“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 ice. 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.