The small, grayish-white head lingered in the crevice for a few seconds before retreating back in. A breeze blew across the lake, carrying a hot, salty, and fishy smell.

Chen Hao stared at the gap, his hand still hovering in mid-air, as if waiting for some follow-up action. Two seconds passed, and nothing happened. He slowly withdrew his hand, brushing the dust off his pants. "Alright, looks like we're not doing wholesale today."

He turned to look at Nana, "Was that its sister just now? A relative visiting? Or a new employee on trial?"

“We can’t determine the kinship.” Nana stood to the side, a slight blue light flashing in her eyes. “But the behavior pattern is similar, and the time spent there was seventeen seconds longer than the previous one, so it may be in the observation and learning phase.”

“Oh, an intern.” Chen Hao nodded. “Then I need to be mindful of my image and not let the newcomer think the company is laxly managed.”

After he finished speaking, he casually pulled a transparent bottle from the side pocket of his backpack. It was half-filled with murky, yellowish water, and some sediment swirled around when he shook it. This was a sample that Nana had collected from the lakeside yesterday using a probe. The water temperature was so high that it could boil an egg; drinking even one sip would probably kill your kidneys.

He held the bottle up to his eyes and looked at it. "This stuff looks like poison now."

“But it’s our only hope.” Nana walked over, and the robotic arm unfolded a small control panel. “The propulsion suit has a built-in filtration system. Although it’s not designed specifically for water purification, it can try to remove some soluble salts.”

"So—we're going to use aerospace equipment to make tea?" Chen Hao unscrewed the bottle cap, smelled it, and immediately frowned. "This water isn't even fit for soaking your feet."

“Starting the filtering program requires connecting to the waist interface.” She pointed to a small panel on the back of his suit. “You need to remove two pieces of the outer armor first, otherwise you won’t be able to reach it.”

Chen Hao sighed, plopped down on a rock, and began unbuttoning his clothes. His chubby hands fumbled back and forth between the narrow buckles, struggling for almost a minute before finally prying off the two pieces of armor and tossing them aside. "You say humans created machines that can travel through time, but in the end, we still have to do our own dressing and undressing."

"Technological progress has never solved the problem of laziness," Nana said calmly.

"If the inventor of the zipper heard you say that, he'd be furious."

He bent down to connect the wires, inserting one end of the water pipe into the sample bottle and the other end into the filter module of the propellant suit. The device emitted a low hum, and the indicator light changed from red to yellow.

"First filtration begins." Nana brought up the data interface. "Current filter grade is C4, expected to remove more than 60% of salt. Check if the exhaust port is blocked by crystals."

"Got it." Chen Hao squatted on the ground, his eyes fixed on the thin drainpipe. "I'm watching this like I'm watching a show, all that's missing is popcorn."

Five minutes later, the water gradually became a clearer color, but some flocculent material was still floating at the bottom of the bottle.

"It looks... like it might actually be working?" He leaned closer to take a look. "At least it doesn't look like pee anymore."

“Visual judgment is unreliable.” Nana took out a miniature detector. “The first treatment is complete. Suspended solids have been reduced by 72%, and conductivity has decreased by 43%. Secondary filtration is recommended.”

"Do we have to do it again?" Chen Hao rolled his eyes. "This water is even harder to handle than my ex. If it doesn't work the first time, we have to talk about feelings."

He removed the filter cartridge, turned it over to look at it in the sunlight, and found that a ring of white particles had formed on the outlet screen, like salt sprinkled on a fine mesh.

"Oh dear, it really is clogged." He gently scraped it with his finger. "This stuff clumps up even more than instant noodle soup."

"Manually rinse the pre-filter," Nana reminded, "to avoid secondary contamination."

He poured some water from his water bottle to rinse it, and white residue fell off, leaving a faint ring of marks on the ground.

"Does this count as environmental protection?" he muttered. "Zero wastewater discharge, and we don't even waste mud."

After the second water injection was completed, the humming sound of the equipment became lighter, and the indicator light quickly turned from yellow to green.

"Filtration complete." Nana took a sample and dripped it into the testing tank. "The mineral salt content has decreased by 80%, the heavy metals are within the standard, and the pH value has dropped to 7.1. It is safe to drink for a short period of time."

Chen Hao was stunned for a moment. "Wait, you mean... this water is drinkable?"

“Short-term intake poses no acute risk,” she added, “but daily intake of no more than 500 ml may lead to electrolyte imbalance with long-term consumption.”

"Five hundred is enough!" He snatched the purified water bottle, unscrewed it, and poured it into his mouth.

After the first bite, his brows immediately furrowed. "Holy crap! What does this taste like? It's like tap water used to rinse salted fish!"

He swallowed, then took another big gulp, this time slower, his Adam's apple bobbing up and down a few times.

"It tastes awful..." He put down the bottle, wiped his mouth, "but it's fucking thirst-quenching."

He drank half a glass in one gulp, and the burning sensation in his chest finally subsided a little. The sun was still blazing overhead, but he suddenly felt less agitated.

"We can finally drink processed water now." He grinned. "Shouldn't we apply for a patent next? 'Desolate Star Salt Lake Direct Drinking Technology,' or chd for short, sounds pretty advanced."

“The system can run three times in a row.” Nana entered the data into the log. “After that, the filter needs to be replaced, and there is only one spare set in stock.”

“Three times…” Chen Hao looked down at the murky bottle of raw water in his hand. “Use it sparingly, one cup per person per day, like afternoon tea.”

He poured the remaining purified water into his water bottle, tightened the cap, and carefully stuffed it into the compartment of his backpack.

"What if this filter breaks?" he asked, looking up. "Can we make a substitute using what we have on hand? Like, a makeshift filter made of socks and sand?"

“It’s theoretically feasible,” Nana said, “but it’s extremely inefficient and could introduce bacteria or impurities.”

"Never mind then." He waved his hand. "I don't want to die before I drink dirty water, and I certainly don't want to die on smelly socks."

He stood up, stretched, and his bones cracked twice. In the distance, the lake still shimmered with heat, and the red grass swayed gently in the wind.

"But then again," he touched the two black stones in his pocket, "the things these little animals give us, maybe one day we can actually exchange them for some useful goods."

“The exchange activity is still in its early stages,” Nana cautioned. “It cannot be relied upon as a stable resource.”

“I know,” he smiled, “but I have a new plan now.”

Tell me about it.

"Bring a pair of clean socks tomorrow," he said seriously. "Let's see if we can get a different straw."

Nana didn't speak, but her eyes flashed blue light twice, as if she was recording some abnormal data.

Chen Hao patted his backpack to make sure everything was packed. After the filtration device cooled down for a minute after being turned off, he stuffed it back into the thruster suit and then fastened his outer armor back on.

“You know, our journey so far, from escaping for our lives to finding water, then doing business with rats, and finally making water purifiers from space debris,” he said, sitting down against a rock and catching his breath. “We’re living more and more like extras in a science fiction movie.”

“But you’re still alive,” Nana said.

“Yes.” He looked up at the sky. “And we can even drink salty boiled water. That’s pretty good progress.”

He pulled out the last energy bar, its foil packaging gleaming in the sunlight. He didn't eat it right away, but instead held it in his hand and twirled it a few times.

"Do you think they'll come back tomorrow?" he asked in a low voice.

“The behavioral pattern indicates an 81% probability of repetition,” Nana replied, “as long as you provide an equivalent exchange.”

“Then it’s coming.” He smiled. “Then I need to prepare some new products for launch and do a promotional event.”

He tore open the packaging, took a bite, and chewed slowly and deliberately. The cloying sweetness melted in his mouth, and combined with the salty water he had just tasted, it was a truly hellish combination.

"Next time I put a bottle of water on the rocks, will they think I'm opening a shop?" he said while chewing. "'Interstellar Convenience Service Station,' mainly selling snacks and intelligence, plus a free sunbathing experience."

“Based on the existing interaction logic,” Nana said, “they are more likely to think you’re setting a trap.”

"Alas, people's hearts have changed," he sighed. "Even alien rats have learned to doubt society."

After finishing the last bite, he carefully crumpled the wrapper into a ball and stuffed it into a sealed bag.

"You can't litter." He patted the bag. "What if one day they evolve environmental awareness and report me for damaging the ecosystem?"

Nana scanned the surrounding area. "System self-check complete. Propulsion suit in normal condition. Remaining energy supports round-trip escape capsule."

"Then let's wait a while before leaving." Chen Hao leaned against a rock, gazing towards the lake. "Let me sit for a bit."

He closed his eyes, the wind blowing on his face, hot, but also a rare moment of peace.

A few seconds later, he opened his eyes again.

"Oh, by the way," he suddenly said, "how about we give this purified water a name?"

“No need to name it,” Nana said.

“That’s so lacking in ceremony.” He thought for a moment, “How about calling it ‘Haoshui No. 1’? It sounds more high-tech.”

"I suggest prioritizing practicality over vanity."

“You don’t understand.” He waved his hand. “If we build a factory and start mass production in the future, we need to register the trademark as soon as possible. ‘Haoshui’—the first reassuring drink from travelers on the desolate planet.”

As he was speaking, a slight noise came from the crack in the rocks in the distance.

He immediately stopped talking and turned to look.

A furry head poked out.

It's not the gray one from before.

This one was smaller, with brown tips on its ears. It sniffed and its gaze fell directly on the sealed bag at its feet.

Chen Hao slowly reached into his pocket and pulled out the remaining energy bar.