot felt Nicole’s weight from below. This time, however, it did not fall. The struggling biot managed to continue slowly on its upward path. Nicole kept her body perpendicular to the surface, as if she were rock climbing, and held onto the suture thread with both her hands.

Nicole was about forty centimeters behind the last segment of the biot as they scaled the wall. When the head of the centipede reached the top of the pit, Nicole was almost halfway out. Her slow and steady climb continued as, segment after segment, a portion of the biot left the pit above her. A few minutes later, however, her progress slowed markedly, stopping altogether when the number of centipede segments remaining on the wall dropped to four. Nicole could almost touch the rear segment of the centipede if she stretched her arms above her. Only about ,one meter’s length of the biot was still on the wall, but nevertheless it was apparently stuck. Nicole was putting too much strain on the joints attaching the rear segments.

Grim scenarios ran through Nicole’s mind as she dangled more than six meters above the floor of the pit. This is great, she thought sarcastically, as she pulled tightly on the suture line and placed her feet firmly against the wall. There are three possible outcomes, none of them good. The thread could break. The biot could collapse. Or I might remain suspended here forever.

Nicole considered her alternatives. The only plan she could conceive with even a reasonable probability of success, and it was still very risky, was for her to climb up the suture thread to the last segment and then, somehow using the body or legs of the centipede as handholds, to muscle her way to the top of the pit.

Nicole glanced down and remembered her first fall. I think I’ll wait awhile first and see if this machine gets moving again. A minute passed. Then another. Nicole took a deep breath. She reached up high on the suture line and pulled herself up the wall. She repeated the process with the other hand. She was now right behind the last segment. Nicole reached out and grabbed one of the legs, but as soon as she tried to put any weight on it, it pulled free from the wall.

So much for that plan, she thought after a moment’s fright. She had restabilized herself just behind the biot. Nicole studied the centipede again very carefully. The carapace of each segment was made of overlapping pieces. It might be possible to grab one of those flaps, . . . Nicole recon­structed her first two attempts to ride on the back of the biot. It was the suction force of the feet that gave out, she thought. Now most of the biot is on the level ground above. It should be able to hold me.

Nicole realized that once she was on the back of the biot, she no longer had any protection against falling. To test the concept, she pulled herself to the top of the suture line and grabbed the carapace flap. She was able to get a firm grip. The only question was whether the flap could support her weight. Nicole tried to assess its strength while holding onto the suture with her other hand for safety. So far, so good.

Nicole grasped the flap on the rear biot segment and cautiously pulled herself up. She released her grip on the suture thread. Then she wrapped her legs around the side of the centipede’s body and scooted along until she could reach the next flap. The legs of the rear segment popped off the wall, but the centipede did not move otherwise.

She repeated the process twice more, moving from segment to segment. Nicole was almost to the top. While she was on her final climb, she had a brief scare when the biot slipped a few centimeters back into the pit. Hold­ing on breathlessly, she waited until the biot was stable and then crawled forward to the first segment that was on level ground. As she was crawling, the biot began walking again, but Nicole just rolled off sideways and landed on her back on the ground. “Hallelujah!” she shouted.

As she stood on the wall around New York and stared out at the moiling waters of the Cylindrical Sea, Nicole wondered why there had been no answer to her call for help. The self-test status flag on her radio indicated that it was working properly, yet she had tried three separate times without success to establish contact with the rest of the crew. Nicole was well aware of the commlinks available to the cosmonauts. Failure to receive a reply meant both that no crew members were within six to eight kilometers of her at present and that the Beta relay station was not operational. If Beta were working, Nicole thought, then they would be able to talk to me from any­where, even the Newton.

Nicole told herself that the crew was doubtless onboard their own space­craft, preparing for another sortie, and that the Beta communications station had probably been disabled by the hurricane. What bothered her, though, was that it had already been forty-five hours since the onset of the melting and more than ninety hours since she had fallen into the pit. Why was nobody looking for her?

Nicole’s eyes scanned the sky for some sign of a helicopter. The atmo­sphere now contained clouds, as predicted. The melting of the Cylindrical Sea had substantially altered the weather patterns on Rama. The tempera­ture had warmed up considerably. Nicole glanced at her thermometer and confirmed her estimate, that it was now four degrees above freezing.

The most likely situation, Nicole reasoned, returning to the question of the whereabouts of her colleagues, is that they will return soon. I need to stay close to this wall so that I can be easily seen. Nicole did not waste much time thinking about other, less likely scenarios. She considered only briefly the possibility that the crew had had a major disaster and nobody had yet been available to look for her. But even in that case, she said to herself, I should follow the same approach. They would come sooner or later.