“Do what you can, Mr. Archer,” Krebs said. “The rest of us have observations to make.”
Fuming at the idea that he was forced to do a grease monkey’s work while the others were acting as scientists, Grant rechecked the maintenance program, then activated the automated sequence that started the repair work without shutting down the thruster.
The problem was a vicious circle, a closed negative feedback loop. The ceramic lining that shielded the thruster tube from the star-hot plasma flowing through it had eroded away in spots, allowing too much heat to soak through the metal walls of the tube and boil away some of the liquid nitrogen that kept the thruster’s superconducting magnet properly cooled. The magnetic field was wavering, kinking in spots, which became hotter than normal, thereby eroding away more of the ceramic heat-shield material.
Grant saw the problem as a visual image against his closed eyelids, felt it as a twitching pain that was spreading across his back. I’ve got to get the magnetic coil cooled down properly, he knew. If it heats up past its critical temperature, the whole magnetic field will collapse and release enough energy to explode like a bomb.
But pumping more liquid nitrogen to the magnetic coils was like sticking a finger in a dike that was crumbling. Nothing more than a stopgap. I’ve got to resurface the tube with ceramic. But how can I do that while the plasma’s still flowing through the goddamned tube?
The maintenance program showed him how. He saw the recommended emergency procedure: Pump the liquefied ceramic into the plasma stream while alternating the magnetic field so that it made the electrically conducting plasma swirl in a helical motion as it moved down the tube. The ceramic will be forced to the outer edge of the swirling helix, plastered against the wall of the tube. Some of the ceramic will stick to the wall and begin to solidify.
Fine, Grant thought as the images flashed through his brain. But most of the ceramic will flow right down the tube and out the thruster nozzle.
It’s a brute-force fix, he realized, but the only one that could be done as long as Krebs refused to shut down the thruster for proper repairs.
Swallowing hard, Grant spoke the sequence of alphanumerics that triggered the repair system. He watched the ceramic being injected into the plasma as the magnets began pulsing according to the preset program. His back throbbed and twitched, his head felt slightly giddy. This isn’t going to work, he told himself. All I’m doing is pumping the ceramic out of the ship.
But slowly the temperature along the thruster tube wall began to creep down. A single sharp ping rang in his ears and the program automatically increased the flow of liquid nitrogen to the superconducting coils. Grant saw the magnetic field stabilize, the plasma’s swirling smoothed to a clean laminar flow.
It’s done, he saw. The heat transfer across the tube wall is back to within tolerable levels. The pain in his back had eased away.
But it was only temporary, Grant realized. A stopgap repair, a thin patch on a gushing wound. The problem would recur. Checking the system reserves, Grant saw that he had used more than half of the available ceramic. If—no, when the thruster got into trouble again, it would take all the ceramic that was left to fix it. If that would be enough.
“Karlstad, prepare a data capsule,” Krebs ordered. “I want everything we have recorded to go into it. Every bit of data.”
“Captain, that’s the communications specialist’s job,” Karlstad replied.
“You do it,” Krebs snapped. “Dr. O’Hara must devote her full attention to piloting.”
Zheng He was still cruising some fifty kilometers from the herd of Jovians. The creatures were still grazing placidly along the stream of organic particles. Grant was still worried about the plasma thruster. It was performing well enough, but the thrusters were running at almost full capacity as the ship struggled to keep pace with the Jovians.
They’re gliding along easily, Grant thought, almost lolling in the water. Even so they’re going so fast that we’re barely able to stay with them. What do we do if they get frightened and run away?
But the idea of anything frightening such massive beasts almost made Grant laugh. What could possibly bother them? They are the lords of this creation, stately and immense, unperturbed in their power.
He had lost track of time. They had all been on the bridge continuously since they’d first detected the Jovians, taking only quick breaks to plug in a squirt of food when the life-support program called out their scheduled mealtimes.
The lights that the Jovians flashed back and forth among themselves fascinated Grant. What can it mean? Are they signaling to one another? Could it be a language of some sort, a visual language? Or is it just some kind of display, like a peacock showing off his feathers?
“They don’t seem to be using sound for communications,” Muzorawa reported aloud. “Our audiophones are not picking up anything except the slight turbulence caused by their rowing motions.”
“They swim stealthily,” Krebs observed.
“Yes,” Muzorawa agreed, nodding. “They hardly make a sound.”
“That could be to keep them from being noticed by predators,” Karlstad said.
“Who would even think of preying on some great huge creature like them?” O’Hara asked.
Karlstad snickered. “You’ve got predators in your bloodstream right now, Lane. We’re thousands of times bigger than bacteria.”
“Less talk, Dr. Karlstad,” Krebs grumbled. “Get that data capsule prepared.”
“It’s almost ready, Captain,” said Karlstad, tapping at his console’s touchscreens.
Grant asked, “Could they be talking to each other at sound frequencies that the phones don’t pick up?”
“They go down to ultralow frequency,” Muzorawa answered, “less than ten cycles per second.”
“What’s the upper limit?” asked Karlstad.
“Nearly a hundred kilohertz, far beyond the range of human hearing.”
“We should have brought a dog aboard,” Karlstad muttered.
“Or a few of the dolphins,” said O’Hara.
“Sound waves of that intensity,” said Krebs, “can destroy living tissue.”
“Or crack this submersible like an eggshell, if they have enough power behind them,” Muzorawa said.
“Happy thought,” Karlstad groused.
“My point is,” Krebs said, “that those creatures would not use such a high frequency to communicate. It would hurt them.”
“But they might use it as a weapon,” Karlstad said.
“If they’re communicating with each other,” Muzorawa said slowly, “I would think it would be visually.”
“They light up like signboards, don’t they?” O’Hara said.
“Like those airships that hovered over football matches when I was a child,” Karlstad agreed.
The lights flickered on and off so quickly that Grant couldn’t tell if they were forming patterns of any sort.
They were almost as fast as strobe lights.
“Where is my data capsule?” Krebs demanded.
“I was just about to tell you, Captain. The capsule is ready for your input.”
Scowling, Krebs pushed off the overhead and settled next to Karlstad like a bulky log sinking down beside a willowy undersea reed. Karlstad tapped one of his touchscreens and the yellow communications light winked on.
“Data capsule number two,” she said, her harsh voice flat, emotionless. “We have encountered a group of very large organisms. They appear to be ingesting the organic particles that drift through the sea. We are following them and will continue to do so until our life-support supplies go critical.”