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 difficult 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.
Suddenly the dam burst. The simple circulation of their weather pattern gave way to the extraordinary pressure at its center and broke into chaos. Strong currents slammed across the armored men. Tem hadn't reset his inertial control secondaries, and he began to tumble until he did so. The gas pressure that surrounded him, his only real protection, began to shudder violently.
As he felt his body begin to pogo inside the suit, Brendan carefully analyzed their position—they couldn't take much more of this. They had penetrated the surface to a depth of about four hundred meters. It wouldn't be long until they broke into the weird cavity, if that's what was going to happen. The tumult grew stronger, and even the gyroscopes were having a difficult time keeping them stable. Another thirty meters or so, thought Brendan, and we will be there. . . . Unexpectedly, they hit bottom. Something soft gave way beneath their feet and, if the instruments were correct, rebounded slowly, without secondary flexes. The neon, now mixed with a hundredth part of argon and methane, still boiled and swirled around them, but it was growing weaker. Brendan bent down and jabbed a steel-rigid finger into the surface. It was resilient, almost like a kind of soft wood. He scored it and the depression quickly healed itself. He shared his findings with Krzakwa. He generated an image of the man's face for himself and studied its convolutions. "So. Now what do you think?"
The Selenite shook his head. "I ... refuse to speculate." He studied the data that were being reported to him. Some light was making its way down through the piled-up gases above. The vapors were rapidly dissipating as he watched.
"Doesn't matter if you do or not. I think . . ."
"Shut up, damn you!" Krzakwa was biting at his lower lip, sucking in some hairs from his beard. Sealock grinned to himself. "Right," he said.
It cleared. They were standing on a flat surface of a dull blue-gray color, almost obscured by a thin layer of small, glassy nodules. The walls of the hole they had dug rose up and up, seemingly solid, about three hundred meters around. Tem looked up and saw a shaft of sunlight slanting across the mouth of the hole.
"Well," said Sealock, "does this look like rock to you?"
"No." Krzakwa let out a long, slow whisper of breath. "It's time to say it. Artifact."
"I guess we've found a little adventure, after all."
Brendan cleared a small area, scraping the surface with his foot to knock the little beads flying in slow arcs. When he was satisfied that a large enough area was clean, he bent over and played his photochips over it, straining his suit systems to tell him anything they could about the material. He looked up at Tem.
"Again: what do you think?"
"We need better instruments." He pulled a geologist's hammer from its waist clip and, kneeling also, slammed the pointed end down. It left a small dimple that slowly sprang back to normal. "You tell me, Brendan. What inert material stays pliable at 43 degrees Kelvin?"
"I might as well be the one to say it this time: alien artifact. This is not our tech."
"Sayyarrin's floor is relatively uncratered—but even so, that surface is old. If Jana's right, we're talking millions of years. Maybe billions."
"What's that?"
Brendan pointed to a place on the hole's wall, where a thin, dark, ruler-straight line over 250 meters high was embedded. It went almost all the way back to the surface. Tem was laughing uncontrollably. He finally got control of himself, breathing heavily, tears running down his face. "That's a fucking fin. This is getting ridiculous."