At 6:58 a.m., Chen Hao squatted by the wall in the northwest corner, holding a piece of newly connected plastic pipe in his hand, the pipe end facing down, dripping water droplets.

He stared at the drop of water for three seconds before it slowly fell to the ground, leaving a small black dot.

"Is this considered a water supply?" he turned and shouted, "Nana, are we connecting water pipes or growing mushrooms?"

Nana stood two steps away, her optical lens scanning the end of the pipe. "Initial pressure test complete. Current flow rate is 0.7 liters per minute, to be interrupted after 15 seconds."

"Translate into human language."

"Not enough time to take a bath."

"Nonsense." Chen Hao threw the pipe on the ground, the plastic hitting the ground with a loud thud. "Ten minutes ago you said you could start work, and now you're telling me there's not even enough water to flush the toilet?"

“The conditions changed two minutes before your arrival.” She raised her arm, and a semi-transparent layer popped up in the air, revealing a slowly rotating cross-section of the underground structure. “The main water tank has 12% capacity remaining, and the replenishment rate is lower than the evaporation loss. If the shower system is activated, it is expected to shut off after 120 seconds.”

Chen Hao stared at the picture, poking at the blue block representing the water tank with his finger. "Couldn't we store more water? Like, dig a pool to collect rainwater?"

"The area where the base is located receives less than 80 millimeters of rainfall per year, and the water collection efficiency cannot support daily consumption."

"Where did the water I used to wipe myself come from?"

"Washing wastewater that has been filtered three times."

Chen Hao was stunned. "...I wiped away dirty water?"

"After ultraviolet sterilization and activated carbon adsorption, it meets basic cleaning standards."

“I don’t want to know what ‘basics’ means.” He stood up, dusting off his pants. “Anyway, there’s no water now, so the bathroom can’t be built.”

"correct."

"You answered quite readily."

"Facts need no embellishment."

Chen Hao went around to the back of the wall, where several wooden planks, intended to be used as partitions, were piled up and covered with dust cloths. He lifted a corner, touched the exposed metal support underneath, and then looked up at the location of the pre-installed drain outlet on the ceiling.

Empty.

Like mouths that never open.

He sighed. "So we're stuck at the very first step? We don't even know where the water is coming from?"

“Inaccurate.” Nana walked over, turning the optical mirror toward the ground. “Detection shows that there is a stable liquid water flow at a depth of 15 meters underground, with an average daily flow of about 300 liters.”

"There's water?" Chen Hao's eyes lit up. "Why didn't you say so earlier?"

“Access is too difficult.” She brought up a new screen, where the rock strata section was dark red. “The overburden is dense basalt with an average hardness of eight on the Mohs scale, which cannot be penetrated by conventional tools.”

What does level eight mean?

"It's like using an iron spoon to chisel a granite step."

Chen Hao was silent for a few seconds, then suddenly burst out laughing, "So, all we're missing for our dreams is a super drill?"

"More precisely, it requires high-temperature melting and cutting or blasting equipment."

"No, none of them."

"No, none of them."

The two stood still. A faint smell of rust lingered in the air, seeping from the aging pipes.

Chen Hao bent down, picked up a short crowbar, and tossed it around in his hand a couple of times. "Let's try it manually then."

"Based on the mechanical model, with continuous manual operation, the daily tunneling progress will not exceed five centimeters."

"That's three months?"

"Based on a 30-day calculation, it will take 12 days to reach the target depth."

"You're pretty quick at calculating."

"The database has a built-in project duration estimation module."

"Alright." Chen Hao walked to the rock wall, raised the crowbar, aimed at a joint, and swung the hammer down.

clang!

Mars jumped.

The stone remained completely still.

He smashed it again, his hand going numb from the impact.

"Is this thing a rock or tank armor?"

"Closer to the latter."

"Can't you say something encouraging?"

Your muscle fatigue index is rising.

"Thank you, I'm very touched."

For the next two hours, Chen Hao tried three different positions while hammering the rock surface—standing, squatting, and kneeling. Finally, he simply sat on the ground, leaning against the wall, panting, his forehead covered in sweat.

The crowbar lay diagonally at my feet, its tip curled up.

There was a shallow pit on the ground, about two fingers deep.

"Even scratching its itch isn't hard enough for its nails." He wiped his face, his collar soaked. "At this rate, by the time I break through, mushrooms will be growing in the bathtub."

Nana crouched down, bringing the optical microscope close to the surface of the rock strata. "I found three tiny cracks, concentrated at their intersection on the southeast side. I suggest focusing the force on them."

"You should have said so earlier."

"You did not ask."

"I've asked now."

She extended her mechanical finger and pointed to the intersection of the rock fissures, explaining, "The structural stress distribution is uneven here, and preferential failure could trigger a chain of fractures."

Chen Hao pushed himself up, picked up a crowbar, walked over, and smashed it hard at that spot.

Clang! Clang! Clang!

The sound was crisper than before.

The gravel finally began to fall, breaking off piece by piece.

He laughed, panting, "Broken?"

"The area is loose, but no through-channel has been formed."

"It's better than nothing."

He continued to smash, slowing down the pace, but each blow landed in the same spot.

Ten minutes later, a rock the size of a fist fell down.

He stopped, reached into the hole, and felt an even deeper chill in his fingertips.

"Is there really something down there?"

"The humidity sensor is showing an upward trend."

"So, the further down you go, the closer you get to the water source?"

"The logic holds true."

Chen Hao sat back down on the ground, the crowbar lying across his lap. "The problem is how to last twelve days. I don't want to finish work every day feeling like I've been run over by a car."

“We can optimize the operation method.” Nana turned and walked to the corner, dragging out several discarded metal reflectors. “By using solar energy to focus and heat the rock surface, and then rapidly cooling it, we can accelerate the cracking process.”

"Thermal expansion and contraction?"

"Basic physical principles".

"That sounds more reliable than my stupid self."

They began setting up reflectors, arranging them into a simple arc, aiming them at the breach in the rock face. Just as they were adjusting the angle, the sky suddenly darkened.

The clouds were low, blocking out most of the sunlight.

Chen Hao looked up and said, "That's it? Relying on the heavens for a living means we have to depend on God's mood?"

"The solar radiation intensity has decreased by 67 percent, and the light-gathering efficiency is insufficient."

“Then let’s not wait for the sun.” He stood up, patted his trousers, and said, “I’ll go to the kitchen to get some fuel.”

Five minutes later, he piled up a small heap of sawdust and tarpaulin in front of the rock wall and inserted a few ventilation pipes as air ducts.

The fire was lit.

The flames licked against the rock surface, and black smoke billowed upwards, making people cough.

"This doesn't look like construction, it looks like alchemy," Chen Hao said, fanning himself with a cigarette. "Are you missing any medicinal herbs? Should I go catch another chicken to offer as a sacrifice to the mountain god?"

“There’s no need for that.” Nana adjusted the angle of the duct to concentrate the airflow. “The current temperature has reached 400 degrees Celsius, and stress cracks have appeared on the surface of the rock.”

Chen Hao took a closer look and saw that the rock surface was indeed covered with fine lines, like a dried-up riverbed.

He grabbed a crowbar and struck the crack hard.

Click!

A large amount of rubble collapsed, revealing a deeper depression.

He grinned, "I've broken down!"

"First effective rock breaking record." Nana updated the log simultaneously, "It is recommended to immediately carry out secondary heating to expand the opening area."

"I'll listen to you."

In the following cycles, efficiency improved significantly. Burning, pouring, and hammering—the three worked together—even though there were only two physical entities.

By noon, the pit was big enough to fit half an arm.

Chen Hao sat on the ground, his face covered in ash, a hole burned in the front of his clothes, and he was taking small sips of water from a half-empty bottle.

How much can we dig today?

"Based on the current progress, we expect to advance eight centimeters."

"That's twelve days?"

"If the weather is stable, there is sufficient fuel, and there are no equipment malfunctions."

Chen Hao stared at the dark, bottomless cave entrance, where the wind whistled softly as it blew in.

He suddenly said, "Actually, I'm not that clean."

"?"

"I mean, back when I was at home, I could manage to take a shower once a week."

"But now you want to flush every day."

“Yeah.” He smiled. “I don’t know why, but once I have a light and a table, I just want a hot bath. It’s like that’s what it means to… be alive.”

Nana didn't say anything, but simply fixed the last reflector in place and then stood next to him.

"Should we continue heating or wait for it to cool down?"

"Wait a minute," he said. "Let me sit for a while."

He leaned against the wall, closed his eyes, and his breathing gradually calmed down.

In the distance, the sound of dripping water could be heard from other areas of the base, one drop after another.

He opened his eyes after an unknown amount of time and saw Nana still standing there, her optical glasses gleaming with a faint blue light.

"You're quite dedicated."

"Mission incomplete."

"What if I fall asleep?"

"I will wake you up."

What if I give up?

You will start over.

Chen Hao glanced at her. "How did you know?"

"Because you always say 'never mind,' but then you still come back to work the next day."

He smiled but didn't refute.

He stood up, brushed the dust off his pants, and picked up the crowbar.

"One more round."

Nana started the timer program and archived today's homework data at the same time.

Temperature: 412 degrees Celsius

Cumulative tunneling depth: 9.3 cm

Expected completion time: early morning of the twelfth day

Chen Hao re-laid the tarpaulin and poured in the last half can of fuel.

The flames suddenly shot up, illuminating half of his face.

He bent down to adjust the air duct and suddenly heard a soft sound coming from deep within the rock strata.

It sounded like a drop of water falling into a cavity.

He stopped moving and held his breath.

Another sound.

It's very light, but it's definitely there.

He looked up at Nana, "Did you hear that?"

She is using an optical microscope to perform acoustic wave analysis.

Chen Hao gripped the iron pipe tightly, squatted at the edge of the fire, and stared at the still-smoking hole.