Looking up at the starry sky together with the "Chinese Sky Eye" (innovative in the "Four Deeps" field) China | Sky Eye | Starry Sky

This is a mosaic photo: the first reflective panel assembled by the "China Sky Eye", nearly half of the reflective panel installed by the "China Sky Eye", nearly 80% of the reflective panel installed by the "China Sky Eye", and the "China Sky Eye" during maintenance ". Photo by Xinhua News Agency reporter Ou Dongqu

Jiang Peng is inspecting the equipment condition at "China Tianyan". Information images

Introduction to Science Popularization of "Chinese Eye". Information images

The picture shows an aerial view of the "Chinese Sky Eye". Photo by Xinhua News Agency reporter Ou Dongqu

What secrets are hidden in the vast starry sky above us? Is the deep space of the universe nurturing new opportunities for human development?

Layered mountains and towering peaks, the emerald forest is like a sea. Between the mountains in Pingtang County, Guizhou Province, a magnificent and atmospheric single aperture spherical radio telescope stands quietly, gazing at the starry sky, exploring radio signals billions of light-years away with human curiosity and anticipation.

The full name of "China Tianyan" is the 500 meter aperture spherical radio telescope, abbreviated as FAST. FAST adopts a new design concept and is the world's largest and most sensitive single aperture spherical radio telescope, capable of searching for weak signals from billions of light-years away in the radio band.

Recently, our reporter interviewed Jiang Peng, the chief engineer of FAST at "China Eye". As a "star chaser" guarding the "Chinese Eye", Jiang Peng's main research direction is radio astronomy technology and methods. Currently, he is fully responsible for the operation and development planning of the "Chinese Eye". Let's listen to the story of Jiang Peng and the "Chinese Eye" looking up at the starry sky together.

Create a "retina" for FAST

In 2009, at the age of 31, Jiang Peng had just graduated with a PhD and was full of energy.

At this moment, he stood at a crossroads in life: one choice was to continue pursuing in-depth research in the doctoral field; Another option is to choose a completely new and challenging research job.

While hesitating, Jiang Peng saw the recruitment information for "China Tianyan" and instantly became interested.

"At that time, in my opinion, the construction of the 'Chinese Sky Eye' was very bold and challenging." Jiang Peng told our reporter that the FAST telescope almost met all of his expectations and ideas for a legendary project - the largest engineering volume, ultra-high precision requirements, and extremely special working methods, which constituted unprecedented technological challenges in the engineering field.

"I really want to know how this project is going to be implemented, so I want to join this innovative team," said Jiang Peng.

Without hesitation, Jiang Peng successfully became a member of the team after submitting his resume. Afterwards, he plunged into the deep mountains of Guizhou and embarked on a 14 year life with FAST.

How difficult is the construction of FAST?

It not only involves dozens of different professional fields such as astronomy, mechanics, mechanical engineering, structural engineering, electronics, and even geotechnical engineering, but also key technologies have no precedent to follow. Key materials urgently need to be tackled, and the on-site construction environment is also very complex.

For the FAST team, the construction of FAST is "crossing the river by feeling the stones". How to design, implement, debug and use after completion... All difficulties can only be solved by the construction team themselves.

"This is much more difficult than engineering projects that we generally understand, and there are many things that we are not confident about," said Jiang Peng.

In the early stages of FAST construction, Jiang Peng felt pressure from the first task he received.

"At that time, Professor Nan Rendong, the Chief Scientist and Chief Engineer of FAST Engineering, asked me if I dared to undertake the key task of FAST construction - the cable network project." Jiang Peng said, "Simply put, it was to install a 'retina' for the 'heavenly eye' of FAST. As my major is structural mechanics, this important task was handed over to me."

Unlike existing single aperture radio telescopes in the world, FAST's "retina" - spherical reflector is a cable network composed of 6670 steel cables, which requires frequent changes between the sphere and the projectile to collect and observe astronomical signals. This places very high demands on the steel cable mesh that supports the bottom of the "big pot" of FAST. The cable mesh engineering is the core component of FAST reflector to achieve displacement function, and it is also the core technical difficulty of construction.

"How to achieve a control accuracy of 2 millimeters for a 500 meter span telescope?" With the topic assigned by Teacher Nan Rendong, Jiang Peng pondered repeatedly and was determined to do a good job in this unprecedented construction project.

Not long after the project started, the team encountered a major challenge - cable fatigue.

The common steel cables on cable-stayed bridges have a strength of 200 megapascals and 2 million bends. Due to the installation of reflective panels on the steel cables of the "Chinese Eye", it requires repeated deformation and continuous stretching; Telescopes, on the other hand, require at least 30 years of application, which places higher demands on steel cables. After repeated consideration and calculation by the designers, a solution was proposed to install steel cables with a strength of 500 megapascals and a bending frequency of 2 million.

"At that time, the excavation project for the site had already begun, and the upper structure could not be finalized due to fatigue issues with the cable network. The implementation of the project was urgent." Jiang Peng said that they had bought dozens of steel cables from the market for experiments, but none of them could meet the requirements. "What should we do? If the problem is not solved, the entire telescope construction will come to a standstill. After discussion, we have decided to conduct a large-scale experimental study on the fatigue performance of steel cables."

Under the guidance of Nan Rendong, Jiang Peng led a team to conduct a two-year large-scale steel cable fatigue experiment. They explored day and night, tested and experimented repeatedly, and after nearly a hundred failures, finally developed ultra-high fatigue resistant steel cables and completed the construction project of cable network structures.

As the main supporting structure for active reflective surfaces, FAST's cable mesh structure is considered the world's largest and most accurate cable mesh structure today.

6670 main cables, 2225 main cable nodes, and the same number of down cables have fully assembled the FAST cable network. After assembly, the huge reflective surface of FAST looks like a "super big pot", with six support towers standing high and the grid gradually crawling up to the bottom of the pot, extending upwards to "bite" the ring beam, and the reflective surface panels are covered with gaps in the cable mesh one after another, weaving the huge web.

This cable network structure is the world's first cable network system that adopts a displacement working method. That is to say, the actuator controls the shape of the cable network based on the mechanical model information, and activates the actuator to control the cable according to the orientation of the observed celestial body. Instantaneous parabolic surfaces with a diameter of 300 meters are formed in different areas of the FAST reflection surface to achieve precise observation.

The "Chinese Eye" is the pride left by Nan Rendong to his motherland

In 1993, the International Congress of the Radio Science Union was held in Kyoto, Japan, and Nan Rendong also attended the conference.

At the scene, scientists proposed that before the global radio environment continues to deteriorate, humans should build a new generation of radio astronomical telescopes to receive more information from outer space.

Upon hearing this news, Nan Rendong, who was nearly 50 years old at the time, was excited and said, "If we can seize this opportunity, China's astronomical research may lead the international community by several decades." The bold idea of building a new generation of radio astronomical telescopes emerged naturally. Nan Rendong, who had always been low-key, couldn't sit still and ran to find Chinese representative Wu Shengyin. Excitedly, he said, "Let's also build one in China!"

However, for China in the early 1990s, the construction plan for a large radio telescope was bold and almost insane. It is difficult to achieve both geological and technical conditions, as well as engineering costs. Therefore, almost all industry experts are not optimistic about this project.

Despite this, Nan Rendong, who is naturally stubborn and loves to face challenges, decided to stick to this plan.

For Nan Rendong, the most difficult time was during the application for project approval. He was well aware that the previous site selection and argumentation process had taken years of everyone's time and energy, and the project approval must be successful in the future. Otherwise, it means that all previous work is in vain.

So, Nan Rendong began to pay for his own transportation expenses, going from northeast to southeast and then to northwest, one unit at a time to negotiate. In the end, with his efforts, more than 20 cooperative unit names appeared on the thick project application form. In order to find a suitable platform site, Nan Rendong spent more than 10 years traveling through the mountains and rivers of Guizhou, and conducted on-site inspections of dozens of nests.

Finally, in July 2007, FAST was officially approved by the government as a major technology infrastructure for the 11th Five Year Plan. From that day on, FAST began its journey of rapid construction, just like its English abbreviation.

"At that time, Teacher Nan told me that China's research in radio astronomy started many years later than other countries internationally. If it started later than others, it would take more time and walk faster than others, otherwise it would never catch up." Recalling Nan Rendong, Jiang Peng told this reporter a story. Once, Jiang Peng's project team encountered a significant change. Nan Rendong called him to the office and asked, "Jiang Peng, you said you are a young man who has just graduated for two years. Can I completely trust you?" Jiang Peng remained silent for a while and answered word by word, "Teacher Nan, I think you can trust me."

After the launch of FAST construction, Nan Rendong gradually entrusted the heavy responsibility of debugging and operating the "China Eye" to the new generation of young scientists and engineers at FAST. On September 25, 2016, the "China Eye" was officially completed. One year later, Nan Rendong passed away due to illness at the age of 72. Jiang Peng said, "The Chinese Heavenly Eye" is the pride that Teacher Nan Rendong has left for his motherland.

Nan Rendong also wrote a few lines of poetry for himself and his beloved motherland:

The beautiful universe and space,

With its mystery and splendor,

Summoning us to overcome mediocrity,

Entering its boundless vastness... "

After the completion of FAST, it quickly entered the debugging phase, and Jiang Peng took over as the second chief engineer from Nan Rendong, continuing to lead the team to overcome one difficulty after another.

In his view, this is a battlefield without gunpowder. The new design concept of FAST means that the team cannot have any successful experience to refer to, and they must establish a measurement and control method system suitable for the special working mode of FAST. For this reason, Jiang Peng led his team to fight at the project site for three consecutive Spring Festival holidays.

During the 2019 Spring Festival, while others were bustling with lights, the FAST team worked almost every day until three or four in the morning. A core member didn't have time to go home to ensure project progress, and even brought his pregnant wife to the site for care.

Hard work pays off for those who have a heart. In August 2017, FAST achieved tracking of fixed target sources for the first time; In April 2019, it passed the process acceptance and was opened to domestic astronomers in China for trial; In January 2020, it passed the national acceptance and officially opened for operation.

The rapid success of FAST construction and debugging is inseparable from the persistence and enthusiasm of the research team and construction team who have been working hard on the front line of scientific research for ten years.

When it comes to his team members, Jiang Peng jokingly said, "We are a group of 'silly kids' who only know how to work and don't know anything else. There is one sentence that best reflects the spirit of our team, and that is - a group of' silly kids' have accomplished things with their own 'silly' energy!"

Jiang Peng believes that research work has three characteristics. Firstly, it may not necessarily be successful, but "unsuccessful" research may not necessarily be good research. Research is about exploring all possibilities and constantly trying and making mistakes. Secondly, the working hours and cycles are very long, and one should not rush for quick success. It is necessary to remain calm, patient, and strive for excellence in order to make progress. "We cannot always magnify the power of one day and ignore the accumulated strength of one year," Jiang Peng said. "Only by choosing the right direction and persistently persisting, as time goes by, you will soon find that those who persist will leave those who follow the trend and those who are eager for quick success far behind." The third characteristic of scientific research is that researchers must persist on the front line, which is the battlefield and battlefield for researchers, and it is where they should stay.

"As a scientific researcher, I believe the most important qualities are seeking truth and being pragmatic. Many scientific research work cannot achieve immediate results, which requires us researchers to endure long-term loneliness and sit on a cold bench. These are excellent qualities that science and technology workers, especially those working on the front line, need to possess." Jiang Peng told our reporter, "The front line of scientific research is the forefront of generating scientific value, and I believe it is very important to ensure the enthusiasm of frontline researchers. What I am working hard to do now is to make more outstanding scientific and technological talents stay on the front line of scientific research with peace of mind and willingness."

Stay awake to continue leading

Astronomy enthusiasts once curiously asked, "Where is FAST really fast?"?

FAST is fast, safe, and efficient, with no one day delay. The construction project took 2011 days from the date of approval of the commencement report on March 5, 2011, to the scheduled completion on September 25, 2016, and there were no major safety accidents throughout the entire process.

FAST is in the debugging period of less than two years. "You should know that even a traditional telescope's debugging cycle is rarely less than 4 years internationally, and we only need about 2 years to complete the debugging task of this extremely complex system," said Jiang Peng.

FAST has already begun early scientific research during the debugging phase. In the process of continuously calibrating the "vision" of the "Chinese celestial eye", Chinese astronomers are racing against time to carry out scientific observations. When the telescope cannot move, they use drift scanning to make the Earth rotate and patrol the sky with the "Chinese Eye". Less than a year after its completion, FAST has achieved precise tracking observation mode, verifying its ultra-high sensitivity and telescope efficiency.

FAST started discovering new pulsars in the system during the debugging phase. This is attributed to the scientific team's early preparation, corresponding observation and data processing training for team members, development of data processing software and databases

Where is FAST really strong?

The key technological achievements of FAST can be applied in many related fields, such as large-scale structural engineering, high-precision dynamic measurement of kilometer range, development of large-scale industrial robots, and multi beam receiver devices.

FAST has extended China's space measurement and control capabilities from geostationary orbit to the outer edge of the solar system, increasing the downlink speed of deep space communication data by tens of times. FAST has increased the accuracy of pulsar timing by several times, enabling observation and construction of the most accurate pulsar timing array and pulsar clocks internationally, laying the foundation for the forward-looking research of autonomous navigation.

As a multidisciplinary basic research platform, FAST has the ability to extend neutral hydrogen observations to the edge of the universe, observe dark matter and dark energy, and study the structure and physical laws of matter in extreme states, thanks to its strong sensitivity; There is hope to discover strange stars and quark matter, discover neutron stars and black hole binary stars, without relying on models to accurately determine the mass of black holes; Can be used to search for and identify possible interstellar communication signals, search for extraterrestrial civilizations

In recent years, over 150 high-level papers have been produced based on FAST open data, with a total number of discovered pulsars exceeding 780, which is more than three times the total number of pulsars discovered by all other telescopes during the same period internationally. A series of internationally influential scientific achievements have been produced in pulsar physics, the origin of fast radio bursts, galaxy formation and evolution, and other fields. Several papers have been published in the journal Nature, and two papers have been published in the journal Science. One of the achievements on fast radio bursts was selected as one of the top ten scientific discoveries and breakthroughs in the world in 2020 by Nature and Science.

In Jiang Peng's view, astronomy is romantic, but competition in the field of astronomical instruments is cruel. Jiang Peng told our reporter, "The competition in astronomy is still relatively fierce, and we need to have a sense of crisis. If we shift our focus towards the future, we need to maintain sufficient clarity, solve key problems solidly, and continuously improve the performance of telescopes. Only in this way can we maintain FAST's hard-earned leading advantage in the increasingly fierce international competition."

When it comes to how to continue the glory of FAST, Jiang Peng said that the first step is to continuously improve the performance of FAST. For telescopes like FAST, improving performance includes several aspects. On the one hand, its field of view coverage requires breakthroughs in receiver technology. Currently, efforts are being made to tackle these challenges. At the same time, from the perspective of single aperture telescopes, there are still limitations in resolution, so the propulsion of array telescopes may be a good solution. It is necessary to find an array solution with extremely high cost-effectiveness and excellent performance. It is estimated that some experiments of the lead array will be launched in 2023 or 2024 to verify the feasibility of the lead array scheme, including conducting some technical reserves, imaging capabilities, and comprehensive aperture imaging tests.

Speaking of the feelings of the "Chinese Eye" team's struggle, Jiang Peng said in an interview at the second "Representative Channel" of the First Session of the 14th National People's Congress, "Our gaze is on the vast sea of stars, but every step we take is down-to-earth."

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