The telescope has a diameter of 305 meters.Arecibo telescopeIt is a fixed telescope and cannot rotate. It can only scan a strip area in the sky by changing the position of the antenna feed.
In December 2020,National Science Foundation(NSF) confirmed that the platform of Arecibo radio telescope collapsed overnight, and no casualties were reported.[1]
Chinese name
Arecibo Observatory
Foreign name
Arecibo Observatory
Management unit
Cornell University
geographical position
Located in overseas territories of the United StatesPuerto Rico[2]
In 1974, to celebrate the completion of the transformation,Arecibo telescopeTo a distance of 25000 light years from EarthGlobular clusterM13 sent a string of 1679Binary digitThe composed signal is called“Arecibo Message ”。If the information is received by extraterrestrial intelligent life, the information shown in Figure 1 will be read, from top to bottom, as follows:
Simple information about members of the solar system;
The aperture and wavelength of the telescope.
The reason that Arecibo telescope sends information to globular cluster M13 is that the stars in it are densely distributed, which is more likely to be received by extraterrestrial intelligent life.Arecibo radio telescope is favored by film and television works because of its spectacular appearance.007 series《Golden Eye》Some scenes of the film Contact were shot here.
Main applications
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Arecibo Radio Telescope
In order to observe distant celestial bodies, astronomers must develop telescopes that can detect extremely weak radio signals of celestial bodies.All over the worldradio telescopeIn 60 years, the energy of all celestial radio sources collected is only equivalent to the energy released by several raindrops hitting the ground.The two radio telescopes that can track signals, made by Germany Eversberg and the United States Greenbank, have an aperture of 100 meters, high sensitivity, strong resolution, wide coverage of the sky, flexible and convenient tracking, and can be called the best of telescopes.However, it is insufficient to observe weaker radio sources.The 305 meter aperture Arecibo radio telescope in the United States has a receiving area about 10 times larger than the antennas of the two telescopes mentioned above, and its sensitivity has been improved by about an order of magnitude, making it the most powerful single antenna radio telescope today.However, due to its limited coverage of the sky, other large radio telescopes still play a very important role.
Scientific exploration
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Arecibo Radio Telescope
To detectMoon、asteroid、comet、planetAndsatelliteIt is equipped with a transmitter and dual polarization microwave receiver with a wavelength of 126cm and a transmission power of megawatt.The signal echo reflected from the received target can obtain the image of the surface of the detected object.The research results of radar detection are very extensive and prominent: the rotation of Mercury and the annular structure of "water ice" near the North Pole have been measured;The radar interferometer formed with the Greenbank 100m radio telescope was used to obtain the high-resolution topographic map of the local area of Venus;Determine the best landing site on the moon for Apollo and Viking with an accuracy of several hundred feet;The Arecibo radar has also found two binary asteroid galaxies that are very close to the EarthNear Earth AsteroidsAnd monitor them.
In 1959, in a pioneering paper published in the British journal Nature, astronomers Ko Connie and Maurison of Cornell University in the United States proposed that the suggestion of using existing equipment to search for extraterrestrial civilization near the 1420 MHz frequency was strongly reflected.In 1960, the United States began its first planned search for extraterrestrial civilizationProject Ozma As well as the second phase of the Ozma plan, using relatively small radio telescopesSun like starDuring the monitoring, Hito received radio signals from extraterrestrial civilization without success, so the United States had to use the largest Arecibo radio telescope in the later "High Resolution Microwave Patrol" plan to monitor more than 800 sun like constellations within 100 light years, but still got nothing.
In order to actively contact with extraterrestrial civilization, in 1974, the United States used the Arecibo radar to send a telegram to the M31 globular cluster in the constellation Hercules, telling“Hercules”It is an intelligent creature, with information about the solar system, the five important elements of hydrogen, carbon, nitrogen, oxygen and phosphorus, human life, human body shape and height, and the population on the earth.Telegrams are written in binary series of pulses and sent at the speed of 10 words per second. They travel at the speed of light, and it will take 2400 years to reach their destination. If a message is sent back to the earth immediately after receipt, it will take 4800 years for people on earth to receive it.
Structural construction
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William E., professor of electrical engineering at Cornell University, developed the Arecibo radar telescopeGordon proposed it for the study of the ionosphere, so its original name was Arecibo Ionospheric Observatory.But this telescope isRadio astronomyandRadar astronomyShanghai has played a more important role.Soon, it was renamed the National Astronomical and Ionospheric Center (NAIC).
The Arecibo Radio Telescope spends 80% of its working time on radio astronomy, 15% on atmospheric research and the remaining 5% on radar astronomy.The world's most sensitive radio telescope and radar, the Arecibo telescope built in Puerto Rico, uses limestoneKarst topographyThe bowl shaped pit with proper scale and symmetry is used as the base, which reduces the cost and technical difficulty.
This radio telescope was built in 1963. The main reflector is spherical, and the original antenna is a metal mesh, which can only work in the 50cm band at the shortest.It was reconstructed from 1972 to 1974, and made of 38778 metal plates, making the working band reach 5cm.After 1980, another reconstruction was carried out to expand the antenna diameter to 366 meters.The reconstruction in 1997 expanded the observation frequency range to 6 meters to 3 centimeters, enabling the telescope to observe more molecular spectral lines.The spherical antenna has a diameter of 305 meters and a depth of 508 meters, and is supported by a wire mesh fixed in limestone.The antenna fixed on the ground can do a great job, but its defect is that it can't aim at the radio sources in different sky areas and track them by rotating the antenna.Spherical antenna andParabolic antennaDifferent from that, there is no main optical axis, which can receive celestial radio waves from a large angle range. With the movement of the feed source, it can scan or track in a large sky area (about 20 °).The radio waves from celestial bodies can not be gathered at a point like a paraboloid, but rather, more complex correction mirrors or linear feed methods should be used to collect energy.
Arecibo Radio Telescope
In order to increase the observable wave band and improve the sensitivity, the method of linear feed with a length of about 28 meters was initially adopted, and later it was improved to the method of correction mirror.A 500 ton triangular platform and movable feed arm are suspended above the main reflector, supported by 18 steel cables connected to three 100 meter high iron towers.Under the platform, there is a round house 508 meters away from the main reflector. The round house weighs 75 tons and has a diameter of 24 meters. Two reflectors (called Gregory sub reflector)radar transmitter And microwave receiver.These two reflectors are the second and third reflectors with diameters of 21.9m and 7.9m respectively.Celestial radio waves that reach the main reflecting surface are reflected to the second reflecting surface and then to the third reflecting surface, and finally reach the focus in the receiver room. Different feeds are connected to receivers of different wavebands. Each receiver is installed on a rotating disk, which can easily move the required receiver to the focus.The round house can move up and down along the curved arm, and the arm can also rotate.The round house is designed to prevent the damage of bad weather to the small reflector, and also to prevent man-made electromagnetic interference.
Observational findings
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Arecibo Radio Telescope
The Arecibo Observatory was officially opened on November 1, 1963. Since then, thousands of scientists have used it, and visitors of all ages and occupations have been welcomed.Film stars and Hollywood film producers also often come here to shoot several films with different themes.The Arecibo radio telescope mainly studies quasars, pulsars and other radio sources at the edge of the universe.The most exciting observation was the discovery of the first radio pulse binary system PSR191316 by Taylor and Hulls in 1974.This is a double neutron star system with an orbital period of 7.75 hours.According to the theory of general relativity, the gravitational radiation of this binary system is very strong.Gravitational radiation will cause obvious changes in the orbital period of the binary system.Professor Taylor made thousands of observations with Arecibo Radio Telescope and obtained the orbital period of this pulsar for 20 years, which proved that the observation results were in good agreement with the results of general relativity calculation, and finally confirmed the existence of gravitational waves.Taylor and Hulls won the award together in 1993The nobel prize in physicsThis has also become the pride of Arecibo Radio Telescope.
Arecibo Radio Telescope [3]
In 1991, astronomers Voszan and Freire used this telescope to find thePlanetary system, which once again shocked the scientific community.This is the first planetary system outside the solar system discovered by astronomers, which is a major breakthrough.For space exploration of the solar system and search for extraterrestrial civilization, radio telescopes were developed with the help of radar technology. Later, radar became a means of directly detecting celestial bodies, and developed into a new discipline radar astronomy.The Arecibo radio telescope is equipped with a powerfulRadio transmitter。The huge antenna has very high directionality, which enables the radio wave to converge into a very small radiation beam and emit. Directional transmission can greatly improve the transmission power.The radio wave will be reflected back when it hits a solid object, but the energy of the echo is very small, and it needs a very sensitive radio telescope to receive it.It is precisely because of the characteristics of this telescope that it has become the most powerful radar in the world.
Fault accident
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The steel cable of Arecibo Observatory is broken
November 9, 2020[4], according to Russian satellite news agency sputniknewsUniversity of FloridaAccording to the releasePuerto RicoThe Arecibo radio telescope was damaged again due to the broken steel cable.Due to the fracture of the steel cable, the telescope reflector was hit with a 30 meter long crack.The scientific observation work has to be stopped, and the repair work is not expected at present.
Arecibo Observatory collapses
On December 1, the owner of the telescopeNational Science Foundation(NSF) confirmed that after two serious cable accidents this year, the receiving equipment platform suspended by the telescope fell and destroyed the surface of the telescope reflector (antenna) that day. At present, there are no casualties, but the telescope is probably no longer usable. Reconstruction is one of the most feasible methods at present.[5]
On December 3, the media reported that the National Science Foundation (NSF) of the United States confirmed that the platform of the Arecibo radio telescope collapsed overnight, and no casualties were reported.[1]National Science FoundationThe video of the incident was released.The accident did not cause casualties.It was reported that the residual steel cables on the three lifting towers could not support the instrument platform weighing about 900 tons at that time, resulting in the whole platform falling on the 305 meter diameter reflective panel, and thus Arecibo completely ended its observation life.[6]
