The woman was indeed large: tall, broad-shouldered, wide-hipped, thick-armed, deep-chested. She approached and stopped before them, looking down at the stranger with her ironic smile. “Ganymede, I know you hate what they plan to do here,” she said. “And yet here you are. What’s going on? Are you planning to hurt them?”
The stranger, who did not look like Galileo’s idea of Ganymede, faced her like an upright ax. “You know what they’ll say about this on Callisto if they hear about it. We hold the same view they do. The only difference is that we’re willing to do something about it.”
“And so you bring this Galileo along with you?”
“He is the first scientist. He will be our witness to the council, and speak for us later.”
She did not think much of this, Galileo saw. “You use him as a human shield, I think. While you have him with you, the Europans won’t attack you.”
“They won’t in any case.”
She shrugged. “I want to be a witness too. I want to see what happens, and I am your appointed mnemosyne, whether you acknowledge that or not. Let me join you, or my people will alert the Europans that you are here.”
Ganymede stepped to the side, gestured at the door of the ovoid vessel. “Be my guest. I want everyone to see just how irresponsible their incursion is.”
Inside the vessel a few people huddled over banks of glass instruments and glowing squares of jewel color. Their faces, lit from below by their glowing desktops, looked monstrous. The livid glare of Jupiter seemed to leak out of their eyes.
Hera stood beside Galileo, and leaned over to speak in his ear. Again her words came to him in a rustic Tuscan Italian, like something from Ruzante. “You understand that they’re using you?”
“Not necessarily.”
“Do you know where you are?”
“This is one of the four moons orbiting Jupiter. I named them myself; they are called the Medicean Stars.”
Her smile was wicked. “That name didn’t stick. It’s only remembered now by historians, as a notorious example of science kissing the ass of power.”
Affronted, Galileo said, “It was nothing of the sort!”
She laughed at him. “Sorry, but from our perspective it’s all too obvious. And always was, I’m sure. You failed to consider that major planetary bodies are not best named for one’s political patrons.”
“What do you call them, then?”
“They are named Io, Europa, Ganymede, and Callisto.”
“Collectively,” Ganymede interjected, “they are called the Galilean moons.”
“Well!” Galileo said, taken aback. For a moment he was at a loss. Then he said, “That’s a good name, I must admit.” After a moment’s confusion, he added, “Not greatly different than a name like Medici, if I am not mistaken,” with a bold look at Hera.
She laughed again. “The discoverer of something is not the same as the discoverer’s patron. His hoped-for patron, to be precise. Making the name a gross bit of flattery, a kind of bribe.”
“Well, I couldn’t very well name them for myself,” Galileo pointed out. “So I had to choose something useful, did I not?”
She shook her head, unconvinced. But she had stopped laughing at him.
When he saw a chance, Galileo drifted over to her so they could speak sotto voce again. “You all speak as if I am someone from your past,” he noted. “What do you mean?”
“Your time is earlier than ours.”
Galileo struggled to comprehend this; he had been presuming that the stranger’s device had merely been transporting him across space. “What time is it here, then? What year?”
“In your terms it is the year 3020.”
Galileo felt his mouth hanging open as he struggled to grasp this news. Transported not only to Europa, but to a time some fourteen hundred years after his own…. Stunned, he said weakly, “That explains many things I did not understand.”
Her smile was wicked.
“Of course it creates new mysteries as well,” he added.
“Indeed.” She was looking at him with an expression he couldn’t read. She was not an angel, or an otherworldly creature, but a human like him. A very imposing woman.
There was a ping, a small jolt, and the room tilted to the side. Ganymede pointed to a white globe, lit from within, floating in the corner of the room. “A globe of Europa,” he said to Galileo. Its whites were faintly shaded to indicate the temperature of the surface. Most of it was pale blue, crisscrossed by many faint green lines. Galileo crossed the room to look more closely at it, checking automatically for geometrical patterns in the surface craquelure. Triangles, parallelograms, spicules, radiola, pentagons … Where the lines intersected, the greens sometimes turned yellow, and in a few cases the yellow shifted to orange.
“The tides break the ice,” Ganymede explained, “and convective upwellings fill some of the cracks in the ice, forming vertical zones like artesian wells, that can serve as channels down to the liquid ocean. On Ganymede we called them flues.”
“Tides?” Galileo asked.
“Under the ice, this world is covered entirely by an ocean. The water is a hundred miles deep. Only the top few miles are frozen, and that ice is shattered by the tides below.”
“So Europa rotates?” Galileo thought that tides were caused by water sloshing on the surface of a body that both rotated on its axis and circled some other object, causing the motion at its surface to vary its speed in a way that tossed the water side to side. He had seen fresh water carried in a barge behave in just that way when rowed across the lagoon, sloshing forward when the barge ran into a Venetian dock.
“Yes, Europa rotates, but at the same speed as its orbit around Jupiter.”
“So how can there be tides?”
All the Jovians stared at him. Hera shook her head briefly, as if the explanation would be beyond Galileo’s understanding. Irritated, he looked to Ganymede, who shrugged uncomfortably.
“Gravity, you see…. Perhaps we can discuss it another time. Because now we have begun our journey into the interior. We descend by melting as we go, to clear the flue.”
The craft tilted first at one angle then another. There was a large rectangular patch of the chamber’s wall filled with glowing primary colors, as if a rainbow had been used for paint. Their vessel was represented as a black pendant in the middle of this rectangle, and flowing upward past it were ribbons of rainbow color—orange strands closest to the black blob, yellow and green twining around them. A larger rectangle on another part of the wall was apparently a window, giving them a view of what passed outside; this consisted of nothing but a field of the darkest blue imaginable—a blue so deep and pure that it captured Galileo’s eye. It exhibited small reticulations and lighter gleams, revealing perhaps that it was an icy slush. It gave him much less information than the other rectangle, with its brilliant colors indicating temperatures.
Down, down, down some more. The blue outside the window flowed upward more swiftly, and darkened. The temperature screen likewise flowed. Otherwise there was only the hum of the vessel’s machines, the brush of its air. Once Galileo had dreamed of falling off a ship and sinking into the Adriatic. Now they were all dreaming together.
Ganymede hated the necessity of this dive, hated the very idea of an intrusion into the ocean under the ice, and it soon became clear that his crew shared his opinion. They eyed their screens with grim expressions, and said little. Ganymede strode back and forth nervously behind them, consulting with them in turn.
On the rainbow panel, a green potato-shaped patch moved upward; it looked like a boulder. Galileo asked about it.
“A meteorite,” Ganymede replied. “Space is full of rocks. The shooting stars you see in your night sky are rocks, often as small as sand grains, burning very brightly.”
“Friction with air is enough to ignite rock?”
“They are moving really very fast. Here on Europa there is no atmosphere, however, so whatever it encounters crashes straight into the ic
e. It happens a lot, but impact craters in ice quickly deform and flow back toward flatness.”
“No atmosphere? What about the air we were breathing up there?”
“We live inside bubbles of air, held in place by forces or materials.”
Their vessel stopped in its descent. It was interesting to Galileo how clearly he could feel the halt, subtle though it was.
Ganymede said, “Pauline, is everything going well?”
“All is well,” said a woman’s voice, apparently from within the walls of the vessel.
“How soon will it be before we reach the ocean?”
“If we maintain this speed, it will be thirty minutes.”
“Is the Ariadne thread unspooling cleanly?”
“Yes.”
Ganymede said to Galileo, “The Ariadne thread is also a heating element, and will keep the central line of our flue liquid, to ease our return.”
They waited, absorbed in their thoughts. The light downward pull of Europa made the crew’s movements around the bridge fluid and slow, like dancing in a dream. Galileo found it hard to keep his balance; it was somewhat like floating in a river.
He drifted to Hera’s side and said, “All these machines have to work for us to stay alive.”
“Yes, that’s right.”
“It seems risky.”
“It is. But because it is, we engineer for safety. Materials and power are terrifically advanced compared to your time. And there is a principle called redundancy at the criticalities. Do you know this term? Replacement systems are available in case of failures. Bad things still sometimes happen. But there you are. They do anywhere.”
“But on Earth,” Galileo objected, “in the open air, the things you make don’t have to work for you to survive.”
“Don’t they? Your clothing, your language, your weapons? They all have to work for you to stay alive, right? We are poor forked worms in this world. Only our technologies, and our teamwork, allow us to survive.”
Galileo pursed his lips. There might be some truth to what she had said, but still he felt it obscured a real difference. “Worm or not,” he said, and she was a rather magnificently shaped worm, he did not add, “you could stay alive on Earth by breathing, eating, and staying warm. Granted these take effort, but you could make the effort. You have tools to help you, but they don’t have to remain unbroken for you to survive. A single man alone on an island could do it. There are no mechanical contrivances that surround you and protect you, like a fortress, that have to function successfully forever or else you very quickly die.”
She shook her head. “It’s like a sea voyage. You could not have your ship sink and survive.”
“But you people never land. You sail on forever.”
“Yes, that’s true. But it’s true for everyone, always.”
Galileo recalled standing in his garden at night, in the open air, under the stars. It was an experience this woman had never had. Possibly she could not imagine it. Possibly she had no idea what he was talking about. “You don’t know what it is to be free,” he said, surprised. “You don’t know what it is to stand free in the open air.”
She shook her head impatiently. “Have it your way.”
“I will.”
Again her amused glance, as if she were looking down on a child. She said, “You were famous for that, as I recall. Until things went wrong.”
The voice Pauline announced they were coming to the bottom of the ice layer, and were in what she called brash ice. They could hear floating chunks and clinkers striking the hull—a grinding noise full of scrapes and thuds.
Then they were moving freely, in water. Galileo had spent so much time on barges and ferries, and on a few well-remembered trips out into the Adriatic, that he recognized the feel in his feet. Such kinetic sensations were so slight as to disappear when one focused on them, but when focusing attention elsewhere, one became aware of the totality of the effect.
Ganymede said, “Pauline, search for the Europans’ flue, also any other vessels, of course. And give us an analysis of the water too, please.”
Pauline reported the water was nearly pure, with trace amounts of salts, floating particulates, and dissolved gases. Some of the crew began tapping madly at their desktops. Outside the window, the omnipresent blue had long since turned black. They might as well have been deep in the bowels of the Earth. Only one’s sense of movement suggested they were in a liquid.
Thus it was a great surprise to see a brief flash of cobalt blue in the window, like the random blue spark one sometimes saw crossing the inside of the eyelid.
“What was that!” Galileo said.
“We call that Cherenkov radiation,” Ganymede said.
“Somebody’s patron?” Galileo inquired, glancing at Hera.
“The discoverer of the phenomenon,” she said firmly.
Ganymede ignored their fencing. “There are tiny particles called neutrinos, which pour through our manifold in great numbers, but very seldom interact with anything. Once in a while one hits a proton—which is a small but substantial part of an atom—hits a proton in such a way that the proton releases a muon, which is a very small component of a proton. If that happens in an ocean like this, the muon will fly through the water in such a way as to spark a short trail of light in the blue wavelength. We will see a few per minute.”
Another little flare of blue appeared, again like the flaws that plagued Galileo’s vision. “Like shooting stars,” he noted.
“Yes. A very subtle fire.”
“A fire in water?”
“Well, a light, let us say. Though some fires will burn in water, of course.”
Galileo tried to imagine that. This dream was testing him in all sorts of ways. Could he find a way to test it back? Maybe answer the basic question: Was this really happening? He looked around to see if there was something small that he could take and conceal in his coat. Stealing ideas from dreams—perhaps it wasn’t so unusual. Perhaps it was a fundamental mode of thought.
The next flick of blue light was followed by a blue ball, which rapidly expanded, then became a kind of diffuse polyhedron, shedding spicules and other radiola of blue light that then curved away from the polyhedron in spirals—some of them tight equable spirals, making cylindrical coils, others equiangular spirals, growing wildly outward in conic shapes. One of these flashed right by the window, and for a second or two their chamber pulsed sapphire.
Some of the crew cried out, then there was silence.
Galileo said, “What was that?”
Ganymede appeared astonished. He stood pressed against the window, his blade of a nose touching it.
He straightened up, expression black, “It’s here. I knew it. The anomalies made it very clear. I’ve been saying so all along.” He turned to his crew. “We shouldn’t be here! Have the Europans shown up yet?”
“We haven’t seen them,” one replied.
“Find their flue, then! Get to it—we have to get to it before they do, to stop them!”
They turned back to their screens and their crowded desktops. After a time one said, “We’ve found it. They’re descending. We’re closing on it—wait. There they are. Two of them, just leaving their flue.”
Ganymede hissed. “Go!” he exclaimed. “Ram them! Get under them and ram them from below! Full speed until you reach them, then get in position to shove them right back up the flue!” He looked stricken, grim beyond telling. “We have to make them leave.”
“How can you do that?” Hera asked.
“We’ll ram them until they turn back.”
“Are you going to warn them?”
“I don’t want to break radio silence. Who knows what effect it might have on what’s in here?”
“What about the sound of collisions? What about the sounds and the exhaust from your engines?”
“That’s what I’ve been saying to them! None of us should be here.”
Another blue conic spiral flashed by them. Ganymede read the screens and
the desks. “That could be some kind of signal. Speech, or thought, in some language of light.”
“Who would it speak to?”
“The light may be secondary. Who knows who it talks to? I have my suspicions, but …”
“Try numbers,” Galileo suggested. “Display a triangle, see if it knows the Pythagorean theorem.”
Ganymede shook his head, visibly trying to remain patient. “That’s what the Europans will do, I’m afraid. Reckless interventions like that. They have no idea what they may be getting into.”
“Is it some kind of fish?”
“Not a fish. But on the floor of the ocean are layers of something—perhaps a slime that is organized into larger structures.”
“But how would a slime make light?”
Ganymede clutched his black hair in his hands. “Light from slime is bioluminescence,” he said tightly. “Slime from light is photosynthesis. Both are very common. They’re like alchemical interactions.”
“But alchemy doesn’t really work.”
“Sometimes it does. Be quiet now. We have to get the Europans out of here.”
On the screen that had held the rainbow images of the flue, there stood now an image all in grays, in which near-white shapes defined an object much like their own vessel, shifting against a rumpled gray field. Ganymede took over at one desk and began to tap gently on the array of tabs and knobs. A solid bump, and then the screen showed nothing but the ghostly image of another ship. “Hold on,” Ganymede ordered grimly, and began tapping harder than ever. “Pauline, keep the vectors such that we push it up into its flue.”
Then a loud bang and instant deceleration knocked them all forward and up into the air. When they fell back, Galileo found himself in a heap of bodies in the corner, with Hera under him. He got up and tried to give her a hand, but staggered back as the vessel tipped again.
The voice named Pauline said, “They’re in their flue now, but they can descend out of it again.”
“Go after the other one anyway. Wait, while we’re in contact with them, speak hull to hull and tell them to get back to the surface. Tell them if they don’t, we’ll ram them hard enough to breach both ships. Tell them who we are and tell them I’ll do it.”