Dr Nan Ren Dong, vice-chairman of the Tenth Department of the International Astronomical Society and chief scientist of the National Radio Telescope Project, told Outlook Oriental Weekly: "One of the dreams of mankind is to really look at the original universe and understand how the structure of the universe formed and evolved before the radio wave environment was completely destroyed. Only large radio telescopes can help mankind realize this dream. "
He explained that both light and radio and television signals are electromagnetic waves that travel at the speed of light, and the only difference is the wavelength. For thousands of years, human beings have only observed the universe through the visible light band, but in fact the radiation of celestial bodies covers the entire electromagnetic wave band. A radio telescope is a telescope that receives radio waves from celestial bodies.
However, the electromagnetic waves radiated by celestial bodies are extremely weak, and the energy collected by all radio telescopes in the past 70 years can't even turn a page. Therefore, scientists hope to have a larger radio telescope for a simple reason-the bigger the telescope, the stronger the electromagnetic waves collected.
At present, the largest radio telescope in the world is located in Puerto Rico, with a diameter of 305 meters. The 500-meter-diameter radio telescope built this time has a receiving area equivalent to the size of 30 football fields, and its shape is similar to that of a satellite antenna. Compared with Bonn 100 meter telescope, which is known as "the largest machine on the ground", the sensitivity is improved by 10 times. Compared with the American 300-meter telescope, which was rated as the "Top Ten Projects of the 20th Century", its comprehensive performance has been improved by about 10 times. After the completion of FAST, it will maintain its leading position in the world for twenty or thirty years.
Dawodang, like a huge sinkhole, is a natural depression hidden deep in the mountains of Guizhou, where only 12 families live. Yang has lived in the local area for 68 years, but he never dreamed that this mysterious big guy who can look for "aliens" would "settle down" here.
In order to determine this unique large-scale radio telescope detection base, it took scientists nearly 10 years to confirm it after the engineering construction scheme was put forward in 1994.
In the summer of 2005, members of the site selection committee of the International Radio Telescope Project arrived in Shanghai by plane from Amsterdam, transferred to Guiyang by train, and then arrived in Dawodang, about 170 km south of Guiyang by bus.
"This is a village where rice is grown, and small green fields are arranged compactly," said Rob, a member of the committee. Milner wrote in his blog, "The scenery is great!"
It is not difficult to understand how difficult it is to open the bracket for a "cauldron" with a diameter of 500 meters. At present, the largest rotating radio telescope in the world is Germany's 100m mirror. Using natural terrain as support, building a large radio telescope that can't rotate can skillfully solve this problem.
Xu Xuwen, director of the Propaganda Department of Pingtang County Committee, who followed the researchers for many times, told this magazine: "The three green hills in Dawodang are isosceles triangles, and the depression in the middle of the triangle is where FAST will land. The distance between the three peaks is about 500 meters, forming a natural' pot rack' on which FAST's' cauldron' can be firmly installed! When the telescope is completed, it will fill the whole valley. "
Miller and others also have a very important task, which is to investigate the radio environment here. "A round of observation needs to be carried out 24 hours a day for 4 consecutive weeks." Researchers at the National Astronomical Observatory said. After Miller and others leave, our working group will observe the radio environment here for at least one year.
The transmission of radio data such as FM radio, TV and mobile phone will interfere with the observation of radio telescope, just like you can't hear the speaker clearly in a whisper conference.
Milner went to South Africa before coming to China. After leaving China, he went to Australia and Argentina. All three countries have proposed suitable sites for building large radio telescopes, and they are competing with China. The site selection working group spent a year investigating candidate sites in four countries.
The site should have a "core area" with a radius of 5 kilometers, no cell phone signal, and no interference with the observation frequency band. There is also a "coordination area" with a radius of 150 km, which also needs a radio environment. Among the four alternative sites, the electromagnetic environment of Dawodang is either the first or tied for the first place.
In order to maintain the unique electromagnetic wave environment, at the beginning of FAST project research, Guizhou Radio Administration planned a radio astronomy protection zone with Dawodang as the center and a radius of 150km, and it was forbidden to set any radio transmitting equipment within 5km of Fiona Fang.
In Australia, the government has established a 25-square-kilometer "Radio Astronomy Park" in the west, where Australia hopes to build a large radio telescope.
This kind of competition between countries is a bit like a draft. Dawodang, China, with its unique geographical and geological conditions and extremely quiet natural conditions, was successfully promoted.
"Dawodang not only has a natural depression where a telescope can be set up, but also the karst geological conditions can ensure that rainwater penetrates into the ground without silting, corrosion and damage to the telescope." Zhang Haiyan said.
FAST will extend China's space TT&C capability from geosynchronous orbit to the outer edge of the solar system, and increase the downlink rate of deep space communication data by 100 times. The measurement accuracy of pulsar arrival time has been improved from the current 120 nanoseconds to 30 nanoseconds, making it the most accurate pulsar timing array in the world and making pulsar clocks for the prospective research of autonomous navigation. It can be used as a passive strategic radar to serve national security and space weather forecast.
FAST research involves many high-tech fields, such as antenna manufacturing, high-precision positioning and measurement, high-quality radio receiver, sensor network and intelligent information processing, ultra-wideband information transmission, mass data storage and processing, etc. The key technical achievements of FAST can be applied to many related fields, such as large-scale structural engineering, high-precision dynamic measurement within a kilometer, development of large industrial robots and multi-beam radar devices.
The construction experience of FAST will have an impact on the development of China manufacturing technology in the direction of informationization, limitation and greening.