Ocean Under the Ice

by Robert L. Forward

  “First,” he said. “Zulu, in its 14.7 hour orbit, will be catching up with Zuni in its 29.9 hour orbit, as it does every 28.9 hours or about once every two Zulu days. This joint conjunction of the two moons causes most of the tidal action on Zulu, an eight meter pulse tide that lasts for three-and-a-half hours. At the same time, they both will be catching up with Zouave in its 48.3 hour orbit. This triple conjunction will add Zouave’s two meter high tide on top of the eight meter Zulu tide. In addition, all this will occur at high noon, so Barnard will be lined up with the three moons, but on the other side of Gargantua. In any case its three-to-four meter tide will be added to all the others, for a total tide of some fourteen meters. On Earth we only see tides like that at the Bay of Fundy. That pull outward on the inner and outer poles should produce a very large strain on the crust, activating all the geysers.”

  “Wait a minute,” said Katrina, who had been listening in from her planetary science console. “Zuni and Zouave are orbiting further out than Zulu, and are going over the outer pole. I can see their gravity pulling up the outer pole region — but shouldn’t they pull in on the inner pole region, not outward?”

  “You’re right that gravity pulls, Katrina,” explained Thomas. “But since the rocky core of Zulu is in free fall, it too is pulled by the outer moons — pulled right out from under the water and ice on the inner pole — which being further away from the outer moons, is not pulled as much as the core. From the viewpoint of someone on Zulu, the net effect is an outward pull on both the inner and outer poles, producing two bulges. That’s why the tides come twice a day on Earth.”

  * * *

  A day later, everyone was awake to watch the quadruple conjunction. Tony had put Prometheus into a powered elliptical orbit with its apogee within sight of the inner pole so they would stay in sight of the geysers during most of the eruption period, yet the sail stayed outside the shadow cone of Gargantua so it could illuminate the geyser during the noon-day eclipse period when Barnard went behind Gargantua. Tony remained at the navigation console past the normal end of his shift partially to make sure Prometheus kept its beam pointed at the right geyser, and partially to free up Thomas to take pictures from outside.

  Everyone else, plus the flouwen in their tank, was watching the view from the big telescope in the science bay Linda was operating. She also arranged to capture the infrared version in the multispectral imager.

  Shirley was at one of the porthole windows, keeping one eye on Thomas walking around the outer hull, and one eye on Gargantua, whose immense presence nearly filled the window of the porthole. Zouave had long ago disappeared into the shadow cone of Gargantua, and Zuni had soon followed. Both were barely visible dark gray ghosts in the black sky, dimly illuminated by the light scattered from the cloud-tops around Gargantua’s rim. Just then, the moon below them faded and went out as it entered Gargantua’s shadow. Only one small spot on the surface was illuminated.

  “Zulu is within forty minutes of conjunction,” reported Shirley.

  “There was already activity at each of the geysers before we entered shadow,” responded Richard.

  Shirley noticed that Thomas was hanging over the safety stringer, camera in action. She looked down with her modest human eye, trying to see what Thomas was seeing through his zoom lens. Through the shifting clouds of water vapor remaining from the preliminary activity, she could barely discern the round dark geyser lake area on the mottled gray-white surface. Looking curiously artificial, the black spot was in reality, she knew, a lake of water, kept melted by the furious heat coming up from the core of the planetoid. Frustrated by the inadequacy of her eyes, she left the porthole window and went to look at the telescope image of the Manannan geyser like everyone else.

  They all watched, almost breathless, as the water vapor clouds over the lake thickened and increased as the geyser erupted. Rising toward them, clearly visible, and with an almost solid shape of its own, was a column of boiling water. Swiftly it ascended, becoming thicker as it rose, until the awed observers were able clearly to see that the water was now tens of kilometers above the surface. At the height of the eruption, huge quantities of water began to fall back toward the surface, blown by the eddying winds far from the parent pool, changing to cool water nearby, and farther out to sleet, and farthest away of all, to snow. For nearly thirty minutes the incredible flow boiled up, was transformed, and fell back to the ice. Finally, slowly, the jet of water began to lower, although still spewing forth vast volumes of hot water onto the air, the water vapor rising into space and the liquid water falling on the surrounding countryside. Almost reluctantly, the giant geyser subsided, grumbling, and finally returned to the surface of the lake, bubbling violently in its final spasms of activity.

  No one wanted to speak. From inside the flouwen habitat tank, Little Red broke the silence with a very small, soft, *Wow!*

  George and Jinjur chuckled. “That’s the word, all right.”

  The quadruple conjunction maximum geyser eruption was over, not to occur again for 68 Earth days — or 111.5 Zulu days, for the next eruption would occur at local midnight, when Barnard would be behind Zulu, but illuminating Gargantua, so instead of having to use Prometheus, the geyser would be fully illuminated, although weakly, by planetlight from the giant planet.

  * * *

  One of the things which had to be decided was where the lander would set down. Since much of the area around Manannan geyser was covered with bodies of coverers-of-the-ice, this required some negotiation with the icerugs.

  Those on the bridge listened, totally absorbed and bemused, to the conversation between James, the robot crawler Splish, and the icerug Pink-Orb.

  “When the humans come down out of the sky to visit your world, they will be arriving in a machine that rides on a strong wind made of flame. It will be putting forth a very loud noise, great heat, and a strong hot wind,” explained James. “You must tell us of an area near you where the noise and heat and strong hot wind will do no harm.”

  “Could have been more tactfully requested,” grumbled George, and Reiki, listening, agreed silently.

  “I understand,” said the deep booming voice.

  “When you have selected a suitable landing site, you will take the Crawler-on-Ice-and-Water to that place so it can direct the humans to it.”

  “I understand,” came the alien response.

  George swiveled in his chair, glanced at Reiki, and instantly understood her look of dismay. Firmly overriding James George spoke in his slowest, most orotund bass: “We come to share knowledge of our world and knowledge of yours. We are glad to know that you exist, as we do, and we intend to do only good as we meet and converse. We are extremely grateful for the opportunity to visit your world, which is so different from anything we have ever seen before. Please show our machine a place where our lander will not hurt or annoy you or the others of your…” he thought desperately for a word “…kind,” he concluded rather lamely. There was a brief delay.

  “I understand,” was the laconic response of the strange being.

  “It understands,” added Splish‘s tiny computer voice.

  “Oh, well, I felt better for it,” muttered George, and grinned at Reiki’s smile of approval.

  * * *

  Selecting the ten members of the exploring crew was Jinjur’s job as Commander of the Barnard Star Expedition. Although she outranked George, she valued his judgement highly, and had no hesitation in talking over the possibilities before each mission.

  “Got to have good pilots for the rocket lander and the Dragonfly airplane, of course. I thought Arielle for this one.” In fact, Arielle was usually selected, for the sound reason that she was simply the best pilot aboard. Her diminutive frame and elfin looks concealed a cool and calculating calm, which, with training and experience, had made her able to deal with any crisis in flight as easily as a bird shifts its wings.

  “Several of the others are competent pilots too, of course. Shirley, then, and Thomas, and Cinnamon.
Shirley’s good at coping with repairs, if needed, and Thomas is almost as good a lander pilot as Arielle.”

  “Besides, think of the pictures he’ll get!” added George.

  “Yeah, we’ll have to limit him on the amount of camera stuff he can take along, or he’ll have the lander full,” agreed Jinjur. “Cinnamon’s ichthyology training just might be a good thing to have along for understanding the coelasharks. I’m including Katrina for her biology background, as well as filling the primary medic slot for the ground crew.”

  “I suggest both Sam and Richard for this excursion, too, Jinjur,” said George. “As geoscientists with experience on the ice-moons Ganymede and Callisto, they’re the best people to get a real understanding of this place. All that ice, and all those boiling geysers! They’ll have a great time.”

  “Sounds good,” said Jinjur. “And David to coddle the computers, if they need it, and they might in those temperatures. And Deirdre — this will be her first chance at exploring. Her knowledge of biology and exotic zoology make her a natural for trying to figure out the workings of the coelasharks and the icerugs. She also might be able to teach them some hydroponics.”

  Privately, George doubted that Deirdre would presume to try to teach anything foreign to the natives — she had always been such a cool observer of life around her, but he dismissed the thought for the much more interesting one of whether or not he, himself, might go.

  “With Cinnamon, Katrina, and Deirdre on the landing party, Nels will have no one to run the hydroponics deck,” George reminded her. “Should we really send all of them?”

  “With Nels to direct me, I can handle the routine work on the hydroponics deck with the Christmas Bush motile,” reminded James.

  “Well, that fills up the slots on the exploration team — except for the commander slot,” said Jinjur.

  There was a long and pregnant pause.

  “Well, George,” said Jinjur, grinning warmly at the hopeful face. The two had shared a great deal over the years, and he didn’t really need to look so blatantly wishful. “One of us has stay on Prometheus to mind the store, both of us would love to go down to visit Zulu, and each of us has had a chance to go on one of the two previous missions. So, for this one we’ll choose scientifically as hell…” George looked puzzled, but almost instantly grinned. He knew this woman very well indeed.

  “We’ll use statistical science,” declared Jinjur, producing a gold coin from her tightest pocket. “I borrowed this from Red. It’s the only one on board. Heads or tails?”

  George left the control room, almost literally walking on air. Jinjur would have the fun of telling everyone the chosen roster, but he certainly didn’t begrudge her that. He’d also succeeded in not being envious, when she commanded the return to Rocheworld, six months ago. But he was jubilant at his luck, and busily running over in his mind all the necessary preparations that must be made for the landing.

  Dropping down the central shaft, he nearly collided with Arielle and David, who were ascending. They looked at him searchingly, but were silent. Briefly, George considered waiting for Jinjur to notify them both officially of their selection, and then compromised by giving them a hugely meaningful grin and wink. The pair responded with equally silent leaps of joy, and their personal imps, monitoring all this physical activity without verbalization, made a notation in the section of memory James had reserved for the task of trying to understand the logic of human behavior. So far, the giant computer was still baffled by many of the things that humans did. The three then went to the airlock in the ceiling of the hydroponics deck to check over the lander they were going to be using.

  “And make sure everything is in good shape,” George reminded them unnecessarily. “Nothing like an eyeball check, although of course James…” He stopped. They all knew James and the Christmas Bush had the lander, as well as all the rest of the equipment, under constant scrutiny and maintenance.

  The others selected for the mission reacted according to character. As predicted, Thomas immediately began the arduous task of choosing which electrocameras and lenses were the most vital, most impervious to cold, and most dependable. Reluctantly, he abandoned the quick idea of bribing some of the others out of their allotted space on the lander. Suddenly excitement hit him. Of all things, he loved seeing something new, and what could be newer than this peculiar planet? He left his room and went down to the galley to get a snack. While practically dancing through the lounge, he met Katrina, bouncing along in her own glee.

  “You, too?” she cried. With mutual whoops, they seized each other firmly and spun in a wild polka, around and around the large lounge until they were both breathless. With an enthusiastic hug they parted, Thomas heading for the galley while Katrina shot up the central shaft to the hydroponics deck. She found Cinnamon, joyfully congratulating herself with a song, but Deirdre was gone.

  In her own comfortable quarters on the deck below, Reiki was listening to Deirdre in one of her rare moments of volubility. As always, when excited, the pure Irish of Deirdre surfaced, and she practically chanted as she revelled in the thought of an adventure. “I’ll be out on the surface of a new world! I’ve been hoping, and wishing for this chance so hard, Reiki! Even dreaming of it, I’ve been, in my dreams I’m wandering in castles of ice and snow — of course that’s just fancies, as the dreaming mind would see, but what I’ll be seeing will be real, and strange, and unearthly like nothing else I’ve ever seen! Dennis and I talked, hours sometimes, of what we’d see, and find out, when we finally got the chance we knew would come to travel to the stars, and explore strange worlds, and touch new creatures! And I wasn’t selected for Rocheworld, but I knew the luck would come, and it has, it has! Fierce, I’m feeling, Reiki, fierce and tingly and proud — what shall I see, down there? What discoveries shall I make? Dennis would love this — he does love it! and shares it, as he is — he is part of my pride, and my joy, as he is still part of myself — this world is frozen and desolate, James says, but there is life there! Intelligent life! World of ice or no, I am burning, it’s all I can do to keep from exploding!” Reiki was touched. Deirdre rarely mentioned Dennis, or the passionate love they had shared with wild intensity until his tragic death. Reiki knew only that it had been enough for Deirdre, so completely engulfing and satisfying that, after her mourning time, she had looked at herself, and concluded that she needed no more. She enjoyed, as did Reiki, the work that she did and the life she lived; and together they derived much entertainment from the behavior of the rest of the crew, but Deirdre’s heart was forever, now, her own.

  “Grand it’ll be to step off our ladder onto this planet! What will it feel like, on that ice? How can it be that thinking beings can survive, could even have come to exist, in such hostile and harsh conditions? Will they be able to tell me how, and when, and what they have done…”

  Still bubbling quietly within herself with joy, Deirdre left Reiki’s quarters and bounded down the central shaft to the galley. Here, the galley imp prepared most of the crew’s meals on demand, utilizing the products of the hydroponics lab, and occasionally putting together one of the “special” meals for a crew member; either one containing some rare spice or preserved food the humans had selected before leaving earth, or one containing their “real meat” ration for the week, using fresh meat obtained from one of the fish tanks, or one of the tissue cultures carefully tended by Nels and his crew on the hydroponics deck, such as “Ferdinand”, “Lamb Chop”, and “Chicken Little”.

  There were, however, some supplies kept on hand for those who fancied doing a bit of cooking on their own; Nels, among them, was an excellent chef. Possibly the most frequent user of the galley, however, was Deirdre; it was her delight to perfume the entire ship with the wonderful aroma of baking bread, or gingerbread, or chocolate cookies. Of course, James soon eradicated every trace of scent, but by then most of the crew would have followed their own noses eagerly, to share in the freshly-made good things. The algae, yeasts, and cultures of the hydroponi
cs lab were transformed, in these bakings, and tasted marvelously of home and hearth. On this occasion, with Deirdre still wildly though privately celebratory, the result was a huge pan full of fat cinnamon rolls, steaming gently through their heavy cloak of melted sugar. By the time they were ready, there were people prowling about the door of the tiny galley, waiting; the last of the fragrant treats was blissfully consumed before it had cooled. Not much was said; Deirdre’s ribs ached from the hugs, and the green eyes glowed.

  Calmer, now, she dove silently up the central shaft and slipped into the empty corridor leading to the flouwen habitat tank. Stretching long fingers over the surface of the glass, she sang softly, her voice trilling a long series of numbers in time and rhyme to a complex tune full of trills and grace notes.

  “Three point one four one five nine, two six five three five eight nine, seven…”

  One idle Sunday back at the university, she had managed to put the first hundred digits of pi to a tune — and with the tune to assist — had soon memorized it. In this manner, Deirdre shared the ability of her druid ancestors, who had passed their history on from generation to generation by rote memorization.

  Upon hearing the song, the milky-white drifting shape within the tank came closer, and joined in for the remainder of the tune. When they finished, they switched to a tune the two had recently created together. This song recited the first sixty-four numbers that represented pi in the octal system — the base eight numbering system that the flouwen preferred.

  “Th-r-ree point one one oh th-r-ee s-e-v-v-e-n-n, f-f-i-v-e f-f-i-v-e t-two f-f-ou-r t-two…” the two sang together, giving each word a trill with the number of stops equal to the number that the word represented, as was the flouwen custom. Little White’s multitoned voice also gave each number a set of overtones that were distinctive as violin, bell, and drum. The number seven emanating from Little White’s body sounded as if it were a multiply-harmonic septuple-tongued trilling chord emitted by a living pipe-organ — which it was. Little White and Deirdre had shared their fondness for the rigid preciseness, yet apparent randomness of transcendental numbers ever since the first tentative effort on Deirdre’s part had elicited an enthusiastic response from the white flouwen, who was impressed that a mere human could display such a memory feat, but Deirdre had spoken of it to no one. After they had finished their second duet, her delight soared again, and she whispered, “I’ll be going along with you to Zulu, Little White!”