Sending 14 cabinets to the sky? What were they thinking?

The Shenzhou-15 crew, including Fei Junlong, Zhang Lu, and Deng Qingming, has been in orbit for nearly 150 days. During this time, they have conducted a series of scientific experiments using scientific experiment cabinets such as containerless, high microgravity, and variable gravity. Many of these projects are firsts.

What supports the astronauts to conduct experiments in orbit are 14 2-cubic-meter experimental cabinets, each of which is comparable to a laboratory of dozens of cubic meters on the ground.

In order to build it, ten years ago, a group of young people with an average age of less than 30 began a journey to break through the blockade and explore the unknown.

From 0 to 100

How difficult is this big step?

At the Space Engineering and Technology Center of the Chinese Academy of Sciences, a team is conducting a "physical examination" of the laboratory cabinet in space through a ground-to-space link, and judging the cabinet's on-orbit status based on parameters such as current, temperature, and "heartbeat."

"Every time we see our astronauts in a happy mood after completing an experiment in the flight control hall, we feel it is worth it." Zhang Lu, deputy director of the Integrated Technology Center, is a young "veteran" of the team. He has accompanied the team from the initial 7 people to 83 people.

But ten years ago, when they received this task, they faced many difficulties.

"The only information we could see was photos and descriptions of the International Space Station. We didn't even know what the space laboratory module looked like, let alone the fancy laboratory cabinets inside. And we had never experienced any major project before."

But "We come from a technical background, so if you give us a job, we can do it," said Wang Ke, director of the Integrated Technology Center.

What is more important is the significance of the space laboratory to the country and to all mankind.

In 1992, China established a three-step strategy for its manned space program. The last step was to build a space laboratory for Chinese people. This was an important step for the Chinese people to explore the deep universe and contribute to the peaceful use of space for mankind.

Zhang Lu's words expressed the aspirations of the group of young people who had just graduated at the time: "This is the first time our country is building a space station. We have such a good opportunity. Since the country supports us, why shouldn't we do our best to get it done?"

This lasted for a full ten years. Xue Jing sighed that everyone was only focused on the work and raced against time. So there was this scene: "We often saw colleagues who got the work, but they were still there when we got off work. They really didn't get off work and kept working," Xue Jing recalled the scene at that time. "Everyone almost didn't have the concept of getting off work. They all regarded the time node of the task as their mission."

Zhang Lu recalled the time before the launch of the Mengtian laboratory module, when the three teams in Beijing, Xi'an and Shanghai worked in a closed environment. "For more than 20 days, there was no day or night, and we slept in a large bunk bed. No matter whether we were ordinary employees or leaders, we ate, drank and worked together. We were completely isolated from the outside world, and we didn't even need to know what time it was, just to send the Mengtian laboratory module and the experimental cabinet into space smoothly."

In the past ten years, they have relied on the spirit of "breaking one day into two days, one week into two weeks, and several months into one year", and finally sent the experimental cabinet into space, supporting the construction of the National Space Laboratory.

And what engineering difficulties have they overcome in the past ten years?

"Brothers with different surnames VS Brothers with the same surname"

Whenever Zhang Lu sees the comparison pictures of the International Space Station and the Chinese Space Station, she is always proud: "We figuratively call them brothers with different surnames and brothers with the same surname. Our experimental cabinets are neat and tidy."

In fact, during the demonstration phase, Zhang Lu and his team also faced the question of whether "each cabinet is independent and self-contained" like the International Space Station. This is equivalent to the first step in building a house.

"If it is like the International Space Station, it seems that there will be more freedom in research and development, but there will be repeated development and inconsistency of the same technology, which will also increase the difficulty and cost of subsequent on-orbit operations. Moreover, if different experimental cabinets encounter common problems, they cannot replace each other."

In the end, Zhang Lu and his team chose to unify the common technologies of the 14 test cabinets, so as to accommodate the independent scientific experimental needs on the basis of unified requirements. This meant that they had to quickly extract the common technical requirements by visiting different teams of scientists in a short period of time. This was a time-consuming, labor-intensive and stressful task.

Zhang Lu took a module thermal control drawer on a laboratory cabinet as an example. "We counted the heat consumption of each module in 14 scientific laboratory cabinets under hundreds of experimental processes. At the same time, we also counted the optimal temperature conditions that need to be achieved when conducting different experiments. Based on the data from these two different dimensions, we simulated and calculated the heat dissipation mode of each cabinet. In the process, we had to continuously design, simulate, verify, and then improve the design. When all the test results and simulation calculation results met the requirements, a year had passed."

There are many such modules in the lab cabinet. But in the end, the team only took three years to sort out all the common and individual needs and meet them. "In the end, our time granularity was in half an hour."

“Light and stable”, how to resolve this contradiction?

Lightness and stability are a pair of contradictions. "Light things are often easily knocked over." Kang Boqi, the structural designer of the experimental cabinet, has gone through three structural iterations of the experimental cabinet.

When the Chinese space station was determined to be 180 tons, it meant that the 200-kilogram first-generation experimental cabinet they developed in 2012 had to "lose weight and gain muscle."

"Our second-generation test cabinet has been reduced to 120 kilograms. It is very difficult to reduce it further from 120 kilograms." Kang Boqi used "weight loss" as an example, "When you are overweight, you lose weight quickly, but the smaller the base, the harder it is to lose weight."

It is their normal state to face challenges head-on:

In terms of craftsmanship, they are very meticulous, and they remove a lot of weight just by removing the nails. But every time they remove the nails, it means a test.

In terms of materials, we explored the use of new lightweight materials. “Having never used them before means we cannot trust our previous experience and past successes. We can only use the clumsy method of adjusting, testing, and checking parameters one by one.”

At this time, Kang Boqi also encountered a conflict between his doctoral studies and engineering. "I felt that the task of losing weight was difficult, and I also needed to pursue further studies. I was thinking about whether I should give up engineering and focus on research."

But the words of Wang Ke, director of the Integrated Technology Center, rekindled Kang Boqi's fighting spirit. "He gave me a belief that if you persist, believe that it can be done, and work hard for it, you will definitely see the effect."

Kang Boqi persisted in doing so. Although her studies "were visibly neglected and she was too embarrassed to see her teachers," it was worth it for her, "because the aerospace industry cannot wait for anyone, and I have done something that I will find interesting and proud when I look back on it in my later years."

In the end, the weight of the experimental cabinet was settled at less than 100 kilograms.

Reducing its weight from 200 kilograms to less than 100 kilograms, China's space experiment cabinet has created a miracle of being both light and stable. "Our 100-kilogram cabinet can carry 400 kilograms of scientific payload into space, which is twice that of similar international equipment."

"There's a noise in the 'heart' of the lab cabinet. What should I do?"

The cooling system in the experimental cabinet is equivalent to the human body's blood circulation system, and the pump is equivalent to the human heart. If a failure occurs, all scientific experiments planned by the country will not be able to be carried out, which will have a huge impact on the national scientific development strategy.

Guo Dong is a deputy chief designer at the Integrated Technology Center. When he received this task, which is "the largest in scale, the most complex in supporting components, the most load demanding, the shortest cycle requirement, and the highest critical level" so far, he was excited but also felt pressured. " Sometimes when I get home and turn on the faucet, all I think about is the working principle of our pump. I am basically in a state of madness where I see no mountain as a mountain."

Guo Dong's colleague, Zou Tianji, always remembered a small episode. "Guo Dong accidentally fell into a ditch on his way home in the middle of the night and had to get 38 stitches. The doctor told him to rest for half a month, but he only stayed at home for three days without removing the stitches or reducing the swelling in his mouth. He returned to work and fought side by side with everyone."

At that time, the circulating pump of the cooling system was noisy and unstable. Before that, the circulating pump had already experienced a major disruption, and at this time, there was no time for disruptive trial and error. Guo Dong said frankly: "At that time, not only the outside world, but also we ourselves began to doubt ourselves, wondering whether we were suitable for such a major task."

At this time, the institute contacted an old expert for Guo Dong. When the old expert helped Guo Dong revise the plan on his hospital bed, this moment opened a gap in Guo Dong's darkest moment.

"Finally, after seven or eight days and nights of concentrated design changes, our team finally completed the adjustment of the circulation pump. When I saw that the parameters and indicators of the prototype were qualified when it was working on the test bench, I couldn't hold it in for a while. I felt like I had been holding on with one breath."

Zou Tianji is a member of the team who was born in the 1990s. When talking about his experiences in the laboratory cabinet project, he quoted an internal joke: "Everything is difficult at the beginning, may be more difficult in the middle, and is still difficult at the end." However, he thought it was very cool. "We young people have gained strong confidence from this experience. That is, we can overcome various difficulties through our own efforts and realize the goal of serving the country through aerospace. Although it is hard, it is also a very cool thing."

Ten years of hard work, the stars are shining, from 0 to 100, it is a dream, it is persistence, it is faith. "In ten years, we have sent the laboratory into space. It is the development of the country that has given us a platform to spend our youth. We also hope to continue to dedicate our youth and old age to China's space industry."

With the approaching of May Fourth Youth Day, the second season of "Aspirational Youth" was launched as scheduled.

We still invite the winners of the "China Youth May Fourth Medal" (group) to tell their hard-core stories in the form of micro-documentaries, such as how they illuminate their journey with their original aspirations, build strength with perseverance, achieve their future with hard work, and build their dreams of home and country with their feelings. It shows that they integrate their personal development into the great cause of building a strong country, respond to the call of the country with their own choices, and show the high spirits of youthful responsibility with unremitting struggle.