Chapter 428 Cabin Crisis

"Oxygen levels are at 19.5 percent and still dropping."

Lin Jianguo's voice came through the walkie-talkie, trembling at the end, like a whistle leaking wind in winter. The quantum communication solution review document in He Yuzhu's hand slipped onto the table, his chair tipping back and crashing to the floor with a loud thud—he didn't turn around to steady it. The green curve on the monitoring screen was descending at a speed he didn't want to see. The technician's hand hovered two centimeters above the alarm button, his fingertips trembling. He turned to look at He Yuzhu, his lips moved, but no sound came out.

He Yuzhu pressed the call button. "Inspect the algae cultivation ponds. Check for large-scale die-offs."

"It's not algae. The lighting and temperature are normal. The circulation pump in the carbon dioxide scrubber has stopped." Lin Jianguo's speech suddenly quickened. "The scrubbing fluid isn't flowing, and carbon dioxide is accumulating. Dean He, what's the current concentration inside the chamber—"

He Yuzhu interrupted him. "I know. Give me the error code."

The sound of keystrokes came through the walkie-talkie for about ten seconds, like someone scratching glass with their fingernails. Lin Jianguo rattled off a string of numbers. "Motor overload protection triggered, automatic power cut-off. There are crystals in the detergent, clogging the pipes, the pump won't turn."

Sun Xiuying's voice cut in from the background, shrill and urgent. "Should we switch to the spare?"

He Yuzhu didn't answer immediately. He stared at the carbon dioxide curve on the screen—0.6%, 0.7%, 0.8%. He calculated in his mind: at this rate, it would reach 1% in twenty minutes, which is the limit of what a normal person can tolerate. There was only one backup pump; what if it malfunctioned again after 72 days? He bit the inside of his lip until he tasted a hint of rust.

"First, clean the crystals in the pipes. If it can be restored, there's no need to replace it with a spare."

Lin Jianguo was silent for two seconds before replying with a single word: "...Okay."

He Yuzhu released the call button and realized that his five fingers on his left hand were gripping the edge of the control panel's metal frame so tightly that his knuckles were white and the veins on the back of his hand were bulging. He slowly released his grip, leaving several shallow nail marks on the metal surface. A technician handed him a glass of water, but he didn't take it.

Fifteen minutes. The curve stopped at 0.85%, like someone who has climbed halfway up a mountain suddenly crouching down to catch their breath. Then, it started to go down. 0.8%, 0.7%, 0.6%.

He Yuzhu pressed the call button. "Situation?"

"The pipe is clear." Lin Jianguo's voice was hoarse, like someone who had just finished a five-kilometer run and finally got their water bottle, carrying a sense of relief. "Crystallization was clogging the bend in the detergent outlet. I flushed it out with hot water. Now the carbon dioxide is decreasing, and the oxygen is starting to rise."

He Yuzhu turned and walked to the wall, slamming his fist into the metal of the fire extinguisher box. A small dent appeared in the door, accompanied by a dull thud. The technician jumped in surprise, and Old Sun peeked out from the doorway, then quickly withdrew without saying a word. He Yuzhu put his hands behind his back, his knuckles burning as if they had been burned. He walked back to the control panel, picked up the walkie-talkie, and his voice returned to its usual tone.

"What are the crystals composed of?"

"The sodium bicarbonate concentration in the detergent is too high, and it precipitates out as soon as the temperature drops. The formula needs to be changed, and the initial concentration should be reduced by 15%."

He Yuzhu jotted this down in his notebook, the pen tip tearing through two pages. He ripped off the torn page, crumpled it into a ball, and stuffed it into his pocket.

The phone rang. Huang Shichang's voice came through the receiver, tinged with barely suppressed anxiety. "Dean He, is the review meeting still going to proceed? Everyone's already waiting in the conference room."

He Yuzhu glanced at the monitor screen: oxygen 20.3%, carbon dioxide 0.4%. He patted the technician on the shoulder. "Keep an eye on it. Call me immediately if there are any changes."

The technician nodded and closed the glass cover on the alarm button.

The review meeting was at the other end of the corridor. When He Yuzhu pushed open the door, Huang Shichang was staring blankly at the design plan on the projection screen, the pen in his hand twirling between his fingers three times before falling and picking it up again. Three researchers from the University of Science and Technology of China, two engineers from the Shanghai Institute of Technical Physics, Chief Designer Sun from the Fifth Academy of Aerospace Science and Technology, along with Lao Sun and Ma Yuejin, sat on either side of the long table. He Yuzhu did not sit down.

He stood in front of the projection screen, picked up a laser pointer, and circled a design on the diagram. "You've chosen passive radiation cooling for the repeater's thermal control. In near-Earth orbit, with the sun's rays from the opposite side and Earth's infrared radiation acting simultaneously, how high will the radiator's temperature rise?"

Huang Shichang turned to the next page, where a thermal analysis cloud map appeared. "The hottest operating temperature is fifty degrees Celsius. The upper limit of the operating temperature of the optoelectronic devices inside the repeater is sixty degrees Celsius, with a ten-degree margin."

"Ten degrees isn't enough." He Yuzhu pointed the laser pointer at the red area of ​​the cloud map. The red dot remained motionless, like an eye fixed on its prey. "Quantum entanglement light sources are sensitive to temperature. Even a slight deviation in the orbital parameters will cause it to exceed the limit. Double the heat sink area, increase the margin to twenty degrees, and add three kilograms to the weight. I approve."

Huang Shichang bit his lip as he wrote on the proposal, the pen tip piercing the paper and causing a small ink smear. An engineer from the Shanghai Institute of Technical Physics raised his hand. "Director He, we've produced a sample of the indium gallium arsenide detector. The dark count is an order of magnitude lower than silicon, and the bit error rate is controlled below 0.5% at 80 degrees Celsius. However, the detector's quantum efficiency is sensitive to temperature fluctuations; for every degree Celsius change, the efficiency drifts by 0.3%.

"in conclusion."

"Temperature control accuracy is ±0.5 degrees Celsius. A miniature constant temperature platform is needed, weighing 1.5 kg and consuming 2 watts."

He Yuzhu jotted down some notes in his notebook, then looked up and glanced around. "The repeater solution, the detector solution, and the main unit thermal control solution—all must be finalized today. The interface parameters will be based on Chief Designer Sun from the Fifth Academy of Aerospace Science and Technology. Raise any objections now. Once we're out this door, no more arguing."