The term "biosphere" was no stranger to the scientists present.

Earth itself was a vast biosphere, spanning from 10,000 meters above sea level to 11,000 meters deep in the ocean, all falling within the scope of the biosphere. The Earth's biosphere mainly consisted of three parts: living matter, biogenic substances, and biologically inert substances. Among them, living matter could be divided into three categories: producers, consumers, and decomposers.

Producers, namely green plants, converted carbon dioxide into organic matter through photosynthesis and released oxygen. Producers and consumers inhaled oxygen and converted organic matter back into carbon dioxide, which was the carbon cycle.

The Earth's biosphere was massive, with high biodiversity and a complex trophic structure, boasting a powerful self - regulating ability. Thus, the concentrations of carbon dioxide and oxygen in the Earth's atmosphere had always remained in a balanced state.

It sounded simple, merely requiring the balance of carbon and oxygen amounts. However, within the complex and vast system of connections, perhaps every wisp of gentle breeze was indispensable for life. Humans had conducted numerous experiments on artificial biospheres, but without exception, all had ended in failure!

In the 1990s, the United States had constructed an artificial closed ecological system named "Biosphere 2". Eight researchers had carried out a 21 - month experiment within it.

They had conducted ecological and environmental research in a closed - state to help humans understand how the Earth functioned and to study under simulated Earth ecological conditions.

However, after 21 months, the experiment failed. The reason was that the atmospheric composition ratio of oxygen and carbon dioxide in Biosphere 2 could not reach equilibrium on its own. Most plants and animals could not grow or reproduce normally, and their extinction rate was faster than expected. Meanwhile, cockroaches and ants thrived. Even worse, the oxygen content dropped from 21% to 14%. If humans were to live in it, it could pose a life - threatening situation.

Scientists thought they had found the cause of the failure. Subsequently, Biosphere 2 welcomed a second batch of inhabitants. But the experiment failed again just half a month later because of excessive accumulation of nitrous oxide.

Since then, people realized that Earth was still humanity's only home.

The existence of the Moon base relied on continuous supplies from Earth and could not survive independently.

"Now, we must establish a real biosphere!" Dr. Roman exclaimed. "Perhaps we can simplify it, just achieving carbon balance will do."

He furrowed his brows. With the existing human technology, could they really establish a completely balanced biosphere? Moreover, once this experiment started, it had to succeed. Failure would mean the extinction of the entire race.

"No, no, Roman, you're thinking too much, too complicatedly!" A female scientist stood up and said loudly. "We don't have that much time to consider these things at present."

"Regarding the carbon dioxide issue you mentioned, we can completely produce carbon dioxide using methane and carbonates on the Moon. The top priority is to solve this food crisis, not anything else!"

"For now, let's not consider oxygen and water. We still have stockpiles."

A group of scientists started arguing. They began calculating the feasibility of various plans, aiming to obtain an optimal result.

As Yu Yifeng listened, he sorted out relevant thoughts. Gradually, his heart started to burn with hope. There was still hope!

After all, these were fifty - thousand people carefully selected from Earth, including the most outstanding scientists, the most skilled technicians, and the most experienced engineers... The productivity of the Moon base was comparable to that of a small country.

The mineral resources here were also much richer than expected. The reason for choosing this location for the Moon base was not only because there was an alien spaceship here but, more importantly, that there were nearly 220 million tons of ice deep underground!

Don't think there's no water on the Moon. It just exists in the form of ice hidden deep within the lunar crust. Compared with the water resources on Earth, 220 million tons of ice was not much, but it was already a substantial treasure.

Human survival was inseparable from water, but water could not be compressed, making transportation extremely troublesome. Transporting such a large amount of water, several hundred million tons, from Earth was almost impossible. Considering that the carrying capacity of the Victory was only 500 tons! Therefore, these ice mines had become the best resource.

Thanks to the ice mines underground, water resources were not in short supply for the time being. Although nearly half of the ice had been mined over the years, there was still at least 100 million tons in storage! With conservation, it would be enough for humans to use for decades. Even if it was used up, humans could still extract crystal water from the mineral rocks underground, though it was more troublesome.

As for oxygen, part of it was transported from Earth, and part was obtained through plant photosynthesis, but most of the oxygen was obtained by electrolyzing minerals. For example, electrolyzing metal oxides or water could yield oxygen.

The Moon base required approximately 15,000 tons of oxygen per year. This amount was not high. Electrolyzing 17,000 tons of water could meet the demand. So the oxygen problem was also solved.

Regarding carbon dioxide, it could be decomposed from carbonates or obtained by burning methane. There were abundant solid methane reserves in the lunar polar regions, near the base. However, carbonates near the surface were extremely scarce and could only be excavated deep underground, which involved a large amount of work. Burning methane, on the other hand, presented new problems. Methane combustion required an oxidant, that is, oxygen!

But producing oxygen required a large amount of energy. Therefore, it was necessary to increase energy production... Solar energy alone was not enough. The simplest way was to increase the development of uranium resources and build nuclear power plants!

In the end, the scope of work expanded, involving more and more aspects. It seemed that everything was in short supply, and everything needed to be rebuilt. Yu Yifeng was already a bit confused.

After all, he was not a professional scientist. He only jotted down some numbers to consider their feasibility, while other detailed issues had to be considered by these scientists.

"You're mortgaging the future!" Roman roared, putting his hands behind his head and rubbing his hair deeply. Currently, the main focus was on food production, and the plan for building an ecosystem was temporarily put on hold.

"Our water resources are also limited..." He wanted to say more but was suddenly pulled back by someone. It was his adopted daughter, Yuriko.

Yuriko said softly, "Father, we must first overcome the current difficulties before we can think about the future, right?"

"Yeah, sigh... You're right. A complete ecosystem can't be completed overnight." Roman said with a bitter smile.

At this moment, Yu Yifeng had a sudden inspiration and thought of a wonderful idea. He jumped up from his seat and said, "Everyone, everyone! Listen to me. Why don't we move into the alien spaceship?"

"The reason we didn't vigorously develop the alien spaceship before was that the government wanted to keep the secrets of the spaceship and the perfect - element. Now that this secret is known to everyone, why should we abandon it?"

"Whether it's for safety or other considerations, it's a very good choice!"

Everyone suddenly fell silent, whispering to each other and discussing the feasibility of this plan in a low voice.

"I agree!" A male voice came from the back. It was Chief Physicist Felix. "If everyone moves into the alien spaceship, we can plant all the vacated surface areas with plants, which can save a lot of time!"