Arecibo’s radio telescope is collapsing. The end of one of the most valuable and famous radio telescopes

The unexpected finale of the device, built in the early 1960s, began in August. Without warning, one of the thick steel ropes supporting the receiver suspended above the 305-meter diameter dish slipped from its mount. Falling down, it caused damage and destabilized the entire structure.

A surprising breakup

At first it seemed as though everything would be fine. Only one of the 12 additional ropes installed in the 1990s broke to strengthen the entire system supporting the receiver platform in the air, on which additional devices were mounted. A new one was ordered and repairs were planned, which, however, could take up to a year.

Unfortunately, before repairs could take place, one of the older main lines supporting the receiver broke on November 6. Although theoretically it should withstand the increased load without any problems. It was mounted on the same of the three tall poles to which the first broken rope was attached. After this accident, the entire structure became unstable and it is risky to even get close to it. In addition, civilian and military experts called on site said that damage was visible to a number of other ropes that now have to withstand greater loads. There is a serious risk that the 900-ton receiver will break, dropping to the dish 150 meters below.

Since there is no safe and quick way to strengthen or repair the structure, it was decided to shut down the radio telescope. It is to be dismantled, as long as it does not collapse first. The specialists now have to figure out how to carry out the entire operation without leading to a catastrophe. This would be a risk not only for people, but also for valuable research equipment, which is still intact.

According to the initial declarations of the consortium of American universities managing it, there are no plans to rebuild the radio telescope in its original shape. In its place, a device with only part of its capabilities, i.e. LIDAR, may be created. It’s kind of like a radar, but it sends a signal not in the form of microwaves, but a laser beam. With its help, you can carefully examine the surface of other planets in the solar system, or asteroids.

A photo taken from a drone showing remains of a broken rope Fot. University of Florida

A unique construction in the Puerto Rico jungle

This is the sad end of the 57-year history of the Arecibo radio telescope. The idea to build it was born in the mind of the physicist William Gordon of Cornell University in the late 1950s. He wanted to create a device that would allow to study the ionosphere in a new way, i.e. the very poorly understood upper parts of the atmosphere, where solar and cosmic radiation reacts with gas molecules, turning them into plasma. His calculations indicated that a device with a huge dish with a diameter of approx 300 meters, which will be able to send a strong radio signal to the area of ​​interest.

It was decided to place the future radio telescope in the mountains, controlled by USA Caribbean island of Puerto Rico. Gordon searched for a suitable karst funnel, ideally suited for building a large canopy inside which, due to its size, could not be placed on some sort of base with rotation mechanisms, but had to be permanently attached to the ground. Over time, his concept was modified, after the involvement of other scientists and the US military, which at that time was very interested in understanding the properties of the ionosphere (in the context of detecting nuclear warheads from intercontinental missiles passing through it).

Apart from the sheer size and the idea of ​​placing the canopy on the ground, the most innovative was how the issue of placing the transmitter / receiver was solved. Initially, it was to be mounted on a tower over one hundred meters high, standing in the center of the canopy. This would, however, drastically limit the capabilities of the entire device and would be useless for radio astronomy. So a construction was invented in which the transmitter / receiver was placed on a platform suspended above the canopy on ropes. The key transceivers are mounted on moving mechanisms, thanks to which it is possible to precisely concentrate the radio telescope’s “look” point on a selected point of the sky and track it along with the rotation of the Earth.

Long video of a radio telescope tour, especially its airborne transmitter / receiver. Lots of details.

Listening to very distant space

The radio telescope was built in 1960-63. Ironically, even before it was launched, it was proved that Gordon’s calculations were wrong. The ionospheric studies he wanted to carry out could be done with much smaller, traditional radio telescopes. Fortunately, the final design of the one from Arecibo was so universal that it could easily be used for a wide range of other tasks. It was also modernized and improved several times.

Already in the first year work The radio telescope determined that Mercury rotates much faster than expected. In 1968, with its help, the first indisputable evidence was obtained that there are neutron stars, that is, the remnants of star explosions that will reach the end of their “life”. In the 1970s, the radio telescope was used to observe a pair of pulsars (one of the types of neutron stars or white dwarfs that send a strong, concentrated beam of radiation into space), the results of which allowed to confirm the correctness of the theory of relativity, for which the authors of the study were awarded the Nobel Prize in physics . In 1990, the Polish astronomer Aleksander Wolszczan, together with the Canadian Daile Frail, discovered the first planets outside the solar system orbiting a pulsar 2.3 thousand light years from Earth.

All this may sound very abstract, but it has a very real impact on our attempts to understand the basics of the world around us and to answer the questions of where our home – Earth came from, and what will happen to it.

View from the footbridge leading to the transmitter / receiver suspended in the air

Searching for alien and Soviet radars

The Arecibo radio telescope was not only our window to the very, very distant space, but also served to study various objects in our immediate vicinity. He did this, not listening to the subtle hints of radio waves emitted by distant stars, but in active mode, like a giant radar. It allowed us to observe potentially dangerous asteroids rushing through the Solar System, or to carefully examine the surface of other planets in our vicinity.

It was also used to search for foreign civilizations and establish contact with them as part of the SETI / METI programs. In 1974, it was used to emit a strong signal towards the spherical star cluster M13 in the constellation Hercules. It contains a coded message to present the possibilities of our civilization and basic information about it. It will reach the region of the M13 cluster in about 25,000 years. The authors of the message did not expect it to actually make contact with an alien civilization, but saw it as a monument to human achievement that would traverse the void of space.

Initially, the radio telescope was also used for more mundane matters. Secretly, the US military and intelligence used it to track Soviet radar emissions as it reflected off the moon. This allowed for a fairly precise location of several large and strong early warning stations.

A message sent into space from Arecibo, saved in graphic form.  Numbers 1-10 from the top, atomic numbers of elements making up organic compounds, DNA components, DNA structure, human, Solar system, Arecibo radio telescopeA message sent into space from Arecibo, saved in graphic form. Numbers 1-10 from the top, atomic numbers of elements making up organic compounds, DNA components, DNA structure, human, Solar system, Arecibo radio telescope Foot. Arne Nordmann / Wikipedia CC BY-SA 2.0

There is still Chinese, but not the same

Due to its enormous size and unique appearance, the Arecibo radio telescope has also made a lasting impression on mass culture. It has acted as an exceptional set design in films many times. Agent James Bond fought in the final scene of Goldeneye. It was also one of the main locations in the film Kontakt, or one of the episodes of the series “From the X-Files”.

Now it is all over. The radio telescope will make a long list of mankind’s unique achievements that have been overcome by time. After a device that only a few decades ago was a symbol of great technical development and enormous learning opportunities, there will be photos, videos and a long list of important discoveries.

There is no other such radio telescope. It is true that since 2016, the name of the greatest wields built in China FAST radio telescope, but it is not as precise and sensitive as the one from Arecibo. Moreover, it has no active space exploration function, it can only listen to it passively.

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