"Light Chasers" on the Silk Road: Gathering the "Power of Xinjiang" in Chinese Astronomy

The Horsehead Nebula was photographed by the 1-meter wide-field optical telescope at the Nanshan Observatory of the Xinjiang Astronomical Observatory of the Chinese Academy of Sciences. It is about 1,500 light-years away from the Earth and is part of the Orion Molecular Cloud Cluster.

On March 7, 2023, a piece of news became a hot topic: the 1-meter wide-field optical telescope (NOWT) at the Nanshan Observatory of the Xinjiang Astronomical Observatory of the Chinese Academy of Sciences discovered a near-Earth asteroid for the first time. This celestial body, about the size of two football fields, orbits the sun 30 million kilometers away from the Earth and poses no threat to the Earth.

How could such a small celestial body be discovered in the vast universe at such a great distance? Why was it discovered in Xinjiang? With a series of questions, the reporter went to the Nanshan Observatory of the Xinjiang Astronomical Observatory for a field investigation to explore the natural heritage and unique advantages of astronomical observation in Xinjiang.

During the interview, the reporter found that the appearance of this near-Earth asteroid in human vision is just the tip of the iceberg of Xinjiang's many achievements in exploring the galaxy. The current story of Xinjiang in the field of astronomy will have an important impact on China's astronomical research.

On the night of April 16, 2023, the moonlight fell on the center of a crater in the East Tianshan Mountains, where the world's largest 110-meter-diameter omnidirectional movable radio telescope is being built. Its observation depth will extend to the deepest part of the universe, becoming an outpost of Earth civilization facing the vast starry sky.

Why did the great national equipment settle in Xinjiang? What role does Xinjiang play in China's modern astronomical layout?

All stories begin with a very long journey.

The 26-meter radio telescope is working at the Nanshan Observatory of the Xinjiang Astronomical Observatory of the Chinese Academy of Sciences. Photo by Wang Xin, a reporter from Shiliuyun/Xinjiang Daily

Xinjiang's "light chasers" in astronomical research

When we look up at the stars, we are actually gazing into the past.

150 million years ago, in a dense and humid jungle, a huge egg suddenly cracked and a little stegosaurus broke out of its shell. At the same second, deep in the universe, the core of the spiral galaxy ESO 269-57, with a diameter of 200,000 light years, emitted a super-strong radio wave, which shot towards the solar system at nearly the speed of light.

When this radio wave passed through the elliptical galaxy Centaurus A, the dinosaur era on Earth had ended, mammals flourished, beasts roamed the earth, and birds flew across the sky; it continued to fly, leaving the planetary nebula NGC 3918 behind, and humans became the ruling force on Earth and moved towards the era of national civilization; in a flash, the radio waves bid farewell to the binary star Crux, and Isaac Newton became the president of the Royal Society of London.

Next, it passed by Proxima Centauri, when humans took the first photo of a black hole; then it passed by the sun, and 8 minutes later, at 12:23:49 on April 16, 2023, it hit the panel of the 26-meter radio telescope at the Nanshan Observatory of the Xinjiang Astronomical Observatory of the Chinese Academy of Sciences.

The fossilized Stegosaurus is lying quietly in the Qitai Dinosaur Valley, and its "peers" from 150 million years ago have arrived one after another, and "particle rain" has fallen heavily on the land around the Stegosaurus. Not far away, the largest omnidirectional movable radio telescope ever built by mankind is about to be erected.

During the vast majority of the time when these super-strong radio waves traveled through the universe, the human species had not yet appeared. But now, humans have begun the journey of exploring the mysteries of the universe. "How did the universe and life come into being? As an ordinary planet, what is the status of the Earth in the universe?" Wang Na, director of the Xinjiang Astronomical Observatory, asked a series of ultimate questions in astronomical research.

Astronomy may seem to have nothing to do with ordinary people, but in fact, this field will produce many unexpected results. "WIFI and GPS are by-products of astronomical research," said Song Huagang, deputy director of the Science Communication Center of Xinjiang Astronomical Observatory.

This is a field that is both far away from the public and very close to the public.

More importantly, basic research, including astronomy, is the source of all technological inventions. Wang Na gave an example, one of the biggest discoveries in astronomy in recent years, "gravitational waves", which is a verification of Einstein's related theory more than a hundred years ago. Astronomical research may not be applied until many years later, but if it is not done, once a gap is formed, it will not be easy to make up for it.

Xinjiang is an important venue for this marathon. In 1957, the Soviet Union successfully launched the first artificial satellite. In the same year, the Urumqi Satellite Observatory was established as one of the first 12 artificial satellite optical observatories in China. Since then, this land has never stopped looking up at the starry sky. In 1987, the Urumqi Satellite Observatory was upgraded to the Urumqi Astronomical Station of the Chinese Academy of Sciences, and in 2011 it was further upgraded to the Xinjiang Astronomical Observatory of the Chinese Academy of Sciences. "The observatory only provides data, while the observatory can carry out cutting-edge research in astronomy. This is a qualitative change." Wang Na said.

Over the past few decades, as my country's national strength has continued to grow, the depth and breadth of Xinjiang's astronomical research has continued to expand - from the earliest near-Earth orbit observations, to solar observations, and now to comprehensive research capabilities in major modern astronomy disciplines such as radio and optics. The Xinjiang Astronomical Observatory of the Chinese Academy of Sciences has developed into a major force in China's modern astronomical layout, an important unit in the international cooperative research network, a supporting base for the development of astronomy in the west, and a key node in the national space mission joint measurement network, becoming one of the five largest comprehensive observatories in China and the only one in the northwest.

And the romance in the hearts of generation after generation of "light chasers" has never faded.

In 2006, Wang Na led a team to survey a new astronomical observatory site in the Nantian Mountains. One evening, the sky was dark and there were only mountains around. The car drove slowly on the mountain road and turned a corner. Suddenly, a bright moon came into view. "I will never forget that scene," said Wang Na. "When there are no traces of human activities, the earth you see is a natural celestial body. Facing this bright moon in the sky, it's like the earth is carrying us on a voyage through the universe!"

Xinjiang's shadow behind the great power

Interviewing astronomers at an astronomical observatory is a very mysterious experience. The reporter found that many ideas in science fiction works are not necessarily science fiction, but serious actions at the national level.

Near the center of the Milky Way, a dense celestial body is rotating at high speed. The weight of a teaspoon of matter is comparable to Mount Everest. It is a pulsar with a diameter of 20 kilometers. In the known universe measured in billions of light years, "a drop in the ocean" is not enough to describe its tinyness.

But this pulsar named J1717-3452 was "captured". When it was hidden in the universe, the 26-meter radio telescope of Nanshan Observatory was receiving the pulse radiation emitted by J1717-3452 80,000 years ago.

For quite a long time, Nanshan Observatory was the only observation base in China to carry out actual measurement data of pulsars. It has observed more than 300 pulsars in total and is still the highland of pulsar research in China.

"Why study pulsars?" the reporter asked.

"It is a natural laboratory for extreme physics in the universe." Yan Wenming, deputy leader of the pulsar group at the Xinjiang Astronomical Observatory, said that pulsars have many extreme physical conditions that are not available on Earth. For example, due to its large mass and small radius, the gravitational field of pulsars is very strong, making it a natural laboratory for the study of strong gravitational fields. Its ultra-strong magnetic field also provides an ideal place for humans to study the acceleration mechanism of magnetospheric particles, high-energy radiation, and radio radiation processes. Due to its ultra-stable rotation period, pulsars can also be used as extremely high-precision clocks to establish my country's independent space-time system. High-precision timing is widely used in high-precision fields.

"At the same time, pulsars are very much like lighthouses in the sea of ​​stars, and have far-reaching significance in the field of autonomous deep space navigation." "Are you talking about interstellar travel?" "Yes, if one day humans want to leave the solar system like in the movie "The Wandering Earth", they can rely on pulsars to establish a reliable navigation system." Han Wei, director of the Science and Technology Department of the Xinjiang Astronomical Observatory, said in a calm tone that he was not joking. His doctoral thesis was about pulsar deep space navigation.

About 2,300 years ago, Qu Yuan looked up and asked: Where is the sky? Where are the twelve divisions? Where do the sun and the moon belong? Where are the stars arranged? Today, humans are gradually revealing the answers. "Basic research is a change in the entire human knowledge system, which promotes the progress of human civilization as a whole. This is difficult, and we still know very little about the universe." Wang Na said, "But people have to look at the long term. If you only look at the present or yourself, it is often difficult to persist when encountering difficulties."

Xinjiang has always been persistent. In fact, Xinjiang Astronomical Observatory is present in many cutting-edge scientific fields in China.

At 2:49:47 a.m. on March 28, the world's first quantum science experimental satellite "Micius" quietly crossed the sky, and green lasers were shot from 2,000 kilometers away to the Nanshan Quantum Communication Experiment Ground Station of the Xinjiang Astronomical Observatory, which is an important part of China's integrated space-ground quantum science experimental system.

In addition, Xinjiang Astronomical Observatory has successively undertaken the orbit measurement tasks of the Chang'e-1 to Chang'e-5 lunar exploration project and the Tianwen-1 Mars exploration spacecraft. The Nanshan lunar exploration project team led by Wang Na has been commended by relevant state ministries and commissions many times, and won the 18th "Xinjiang Youth May Fourth Medal Group". The Kashgar Observatory under the Xinjiang Astronomical Observatory serves China's second-generation satellite navigation system. It is the only observation station in the western part of China for the orbit determination subsystem of the forwarding experimental system. It is also the station with the most comprehensive observation configuration in the subsystem. It now provides support and guarantee for the Beidou system related experiments.

The Nanshan Observatory, which currently has the best radio and optical comprehensive observation conditions in China, is providing support for the other two grand projects with the theories and technologies accumulated over the years. In 2016, the selection of the site for the optical/infrared large radio telescope observation station on Muztagh Ata brought important opportunities for the development of optical astronomy in my country. In 2022, the construction of the 110-meter-diameter Qitai Radio Telescope (QTT) project started, and was rated as one of the most noteworthy scientific events in the world that year by the world's top scientific journal Nature. Both projects started from the Nanshan Observatory. It is here that the secret of the great power's heavy equipment settling in Xinjiang lies.

World-class astronomical observation advantages

Sitting on the lawn of Nanshan Observatory in the evening, looking at the top of the receiver antenna of the 26-meter radio telescope pointing to the sky, the setting sun melts gold, the mountains are silent, and there is only the steady low hum of the huge antenna turning, which easily reminds people of the scene of the Red Coast Base in the novel "The Three-Body Problem".

Cui Lang, director of the Nanshan Observatory, pointed to a waveform image on the screen and joked, "People say we look up at the stars, but most of the time we actually look down at the screen. The development of human technology has long pushed astronomical observation beyond the scope of outdoor sky viewing."

The Nanshan 26-meter radio telescope is an important node in the international VLBI (very long baseline interferometry) joint measurement. Cui Lang explained that very long baseline interferometry is to use multiple telescopes at different locations to observe the same target at the same time. The distance between telescopes is equivalent to the telescope diameter. Assuming that the distance between the two telescopes is 5,000 kilometers, it is equivalent to the resolution of a giant telescope with a diameter of 5,000 kilometers. "You can see an orange on the surface of the moon clearly from the ground." He said.

Optical astronomy is a different story. At 3 a.m. on March 28, Bai Chunhai, deputy director of the Optical Research Laboratory of Xinjiang Astronomical Observatory, wrapped in a thick coat, came to the telescope array in the optical area of ​​Nanshan Observatory to debug a new device with a 43-centimeter aperture. With a slight motor sound, the moon-white protective cover opened and starlight entered the mirror.

70 kilometers away, the lights of Urumqi city illuminate the sky red. Optical observation requires a dark environment, and radio telescopes must avoid radio interference. With the economic and social development around Nanshan, both problems are intensifying. "Even so, the observation and experimental conditions at Nanshan Station are still very good compared to the rest of the country," said Bai Chunhai.

It is precisely based on the superior observation conditions and with the Nanshan Observatory as the support, that the Xinjiang Astronomical Observatory has achieved top domestic results in theoretical and experimental research on pulsars, star formation and evolution, galaxy cosmology, high-energy astrophysics, astrochemical evolution, particle astrophysics, space targets and debris, satellite navigation, as well as technical equipment and research and development in microwave receivers, radio telescope structure and control, digital signal processing, etc., with far-reaching international impact.

If we were to select the discipline with the most demanding work location in the world, astronomy would definitely be one of the strong contenders. Few people know that Xinjiang, with a vast area of ​​1.66 million square kilometers, enjoys world-class conditions for astronomical observation. "Astronomical observations must be conducted in dry, clear air environments, and places with little human activity. Xinjiang has a vast territory and diverse landforms, so there is a lot of room for choice," said Ma Lu, deputy secretary of the Party Committee of the Xinjiang Astronomical Observatory and a senior engineer. "The superior number of sunny days and other factors make the same telescope much more efficient in the west."

The excellent clear air environment is a special strategic resource for Xinjiang to support basic research and develop science and technology. The Muztagh Ata Optical Astronomical Observatory, located at an altitude of 4,500 meters, has indicators such as seeing and water vapor comparable to those of world-class observatories. Many projects such as the 1.93-meter optical telescope and moon flash are under construction here. The 1.93-meter optical telescope is currently the third largest general-purpose optical telescope in China. The superior optical observation conditions of the Muztagh Ata Observatory will give full play to the design performance of the telescope and lay a solid foundation for the construction of larger-diameter optical telescopes in the future.

The QTT project has long been the focus of the entire international astronomical community. Its observation range extends from meter waves to millimeter waves, greatly improving the depth and breadth of observations, allowing humans to not only conduct more comprehensive and in-depth research on individual stars, but also capture massive amounts of information from more distant space and more hidden cosmic matter.

"Apart from good observation conditions, what other reasons are there for this major scientific infrastructure project to be located in Xinjiang?" the reporter asked.

Wang Na stood up from her desk and handed over her phone, so everything was clear at a glance. On a global distribution map of large astronomical facilities, there are many points in East Asia and Western Europe, but only the hinterland of Eurasia is blank. "Astronomical research is something that can only be done in times of peace and prosperity, and it is closely related to national strength." Wang Na said that in the global astronomical observation network, the hinterland of Eurasia is a very important support point. In terms of the comprehensive situation of countries and regions in this region, only China has the ability to fill this gap. At the same time, the QTT project settled in Xinjiang, which also completed the layout of my country's astronomical observation network, supported the development of Chinese astronomy to the west, and thus more effectively served the "Belt and Road" construction.

However, the birth of this national treasure was full of twists and turns.

At the Nanshan Observatory of the Xinjiang Astronomical Observatory of the Chinese Academy of Sciences, everyone is analyzing the feedback data from the 26-meter radio telescope. Photo by Wang Xin, reporter of Shiliuyun/Xinjiang Daily

An important town on the astronomical "Silk Road"

In order to give full play to Xinjiang's unique advantages in astronomical observation, Wang Na and her colleagues began to look for ideal large-scale radio astronomical observatory sites in the north and south of the Tianshan Mountains as early as 2006. In 2010, the Qitai area was selected from more than 40 locations. "The first batch of people who entered cheered and jumped for joy, and they couldn't contain their excitement at all. They were all jumping and shouting there," said Wang Na.

Surrounded by mountains, it completely shields us from external radio interference, and in the middle there is open space, clear weather, and stable airflow. Perfect, this is it!

In 2010, the Chinese Academy of Sciences decided to build the world's largest 110-meter omnidirectional movable radio telescope in Qitai, which was led by the Xinjiang Astronomical Observatory.

In 2011, Wang Na submitted a project application report to the autonomous region, but she was worried. "As a basic research, astronomy will not have an immediate effect on the local economic and social development, and the environment in that area is very beautiful and can be developed into tourism," said Wang Na.

After the regional leader carefully learned about the content of the QTT project, he said, "Then we will give the best places in Xinjiang to you astronomers!"

The overall situation has been determined, but endless difficulties are also coming one after another.

The first thing to be questioned is the construction capacity of the Xinjiang Observatory. The questioners are all domestic astronomy experts, and their reasons are not groundless. Unlike the "China Sky Eye" fixed on the ground, the antenna of the QTT project is designed to be omnidirectional and movable to achieve the maximum exploration range. The reporter felt the difficulty of the construction of the QTT project in the most intuitive way. Standing at the foot of the 26-meter-diameter radio telescope in Nanshan, people are like squirrels under the tree, with a huge sense of oppression. The diameter of the optical antenna of the QTT project is more than 4 times larger than the former, 40 stories high, weighing 6,000 tons, and can rotate freely in all directions. To build such a behemoth and let it run smoothly for decades to come, the difficulty can be imagined.

Moreover, the construction of the largest omnidirectional movable radio telescope on Earth required construction techniques and materials that far exceeded the capabilities of the domestic industry at the time, and there was no precedent in the history of astronomical radio telescope construction in the world. Over a long period of time, the QTT project underwent the most rigorous demonstration in history. Countless repetitions, tens of millions of details, and countless failures were enough to make people collapse.

But Wang Na didn't. This female scientist with a calm gaze and refined language has pushed the QTT project forward step by step with an iron will that is admired by all Taiwanese. In fact, long before the QTT project, Wang Na was already famous in the international astronomical community for her outstanding achievements in the field of pulsars. "The universe is infinite. As an individual, there are countless things I can do." Wang Na said, "But we chose to develop and build a scientific research platform in Xinjiang. Xinjiang not only has magnificent scenery and fat cattle and sheep, but also has the most advanced facilities and fruitful results for human exploration of the starry sky. It is an important town on the astronomical 'Silk Road'. We hope to promote the development of Xinjiang through the construction of the astronomical field. The QTT project is difficult, but if you don't start, you will never be able to do it. You can't retreat!"

"Another reason why we can't withdraw is that the autonomous region's party committee and government have always been very supportive of us." Wang Na told reporters that from 2011 to date, Xinjiang has given firm support to the QTT project in many aspects such as funding, construction, approval procedures, and ancillary facilities. Together with the Chinese Academy of Sciences, it has become a key force in promoting the project.

For 12 years, the QTT project has been like a flame illuminating the ideals of young people. Nearly half of the 160 employees of the Xinjiang Astronomical Observatory have participated in the construction of the QTT project, and many of them came for the project after graduating with a doctorate. "Young people come here with dreams, and I can't let their dreams be shattered, right? I have to work with them to make the project a success!" Wang Na seemed to be asking herself, and then she revealed pride in her words, "For more than ten years, the core members of our scientific research team have never given up!"

On September 21, 2022, the largest omnidirectional movable radio telescope project in human history was laid in Xinjiang, China!

The Orion Nebula, photographed by the 1-meter wide-field optical telescope at the Nanshan Observatory of the Xinjiang Astronomical Observatory of the Chinese Academy of Sciences, looks like a flying firebird, also known as the "Firebird Nebula." Photo courtesy of the Xinjiang Astronomical Observatory

The young people here are very strong!

"How many hours do you sleep a day when you are solving technical problems?" The reporter asked Xu Qian, the person in charge of the QTT antenna project. "You should ask me how often I sleep!" The 40-year-old director of the antenna technology laboratory of the Xinjiang Astronomical Observatory immediately raised his voice when talking about the QTT project, "This thing is always exciting and challenging."

"Young people like challenges and are more willing to take on challenges," said Wang Na. People born in the 1970s and 1980s formed the main body of the QTT project construction team. The youngest, Gulijiaina Hazaizihan, just turned 30. She is responsible for the rapid measurement of the active surface of the antenna, which is a pioneering technology.

The QTT parabola is made up of 1920 panels, and the huge deadweight will cause the panels to deform. The observation requires the panel surface accuracy to be controlled within 0.2 mm, which means that the panel deformation cannot exceed the thickness of half a hair. Guli Gayina needs to quickly measure and transmit accurate data to the actuator behind each panel within 2 minutes. The latter will continue to apply force to the panel to keep it within the standard surface accuracy. "Our adjacent actuators can be linked, unlike those abroad, they don't 'shake hands'." Guli Gayina said.

“You are the youngest. Are you afraid during team discussions?” the reporter asked.

"Don't be afraid. If I make a mistake, I'll just try again. We have such a scientific research environment in the station," said Guligayna.

Over the past 12 years, young people who have just graduated from school have struggled under the starry sky and grown into the backbone of Xinjiang astronomical research. They are proud of the QTT project. "Take high-frequency observation as an example. Germany can observe for less than one month a year, and the US GBT telescope can observe for more than one month. After the completion of our QTT project, we will have an observation time of 6 months. What a huge advantage." Xu Qian said, "We must succeed despite all difficulties!" This "post-80s" who has participated in the QTT project since 2011 is now a doctoral supervisor.

On the morning of March 23, a demonstration meeting on the implementation plan of the autonomous region's major science and technology special projects was held. The scientific research backbones of the project topics were all trained by the Xinjiang Astronomical Observatory in the past 10 years. The young talents took turns to present their speeches, and no one noticed the glow in Wang Na's eyes. "The report has a strong academic accumulation and the content is very cutting-edge. I am very pleased!" Wang Na said.

This is not just a simple feeling of being touched.

Astronomy is one of the most open disciplines on earth. Xinjiang Astronomical Observatory has always shared observation data with astronomers around the world. Civilian teams have also benefited from this openness. It was through the data shared by NOWT that Zhang Mi, a member of the Xingming amateur astronomical observation team who has in-depth cooperation with Xinjiang Astronomical Observatory, discovered a fast-moving celestial body in the NOWT open cluster observation data on February 26. It was the near-Earth asteroid 30 million kilometers away, temporarily numbered 2023 DB2. This makes Xinjiang Astronomical Observatory the third Chinese Academy of Sciences unit in China to discover a near-Earth asteroid.

After the QTT project is completed, scientists from all over the world can apply for time to use the telescope. In fact, since the groundbreaking ceremony last year, foreign astronomers have applied to come to Xinjiang. This means that Xinjiang will become an arena for global astronomers because of the QTT project.

"You can't say Xinjiang has built world-class astronomical facilities but is incapable of producing first-class scientific research results," said Wang Na. "In the past 12 years, our scientific research and management teams have accumulated a lot of experience. Facts have proved that the young people here are very strong! The project will be completed in another six years. Our scientific research team and training model can support this now and in the future!"

"Since we can't buy core components and core equipment, we have to study them ourselves. Project construction must not only consider the cutting-edge, but also the feasibility. We use the world's best technology to do this." Chen Maozheng, deputy director of the Xinjiang Astronomical Observatory, said one sentence that expresses so much hardship and pride.

At the Nanshan Observatory, senior engineer Yan Hao pointed to the core components in the machine room of the 26-meter radio telescope and said: "We used to learn from the West, but now we are on par with them and have all independent intellectual property rights." On this basis, the QTT project, with the Xinjiang Astronomical Observatory as its core, has brought together China's top teams in various fields. It is not only making steady progress, but is also promoting the overall improvement of the domestic manufacturing process level of high-end technology equipment.

On both sides of the gate of Xinjiang Astronomical Observatory are several small shops and street markets, selling vegetables, snacks, and children's toys. In the evening, astronomers who temporarily withdrew their gaze from the deep universe walked out of the gate one after another, spreading out like waves. They shouldered the stars and blended into the fireworks of the world. (Text by Liu Donglai and Xie Huibian)