A Tribute to the Arecibo Observatory

NASA - via Wikimedia Commons.

Arecibo, Puerto Rico, the home of the world’s most famous radio observatory. For 53 years, the Arecibo observatory – a 305-meter bowl in the middle of rural Puerto Rico – was the largest radio telescope on the planet. Constructed in 1963, it led significant advances in the astronomical sciences. Some of its most profound discoveries, actions, and advances include:

  • 1964: Mercury’s actual rotational period, which is 59 days, rather than 88 days. It had been believed to have been tidally-locked with the Sun, which would have made its 88-day orbital period its rotational period, as well.

  • 1968: the Crab Pulsar, providing the first observational evidence of neutron stars.

  • 1974: the first binary pulsar, which later earned the Nobel Prize in Physics.

  • 1989: the first direct image of an asteroid.

  • The first extrasolar planets, which surround pulsar PSR B1257+12.

  • The Arecibo Message, a radio transmission from the Arecibo to the Hercules Globular Cluster, Messier 13, which contained a 1,679 bit pattern of zeroes forming a 23 by 73 pixel “bitmap” image. The image had stick figures, numbers, chemical formulas, and an image of Arecibo.

Arecibo also was the lead telescope for SETI (Search for Extraterrestrial Intelligence) and METI (Messaging to Extraterrestrial Intelligence) projects, both initially formed by NASA, but now run by nonprofits. The Arecibo Observatory is, as I said, the most famous radio telescope on the planet, having been featured in popular novels like Contact by Carl Sagan – my favorite book – movies like Contact (the movie of the book) and James Bond, and TV shows like The X-Files. The Arecibo Observatory is also famous for its contributions to the advancement of the astronomical sciences.

Yet, as we say, it appears that all good things come to an end.

The Tragedy

On August 10th, 2020, a supporting cable at Arecibo snapped, falling onto the main dish and ripping a 100 foot-long gash in it. Two major earthquakes had hit the surrounding area near Arecibo prior to the collapse, which may have caused the instability that resulted in the snapped cable. Engineers analyzing the cable situation at Arecibo deemed it safe for use; the observatory seemed as if, once the massive gash in the radio dish was fixed, it would once again continue to operate.

In a most heartbreaking fashion, in early November, a second supporting cable at Arecibo unexpectedly snapped, despite the assurances of the system’s stability. This was yet another blow to the prospect of continuing the lasting scientific advancement at Arecibo. The structural damage that resulted totaled the observatory, rendering it impossible to be restored.

On November 19th, 2020, the National Science Foundation (NSF), which runs the Arecibo Observatory, made the choice to decommission the observatory 57 years after it was commissioned.* The science community was heartbroken, and astronomers around the world expressed their shock. Nevertheless, Arecibo was virtually unrepairable following the two tragedies.

A Tribute

The observatory was first designed in the late 1950s to develop anti-ballistic missile defenses, which means that, of course, the foremost radio observatory of our generation was built not for science, but for war. 

In the original plans for the observatory, researchers planned to study potential physical signatures that resulted from the reentering of a nuclear warhead into Earth’s atmosphere; our limited knowledge of the ionosphere at the time caused the studies not to materialize in the manner we had wanted. The observatory was, therefore, built to study the ionosphere, and later for solely scientific research – mainly the astronomical and atmospheric sciences. 

The observatory was built in northwestern Puerto Rico from 1960 to 1963 and opened on November 1st, 1963. Its primary purpose was to advance research in radio astronomy, radar astronomy, and atmospheric science; nevertheless, it would mainly be used for astronomy.

Arecibo also has a remarkable presence in popular culture. On page 29 of Carl Sagan’s Contact, the protagonist, Ellie Arroway, is given a job as a research associate at Arecibo, “After receiving her doctorate, Ellie accepted an appointment as research associate at the Arecibo Observatory, a great bowl 305 meters across, fixed to the floor of a karst valley in the foothills of northwestern Puerto Rico.”

The Arecibo serves a significant presence in the movie version of Contact, and Ellie, the protagonist, spends a significant amount of time at Arecibo in the movie.

Later, Sagan speaks to the importance of the facility: “[It] was known to the locals as ‘El Radar.’ Its function was generally obscure, but it provided more than a hundred badly needed jobs. The indigenous young women were sequestered from the male astronomers, some of whom could be viewed at almost any time of day or night, full of nervous energy, jogging along the circumferential track that surrounded the dish.”

With Sagan’s testament, we realize that not only will we lose the scientific research that comes with the telescope but the loss of jobs for many in an impoverished area of Puerto Rico.

The Arecibo Observatory experienced significant funding issues throughout the early 21st century, but despite limited funding, it nevertheless remained in operation the entire time.

Since Arecibo’s development, NASA supported the astronomical and atmospheric sciences division of the NSF for its maintenance, but between 2001 and 2006, NASA decreased – and then cut – all funds to Arecibo.

The astronomical sciences division of the NSF was recommended to cut funds to the Arecibo; they later cut funding for the Arecibo from $10 million yearly to $4 million yearly. The report also recommended that the observatory be closed if resources cannot be found. This put the observatory in deep financial troubles, almost forcing them into permanent closure.

The jeopardy Arecibo faced was not taken lightly. Academics, intellectuals, scientists, celebrities, media moguls, and politicians all fought with Congress to reestablish funding for the observatory. In 2009, their efforts would prove successful when Congress passed the American Recovery and Reinvestment Act, which appropriated $3.8 million in funding for Arecibo.

In another win, NASA also renewed its funding, adding an additional $2 million a year starting in 2010, then increasing funding to $3.5 million in 2012.

Yet the NSF announced that it planned to eventually shut down the Arecibo Observatory, citing environmental impacts. The NSF also sought to, before shutting it down, defund the observatory. As a result, many academics struck back, arguing that scientific losses would outweigh environmental and economical benefits.

Early Damages and Demise

The Arecibo Observatory also underwent significant damages in 2017 and 2019, as well as in 2020.

In 2017, Hurricane Maria devastated the island of Puerto Rico, including the Arecibo Observatory. When Maria hit the island, high winds caused the 430 MHz line to break and collapse onto the observatory, which damaged 30 of the 38,000 aluminum panels on the dish. Although – remarkably – the damage resulting from Maria was minimal, it was evident that Arecibo was in trouble.

Two significantly damaging events – one of which was aforementioned – also took place at Arecibo, the final of which led to its decommissioning. The first directly resulted from Tropical Storm Isaias and earthquakes occurring in the area in 2019 and 2020; the second resulted from the original damage, which caused the science center above the radio telescope to be unstable. After the second cable collapsed, the NSF announced that it would decommission and demolish the observatory.

Wrapping it up

The Arecibo Observatory will live on in every scientist’s, every science enthusiast’s, every academic’s, every intellectual’s, every popular culture fan’s, every engineer’s, heart. This observatory’s marvel and haven for scientific advancement will not be forgotten, and the great minds inspired by this observatory will continue to tell its story. The loss of Arecibo is only a temporary setback in humanity’s unquenchable thirst to understand the universe. As always, take care and stay curious, everyone.

* This piece was written the weekend after the National Science Foundation’s announcement on November 19th, 2020. The NSF announced that it will run a controlled demolition of the observatory, but on December 1st, 2020 – before the planned demolition – the remaining cables snapped, leading to the complete collapse of the observatory. The instrument platform – the large structure occupying the middle of the dish, several hundred feet above it – collapsed onto the dish, destroying it. No injuries were reported, and the NSF has announced that it will seek to keep all the remaining observatories open and build a new dish in the place of the prior one.

If you have any questions, comments, or corrections, please comment on this post or email learningbywilliam@gmail.com with your concerns. Thank you.


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Arecibo message. (2022, July 20). Retrieved from https://en.wikipedia.org/wiki/Arecibo_message

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Overbye, D. (2020, November 19). Arecibo Observatory, a Great Eye on the Cosmos, Is Going Dark. Retrieved from https://www.nytimes.com/2020/11/19/science/arecibo-observatory.html

Witze, A. (2020, November 19). Legendary Arecibo telescope will close forever - scientists are reeling. Retrieved from https://www.nature.com/articles/d41586-020-03270-9