Die on Mars

Early the next morning, the old cat drove the Martian stray dog ​​out and stopped beside the Eagle spacecraft.

Tang Yue stood on the sand wearing Mingguang Armor, looking up at the tall lander as it descended. Although the ascent stage had been launched, the Eagle spacecraft was still the tallest and most conspicuous object in Kunlun Station.

The originally white paint was burned black by the rocket engine tail flame. Tang Yue walked around the lander several times. The ground under his feet was covered with a layer of gravel. The gravel was brownish red, which showed that they were rich in hematite. The sand The bottom is hard basalt. Mars is a nearly dead planet. Geological activities have been silent for a long time. These ancient rocks were formed three billion years ago. They gradually broke under the long wind and sun. Turning into gravel and then into dust.

The old cat opened the door and jumped out of the cab.

Tang Yue gently tapped the hard shell of the lander, "How much propellant is left in this?"

"There should be some left. The propellant of the descent stage engine is redundant and most likely it has not been burned out." The old cat put his hands on his hips and looked up at the Eagle spacecraft. "But how much there is depends on opening the shell. Only you can know."

The Raptor 3C rocket engine of the Eagle spacecraft's descent stage uses methane and liquid oxygen as propellants. Junior high school students all know that the product of the combustion of methane and oxygen is carbon dioxide and water. The reaction of one mole of methane and two moles of oxygen can produce One mole of carbon dioxide and two moles of water, which is an excellent source of fresh water.

This is Tang Yue's plan, to use the propellants in the lander and rely on their reaction to obtain fresh water.

The old cat returned to Kunlun Station and came back with the toolbox.

There was no gangway on the descent stage, so the old cat had to use a Martian stray dog ​​to step on its feet. It climbed onto the roof of the rover and got close to the outer shell of the Eagle spacecraft, with wrenches and screwdrivers hanging all over its body.

Although it sounds simple, it is not easy to get the methane and liquid oxygen sealed in the propellant tank. They cannot smash through the propellant tank to release the fuel, so the methane and liquid oxygen will be released in a short time. Once the leakage is complete, the only opening that can be used to divert water is the pressure relief valve - the liquid methane and liquid oxygen in the tank are constantly evaporating. If there is no pressure relief valve, the air pressure in the tank will be higher than the danger line.

In order to successfully utilize the fuel in the lander, the methane and oxygen must be slowly and safely introduced from the tank, and finally mixed and burned.

For Lao Mao and Tang Yue, this was a very complex project. They first needed to disassemble the fairing of the lander.

It was inconvenient to do this kind of delicate work while wearing the Mingguang Armor, so the old cat could only help.

The old cat held a screwdriver in his mouth, opened the access port of the lander, squinted his eyes, and found the pressure gauge.

"How is it?" Tang Yue asked from below, "How much propellant is left?"

"Well... it's a little less than I expected. It may be because the propellant continues to evaporate. We still have about two hundred kilograms of methane." The old cat frowned, "With so much methane, we can only produce up to four One hundred and fifty kilograms of water, but this amount of water should be enough to grow some tomatoes and carrots.”

"Can these 450 kilograms of water be replenished directly into the water tank?" Tang Yue asked.

"No." Old Cat shook his head. "This water cannot be drunk directly without treatment and purification... But how do you collect this water? The combustion of methane and liquid oxygen produces water vapor."

"Don't worry, leave the collection to me."

Tang Yue is confident.

At two o'clock in the afternoon, Lao Mao removed the lander's fairing, exposing the entire propellant tank and rocket engine. Then they began an intensive modification plan. Tang Yue found two long rubber tubes from the Kunlun Station. tube and a glass Y-shaped tube. These bits and pieces were used by the scientific expedition team members for experiments, and now Tang Yue has put them all away.

Lao Mao put rubber tubes on the pressure relief valve of the propellant tank. One was used to transport methane and the other was used to transport oxygen. They were tied tightly with iron wire to confirm that there would be no leakage.

"OK!" The old cat stood on the roof of the Martian Stray Dog's car and waved his paw.

Tang Yue stood underneath, picked up two rubber tubes, put them on the two manifolds of the Y-shaped glass tube, and tightened them with iron wire. When the time comes, methane and oxygen will mix and burn in the glass tube to produce carbon dioxide. with water vapor.

Tang Yue felt like he was back in high school doing chemistry experiments.

"OK!" Tang Yue raised his hand, "Old Cat, you can come and try it!"

The old cat nodded, grabbed the wrench, and slowly turned the throttle. One mole of methane can react with two moles of oxygen. In order to avoid the waste of propellant and ensure the full combustion of methane, the old cat must carefully adjust the fuel. With the flow rate of the oxidant, it stared at the pressure gauge with a solemn expression.

"Attention——!" the old cat reminded, "I opened the valve!"

Tang Yue took out the arc igniter, leaned in front of the glass tube, and lit the methane with a click.

A small light yellow flame swayed at the end of the glass tube. When the high-temperature water vapor came into contact with the cold outside atmosphere, it immediately condensed into small droplets and turned into a curl of white mist. Tang Yue looked at the methane through the thick glass mask. The burning fire let out a sigh of relief.

The source of fresh water has been secured.

"Old Cat! Success!"

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Lao Mao and Tang Yue stood on the sand, looking down at the glass tube on the ground.

After many experiments, the two finally proved that the methane in the lander could be burned safely—it would not explode suddenly and send them back home.

The next question is how to efficiently collect the water vapor produced by combustion.

"You said you have a way to collect this water vapor." The old cat said, "What method? I have to tell you in advance that we don't have a condenser tube. Those large experimental equipment are either damaged or have all been taken away. We are now even It’s impossible to find a glass tube long enough to make a condenser tube.”

"We don't need a condenser tube. The condenser tube is too slow." Tang Yue shook his head. "To use such a thin glass tube to collect 400 kilograms of water, we have to collect it until next year."

Tang Yue really does not intend to use conventional condenser tubes to collect fresh water. This method is commonly used in laboratories, but it is inconvenient on the windy and sandy surface of Mars. The glass is too fragile, and long glass tubes are even more fragile, and the condenser tube is The collection speed is too slow, and if it is accelerated, it will easily cause waste.

"Then what method are you going to use?" asked the old cat.

Tang Yue turned around and returned to the garage. A few minutes later, he came back with a long-handled shovel in one hand.

Tang Yue threw a shovel to the old cat.

The old cat held the shovel and looked at it for a long time, with a blank look on his face.

"shovel?"

Use a shovel to collect fresh water?

"Yes!" Tang Yue nodded and waved the shovel in his hand, "We use the shovel to collect fresh water!"