How-to China: Sky eye wide open

Editor's Note: The eyes of the world are turning to China. In this ongoing series How-to China, we tell stories about how Chinese approaches promote understanding and solve problems around the globe and how Chinese and foreign cultures meet and mingle.

The Five-hundred-meter Aperture Spherical Radio Telescope, or FAST — the world's largest single-dish radio telescope — is revealing wonders of the cosmos at an astonishing rate.

Listed among China's top 10 scientific breakthroughs of 2021 by the Ministry of Science and Technology, the telescope has placed China in the pole position for space studies worldwide.

Located in a karst depression in Qiannan Bouyei and Miao autonomous prefecture of Guizhou province, FAST has a receiving area equivalent to 30 soccer pitches and is able to detect distant and dark celestial bodies through real-time positioning.

FAST has found 500 new pulsars — four times the number found by all other telescopes over the same period in the world combined, according to the National Astronomical Observatories of the Chinese Academy of Sciences. Annual observation time has exceeded 5,300 hours, which is far more than similar devices globally.

Pulsars, or fast-spinning neutron stars, are believed to originate in the imploded cores of massive dying stars after supernova explosions. With their high density and fast rotations, pulsars are an ideal laboratory for studying the laws of physics in extreme environments.

Using FAST, scientists have also detected the largest set of fast radio bursts, or FRB, which may help clarify the origins of mysterious signals from deep space. FAST should be able to detect up to 120,000 FRB daily with high sensitivity.

In addition, researchers believe FAST will be able to see images from the boundary of the universe in eight to 10 years.

China Daily interviewed Lin Hao, first-level inspector of the Guizhou Science and Technology Department and a member of the National Committee of the Chinese People's Political Consultative Conference, together with Jiang Peng, chief engineer of FAST at the National Astronomical Observatories of the Chinese Academy of Sciences, to introduce some of the highlights of the device.

Why did China build such a large telescope and why was it built in Guizhou province?

Lin: The idea was first proposed at a conference of the International Union of Radio Science held in Kyoto, Japan, in 1993. Scientists agreed that a huge radio telescope should be built to explore origin of the universe. Chinese astronomer Nan Rendong attended the meeting and discussed it with other scientists back home, who put forward the idea to build the world's first radio telescope with a diameter of 500 meters. At that time, the largest radio telescope in China is only 25 meters in diameter.

With support of the government, site selection and preliminary research kicked off in 1994, and in 1995 a special team was established for the program. In the late 1990s, the world's largest radio telescope was the 305-meter-diameter Arecibo Telescope of the United States, located in Puerto Rico.

Construction of FAST began in 2011 and finished in September 2016. It was opened to domestic astronomers in April 2019. In December 2020, the Arecibo Telescope collapsed, and FAST, which can receive electromagnetic signal 10 billion light years away, became the only "eye" to see that far into space. FAST was opened to the global science sector in April 2021.

Jiang: Karst is a special landform in which water will permeate into underground soil and not cause sedimentation. So the telescope will not be influenced by rainwater or rotation. In late 1995, about 300 candidate locations were found, and the Dawodang area in Guizhou was selected. The place was deep in the mountains, with only a few villages around.

What difficulties arose in building the telescope and how were they overcome?

Lin: In the beginning we made a lot of investigations on the landscape and geology to find an ideal location. For about 10 years, researchers trudged over hills and dales, learning the surrounding farming conditions and asking farmers about climate. Guizhou also tried to produce components for FAST, but only a few were selected for manufacture.

Operation and maintenance are essential to guarantee normal space observations. Since 2017, the team has developed what are called microgravity spidermen — maintenance workers suspended by helium balloons to reduce weight — so they can do inspections anywhere with minimum impact on the big device.

However, with its high cost, low efficiency and safety risks, the Guizhou Science and Technology Department proposed the development of an intelligent maintenance system that would use robots instead of humans.

Jiang: Robots can work in dangerous areas that humans cannot reach and can operate despite factors such as weather. These will greatly increase safety and automation. The first robot is expected to be put into trial operation in July.

Academician Wu Xiangping said in October that China planned to build five more 500-meter telescopes to form a huge array. Is that real? Where would these new FASTs be located?

Jiang: The feasibility and locations are under discussion. There is no information to tell now.

How does FAST relate to the public?

Jiang: In 2009, the National Astronomical Observatories began to organize summer vacation classes for students to learn about FAST and radio astronomy. The classes are also meant to train potential talent for the future maintenance and upgrading of FAST.

National Astronomical Observatories also cooperates with Guizhou Normal University and Guizhou University in data analysis. In November 2021, the Guizhou Provincial Key Laboratory of Radio Astronomy and Data Processing at Guizhou Normal University was put into operation, focusing on using data collected from FAST to conduct research on compact objects.

Wang Jin in Guiyang contributed to this story.

About the interviewees

Lin Hao, 60, is a first-level inspector of the Guizhou Science and Technology Department. He graduated from Donghua University in Shanghai in 1983. In 1984, he was hired by the provincial science and technology department, rising to deputy director in 2014. He left the post in May 2021. He is now vice-chairman of the Guizhou committee of the China National Democratic Construction Association.

Jiang Peng, 44, is a researcher and doctoral adviser for the National Astronomical Observatories of the Chinese Academy of Sciences. He focuses on radio astronomy technology and is currently chief engineer of FAST. He is in charge of the operation and maintenance of the telescope. He has published more than 50 papers and holds about 30 patents.