He traveled across the mountains to find a home for the "China Sky Eye"

In the mountains of southwest China, there is a huge "sky pot" facing the vast universe, silently capturing electromagnetic pulses billions of light years away. This is the "China Sky Eye" FAST - the world's largest and most sensitive single-aperture radio telescope.

As we gaze at the stars reflected on the FAST mirror, the silhouette of a white-haired old man seems to be still watching from the top of the mountains - he is Nan Rendong, who spent 22 years building a powerful astronomical instrument for China. February 19 is the 80th anniversary of Nan Rendong's birth. Let us follow his footsteps, review the construction process of the "China Sky Eye", and feel his innocent heart that burned for his scientific dream all his life.

Nan Rendong, chief scientist and chief engineer of "China's Sky Eye" Photo source: Xinhua News Agency

Traveling across the mountains to find a home for the China Sky Eye

Nan Rendong's fate with the "China Sky Eye" began in 1993. That year, the International Union of Radio Science Conference was held in Tokyo, Japan. At the conference, astronomers from many countries jointly proposed a grand plan: to build a new generation of radio telescopes to receive more information from outer space. Nan Rendong, who was engaged in radio astrophysics research, keenly realized that this was an excellent opportunity to develop Chinese radio astronomy.

"Others have their own large equipment, but we don't. I really want to give it a try." It was this sentence that made Nan Rendong closely connect the rest of his life with the "China Sky Eye".

In 1994, Nan Rendong proposed the engineering concept of "China's Sky Eye" - a 500-meter aperture spherical radio telescope, and as the chief engineer, he shouldered the heavy responsibility of project research and development and promotion.

To build such a large-diameter radio telescope, the first hurdle is site selection. In the mountains of southwest China, the valley of several hundred meters is surrounded by mountains on all sides, which naturally blocks the electromagnetic waves from outside. This is an excellent geographical condition for building the "China Sky Eye".

In order to find the ideal site, Nan Rendong led his team on a long and difficult journey of site selection. They first used remote sensing technology to preliminarily screen out more than 3,000 depressions, then circled more than 300 of them, further screened to more than 100, and finally "selected them on foot" one by one. At that time, the green train from Beijing to Guizhou took nearly 50 hours one way, and Nan Rendong took the satellite map and went to the southwestern mountainous area one by one without any effort.

The average age of the site selection team was only 30 years old, but Nan Rendong was nearly 50 years old. Faced with the steep mountains and forests, he used his hands and feet to climb up with difficulty; where there was no road, he moved through the bushes between the cracks of the rocks, one foot deep and one foot shallow. Once, heavy rain poured down, and the mountain torrents carried sand and gravel, even uprooting large trees. Nan Rendong, who was exploring outside, climbed back to the pass with the help of heart-saving pills. Such hardships accompanied Nan Rendong all the time during the more than ten years of site selection. He said, "If I can't find a suitable depression, I will die with regrets in my life!"

Nan Rendong during the FAST site selection period. Image source: Museum of Chinese Scientists

From 1994 to 2005, Nan Rendong traveled to hundreds of pits in the mountains of Guizhou for more than 4,000 days and nights, and even found roads in places where there were no roads before, just to find a round and large pit for the "China Sky Eye". Finally, they successfully locked on Dawotang, the ideal site.

In 2007, FAST was officially approved by the state as a major scientific facility in the 11th Five-Year Plan. In March 2011, the villagers were relocated and the FAST project officially started.

The dream-chasing journey of the "China Sky Eye" has set sail.

Personally involved in creating important tools for the country

Manufacturing a telescope is a large and complex system engineering project, involving the collaboration of many disciplines. In order to ensure the smooth progress of the project, Nan Rendong personally took care of everything and stayed at the construction site all year round. From the measurement and calculation of the steel structure to the overall planning of the project, he personally checked and repeatedly confirmed every detail.

When reviewing the plan, Nan Rendong encountered a geotechnical engineering field that he was not familiar with. He did not back down, but spent a month studying the relevant knowledge, repeatedly calculating and reviewing each drawing. The construction party was surprised to see how professional he was, saying: "How can this astronomical scientist also understand civil engineering?" Once, in order to solve the error problem of a ground riveting project, Nan Rendong put down his chopsticks and rushed to the construction site, fearing that the technicians' measurements would be slightly off. Xing Chenghui of the 54th Institute of China Electronics Technology Group Corporation once met Nan Rendong by chance on a sultry summer afternoon, and still sighs: "The Sky Eye is the child that Nan Rendong has devoted his heart and soul to!"

During the construction of the "China Sky Eye", Nan Rendong led his team to overcome many technical difficulties and built the world's largest span and highest precision cable net structure. This achievement not only laid a solid foundation for the "China Sky Eye", but was also successfully applied to major projects such as the Hong Kong-Zhuhai-Macao Bridge, demonstrating its outstanding technical value.

In 2013, the 500-meter-diameter ring beam was successfully connected. Nan Rendong, wearing work clothes and a helmet, was the first to climb the high ring beam, running in the cold wind like a child, releasing his excitement and joy. After that, every time a feed support tower was built, he would be the first to climb up and stand on the top of the tower to overlook the whole picture of the "Sky Eye".

Nan Rendong at the construction site. Image source: CCTV-1

"The beautiful universe, with its mystery and splendor, calls us to step over mediocrity and enter its boundless vastness." Nan Rendong once confessed to the universe in this affectionate way. In his mind, the "China Sky Eye" is not only a telescope, but also a bridge for mankind to explore the mysteries of the universe. It is a great national weapon that he has created with his life's hard work.

Opening the "Sky Eye" for China before fighting the disease

However, just as the legendary project "China's Sky Eye" was about to be completed perfectly, people around him discovered that Nan Rendong, who once walked with the wind and had a voice like a bell, had changed - he could no longer climb to the top in one breath, his steps became heavier, and his breathing became more and more rapid when he stopped to rest.

Nan Rendong was diagnosed with advanced lung cancer. The disease eroded his body mercilessly, but his spirit was never defeated. Even after undergoing a major operation and being extremely weak, Nan Rendong still stayed at his job. Every day, he communicated with the team via email, repeatedly considering the plan and confirming the details. Just three months after the operation, he returned to the construction site despite the pain. At this time, his voice was hoarse and he had to speak in one breath, but he still asked and explained word by word, not letting go of any problem.

"'Sky Eye' is the result of the hard work and efforts of a large group of people, not just me personally. We can even say that it is the effort of a generation." He repeated this sentence over and over again, "If 'Sky Eye' has any flaws, we will be sorry for the country!" This is his deep persistence and belief, and it is also his loyalty and responsibility to the country and the cause of science.

In 2016, the "China Sky Eye" was completed and put into use. This is the world's largest single-aperture and most sensitive radio telescope with independent intellectual property rights in my country. On the afternoon before the inauguration ceremony, Nan Rendong, who was already very weak from illness, insisted on flying from Beijing to Guizhou to the FAST base. It was the first time he saw the appearance of this "giant eye" after it was fully built. It was the "Sky Eye" that he had spent 22 years of hard work to finally open for China in the mountains and ridges in the southwest of the motherland.

Panoramic view of the "China Sky Eye" (drone photo, taken during maintenance) Photo by Xinhua News Agency reporter Ou Dongqu

On September 15, 2017, Nan Rendong’s lung cancer suddenly worsened, and he closed his eyes forever, looking up at the stars and exploring the universe. Less than a month after Nan Rendong’s death, on October 10, 2017, the “China Sky Eye” discovered a pulsar for the first time. On October 15, 2018, the National Astronomical Observatory of the Chinese Academy of Sciences announced that the asteroid with the international permanent number 79694 would be officially named “Nan Rendong Star”.

Today, the "China Sky Eye" has produced many results, continuously expanding the limits of human observation of the universe. With 22 years of faith and enthusiasm, Nan Rendong opened the "Sky Eye" of the astronomical community in China, and he also turned into a star in the sky, using his shining light to guide Chinese astronomers to continue exploring the deepest mysteries of the universe.

He has left us for many years, and he did not have the chance to witness the current achievements of the "China Sky Eye", but his spirit of persistent pursuit of scientific dreams will surely inspire generations of scientific and technological workers to continue their struggle and bravely scale the world's technological heights.

Today, let us once again look up at the stars and pay tribute to Mr. Nan Rendong!

References:

1. Guangming Daily. Even a little flaw would be a shame to the country!

2. Xinhua News Agency official account. Over 900! I really hope he can see it...

3. CCTV-1 official account. Look up at the starry sky, don’t forget the “Nan Rendong Star” in the sky…

4. "Chinese Scientists Museum" public account. 12 years, just to find a round and big "pit" for the "China Sky Eye"丨Nan Rendong

5. "Voice of the Chinese Academy of Sciences" public account. Search for it piece by piece, don't miss it | This prosperous era is what you wish for

6. "Voice of the Chinese Academy of Sciences" public account. Nan Rendong: We don't have it, I really want to give it a try

7. "CCTV National Memory" public account. He spent 22 years to open China's "eye of the sky", but he didn't see this scene today. Produced by: Beijing Association for Science and Technology Media Center

Reporter: Zhao Ling