radio telescope

Basic equipment for observing and studying radio waves from celestial bodies

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The radio telescope (English name: radio telescope) is similar to the reflective optical telescope. The projected electromagnetic wave is reflected by an accurate mirror and converged in a common focus.^[9]

Different from optical telescopes, optical telescopes focus on visible light while radio telescopes focus on long wave electromagnetic waves.^[9]

Radio telescope refers to observing and studying Radio wave It can measure the radio intensity of celestial bodies spectrum and polarization equal. Including radio wave collection directional antenna High sensitivity of amplified radio signal Receiver , information recording, processing and display system, etc. In the 1960s, astronomy made four very important discoveries: Pulsar 、 a quasar 、 Cosmic microwave background radiation 、 Interstellar molecules , known as the "four major discoveries". These four items find It's all about radio telescopes.

On December 5, 2022, after 30 years of preparation, the construction of SKAO, the world's largest radio telescope, broke ground at two locations in Africa and Australia.^[7]

Chinese name: radio telescope
Foreign name: radio telescope
Role: Measuring the Intensity, Spectrum and Polarization of Celestial Radio

Amplification capacity: λ/16～λ/10
Weakest level: 10~20W
Physical judgment: Dimension D, wavelength λ

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Fundamentals

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40m radio telescope

The basic principle of the classical radio telescope is Reflecting telescope Similar electromagnetic wave After being reflected by an accurate mirror, it reaches the common focus in phase. Using a rotating paraboloid as a mirror is easy to achieve in-phase focusing, so most radio telescope antennas are paraboloid 。 The mean square error rate of the radio telescope surface and an ideal paraboloid is not greater than λ/16 ～ λ/10, and the telescope can generally wavelength It works effectively in the radio band greater than λ. For meter wave or long decimeter wave observation, metal mesh can be used as mirror; For centimeter wave and millimeter wave observation, smooth and accurate metal plate (or Coating ）Make a mirror. The radio wave projected from the celestial body and gathered to the focus of the telescope must reach a certain power level before it can be detected by the receiver. The detection technology level requires that the weakest level should be 10 - 20 watts. The power of the RF signal is amplified at the focal point for 10-1000 times and converted to a lower frequency (intermediate frequency), then transmitted to the control room by cable, where it is further amplified and detected, and finally recorded, processed and displayed in a way suitable for specific research.^[1]

title

Antenna collecting celestial Radio radiation The receiver processes and converts these signals into a form that can be recorded and displayed. The terminal equipment records the signals, performs some processing according to specific requirements, and then displays them. The basic indicators of radio telescope performance are spatial resolution And sensitivity. The former reflects the ability to distinguish radio point sources close to each other on two celestial spheres, and the latter reflects the ability to detect weak radio sources. Radio telescope usually requires high spatial resolution and high sensitivity!

Radio telescope is mainly used to receive celestial radio band Radiation telescope. The shapes of radio telescopes vary greatly. There are single aperture spherical radio telescopes fixed on the ground, radio telescopes similar to satellite receiving antennas that can rotate in all directions, radio telescope arrays, and radio telescopes made of metal rods.

Basic indicators

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The objects studied by radio astronomy include radio sources with continuous spectrum as strong as the sun, quasars with strong radiation but extremely far away, and small angular diameter and flow density fixed star There are also very narrow spectrum and small angular diameter celestial maser Etc. In order to detect the signal of the studied radio source, distinguish it from the adjacent background source, and then observe its structural details, the radio telescope must have sufficient sensitivity and resolution.

sensitivity

Sensitivity refers to the "lowest measurable" energy value of the radio telescope. The lower the value, the higher the sensitivity. The common methods to improve the sensitivity are to reduce the inherent noise of the receiver itself, increase the receiving area of the antenna, and extend the observation integration time.

resolving power

Resolution refers to the ability to distinguish two identical point sources close to each other, because the angular distance between the two point sources must be greater than that of the antenna pattern Half power beam width The resolution of the radio telescope should be defined as the half power width of its main beam. Radio diffraction However, for a simple radio telescope, it is determined by the physical size D of the antenna aperture and the wavelength λ, that is, the Limit resolution It depends on the aperture of the telescope and the wavelength used for observation. The larger the aperture, the shorter the wavelength and the higher the resolution. Because the wavelength of radio wave is much larger than visible light The resolution of radio telescopes is much lower than that of radio telescopes with the same aperture Optical telescope The antenna of the radio telescope cannot be expanded indefinitely. This is Radio astronomy The early days of its birth seriously hindered the development of radio telescopes.

For a single antenna radio telescope, the larger the diameter of the antenna, the higher the resolution. However, it is difficult to make the diameter of the antenna very large. The maximum diameter of a single antenna is 500 meters^[2] 。 yes Radio interferometer For example, the larger the maximum spacing between the two antennas, the higher the resolution. In addition, when the diameter of the antenna or the distance between the two antennas is fixed, the shorter the received radio wave length, the higher the resolution. High sensitivity. High resolution radio telescope can make us "see" farther and clearer in radio band Cosmic celestial body 。

Development History

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In 1931, in the United States New Jersey American radio engineer in charge of searching and identifying telephone interference signals in Bell Laboratories Karl Jansky (Karl Guthe Jansky) found that there is a kind of radio interference with maximum value every 23 hours, 56 minutes and 04 seconds. After careful analysis, his article published in 1932 interrupted: This is from Galaxy Medium radio radiation. As a result, Jansky ushered in a new era of using radio waves to study celestial bodies. At that time, he used a 30.5m long and 3.66m high rotating antenna array, and obtained a 30 degree wide "fan-shaped" beam at the 14.6m wavelength. Since then, the history of radio telescopes has been the history of continuously improving resolution and sensitivity.

Since Jansky announced that he had received radio signals from the Milky Way G. Leiber He devoted himself to the trial production of the radio telescope and finally succeeded in manufacturing it in 1937. This is a the Second World War Previously, the world's only parabolic radio telescope. its Parabolic antenna With a diameter of 9.45 meters and a 12 degree "pencil shaped" beam at a wavelength of 1.87 meters, radio waves from the sun and other celestial bodies were measured. In 1939, G. Leiber Received from Galaxy The first radio sky map was drawn according to the observation results. Radio astronomy From then on. The antenna used by Leiber is the first radio telescope dedicated to astronomical observation in the world, and Leiber is also known as the pioneer of parabolic radio telescope.

In 1946 university of manchester Start construction of fixing with a diameter of 66.5m Parabolic radio telescope In 1955, the world's largest rotating parabolic radio telescope with a diameter of 76 meters was built. At the same time, Australia, the United States, the Soviet Union, France, the Netherlands and other countries are also competing to build early radio telescopes of different sizes and forms. In addition to some equipment with a diameter of less than 10 meters, which is mainly used to observe the sun, there are also some parabolic telescopes with a diameter of 20 to 30 meters, which developed the early Radio interferometer and Synthetic aperture radio telescope 。 Since the 1960s, American National Radio observatory 42.7 m, 45.8 m in Canada, 64 m fully rotatable paraboloid in Australia, 305 m diameter fixed sphere in the United States, and radio telescopes operating in centimeter and decimeter bands (see Fixed spherical radio telescope ）And a number of millimeter wave radio telescopes with a diameter of about 10 meters. Because it can be transferred Parabolic antenna Expensive, fixed or semi fixed aperture shape (including paraboloid, sphere, paraboloid cylinder, paraboloid strip cut) antenna technology has been developed, thus more interferometers and cross arrays have been built (see Mills Cross ）。

1960, UK University of Cambridge Cavendish Laboratory Of Martin Ryle (Ryle) Utilization interference The principle of Synthetic aperture radio telescope The resolution of the radio telescope is greatly improved. The basic principle is that two radio telescopes separated from each other receive the radio waves of the same celestial body, and the two beams interfere, with the highest equivalent resolution equivalent to a single aperture radio telescope whose aperture is equivalent to the distance between two places. Ryle was awarded 1974 for this invention The nobel prize in physics 。

The initial start and development of radio astronomy technology benefited from the "military to civilian" transformation of a large number of retired radars after World War II. The radio telescope and radar work in different ways. The radar transmits radio waves first and then receives the echoes reflected by objects. The radio telescope only passively receives radio waves emitted by objects. In the 1950s and 1960s, with the development and improvement of radio technology, people successfully researched Radio interferometer ， Very long baseline interferometer New radio telescope radio interference technologies such as synthetic aperture telescope enable people to extract useful signals from noise more effectively; Very long baseline interferometers are usually thousands of kilometers apart. Several radio telescopes are used for interferometer observation, which greatly improves the resolution. From the late 1960s to the early 1970s, not only a number of technologically mature synthetic aperture radio telescopes with high sensitivity and resolution were built, but also a very long baseline interferometer with very high resolution, which is called a modern radio telescope, was invented. On the other hand, we also improved the design of classic radio telescope antenna on the basis of computing technology, and built a large precision antenna with a diameter of 100 meters Tracking parabolic radio telescope (Federal Republic of Germany bonn Nearby.

Since the 1980s, the VLBI network in Europe, the VLBA array in the United States, and the space VLBI in Japan have been put into use one after another. This is the representative of the new generation of radio telescopes, whose sensitivity, resolution, and observation band have greatly exceeded those of previous telescopes. Among them, the ultra long baseline array (VLBA) of the United States is composed of 10 parabolic antennas, which span a distance of 8000 kilometers from Hawaii to St Space telescope 500 times that of the human eye, 600000 times that of the human eye. The resolution it achieves is so high that a person can stand in New York and read a newspaper in Los Angeles.

After the 21st century, the resolution of radio is thousands of times higher than that of other wave bands, which can reveal the core of radio celestial bodies more clearly; The successful development of synthetic aperture technology enables the radio telescope to have a convenient imaging capability, Synthetic aperture radio telescope It is equivalent to a camera working in radio band. In order to receive the signals from the universe more clearly, scientists suggest moving radio telescopes into space.

On February 10, 2015, scientists are planning to universe Sending information, hoping to actively contact other life in the solar system and obtain their signals. Astronomers will send signals to hundreds of distant galaxies through radio telescopes in the hope of making groundbreaking discoveries.

This plan is made by California Scientists of the "Institute of Extraterrestrial Intelligence Search" are in charge. They believe that this plan is an important step in human space exploration. If the plan goes well, the space area 20 light years away from the Earth will receive this information.

In October 2023, the Changbai Mountain 40 meter aperture radio telescope project led by the Shanghai Astronomical Observatory of the Chinese Academy of Sciences was launched.^[8]

classification

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According to the different general structures of antennas, radio telescopes can be divided into Continuous and discontinuous aperture radio telescopes Two categories.

Continuous aperture radio telescope

The main representative is to adopt Single disk Parabolic antenna A classical radio telescope. According to the mechanical device and driving mode, the continuous aperture radio telescope (which is usually the basic unit of discontinuous aperture) can also be divided into three types.

Fully transformable or traceable

It can rotate in two coordinates, divided into Equatorial device and Horizontal device Two, as in Tracking parabolic radio telescope Used in.

Partial transformability

It can rotate in one coordinate (declination direction). The declination direction is scanned by the earth's rotation, also known as the Zhongxing ceremony (see Ribbon radio telescope ）。

Fixed type

The main antenna reflector is fixed, generally by moving the feed (also called illuminator) or changing the feed phase.

Radio observation is carried out in a wide frequency range, and the radio technology of detection and information processing is far more flexible than that of optical band, so there are many kinds of radio telescopes, which can also be classified according to other criteria: for example, according to the shape of receiving antenna, radio telescopes can be divided into paraboloid, paraboloid cylinder, sphere, paraboloid strip, horn, spiral, traveling wave, dipole antenna and other radio telescopes; According to the beam shape, it can be divided into pencil beam, fan beam, multi beam and other radio telescopes; According to the type of work, it can be divided into full power, frequency scanning, fast imaging and other types of radio telescopes; According to the observation purpose, it can be divided into such radio telescopes as surveying and mapping, positioning, calibration, polarization, spectrum and solar image. For discontinuous aperture radio telescopes, mainly various Radio interferometer 。

Discontinuous aperture radio telescope

Various combinations based on interference technology antenna system 。 In the 1960s, two new types of discontinuous aperture radio telescopes, the very long baseline interferometer and the Synthetic aperture radio telescope The former has very high spatial resolution, while the latter can obtain clear radio images. The world's largest traceable classical radio telescope Parabolic antenna Diameter up to 100 meters, installed in Germany Max Planck Institute of Radio Astronomy; The largest discontinuous aperture radio telescope in the world is the very large antenna array, which is installed at the National Radio Observatory of the United States.

In order to observe weak radio sources, radio telescopes must have large aperture and be able to track or scan radio targets for a long time. In addition, the cost of equipment and the reality of technology must be comprehensively considered.

Features and advantages

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Radio telescope and Optical telescope Different, it has neither a high and upright telescope tube nor objective lense , eyepiece, which is composed of antenna and receiving system.

Giant antenna is the most obvious symbol of radio telescope. There are many kinds of antenna, including parabolic antenna, spherical antenna, half wave dipole antenna, spiral antenna, etc. The most common is Parabolic antenna 。 For a radio telescope, an antenna is like its eye. Its function is equivalent to Optical telescope The objective lens in. It collects weak cosmic radio signals, and then transmits the collected signals to the receiver through a special tube (waveguide) for amplification. The working principle of the receiving system is similar to that of an ordinary radio, but it has extremely high sensitivity and stability. The receiving system amplifies the signal, separates the useful signal from the noise, and transmits it to the back-end computer for recording. The recorded results are many curved curves. Astronomers analyze these curves and get various cosmic information sent by celestial bodies.

Observation network

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Scientists from China, Japan and South Korea are using the world's largest radio telescope array they have jointly built to detect Galaxy structure 、 Supermassive black hole The mystery of deep space.

On the basis of their independently developed radio celestial body detection network, the astronomical circles of the three countries have integrated 19 radio stations in East Asia with a diameter of about 6000 kilometers Astronomical telescope , covering areas from Ogasawara Hokkaido To Urumqi and Kunming in China, it has become the largest radio astronomical observation network in the world. If cooperating with Japan“ Moon Goddess ”The diameter of this telescope array will be expanded to 24000 kilometers with the sky observation equipment carried on the moon orbiting satellite.

East Asia Very long baseline interferometry Shen Zhiqiang, a Chinese scientist in the VLBI observation program and a researcher at the Shanghai Astronomical Observatory of the Chinese Academy of Sciences, said on the 31st, "The VLBI network built by Chinese astronomers after more than 30 years of efforts has a great impact on the international community Radio astronomy Has made great contributions. We have also successfully applied VLBI technology to the orbit measurement of China's first moon orbiting satellite, which has achieved great success. "

Very long baseline interferometry It is an observation technology with high resolution and high measurement accuracy used by the international astronomical community for precise positioning and fine structure research of celestial bodies. A complete VLBI observation system usually consists of more than two radio telescope observation stations and a data processing center. The VLBI observation system of the Chinese Academy of Sciences consists of four radio astronomical telescopes with a diameter of 25 meters in Shanghai, 50 meters in Beijing, 40 meters in Kunming and 25 meters in Urumqi, as well as the Shanghai Data Processing Center.

Shen Zhiqiang said that each observation station tracks and observes the same target at the same time, and records or transmits the observation data to the data processing center in real time. The computer calculates the precise position of the target object based on these observations.

China VLBI Just three weeks ago, a remote data acquisition, mass storage and data processing experiment was carried out. The VLBI observation data was transmitted to the data processing center in real time using high-speed Internet, and real-time correlation processing was carried out to replace the traditional VLBI data mailing method. Half a month ago, the real-time relay observation demonstration conducted by 17 radio telescope observation stations in the world, including Shanghai and Urumqi, was also successful.

The main work of the East Asia VLBI observation network will be to improve the map of the Milky Way being drawn by the Japanese radio celestial exploration program. Japanese scientists believe that the Japanese Radio Astronomy Observation Network, consisting of 12 telescopes, plus four telescopes in China and three 21 meter telescopes just built in South Korea, will double the accuracy of star positioning.

"This unique work will help us obtain high-quality data on the structure of galaxies." National Astronomical Observatory of Japan Radio astronomy professor Xiaolin Xiuxing said in an interview with Xinhua News Agency.

South Korean and Japanese scientists are developing a special computer to integrate massive observation data. This set of computing equipment is planned to be put into use in Seoul, South Korea. Scientists predict that the VLBI observation program in East Asia will be fully launched in 2010.

Since Galileo, an Italian, observed the sky with a telescope for the first time 400 years ago, humans usually rely on optical equipment for astronomical research. It was later discovered that celestial bodies emit electromagnetic waves in addition to visible light. In 1932, the United States Bell Laboratories The engineer Carl Jansky accidentally discovered Galactic center Radio waves, Radio astronomy From here. The general radio astronomical telescope with dish antenna determines the shape and structure of distant celestial bodies by receiving celestial radio waves or actively transmitting radio waves and receiving echoes.

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Shanghai Sheshan 65m Aperture Rotatable Radio Telescope

In March 2012, the 65m diameter rotating radio telescope project was under construction at the foot of Shanghai Sheshan. It will be the largest radio telescope of this type in Asia, and its overall performance ranks fourth in the world. It is reported that this telescope is a major cooperative project between the Chinese Academy of Sciences and the Shanghai Municipal Government and was launched in Shanghai on October 28, 2012.^[3]

performance parameter

It is understood that this 65m radio telescope is Chinese Academy of Sciences and Shanghai Municipal People's Government Major cooperation projects jointly established at the end of October 2008. Its reception range covers 8 bands, and its overall performance ranks fourth in the world.

The 65 meter radio telescope is like a sensitive ear, which can carefully identify radio signals from the universe. It covers eight reception bands from the longest 21 cm to the shortest 7 mm, covering the centimeter wave band and the long millimeter wave band for radio astronomy observation. It is a fully movable high-performance radio telescope with the largest aperture and the most complete bands in China, and its overall performance is only inferior to the 110 m radio telescope in the United States Germany's 100 meter radio telescope and Italy's 64 meter radio telescope.

Correction type adopted by telescope Cassegrain antenna It can rotate in both azimuth and pitch directions. There are 6 groups of 12 wheels on the lower orbit to drive the azimuth rotation of the antenna. The upper pitch gear controls the pitch movement of the antenna, which enables the telescope to point to the celestial bodies and spacecraft to be observed with high accuracy, with the highest pointing accuracy better than 3 angular seconds.

The main reflecting surface area of the telescope is 3780 square meters (equivalent to 9 standard basketball courts), which is assembled from 1008 high-precision solid panels in 14 circles. The accuracy of each panel unit is 0.1 mm, representing the highest level of large-scale high-precision panel design and manufacturing technology in China.

The installation of the main reflector adopts the first domestic active surface technology. 1104 high-precision actuators are installed at the connection between the panel and the antenna back frame structure to compensate for the deformation of the reflector caused by gravity during tracking observation and improve the antenna reception efficiency for high-frequency observation. The unit precision of the actuator can reach 15 microns, which is about half of the diameter of a hair.

The track where the telescope is located is fully welded by seamless welding technology. This is the first time that full track welding technology is adopted in China, which solves many technical problems such as track welding deformation.

The first signal - 37000 light years from the earth

A world-class "expert" who has been raised in Sheshan's "boudoir" for several years to explore the mysteries of the universe officially "came out of the mountain" yesterday. It is not necessary to be limited by the weather. With its "ears" in multiple wavebands, this large radio telescope, the largest in Asia and the fourth in the world in overall performance, can sensitively "listen" to the radio signals from various celestial bodies in the deep universe, and then carry out measurement and research.

Yesterday afternoon, the telescope received the first signal from a region 37000 light years away from the Earth.

Aperture rotatable radio telescope

In order to win the largest international radio telescope cooperation plan to come to China, China is building the largest radio telescope in the world in Guizhou Province. This project was approved by China in 2007 500m Aperture Spherical Radio Telescope The (FAST) project has recently started infrastructure construction in Guizhou Province, with a total investment of 627 million yuan and a construction period of five and a half years. It was officially started in March 2011 and is expected to be completed in September 2016. After completion, it will not only become the world's largest single aperture astronomical telescope, but also maintain its leading position in the world in the next 20 to 30 years.

Academician of Chinese Academy of Sciences, Yuan International Astronomical Union Ye Shuhua, vice chairman of FAST, said that FAST's biggest technical achievement was to solve the difficulty of changing the spherical mirror to a mirror with a polished surface at any time. China was the first country in the world to master this technology. Guizhou Province was chosen because it is necessary to build a radio telescope with a large aperture of one square kilometer. It is estimated that 30 telescopes will be put together. There are many huge valleys in Guizhou, China, which can hold such a telescope.

Since the scientists put forward the project construction plan in 1994, they have searched hard and repeatedly demonstrated for nearly 10 years before confirming that the FAST detection base of the large radio telescope is located in Guizhou Province Pingtang County A karst depression called Dawodang. "Dawodang not only has a natural depression where telescopes can be set up, but also the karst geological conditions can ensure that rainwater can penetrate into the ground without silting, corrosion and damage of the telescopes on the surface", said Zhang Haiyan, deputy director of FAST Engineering Office. Here is a large group of funnel sinkholes unique to the karst landform - it is like a natural "giant bowl", which just holds the telescope, such as a giant reflector with an area of 30 football fields. When the telescope is completed, it will fill the valley.

As the telescope is located in the "Big Cotai" pit, it is very suitable for observation. In addition, although the observation of the large radio telescope is not affected by the weather, the radio environment is highly required in the site selection. The transmission of FM radio, TV, mobile phones and other radio data will interfere with the observation of radio telescopes, just as it is impossible to hear the speaker clearly in a whispering meeting. The large radio telescope project requires that the station site must be quiet within a radius of 5km, and the electromagnetic environment must not be disturbed.

Zhang Haiyan It said that there is no market town and factory near Dawodang, no township within a 5km radius, and only one county within a 25km radius, which is the most ideal site. With FAST, remote blocking Karst mountainous area It will become an international astronomical academic center attracting worldwide attention and a new window to show Guizhou to the world.

China Weijian Super astronomical telescope Nearly 10000 local residents will be relocated. Chinese officials have reported that the local government has started the relocation, offering economic compensation and housing assistance to the relocated residents. According to the report, the Guizhou Provincial Reservoir and Ecological Resettlement Bureau will provide subsidies of 12000 yuan per person; The Ethnic and Religious Affairs Commission of Guizhou Province subsidizes ethnic minority households with housing difficulties according to the standard of 10000 yuan per household.

On July 3 500m Aperture Spherical Radio Telescope (FAST). The successful installation of the last reflector unit marks the completion of the main project of FAST and the beginning of the testing and debugging phase. FAST active reflector consists of 4450 reflective panel units, with an area of about 250000 square meters and nearly 30 standard football fields, used to reflect radio waves. It is reported that FAST aims to achieve large sky area and high-precision astronomical observation. Its scientific objectives include patrolling neutral hydrogen in the universe, observing pulsars, detecting interstellar molecules, searching for possible interstellar communication signals, etc. Its application goal is to play a role in national major needs such as solar terrestrial environment research, searching for extraterrestrial civilization, national defense construction and national security.^[4]

Other projects

Modern advanced radio telescopes include: Federal Republic of Germany Large and medium-sized centimeter wave traceable parabolic radio telescopes represented by the 100m telescope; with National Radio Observatory ﹑ Sweden Onsala Observatory and Japan Tokyo Observatory The equipment of is the representative millimeter wave radio telescope; With the upcoming US Very large antenna array 。

Important functions

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Explore remote "extraterrestrial civilization"

The shape of this huge telescope is similar to Satellite antenna Similarly, a single aperture of 500 meters, like a huge "heavenly eye", will detect the remote and mysterious "extraterrestrial civilization". For thousands of years, humans have mostly observed the universe through the visible light band. In fact, the radiation of celestial bodies covers the whole electromagnetic wave band, and visible light is only a part of it that human beings can perceive.

The radio telescope can be used to monitor cosmic radio waves in outer space, including "artificial radio waves" that may come from other intelligent life; With sufficient power, this huge "heavenly eye" can also send radio signals, and the "alien friends" tens of thousands of light years away may receive greetings from China.

Can search for the first generation of celestial bodies

According to the researchers from FAST Engineering Office, after the project is completed, it will extend China's astronomical observation ability to the edge of the universe to observe dark matter and dark energy and find the first generation of celestial bodies.

It can discover thousands of pulsars in one year and study the material structure and physical laws in extreme states. Moreover, it is possible to discover strange stars and quark matter without relying on the model to accurately determine the mass of the black hole; Gravitational waves can be detected by accurately measuring the arrival time of pulsars; It is also possible to discover a giant maser galaxy with high redshift, realizing the observation breakthrough of the first methanol super maser outside the Milky Way.

For space weather forecast

FAST will also extend China's space measurement and control capability from geosynchronous orbit to the outer edge of the solar system, and increase the data downlink rate of deep space communication by 100 times. Pulsar timing array For autonomous navigation Prospective research Make a pulsar clock.

At the same time, it can carry out high-resolution microwave patrol, diagnose and identify weak space signals with 1Hz resolution, and serve as a passive strategic radar for national security. It can also track and detect Coronal mass ejection Events serve the space weather forecast.

Drive the development of manufacturing technology in China

FAST research involves many high-tech fields, such as antenna manufacturing, high-precision positioning and measurement, high-quality radio receivers, sensor networks and intelligent information processing, ultra wideband information transmission, massive data storage and processing, etc. The key technology achievements of FAST can be applied to many related fields, such as large-scale structural engineering, high-precision dynamic measurement in kilometer range, large-scale industrial robot development, and multi beam radar devices. The construction experience of FAST will have an impact on the development of China's manufacturing technology in the direction of informatization, limitation and greening.

Serve China's aerospace projects

As a major observation equipment in China and even in the world, the 65m radio telescope will achieve first-class scientific achievements in radio astronomy, astrogeodynamics, space science and other fields, and will implement Lunar exploration project Phase III VLBI orbit determination and positioning missions, as well as China's future lunar and Mars exploration and other deep space exploration missions, are also used for radio astronomy observation and other scientific research. It participates as a unit China VLBI The sensitivity will be increased by 42%. Participation in the European VLBI network will increase its sensitivity by 15% - 35%. As the largest antenna in East Asia VLBI network, it will play a leading role. In addition, the telescope will further improve China's deep space orbit determination capability and serve the major national strategic needs such as the Chang'e lunar exploration project and the long-term deep space exploration.^[5]

Future Outlook

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Considering the cost and efficiency together, in the future, large radio telescopes with a diameter of 100 meters can only be slightly increased, while single medium aperture centimeter wave radio telescopes are less and less used. Main orders Parabolic antenna It will be more generally incorporated or expanded to work with very long baselines, in-line interferometers and synthetic aperture systems. With the improvement of design, process and calibration technology, more and more accurate millimeter wave telescopes will appear. Synthetic aperture telescopes will be developed to achieve greater space, time and frequency coverage. In addition to increasing the number of VLBI systems, it is expected that they will eventually be able to use fixed satellites to achieve real-time data processing. The experiments of VLBI networks and interferometers arrays that combine aperture synthesis technology with VLBI technologies are likely to breed a new generation of radio telescopes.

Have you ever seen a telescope with an aperture of 500 meters that "fills" the whole valley? This is the world's largest single aperture radio telescope - FAST telescope, which was officially started in China at the end of December 2008 and is the size of 30 football fields.

Not only Chinese astronomers are excited about it, but astronomers around the world are also keeping an eye on FAST - hoping that the largest "heavenly eye" may find aliens and solve the mystery of the origin of the universe.

FAST design comprehensively reflects China's high-tech innovation ability, represents China's advanced level in the field of astronomical science, and will maintain a leading position in the world in the next 20 to 30 years.^[6]

FAST is a national major scientific project, which has significantly increased the observation area and sensitivity of the largest American Arecibo astronomical telescope in the world by 2.25 times.

Set location

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Located in the United States Puerto Rico Insular Arecibo telescope , fixed in nature crater The single aperture spherical antenna in the center has a diameter of 305 meters and will be expanded to 350 meters later.
Located in the United States New Mexico Desert Very large antenna array (VLA), consisting of 27 antennas with a diameter of 25 meters mounted on the rail, arranged in a Y-shape.
Atacama large millimeter wave antenna array 。（ALMA）
Greenlandic Submillimeter baud long baseline interferometer for greenland telescope 。
Japan VSOP, using the 8-meter radio telescope carried by the Japanese HALCA satellite and the radio telescope on the ground to form an interferometer.
Germany Of Eiffelsberg radio telescope , diameter 100 meters.
Located on the Green Bank of Pocahonta County, West Virginia, USA Green Causeway Telescope The antenna size is 100 m x 110 m.
China The 65 meter radio telescope at Shanghai Sheshan Observatory.
China National Astronomical Observatory at the north bank of Miyun Reservoir, Miyun County, Beijing, with a 50 meter aperture radio telescope.
China In Dawo Taipa depression, Kedu Town, Pingtang County, Guizhou Province 500m Aperture Spherical Radio Telescope （FAST）
Japan Yebianshan Cosmic Radio Observatory The 45m radio telescope and the Yebian Mountain millimeter wave array.
Located at Nan ç ay Observation Station in South Sai, France, it was completed in 1964.
Under preparation Square kilometer array 。（SKA）

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Astropulse
Radio astronomy
Shumanbo
Search for extraterrestrial civilization plan
List of observatories
List of telescope types
telescope

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