Iris

by William Barton

  It looked much like Mimas: a small, spherical worldlet punched open by deeply inset bowllike craters. Unlike those on Podarge, the craters were deep enough relative to the curvature of the satellite to show perceptible shadows well away from the terminator, making the moon appear even more ravaged. There was a disproportionately large crater on its leading hemisphere. It was not so relatively large as Herschel, Mimas' great eye, but it still stood out from the rest, had stared at them as Polaris closed in. They remembered how Jana had remarked that this crater, Sayyarrin byname, was unusual not only in its size but in its shallowness, given the fact that Aello had no viscous relaxation to buoy up the middle. Now Sayyarrin was over the limb, in night. Here too, orbiting was a very inefficient process, and they were accelerating downward, watching the broken surface come up to eclipse the large blue circle that was the

  "day" side of Iris.

  "Not very impressive, huh?" said Brendan,

  "I don't know," said Krzakwa. "Maybe our expectations were just too high. After Podarge, I'm developing a more philosophical approach."

  Sealock stared at the cold, dim worldlet through the ship optics for a while, then said, "We're going down, this time. That should be something."

  "Are you kidding? This is it, Bren! We're going down onto that most elusive of all things, a primordial world. What we'll be seeing down there has never been seen before."

  "Come on!" said Sealock, grinning as he continued to inspect the vista that was unfolding below them.

  "That's a pretty fine distinction, if you ask me. I mean, you can have all the planetesimals you want out in the Oort belt—what difference does it make if we pick them up here?" Krzakwa wondered if Sealock meant what he'd said or was merely being aggravating. He decided it didn't matter. "Well, Iris doesn't have a cometary ring, for one thing, so this is it as far as Iridean planetesimals go ... but it's more than that: this isn't even a piece of the Solar System! Aello not only has all of its materials intact, but they are laid down in the same order they originally came in. It's like a Grand Canyon—you can dig directly into the history of Aello and, in effect, into the history of the formation of Iris and its moons. Things are disturbed by the craters, but only a bit."

  "OK. I give up. I'm impressed. So what do you want to do?" he asked, sitting back in his harness.

  "Looking at this thing, I begin to realize just how difficult it would be to land our ship. It'd be pretty hard to come down with the engines flaming. On H2vent-thrust only, I guess, we could . . ." Krzakwa cut him off. "I've been thinking about it," he said.

  "How does this sound: we suit up, eliminate radiation from the worksuits, and jump . . ." Sealock suddenly stopped moving, staring into dead space for a second, then he turned to look at the Selenite again, his eyes seeming to glow. "You son of a bitch. Sure! Like that boil-gliding business ..." His imagination chewed at the details of the notion: "I'll put her in a low orbit, maybe half a kilometer up. The jump won't kill us. We use pressurized O2from our life-support systems like jets to get back." He sat back in his couch, gloating to himself. "And we make a suit-instrumented rendezvous with Polaris at the end of it all. . . . Hell, this is really going to be fun!"

  Aello spun underneath them as Brendan maneuvered the ship down into an orbit so low that they could make out the unmistakable shadow of the craft near the huge, uneven horizon. Even with the weak gravity, this deep in her gravity well Aello effectively swept them along, and the wells of shadow that were craters moved under them quickly. Brendan was fully engrossed in his piloting, plugged into systems that effectively made him an incredibly sensitive receptor. He rushed along, sensing his passage with radar, and could feel the gravitational anomalies caused by variations in the moon's shape and constituents as a series of small velocity changes. He cataloged them as he flew, feeding data to the calculations that Krzakwa was making, fine-tuning their notions about how the orbit of the ship would precess while they were down on the moon. They needed to know. As he delved deeper into the substance of the world, reading it carefully, all the while avoiding an intense radiation flux that would disturb sensitive materials, his eyes became totally blind to the bottomless craters that were calling forth the nightside.

  He was just about to disconnect from his systems, in preparation for going down, when something in the residuals of the newest ship computational ephemeris caught his attention. He checked a map and saw that they were passing over the very center of Sayyarrin. This is some kind of a weird little anomaly, all right, he thought. Really weird . . .

  "Tem," he said, "are you monitoring the external sensor returns?"

  "Uh-huh," said Krzakwa, "what is it?"

  "You're the physicist, buddy, you tell me."

  Tem studied the figures of the ephemeris in his head, brought in a calc overlay, and spent a full minute processing. Finally he said. "I think we must've put one of our machines together backward. It's a glitch."

  "Oh, yeah? OK. Here's an updated computation, seven seconds old. If that's a glitch it's got a sense of humor."

  " Materi bogu!There's some kind of void down there, under the ice."

  "Impossible. It's not a void, it's a shell of some kind. A thin layer of mass around an almost massless core. Now what in the fuck could cause that?"

  "Speculation, you mean? Some kind of hollow meteorite?" As he said it, he realized how unlikely a thing that was. It could happen, yes, but on this scale?

  Sealock said: "But look at the size, the dimensions. This is not exactly a high-resolution picture—but even the parameters of the orbit suggest something more like ..."

  Krzakwa shook his head. This was ridiculous. There were explanations. Besides . . . "There's nothing in the view that suggests anything unusual. There are volcanic chambers all over the outer Solar System." He marked the spot, now rapidly disappearing behind them, with a bright optical V. In the deep IR

  they could see the low rim of Sayyarrin and its rather smooth floor. Perhaps it was just a tiny bit darker, colder, than its surroundings: a dim shape under the ice. Then it was gone over the horizon. Brendan violently spun Polaris around, inertia tugging at their bodies, and lit off the engine. The craters slowed, stopped, and the bright line that was day receded back behind the world. Sayyarrin popped over the horizon and, when they were directly over it, Sealock repeated his action, this time slowing the ship to a dead halt over the center of the crater. Tem could only tell from his instruments that they were falling, gently, toward the ice less than half a kilometer below. Brendan turned up the gain on the photochip , isolated a narrow region in the far infrared that would best define the heat differences they had seen, and, yes, there it was.

  He pushed the ship back into an orbit, paying little attention to its parameters. When they were flying above the ice once more he turned to look at the Selenite. "So. You're saying Sayyarrin is a caldera?" He called up some imagery from the Shipnet element and its source files, staring so hard into the image in his brain that he squinted malevolently. "That sort of contradicts the picture you were drawing before." Krzakwa nodded slowly. That was the way it seemed, but . . . Damn it, there had to be some kind of reasonable explanation. "I don't know. Day comes in about three hours. It will take about half an hour to suit up. I say we get Polaris back in the right orbit and go down in the suits. There really is no telling what will happen if we try to land in that stuff. It might be the most effective way to reach the lower stratum—but the ship could easily be damaged by the violent sublimation, even in this paltry gravity." Brendan seemed to pull back into himself somewhat. "Mmm. Yeah. We turn up the heat of our suits and fall through the neon. Any turbulence that creates, we can certainly deal with. OK—full speed ahead."

  Downlink Rapport wasn't getting any easier. Insofar as the thoughts and feelings of John and Beth were couched in linguistic or sensory terms, the transfer was without effort. But underlying personal emotions and states of being were more difficult, flooding into the brain as strange, ephemeral data. Understanding required a great
deal of work. Memories were a lingua franca between them, perhaps because, even in an individual, memories come from somewhere far off, separate from the "self." It was easiest to tap into the full experience of being another person through the facility of the past. It came: they were annoyed. No matter what subject John tried to initiate, Beth would turn it aside. In bed, back in her condo in Yellowknife after a long winter walk through the streets, their bodies touched and his cold hands were enfolded within the damp warmth of her armpits. Their wet clothing was strewn across the floor, and waves of heat billowed up from the vents. Snow tapped against the window. Their faces were still flushed from the cold, his a ruddy orange and hers an empurpled brown. Despite the physical closeness, they were in sealed, isolated worlds. John was struggling to overcome a feeling of futility, and the emotion emerged into the world as a series of quick, occasionally savage ripostes. Beth swallowed these outbursts quietly, if only because they were so unlike what she had come to expect in his behavior.

  "That's the point, Beth. The money keeps coming. Something should be done with it; something purposeful. And I . . . I've lost a context. I know I say things about living for the moment. At one time I could do that, but not now. The time has come to do something." He laughed. "I've come back to the place where I started, and for the first time I know it's boring."

  "If your music isn't an accomplishment, I don't know what is." How could he explain to her that the time of their courtship, when he had felt a context, largely defined by their passion, had ended? That he needed to break through into something deeper, something to convince himself death wouldn't come sneaking up and claim him unawares? He thought about the money again. "What have I done with the money? Bought a house, two houses, an asteroid? What good is it all?" A new bond was growing between them, out of their disparity. The unresolvable dilemma had been resolved, and the truth was being found out. Gladness filled him.

  They broke. "Well," Cornwell said, "hello again." His voice was quiet but amused, "How are you?" They kissed, briefly, without passion. He stood, woozy even in the low g. Beth was staring at him. She felt tired. "All right," she said.

  "Let's go get something to eat."

  Shutdown.

  They had to don the worksuits and exit one at a time. Though the things were not terribly bulky, no larger than theordinary vacuum suits of a century earlier, they were rigid and maintained their fixed shape. It was in stark contrast to the usual sort of spacesuit, which could be crushed into a tiny ball when not wrapped around the form of a human being. Sealock went into the airlock, which was a cylindrical chamber two and a half meters across by two high and looked around. The two suits were like two extra men, and there was no room for the Selenite. He sighed, wondering why they simply hadn't made it a little larger. Some aesthetic pressure. Who knew? This had just seemed like the right size and shape to use, and that seeming had obviously been wrong. Krzakwa closed the hatch, cutting him off from the CM, a last view of him looking like a troglodyte in his cave. Temporarily, Sea-lock had donned a communications circlet, though he'd always ridiculed the things. "I'll let you know when I'm done," he said. The suit was permanently made in one piece, its helmet and backpack already attached. Before climbing in through the opening that split the front, Sealock reached up into the helmet and unreeled the twelve brain-taps that marked this suit as his alone. He discarded the circlet and quickly plugged himself in, powering up the suit. "Do you read me?" Affirmative. He crawled in through the opening, squirming as he put his arms and legs down their proper holes. It was difficult, though possible, and he wondered just how Krzakwa managed to do it, fat as he was. The designers probably could have come up with something better, but . . . this was as sturdy a system as twenty-first century could come up with. By using appropriate settings, a man in a worksuit could walk around on Mercury or go for a stroll beneath the soupy seas of Titan. . . . He closed the front, lit off the life-support systems, and established a link with the ship's 'net element. "I'm going out now."

  "OK." The pressure in the airlock dropped swiftly and was gone, the gases pumped back into a storage tank.

  When the vacuum was fully established, he popped the outer hatch and floated into the night. The hatch closed behind him, leaving him physically isolated, floating beside the smooth length of Polaris, with the cold landscapes of the small moon running by below, an unending vista ofexcavated features, all of them similar. He could see the ragged terminator coming up over Aello's horizon; and Sayyarrin wasn't much beyond that.

  After a while the hatch opened again and Tem emerged to join him. Things were about ready. Wordless, they floated away from the ship, orienting themselves so that the primary cold-gas thrusters of their suits' OMS/RCS harnesses were facing in the direction of orbital travel. The suits' internal logic units were designed for this sort of operation, and so they would lose little information if they had to disconnect from the ship's systems. Hopefully, they would be able to maintain communication with the more powerful 'net element but, if not, it would probably be all right. They watched the craft drift away from them. The surface of the moon was as dark as the starry sky around them, and only the great burning crescent at Aello's limb gave any sort of perspective. The mind tends to place itself as the stationary center of the universe, and here, hanging between Polaris and Aello, it did its best to define their situation thus. It tended to view Aello as "down," but, in little bursts of alienness, they could see themselves as suspended below a dark sky with a curiously inverted sunrise rushing toward them, flying above their craft on silent wings. Their orientation was very dependent on which way their feet pointed, and they tried to keep them toward Aello. As they applied the jets, their speed dropped and they fell, moving away from the ship. It became a small, dark thing with inappropriate-seeming highlights.

  The sun rose, its rays washing over them in streamers. The broken rim of Sayyarrin was visible now, and the terminator came on like the edge of a fragmented planet. Another moment for action came: what in a normal landing would be the high-gate procedure was required, so they initiated a continuous "burn" that stopped their forward movement and dropped them toward the surface. Through the suit optics they saw their spaceship flying away. In a matter of minutes it was gone beyond the horizon. Aello, dominated by bright-lipped pools of black, looked like a shallow mud puddle through which a hundred childrenhad run. They were no more than two hundred meters up, and the little world suddenly seemed very big. Sayyarrin, a dark, crumbled rise preceded by a great apron of shadow, came to meet them. Tem noted that it seemed a normal enough impact crater, shallow, as Jana had said, but having a general morphology well in accord with what he knew about large impacts on worlds of this sort. Its lack of a central peak was not strange, given the volatile nature of the target—the energy of impact easily liquefied the neon, causing a flowback that would drown the rebounding bed-ice. If the hot spot on Ocypete was caused by a radioactive infall, wasn't it possible that a similar object had somehow caused a shield cryo-volcano? He wished he knew more about all this. Sayyarrin certainly didn't look like Olympus Mons, or even Eblis Mons on Ariel.

  They were over the relatively new, randomly peppered floor of the sunlit crater, and the anomaly was now coming over the horizon. In a matter of minutes they had come to a stop about a hundred meters over its center, their suit systems registering only a slight drop in the minimal heat flow emanating from deep within the moon.

  "Look down there, Tem," said Sealock. "It's sublimating already, from the jets. As a physicist, what do you think is going to be the greatest danger if we just land?"

  "Really, not much. I have the feeling that the turbulence will buffet us around, but well within the stress limits of these suits. You may feel cool as the suit's heating unit struggles to keep up with the enthalpy. I am certain that the pressure won't build up sufficiently to produce a liquid phase." They were now slowly falling toward the white ground. "If it gets too violent, we can just activate the thermal dampener fields. It shouldn't be too dif
ficult to do this in stages."

  "I guess not." Brendan was hardly listening to him as he looked around. This had the precise flavor of an adventure, a real one, and if he could only pay close enough attention . . . A shroud of neon mist began to hide and soften the small craters. As it grew in opacity, they could see it swirling outward, caught in little eddies and boiling upward. Ranginginstruments revealed that the ice directly below them was caving downward; mists were lightening the sky and streaking it with moving nebulosities . Their speed of descent was increasing.

  Just before the neon totally obscured everything, Tem saw that the small motions had combined into a spinning weather system, driven by the heat at its center and Aello's not insignificant Coriolis force. He could imagine it slowly spreading across the world's surface until the various powers interacted and a global meteorology began. It would all end as the neon quickly froze and precipitated. They fell past where ground level had once been. Although they were in a clear pocket—neon vapor could not exist at the temperatures in their vicinity—visual input gave no clue as to what was going on. The world was formless.

  The clouds pressed in closer to them, and the sound of crackling and snapping was brought to their ears by the tenuous gas around them. Brendan felt the first tentative surgings of the gas against the suit. Somewhere, electrostatic discharges were occurring in the mist. He upgraded his gyro control, just in case.