Die on Mars

Tang Yue rummaged through the box and pulled out several large sheets of polyethylene plastic film from the packaging box. These plastic sheets were originally used to pack and wrap food, but are no longer used.

He then carried the plexiglass sink on the workbench in his hands, put on his Mingguang armor, waved to Maidong and left Kunlun Station.

The old cat was standing on the edge of the pit, holding a long-handled shovel, covered in dust and sand, looking into the distance with a face full of vicissitudes of life.

The pit has been dug, with a diameter of almost one meter and a depth of about half a meter. The excavated sand and gravel are piled on the side - the old cat is an old cat, and he is a good digger.

"Tell me." The old cat pointed to the pit at his feet, "How on earth do you use this pit to collect fresh water?"

It will decide whether to bury this guy in this pit based on Tang Yue's answer.

"Condensation." Tang Yue put the plastic film and the water tank on the ground, and slowly leaned down to grab a handful of soil in the pit. The soil was still very dry, mixed with hard silica and layered rocks. Tang Yue picked up the shovel and began to repair the pit. He expanded the bottom of the pit, removed sharp gravel, and smoothed the walls and bottom of the pit.

"What's the temperature now?" Tang Yue asked.

The old cat glanced at the sun in the sky and said, "Thirteen degrees below zero, it will be noon soon, so the temperature is relatively high."

Tang Yue nodded.

"Here, do me a favor and unfold this plastic sheet."

Tang Yue and Lao Mao unfolded the smooth plastic film and placed it flatly on the bottom and wall of the pit. They flattened the plastic film carefully and made it fit tightly with the entire pit. The LDPE plastic film It was very soft and very malleable. Next, Tang Yue placed the water tank in the center of the bottom of the pit.

"Is this sink used to collect water?" the old cat asked.

"Yes." Tang Yue pulled the rubber pipe that transported fuel over and probed the glass Y-shaped pipe at the end into the pit.

Tang Yue and Lao Mao unfolded the second plastic film. They straightened and tightened the plastic film and completely covered the pit mouth. After confirming that there were no gaps and no air leakage, they pressed the edges of the plastic film tightly with earth and rocks.

Next, Tang Yue picked up a stone and gently placed it in the center of the film at the entrance of the pit.

Gravity depressed the plastic film slightly.

"It's done." Tang Yue clapped his hands, "This is a condensing device, much faster than the condensing tube."

The old cat circled the pit and understood Tang Yue's intention.

This is indeed a condensation device. As long as they ignite the methane, the water vapor produced rises and contacts the cold plastic film. The ambient temperature of Mars is very low, which will keep the plastic film at the crater cold. Once the water vapor cools down, it will condense. It forms water droplets, and then gathers along the inclined film surface to the lowest point in the center of the plastic film under the action of gravity.

All the water droplets will gather here and eventually drip into the water tank at the bottom of the pit.

The first plastic film laid on the bottom of the pit is to prevent water droplets from falling into the soil. This condensation device is almost a fully enclosed structure. Water vapor will not leak. All water will either fall into the sink or be absorbed by the bottom of the pit. The plastic sheet was intercepted.

"The entire plastic film is a condenser. The larger the pit, the more fresh water is collected." Tang Yue said.

The old cat pondered for a moment, "But it shouldn't be too big, otherwise the water will freeze on the film. The heat generated by methane combustion is limited after all."

Tang Yue was startled for a moment, and after thinking about it carefully, this was indeed the truth.

The old cat turned around and climbed onto the roof of the Martian Stray Dog's car and opened the valve of the pressure relief valve.

Tang Yue lay down, carefully opened a corner of the plastic film, reached in and adjusted the height of the glass tube. He couldn't let the methane flame get too close to the plastic film. After all, polyethylene material is not heat-resistant and will melt as soon as it is baked. Then Tang Yue Yue used an arc lighter to ignite the methane.

Lao Mao and Tang Yue gathered around the pit, staring intently at the plastic film.

The LDPE film is transparent, and through it, Tang Yue can see the light yellow flames burning in the pit.

He was a little nervous. No one knew whether this method would really work, but fresh water was such a vital resource. If this method failed, they would have to find other ways to collect fresh water.

Five seconds later.

The transparent plastic film was covered with a vague layer of water mist. The water gathered at an extremely fast speed, and soon large drops of water appeared. They slowly flowed along the plastic film and gradually solidified.

Tang Yue and Lao Mao both sat down on the sand and let out a sigh of relief.

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Tang Yue and Lao Mao calculated that by collecting fresh water in this way, an average of three to five liters of water should be obtained per hour - this depends on the burning speed of the propellant. If Lao Mao increases the consumption of methane and liquid oxygen, dosage, more water vapor will be produced.

Of course, this increase cannot be unlimited, and the flames of larger doses of methane will burn through the plastic film.

An hour and a half later, the water tank was full. Old Cat took the water tank out from the bottom of the pit and immediately returned to Kunlun Station. However, the water in the water tank began to freeze as soon as it was exposed to the air. When Old Cat closed the airlock door, the water tank started to freeze. There is already a thick layer of ice floating on the surface.

They were groping to find a more suitable collection speed.

The old cat drove Tang Yue back as usual so as not to waste Mingguang Kai's power. It sat on the edge of the pit and took care of the condenser.

Tang Yue maintains the OGS system and water circulation collection system at Kunlun Station.

"The flow rate of three cubic centimeters is too slow, and the temperature of the flame is not high enough." Old Mao's voice came from the earphones, "The water on the edge of the film has been completely frozen. I think it is best to maintain the temperature in the pit at zero to Between five degrees... I should get a thermometer."

"Then increase the dose of methane." Tang Yue opened the lid of the OGS cabinet, holding a wrench in his hand, "increase it to five centimeters and have a look."

"Well... it has increased to five centimeters, and the fresh water collection speed is twice as fast as before, but the water at the edge of the film still shows signs of freezing." The old cat's voice sounded, "The temperature at the bottom of the pit is... …One degree Celsius above zero, the temperature of the pit walls is still below zero.”

"Is the temperature uneven in the pit?"

"Well, it's not uniform." Old Cat said, "After all, the heat source is only the methane flame, and the hot air flow rises, so the air in the upper layer of the pit heats up faster than the surrounding and bottom. We'd better speed up the heating rate."

"Then let's make it bigger."

Tang Yue closed the lid of the OGS system cabinet, patted the old man, and turned to look out.

He saw the old cat climbing down from the Martian stray dog ​​in the distance. He moved very neatly. He must have just unscrewed the pressure release valve of the propellant.

The cat lay on the ground with its butt stuck out, lifted the plastic film, and ignited the methane.

One second later.

"Bang!" There was a loud noise and fire flashed.