Most of our exploration of the universe is based on the observation of electromagnetic waves, because the earth's atmosphere will hinder most of the electromagnetic waves from the universe, so we on the earth can only explore the universe through electromagnetic waves in specific bands, in general, there are about three "windows", namely "optical window", "infrared window" and "radio window".
The range of bands observed by radio telescopes is actually the "radio window", because the electromagnetic waves in the radio band are actually radio waves in a specific band, and their wavelengths are relatively long, so they can easily pass through the gas and dust in the universe, and then can travel very far, so we can use radio telescopes to observe those deep space in the universe that is difficult to observe in other bands.
It is precisely because of the longer wavelength that the aperture of radio telescopes needs to be larger than other types of telescopes, and its construction is relatively difficult, so human radio astronomy only really began to develop in the 40s of the 20th century.
Located in a valley on the island of Puerto Rico in the United States, the Arecibo Telescope was built in the early 60s of the 20th century and officially opened on November 1, 1963, at a construction cost of about $260 million, including the construction of observatories, transceivers, detectors and other equipment and facilities.
The main structure of the Arecibo telescope is a parabolic reflective disk with a diameter of about 305 meters (later expanded to 350 meters), which can focus the radio waves incident above the disk onto a mobile antenna structure, which weighs about 900 tons and is supported by more than 10 steel cables attached to three towers, which can rotate in different directions and thus track objects in different celestial regions.
Once the world's largest radio telescope, the Arecibo telescope was called the "eye in the sky" on Earth, and since its use, it has made great contributions to radio astronomy, radar astronomy and other fields, such as the Nobel Prize in Physics in 1993, which is closely related to its observations (this research has discovered a new class of pulsars, which in turn has opened up new possibilities for studying gravity).
In addition, the Arecibo telescope has also been used in the Search for Extraterrestrial Intelligent Life (SETI) program, and scientists have even used it to send radio signals carrying information about Earth to extraterrestrial civilizations that may exist in the depths of the universe.
Unfortunately, on December 1, 2020, the Arecibo telescope suffered a catastrophic collapse. At that time, one of the support towers on the antenna structure suddenly broke, causing the entire antenna structure to fall, while also tearing and smashing large areas of its parabolic reflective disk.
(↑ Drone captured the scene at that time)
After that, the Arecibo telescope was abandoned because it could not be operated and repaired, and after about three years of wind and rain, the "Sky Eye" radio telescope, which cost 260 million yuan to build, has now become a "garbage dump". And the reason for this ending is simply four words: disrepair.
With the passage of time, the equipment and facilities of the Arecibo telescope are aging, in addition to the fact that it has experienced many hurricanes, which have brought higher costs to its repair and restoration, but since the beginning of the 21st century, the related financial investment has been decreasing, so that the Arecibo telescope cannot be maintained in a timely and effective manner.
In fact, before the collapse on December 1, 2020, the Arecibo telescope had already had frequent failures, such as two secondary and main cable failures in August and November of the same year, so people were not surprised that it finally collapsed.
Fortunately, the dismal exit of the Arecibo telescope has not stopped mankind's exploration of the deep space of the universe, because there is an even more powerful "eye in the sky" that has made its debut.
Yes, this "Sky Eye" is located in Guizhou, the mainland of the "China Sky Eye", the full name of the telescope is the "500 meters aperture spherical radio telescope" (FAST), its huge aperture and a large number of technological innovations, it can detect faint signals from tens of billions of light years away, and thus become the world's largest aperture, the strongest detection ability, the highest detection sensitivity of the single aperture radio telescope.
Since its official opening on January 11, 2020, the "China Sky Eye" has achieved many important results, so far, more than 800 new pulsars have been discovered, and hundreds of high-level papers have been published based on its observation data. It can be expected that the "China Sky Eye" will help us uncover more secrets in the universe in the future.