What is (or was) the Arecibo Observatory?
Figure 1: The Gregorian dome was installed as a part of the observatory in 1997. With its two sub reflectors and multi-beam receiving capabilities, the Gregorian dome improved the telescope’s ability to focus radiation on specific points in space. However, weighing at over 110 tons, it likely accelerated the demise of the telescope.
Source Credit: ScienceMag.com (LINK)
The Arecibo Observatory is a 57-year old radio telescope located in Puerto Rico, best known for being the biggest radio dish in the world up until 2016. Curved almost like a bowl, the radio telescope collected naturally occurring radio light from extraterrestrial sources (stars, galaxies, planets) in order to allow astronomers to detect the contours of the surfaces.
Originally, the Arecibo Observatory was not intended for astronomers. When it was founded in the early 1960s, the construction was part of a military initiative, with its main purpose being the detection of airborne Soviet missiles. However, as upgrades—such as the installation of aluminum panels that allow detection of higher frequencies—were made, scientists began to realize that the instrument could be used for far more than what was inside of the Earth’s atmosphere. Instead, it could be used to track asteroids that could threaten the entire planet, rather than just local regions. With targeted engineering towards scientific needs (e.g. installation of radio transmitters and aluminum panels that could collect waves of higher frequencies), the telescope had allowed several significant discoveries in the past decades, including the evidence of gravitational waves, evidence of volcanic repaving on the foggy surface of Venus, and the first-ever planet discovered outside of our solar system.
Beyond the pure technological power of the telescope, the Arecibo Observatory was also a cultural icon, with cameos in blockbusters such as Contact and GoldenEye. Puerto Ricans had fully embraced this marvel as the face of their technological innovations, so the collapse had been a painful blow to the citizens. To the local community living in the Arecibo neighborhood, the observatory had been the destination of field trips for many children, helping plant in them an interest in astronomy.
How did it fall?
Figure 2: A drone positioned on Tower 4 captures heart-breaking footage of how the Arecibo Observatory collapses. The sequences of suspension cable failure can be observed, starting from the top cable.
Source Credit: youtube.com (MDx Media/Arecibo Observatory) (LINK)
How did this marvelous, decade-old titan fall? Simply put, the suspension cables broke. But according to Sravani Vaddy, an astronomer at the Arecibo Observatory, the telescope had collapsed spectacularly. On Aug. 10, 2020, the first of the 18 cables had broken, all of which suspended the 900-ton telescope in the air. Three months later, the second support cabled had also disconnected. The National Science Foundation had known about these cables but decided that it would be too dangerous to attempt to repair the giant telescope. As a result, it died a slow, dramatic death, eventually collapsing on the dish on Dec. 1, 2020.
Future implications for astronomy
Figure 3: On December 1, 2020, the 900-ton instrument collapsed, leaving sinkholes in the dish. Source Credit: Nature.com (LINK)
Despite the shock that was felt by astronomers worldwide, researchers at the observatory have ambitious plans for the reconstruction of the telescope. According to the plan that was submitted to the National Science Foundation, the researchers are looking for a telescope that would have a 300-foot wide platform, a more rigid structure, and most importantly, a dish that would contain over one thousand dishes with modern designs. With these plans, the new telescope would have a more powerful beam than the original, double the sensitivity, and quadruple the radar power. It would be named the Next Generation Arecibo Telescope. With such a creation, the researchers will be able to investigate double the original view of the sky and a field of view that is 500 times bigger.
Due to the scale of the project, the Next Generation Arecibo Telescope may take years to be constructed. Some have even called it a pipedream. Truly, this represents a time of adversity for the world of astronomy, as well as a moment of opportunity.
Q&A:
Xavier: How exactly does a radio dish function? What information can be derived from studying the surfaces of planets and asteroids?
The radio dish functions as a receiver of the naturally occurring waves that are emitted from various objects in outer space. It then uses that information in order to graph out the surfaces of those objects, essentially making the information available for analysis. Great question, so why is astronomy so essential to mankind? Simply put, it allows us to understand the Earth better, as a celestial object in its own right. While we can learn about Earth mostly from our perspective, there are also many things that are simply impossible or difficult to learn from our grounded perspective. Beyond that, understanding space and the place we live in simply helps us answer fundamental questions about our history, and the challenges that we face in exploration has proven to be important triggers in the expansion of technology, new industries, and global peace. Even in our own lives, the first prototype of wireless earphones was created for space exploration. You can credit those AirPods to the astronomers.
Jiwon: While the Arecibo Observatory had much symbolic value, did it contain any scientific abilities unique to itself? (How is it different from other radio dishes?)
The Arecibo Observatory was considered a trailblazer among telescopes. What made it unique was simply its ability to detect emissions that were far more distant than the distances that other telescopes (until it was surpassed by the power of the Five-hundred-metre Aperture Spherical Telescope in 2020). For the past decade, there has been a hunt for fast radio bursts. The Arecibo Telescope immensely aided in this search by discovering that the burst was repeating, indicating that the source of these mysterious radio bursts from space was still present.
Sally: How did they engineer the telescope to make more significant discoveries?
As can be seen in the first picture, one of the most notable engineering changes made during the lifetime of the Arecibo Observatory was the installation of the Gregorian Dome in 1996, which contained two sub-reflectors (which would become the secondary and tertiary reflectors) that would essentially assist in focusing the radiation on the space object that it is studying, whether its a planet or star. It also had a horn antenna that would allow a boost in the telescope’s ability to collect these signals. However, unfortunately, many researchers believe that the Gregorian Dome accelerated the fall of the telescope, as it added 300 more tons to the weight that the cables held.
Wooseok: Why did the radio dish break in the first place? Could this possible factor of downfall be considered in future construction plans? (e.g. lack of care, design issues, etc.)
Beyond the weight that the cables had to carry, many of the researchers also suspect that water corrosion may have been a big factor. There was a hurricane in 2017, called Hurricane Maria, that likely accelerated the collapse of the cables. The storm winds carried seawater from the shores onto the telescope, and due to the salt composition of the water, the cables were very vulnerable to corrosion. Scientists are especially considering weather issues in the tropical climate of Puerto Rico. However, despite the fall, many researchers have reportedly said that the Puerto Rico staff were very caring and scrupulous with the observatory, so they are not to be criticized.
Eric: What other technologies exist that overlap with the function of a radio dish, and are radio dishes a relic of the past as other technologies advance further?
Satellites actually work in a similar way as radio dish telescopes. They use the curved design in order to receive radio signals transmitted from distant objects, while radio dishes capture naturally occurring waves. As satellites are still at the forefront of space exploration, radio dishes are also far from being outdated technology. Even recently, the Chinese government-funded the construction of the Five-hundred-meter Aperture Spherical Radio Telescope (FAST) in southern China for over $180 million USD, which is actually the one telescope that has surpassed the Arecibo Observatory in size, prior to its fall.
John: How can improved government funding towards science help resolve these kind of problems in the future?
Good question. One positive aspect of the collapse of the Arecibo Observatory was that it brought many of its discoveries to the public eye again. Hopefully, this event will remind governments of the immense importance of these astronomical instruments and dedicate more funds. Due to the newer and more powerful Five-hundred-meter Aperture Spherical Radio Telescope (FAST) that was constructed in 2020, there are many factors that may lead to the telescope not being constructed, but hopefully, we can at least see more government funding in other areas of astronomy.
Works Cited
Australia Telescope National Facility. How Does a Radio Telescope Work?, 17 Nov. 2020, www.atnf.csiro.au/outreach/education/pulseatparkes/radiotelescopeintro.html.
Clery, Daniel. “How the Famed Arecibo Telescope Fell—and How It Might Rise Again.” Science, 2021, doi:10.1126/science.abg5640.
Eric HandDec. 1, 2020, et al. “Arecibo Telescope Collapses, Ending 57-Year Run.” Science, 3 Dec. 2020, www.sciencemag.org/news/2020/12/arecibo-telescope-collapses-ending-57-year-run.
Gibney, Elizabeth. “Gigantic Chinese Telescope Opens to Astronomers Worldwide.” Nature News, Nature Publishing Group, 24 Sept. 2019, www.nature.com/articles/d41586-019-02790-3.