Jupiter

“Be quiet!” Krebs snapped. “Attend to your duties. Make certain that everything is being recorded.”

Grant’s heart was racing with excitement. He could see the giant creatures flicking lights along their massive flanks, red, yellow, a piercingly intense green. What does it mean? Are they intelligent signals? Can we make any sense of them?

“Maintain this distance from them,” Krebs repeated. “Conform to their course and speed.”

Grant had never felt so small, so dwarfed. From a distance of fifty-some kilometers the Jovians reminded him of a stately herd of elephants, but they were so blessedly big. Bigger than any creature that had ever lived on Earth. Bigger than a city. We’re just puny little insects compared to them. Ants. Microbes.

“They’re following the flow of organics,” O’Hara said.

“Cruising in the current,” Karlstad agreed.

“I can see that,” snapped Krebs. “Stop this chattering! Check all systems. Now.”

Grant felt resentful as he disengaged from the sensor data. Why can’t we all watch them? he grumbled to himself. We don’t need to check the damned systems. If there’s something wrong we’ll know it right away.

He realized that his headache was still pulsing away; he had ignored it during the excitement of seeing the Jovians. But the pain in his back was nagging at him, too, no longer merely stiffness but an ache that he couldn’t quite pin down, like an itch that moved when you tried to scratch it.

Then he saw it in razor-sharp clarity. The number-two thruster was sputtering, its plasma flow no longer smoothly laminar. The hot ionized gas was crinkling, twisting in the thruster tube. The magnetic fields that should be guiding and accelerating the plasma were pulsating fitfully.

Grant felt the thruster’s imminent failure as an increasingly sharp pain. His first instinct was to shut down the thruster and allow the automated repair program time to reline the tube with heat-shielding ceramic spray and replenish the liquid nitrogen coolant for the magnets.

To do that, though, he needed the captain’s approval. The thruster could not be shut down unless Krebs physically relinquished her control of the propulsion system.

“Captain, thruster number two—”

“I see it,” Krebs said.

“We should take it off-line for repair,” Grant told her.

“Not now.”

“But it’s headed for catastrophic failure.”

“Not for another twenty hours.”

Grant saw the diagnostic and double-checked it with a glance at his console screens. “But, Captain, that’s only an estimate. It could fail much sooner.”

Her voice heavy with disdain, Krebs said, “If we shut down the thruster we will slow down. The beasts out there will move away from us. We must keep pace with them.”

“Even if we lose the thruster altogether and can’t get ourselves out of the ocean?” Grant demanded.

“We are here to get data. We can always fire off a data capsule.”

“But we’ll die!”

“The data comes first. That is what is important.”

She doesn’t care if we live or die, Grant said to himself. Our lives, even her own life, isn’t as important to her as observing these creatures.

“The thruster can be repaired without taking it offline,” Krebs said calmly.

Grant checked into the maintenance program and found that she was right, up to a point. “It would only be a temporary patch,” he said. “The program recommends complete shutdown for necessary repairs.”

“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?