Bony was no deep-sea diver; still less was he a bold explorer. As he took that first, possibly fatal step, he paused and looked down.
The base of Airlock Number Two sat about three meters from the bulbous rounded end of the Mood Indigo. That base was where the drive unit was housed, and as the heaviest part of the ship it had hit the seabed first when the vessel drifted down through the water. Bony could see, directly beneath him, a broken array of sharp-pointed gold-and-green shafts, two meters long and scattered like toothpicks by the impact.
He held the side of the hatch and lowered himself slowly through the opening. When he was in water up to his waist, he hesitated. He had stated, very confidently, that the chemical properties of deuterium oxide were the same as those of ordinary water. But was that true? Was heavy water just like regular water for all normal purposes, except for its greater density? Bony thought so, but he was no more a trained chemist than he was a trained engineer. Also, he could not tell how strong those pike-like stems beneath him were. He had to be sure that he didn’t impale himself on one that still stood upright.
“Are you all right?” said Liddy’s voice in his helmet.
“Yes. Just being cautious.” Bony had another thought. “I’ve realized something: radio signals designed for space or air use won’t travel through water. Once I’m immersed we won’t be able to talk to each other. Don’t worry, though, I’ll be all right.”
I hope. Bony lowered himself farther. Mid-chest. Shoulders. Chin-level, nose-level, eye-level. He was fully immersed, staring into limpid depths. Was this what the oceans on Earth or Europa looked like? He had never been totally under water before, so he had nothing with which to compare. The water had a bluer tinge than he had expected. All the old talk about “the deep blue sea,” and it really was. After hanging for a few seconds, he released his hold on the side of the hatch.
He was ready for a sudden drop. Instead, nothing seemed to happen. Another disturbing thought crept into Bony’s head. Heavy water was quite a bit denser — eleven percent denser — than ordinary water. Suppose that he, in his suit, was lighter than the salty heavy water that he displaced? Then instead of falling to the seabed he would rise toward the surface. He did not know if he could use his suit’s thrustors under water. If he went up, he might have no way to return to the ship.
And then he realized that he was in fact drifting downward, so slowly that he had time to tap on the lowest port of the Mood Indigo when he reached it, and still be there to wave reassuringly to Liddy when she hurried over to look out. She mouthed at him, he was not sure what. “Be careful,” that seemed clear enough. But the rest of it? “Don’t something-or-other.”
Whatever it was, he would try not to. Bony turned his attention downward. He was just a meter above the surface, and there was no way that he could avoid landing on the flattened pikes. He was lucky to be so close to the ship, because a couple of meters farther out the thicket of spears still jutted upright.
The final impact was feather-soft. Even so, as his boots touched the spikes they crumbled to a cloud of dust that rose up all around him. They seemed like crystals, infinitely delicate and fragile. Bony realized that he had never been in a moment’s danger.
Danger from the spears, that is. Bony stared along the gentle slope of the seabed, and as he did so the light around him dimmed. Just as quickly, it brightened back to its earlier level. Bony looked up. Far above him he saw a vague tri-lobed outline, moving away. Something huge, in the water or above its surface, had passed over his head.
Bony shivered. The smart thing to do was to return at once to the Mood Indigo . He had made his point. He had proved that they could leave the ship and make necessary modifications to the auxiliary drive, enough to allow them to leave Limbo’s ocean floor. But Bony could see better now, as the dust from shattered pikes settled in the still water. The ship had landed in the lowest part of what seemed to be an underwater valley, right where the standing spears grew thickest. Forty meters away, the world of the seabed faded and merged into a sea of uniform green; but just before that, the array of spears ended. Bony could make out the faint outline of rounder shapes on the slope.
He stood still and checked the condition of his suit. He had air enough for eight hours, ample drinking water if he needed it, and good thermal balance. He felt neither too hot nor too cold. The light around him seemed a fraction brighter than when he first emerged. Assuming that they were on the seabed of a planet somewhere in the Geyser Swirl; that the planet rotated on its axis with a period to give it a day comparable in length with an Earth day; and that the planet moved in orbit around a star — lots of assumptions, but each of them reasonable — then the brighter light indicated that it was still morning on Limbo. The only thing at all abnormal was the tendency of his faceplate to become covered with small bubbles. That must be a side effect of the superaerated sea, and it ought to decrease as the suit visor became the same temperature as the water. Bony could go quite a bit farther, without a danger of being caught by darkness. And if he went back now, Liddy would wonder why.
He moved carefully forward, passing across the broken shafts until he came to the array of upright ones. Each standing spear was a couple of centimeters across and rose taller than his head. Close up, he could see a brighter line running up the middle of each. He reached out to take one between finger and thumb, and at once it shattered. He tried again, with the same result. No matter how delicate his touch, the shafts fell in two. As they broke he heard a faint chime like a crystal bell, and the bright line faded within seconds.
If he wished to know what lay farther up the side of the drowned valley, he had to cross the field of spears. Feeling like a ruffian, too ham-handed to touch anything on this planet, Bony pushed his way through. He left behind him an avenue of destruction. If everything on Limbo was like this, the planet should be off limits to humans. It was far too delicate to withstand human contact.
At the edge of the field of spears, Bony halted and turned to look back at the Mood Indigo . The ship had faded to an outline of dark gray. Its dumbbell shape, the rounded bulbous lower part of drive and cargo hold topped by the slightly smaller ovoid of crew quarters, had an oddly out-of-place quality. Here on Limbo it was the Terran vessel, and Bony himself, who were the aliens.
He waved, wondering if Liddy would be able to see him from so far away. He fixed in his mind the contours of the underwater valley, so that even when the ship was out of sight he would have no trouble returning to it. Finally, he turned and began the slow, buoyant walk that would take him up the slope and onto the undersea ridge that marked the end of the valley.
He was almost floating, but in order to make forward progress up the steep incline he still had to put his feet down and exert pressure on the seabed. A carpet of spheres of dull orange-red had replaced the standing pikes, and he could not avoid treading on some of them. They flattened, even under his sea-supported weight of what could not be more than a few pounds; but at least they did not shatter and crumble to dust. Instead they produced an odd wheezing sound, like a chesty old man’s sigh of complaint. When he had passed by, they slowly and silently resumed their original shapes.
Life-forms? Bony was not sure, but his guess was yes. Experience throughout the Stellar Group showed that life popped up everywhere you thought it possibly could, and in a lot of places where you felt sure that it couldn’t possibly. There was life in the sulfur volcanoes of Io, life in the ammonia clouds of Uranus, life on fifty-kilometer fragments of radioactive ice in the far reaches of the Oort Cloud, even viral life of a sort coating arid rock shards of the Dry Tortugas. And this was all within the limits of the extended solar system. When you included the domain of the whole Stellar Group, the variety of life-forms, life-tolerances, and life-locations seemed endless. The idea of life on Limbo seemed very reasonable.