Just as Chen Hao walked to the red box and placed his hand on the lid, before he could even open it, Nana's voice rang out.

"The environmental monitoring module detected three indicators that deviated from the benchmark value."

He paused. His fingers hovered in mid-air, as if frozen.

“Speak like a human being,” he said.

"Temperature, groundwater level, and photosynthetic rate have all been abnormal over the past 72 hours, exceeding the normal fluctuation range." Nana's voice remained the same, but her speech was a little faster. "Preliminary assessment indicates that the ecosystem is experiencing a structural shift."

Chen Hao pushed the red box aside and turned to walk towards the control room. His steps were unhurried, but each step was firm and measured.

Susan looked up from the supplies list. "Something happened again?"

"We don't know yet whether it's a major issue or a minor problem." Chen Hao sat down. "Let's look at the data first."

Nana pulled up the chart. Three lines climbed crookedly upwards, like the gait of a drunk person.

“This thing has floated before, right?” Carl leaned against the door frame, still clutching the welding gun in his hand. “The sensor has been used for three years; maybe it’s just getting senile.”

“Compare with historical footage.” Nana ignored him and tapped the screen.

The scene shifts to the same season three years ago. Greenery abounds, riverbeds are filled with water, and a thin mist hangs over the mountainsides. Now, the vegetation is sparse, the riverbeds are cracked, and even the wind direction has changed.

“This isn’t a problem with the sensor,” Susan said softly.

“It didn’t happen overnight.” Chen Hao stared at the photosynthetic rate curve. “It’s been moving all along, but we didn’t notice.”

The air was heavy. No one spoke.

"So what's next?" Carl placed the welding torch on the table. "Change the plan? Postpone the departure?"

"No postponement," Chen Hao shook his head, "but it has to be changed."

"Change what?"

“The route, equipment, and supplies all need to be recalculated.” He stood up and walked to the whiteboard. “The original route passed through East Valley, but the groundwater level there is dropping too fast, and the ground may collapse. We can’t go there.”

“Then let’s go up the north slope.” Susan opened the topographical book. “Although the altitude is high, the geology is stable.”

“Okay.” Chen Hao drew a circle. “Set up two rendezvous points so that if the connection breaks down in the middle, we can still reunite.”

"What about navigation?" Carl asked. "The terrain has changed, will the signal be off?"

“Add beacons to the equipment,” Nana continued. “I’ve already marked three high-risk areas in the database, and we need to deploy additional beacons.”

"What about clean water?" Susan asked again. "With fewer plants, the air humidity is also decreasing, and water resources will become even more scarce."

"Refill two sets of filter cartridges," Chen Hao noted. "Also, bring a portable distillation apparatus."

“The protective shield also needs to be replaced,” Nana continued. “With the increase in the frequency of sandstorms, the existing outer material is not wear-resistant enough.”

“I’ll reinforce it.” Carl nodded. “The shipping containers also need to be upgraded. This time, they can’t just be drop-proof; they also need to withstand pressure.”

“Okay.” Chen Hao looked at Susan. “You’re in charge of the medical kit and nutritional supplies. See which medicines we need to stock up on, and make sure we don’t forget the ones that pregnant women can eat.”

Susan responded and looked down at the manual.

"I'll fly the drone tomorrow to scan the new route," Chen Hao said, tossing his pen into the pen holder. "One last top-down check of the terrain."

No one objected.

The meeting adjourned. The four people returned to their respective posts.

Chen Hao stood by the window, the mountain shadows outside blurred. He held a freshly printed route map in his hand, the edges already damp with sweat.

Nana was running a simulation in the background, and warning boxes kept popping up on the screen. She marked them one by one in red, without stopping.

Susan sat in front of the medical cabinet, checking off medications against the list. Her pen scratched across the paper.

Carl opened the tool cabinet and took out a piece of alloy sheet. He compared the size to the dimensions, squatted down, and began to cut it.

Time passes little by little.

Half an hour later, Nana suddenly spoke up.

"Latest data update."

Everyone stopped what they were doing.

"Wind speeds on the north slope have increased by 18 percent, with dust clouds appearing in some areas. A small storm belt is expected to form within six hours."

Chen Hao frowned. "Will it affect the drone's flight?"

“Yes,” Nana replied. “I suggest postponing the scan and waiting for the airflow to stabilize.”

"We can't wait." Chen Hao shook his head. "The later we scan, the less time we'll have to adjust."

“Then you need to lower your flight altitude and avoid the troposphere.” Nana brought up the weather model. “I will guide the flight path in real time.”

"Okay." He picked up the walkie-talkie. "Prepare for takeoff."

"Wait a minute." Susan looked up. "Are you wearing that old protective suit?"

"What's wrong?"

"The cuff seam came undone," she said. "It rubbed against the shoulder strap yesterday when I was testing it, didn't you remember?"

Chen Hao looked down at his sleeve. Sure enough, a thin crack ran from his elbow to his wrist.

"It's okay," he said. "Just put some tape on it."

“It’s not a problem with the tape.” Susan got up and took out a piece of grayish-white fabric from the cabinet. “This is an insulating lining that I found before. It’s strong enough, so I’ll just use it as a temporary fix.”

Chen Hao took it and handed it to Karl.

"Please sew up two stitches for me."

Karl took the cloth and needle and thread, said nothing, and began to sew. His fingers were thick, but his stitches were fine.

Five minutes later, he threw the clothes back.

"It can last for an hour."

"That's enough." Chen Hao put on his clothes and stretched his arms. "Check the equipment before takeoff."

Nana simultaneously started the drone's self-check program. Green lights lit up one by one on the screen.

"Power system is normal."

"The communication link is stable."

"Navigation calibration complete."

"Environmental airworthiness rating: Low".

"Risk warning: Sudden turbulence may occur during flight. It is recommended to shorten the mission duration."

"Received." Chen Hao picked up his backpack. "I'm going to the launch pad."

“I’ll go with you,” Nana said. “Leave the remote control to me.”

"OK."

The two went outside. The corridor lights flickered, and the numbers on the vibration monitor jumped—once every twenty-three seconds.

Susan watched their figures disappear around the corner, then lowered her head and continued writing her list.

Karl was still welding the box. The sparks from the welding torches reflected on his face.

The wind is starting to pick up outside.

Chen Hao walked to the launch pad and placed the drone onto the track. He pressed the button, and the machine hummed as it ascended into the air.

"Altitude 100, speed 30, heading due north," Nana's voice came through the earpiece. "Maintain a straight course."

"clear."

The drone flew through low-altitude clouds, and the footage was transmitted back to the main control screen.

The ridgeline was clearly defined, but several cracks appeared on the ground. The once gentle slope showed signs of landslides.

“Record the coordinates,” Chen Hao said. “These are places you can’t go.”

“Marked,” Nana replied.

Suddenly, the screen jerked.

“Wind shear.” Nana immediately adjusted her posture. “Lean 15 degrees to the left, slow down.”

The drone tilted to avoid a gust of current.

"Try one more time and then we'll retreat." Chen Hao stared at the screen. "Don't push yourself too hard."

"No need to wait until next time." Nana quickly operated the system. "A dust column has appeared three kilometers ahead, about fifty meters in diameter, and it's moving."

"sandstorm?"

"Initial form. It will expand within five minutes."

"Return to base."

"It's already turning."

The drone turned around and flew against the wind. The fuselage shook violently, and the signal bar flashed twice.

"Hold on tight." Chen Hao gripped the handrail tightly.

"I can hold on." Nana's fingers flew across the keyboard. "Just thirty more seconds."

The screen shook violently. In the distance, a column of dust rose, like a grayish-yellow pillar piercing the sky.

"Altitude decreased by twenty!"

"100% power output!"

"Eight hundred meters to the base!"

"five hundred!"

"three hundred!"

Upon landing, the aircraft jolted violently and glided for a distance before coming to a stop.

Chen Hao rushed over to check.

The outer shell has scratches and the propeller is slightly deformed, but it is in good condition overall.

"It still works," he said.

"Fix it and then fly it again." Nana pulled up the damage report. "At least two bearings need to be replaced."

"There's not that much time," Chen Hao shook his head. "We have to leave tomorrow."

“Then we can only fly once,” Nana said. “We must get all the data on this one trip.”

“I know.” He patted the fuselage. “I’ll personally accompany them in the next round.”

“No.” Susan had arrived unnoticed. “You’re the commander; you can’t take the risk.”

"No one knows this line better than me."

“You can watch it remotely,” she said, “but you can’t go up there.”

Chen Hao opened his mouth to refute.

Susan simply stuffed the fabric in her hand into his pocket.

“There’s more than one patch,” she said. “Look under the cuffs yourself.”

Chen Hao touched it. Another seam, hidden in the folds, was deeper.

He didn't say anything.

Carl walked over, holding the newly made arm guards in his hand.

"Put them on," he said. "So your arms don't get exposed to the wind."

Chen Hao took it and put it on.

The size is just right.

Thanks.

"Don't thank me too soon." Carl tightened the last buckle. "This thing hasn't been through the storm yet."

"Then let's give it a try."

Nana suddenly looked up.

"The groundwater level has dropped again."

"How many?"

"It dropped by 0.7 meters in ten minutes."

What does it mean?

"This means that the ground beneath our feet is becoming hollow."

Chen Hao looked at the red warning zone on the map.

That was the place they originally planned to pass through.