Arecibo, Puerto Rico, Central America


Arecibo, Puerto Rico, Central America

Photo by: John Elk

John Elk

It’s Time to Say Goodbye to Arecibo

There aren’t a lot of telescopes that are also movie stars. In fact, I can think of only one: the famed Arecibo Observatory in Puerto Rico.

January 07, 2021

It must have a great talent agent, because it’s been featured in GoldenEye, Contact, and even the X-Files. If I said to you the phrase “think of a giant radio dish in a jungle”, you’d probably think of Arecibo.

When Bigger Was Better

Arecibo Radio Telescope Receiver Array in Puerto Rico.  Part of the Arecibo Radio Telescope in Puerto Rico. The largest single-unit radio telescope in the world.


Arecibo Radio Telescope Receiver Array in Puerto Rico. Part of the Arecibo Radio Telescope in Puerto Rico. The largest single-unit radio telescope in the world.

Photo by: TexPhoto


Arecibo Radio Telescope Receiver Array in Puerto Rico. Part of the Arecibo Radio Telescope in Puerto Rico. The largest single-unit radio telescope in the world.

Arecibo is so iconic because it’s so dang big. It’s a giant dish 1,000 feet across, nestled in a natural sinkhole that provides the structural integrity that money can’t buy. The disk itself is made of over 38,000 individual aluminum panels. Those panels reflect and focus radio signals to a receiver sitting almost 500 feet above the dish. Did I mention that the receiver, which is suspended in the air through a system of 18 cables, weighs 820 tons?

All that engineering and technological might has been focused for over half a century on the advancement of understanding of our universe. Arecibo has contributed to many important scientific results, including a couple Nobel prizes. With the dish, we’ve been able to accurately measure the rotation period of Mercury, discover some of the strangest stars in the universe, find prebiotic molecules in distant galaxies, and more.

So, About Those Aliens?

Arecibo has also played an important role in SETI, the Search for Extraterrestrial Intelligence. Astronomers have used the giant dish to scan the heavens for any signs of distant alien civilizations. We’ve also used it in reverse-mode: blasting out a super-loud radio signal for any far-flung friends to pick up. So far all those messages and all that listening has come to naught, but that’s another article.

But, It's Over Now

radiotelescope in the observatory of Arecibo Puerto Rico


radiotelescope in the observatory of Arecibo Puerto Rico

Photo by: IsaacRuiz


Alas, all good things must come to an end. The telescope has been in operation since 1960, but has suffered some major setbacks in recent years. Hurricane Maria packed a wallop and snapped some cables in 2017. Earthquakes shook its foundations in 2019 and in 2020. But in August of 2020 and again in November 2020, critical cables snapped, damaging the underlying structure and threatening the integrity of the receivers.

The National Science Foundation, which decades ago was the main sponsor of Arecibo but has steadily been reducing its funding (down to around $1 million annually for the past few years), has announced that it will not revive the great observatory after these latest setbacks. Instead, it will decommission the main dish and return the site to its natural state.

Honestly, it’s not going to be a big loss for astronomy. Since Arecibo first came online, our radio technology has advanced considerably. We now have large networks of smaller dishes that are much more powerful–and much more nimble–than the behemoth of Puerto Rico. And speaking of behemoths, if you’re in the mood for huge valleys-turned-into-telescopes, there’s always that newly-constructed FAST telescope in China, which is 60% wider than Arecibo.

While the Arecibo Observatory has had a long and illustrious career in service to astronomy (and cinema), it’s time to move on.

Paul M. Sutter

Paul M. Sutter is an astrophysicist at Stony Brook University and the Flatiron Institute, host of Ask a Spaceman and Space Radio, and author of How to Die in Space.

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