On September 25, 2016, the world's largest 500-meter aperture spherical radio telescope (FAST) was completed in a remote mountain and deep ravine in Guizhou, China, becoming a milestone in the construction of major scientific infrastructure projects in China and creating a new record in the construction of large radio telescopes in the world.
On January 11, 2020, FAST, known as "China's Sky Eye", passed the national acceptance and was officially opened for operation. This 500-meter aperture spherical radio telescope, the world's largest and most sensitive telescope, can receive electromagnetic signals more than 10 billion light-years away. In the nearly one year of operation, more than 240 newly discovered pulsars have been discovered through FAST, which has greatly improved the "field of vision" of human beings.
In December 2020, the Arecibo radio telescope in the United States suddenly collapsed, leaving the stage of history. "Lose Arecibo, now we have only one eye." Astronomers around the world have invariably turned their attention to the "Chinese Sky Eye" FAST.
At the beginning of 2021, the Chinese side announced that FAST will be officially opened to the global scientific community from April 1, 2021, and it is expected that the observation time allocated to foreign scientists in the first year will account for about 10%. China's "heavenly eye" has become the world's "giant eye", which has excited scientists around the world.
The construction of FAST lasted five and a half years and a total cost of UP TO 1.15 billion yuan. Its construction began with a magical and bold dream in the 1990s. In the book "Sky Eye Project - Fast Dream Pursuit of Large Radio Telescope" published by Shanghai Science and Technology Education Publishing House recently, Peng Bo, the core member of the FAST Project project and director of the FAST Key Laboratory of FAST of the Chinese Academy of Sciences, restored the birth process of "China's Sky Eye" through 300 precious pictures and a large number of first-hand materials from the perspective of the whole process.
Why build the "Sky Eye Project"?
During the International Radio Science Union (URSI) Conference held in Kyoto, Japan in 1993, astronomers from 10 countries discussed and formed a consensus to build a large radio telescope array with an area of one square kilometer to study the origin of the universe, microwave background radiation, redshift and other issues. This plan reflects the imagination of scientists, but at the same time has great risks, is a large scientific project with huge investment, complex technology, and difficult to achieve without extensive international cooperation.
At that time, Chinese astronomer Wu Shengyin attended the meeting, and after returning to China, he consulted with Scientists such as Nan Rendong to build the world's first 500-meter large radio telescope in China.
At that time, the maximum aperture of domestic radio telescopes was only 25 meters. After the bold idea of building FAST was proposed, it received a positive response from the relevant departments of the state. At the end of 1995, the China Promotion Committee of the Radio "Big Telescope" was established. The old, middle-aged and young scientists, represented by Wang Shouzhen, Nan Rendong, Peng Bo, etc., have devoted themselves to hard work with a strong sense of conscience and responsibility as scientists.
FAST's full English name is "Five-hundred-meter Aperture Spherical Radio Telescope", which means "500-meter aperture spherical radio telescope" in Chinese. Why 500 meters?
At the beginning of 1997, the research group gradually refined the main performance indicators of the "Sky Eye", including the observation frequency band and caliber.
At that time, the world's largest radio telescope single aperture was the American Arecibo Telescope, with an aperture of about 305 meters, an illumination aperture of about 200 meters, and a maximum zenith angle of about 20 °. The "Sky Eye" should be comparable to or even higher than its overall performance to be attractive.
After precise calculations, if the effective caliber of the "Sky Eye" is to reach 300 meters, the overall caliber must reach 519 meters in order to have a 30 ° zenith angle. If it continues to expand to a 40° zenith angle, the pilot telescope will have aperture of 560 meters. Considering various factors such as cost, the final project proposal is clear: FAST caliber 500 meters.
Panorama of the "China Sky Eye" taken on March 28 (taken during maintenance, drone photo) Photo by Xinhua News Agency reporter Ou Dongqu
Why choose Pingtang, Guizhou?
People often ask, why was the site of the large radio telescope chosen in Guizhou? Why was the depression in Pingtang County chosen?
The actual situation is that after countless studies and investigations, and countless treks through the desolate mountains and mountains, this site was determined.
Why did you choose karst landforms? Because karst is a geologically developed lithological "hilly" landform, formed by water, but does not accumulate water, it is a "flush toilet" in nature. In order to reduce the construction cost of large spherical reflective telescopes, it is necessary to use natural karst depressions as sites. Since 1994, geological experts from the Institute of Remote Sensing of the Chinese Academy of Sciences have conducted long-term and arduous karst depression site surveys and comprehensive geological geography surveys in Guizhou, based on aerial photos and topographic maps, to find a number of candidate depressions suitable for the construction of large radio telescopes with a diameter of 300 meters to 500 meters.
At the end of 1995, the basic database of topography and geomorphology of nearly 400 candidate depressions was formed, and the data of the long axis orientation, long and short axis ratio, depression depth, number of surrounding peaks, diameter, geographical coordinates, and peak altitude of each depression were recorded. For more than a decade, site selection staff have trekked between the green waters and green mountains of Guizhou, inspecting the size of the recent settlements, the surrounding vegetation conditions, the cultivated land of the depressions, etc., and also inquiring from farmers in the villages near the candidate depressions about the climate conditions such as rain, snow, hail, lightning, and floods. In the end, the selection of the site was decided after considering many aspects such as physical geography, geomorphological development control factors, depression morphological characteristics, constituency hydrogeology, engineering geology, resource environment and electromagnetic tranquility.
FAST is Guizhou, Chinese, and ultimately human. He Chongyuan, former deputy secretary-general of the People's Government of Guizhou Province, said: "Take a moment to read the "Sky Eye Project", I believe that readers will be touched by the spiritual outlook of fast people and trigger thinking, and constantly climb on the rugged mountain road of scientific and social and economic development without fear of hardships. ”