See the Dramatic Footage of the Collapse of Arecibo Observatory’s Massive 305-Meter Telescope

Starry Sky Above Arecibo Observatory

A starry sky above the Arecibo Observatory in Puerto Rico. Credit: University of Central Florida

The instrument platform of the 305-meter telescope at Arecibo Observatory in Puerto Rico fell at approximately 7:55 a.m. Atlantic Standard Time on December 1, resulting in damage to the dish and surrounding facilities.

No injuries were reported as a result of the collapse. The U.S. National Science Foundation ordered the area around the telescope to be cleared of unauthorized personnel since the failure of a cable on November 6. Local authorities will keep the area cordoned off as engineers work to assess the stability of the observatory’s other structures.

Top priorities are maintaining safety at the site, conducting a complete damage assessment as quickly as possible, and taking action to contain and mitigate any environmental damage caused by the structure or its materials. While the telescope was a key part of the facility, the observatory has other scientific and educational infrastructure that NSF will work with stakeholders to bring back online.

Damage sustained at the Arecibo Observatory 305-meter telescope. Credit: University of Central Florida

“We are saddened by this situation but thankful that no one was hurt,” said NSF Director Sethuraman Panchanathan. “When engineers advised NSF that the structure was unstable and presented a danger to work teams and Arecibo staff, we took their warnings seriously and continued to emphasize the importance of safety for everyone involved. Our focus is now on assessing the damage, finding ways to restore operations at other parts of the observatory, and working to continue supporting the scientific community, and the people of Puerto Rico.”

The investigation into the platform’s fall is ongoing. Initial findings indicate that the top section of all three of the 305-meter telescope’s support towers broke off. As the 900-ton instrument platform fell, the telescope’s support cables also dropped.

Preliminary assessments indicate the observatory’s learning center sustained significant damage from falling cables.

Engineers arrived on-site today. Working with the University of Central Florida, which manages the observatory, NSF expects to have environmental assessment workers on-site as early as tomorrow. Workers at the observatory will take appropriate safety precautions as a full assessment of the site’s safety is underway.

“We knew this was a possibility, but it is still heartbreaking to see,” says Elizabeth Klonoff, UCF’s vice president for research. “Safety of personnel is our number one priority. We already have engineers on site to help assess the damage and determine the stability and safety of the remaining structure. We will continue to work with the NSF and other stakeholders to find ways to support the science mission at Arecibo.”

NSF intends to continue to authorize UCF to pay Arecibo staff and take actions to continue research work at the observatory, such as repairing the 12-meter telescope used for radio astronomy research and the roof of the LIDAR facility, a valuable geospace research tool. These repairs were funded through supplemental congressional appropriations aimed at addressing damage from Hurricane Maria.

Once safety on site is established, other work at the observatory will be carried out as conditions permit.


Although the platform’s fall was unplanned, NSF, UCF, and other stakeholders, including engineering firms contracted by UCF, had been monitoring developments at the 305-meter telescope that indicated an increased risk of a collapse.

In August, one of the 305-meter telescope’s cables unexpectedly detached. The remaining cables were expected to bear the load without issue as engineers worked on plans to address the damage. However, a second cable broke on November 6. Engineers subsequently found the second snapped at about 60% of what should have been its minimum breaking strength, indicating that other cables may be weaker than expected, and advised that the structure could not be safely repaired.

Both cables were attached to the same support tower. If the tower lost another cable, the engineer of record noted, an unexpected collapse would be the likely result. Since NSF’s November 19 announcement that it would plan for decommissioning of the 305-meter telescope,  surveillance drones found additional exterior wire breaks on two cables attached to the same tower. One showed between 11-14 broken exterior wires as of November 30 while another showed about eight. Each cable is made up of approximately 160 wires.


View Comments

  • What goes up, must come down. It's odd that the videos were not released immediately after the collapse.

  • An icon for SETI. It had a small showing in the movie Contact and a fight scene in Golden Eye. Better equipment is available now but it's loss raises nostalgia in me.

  • Let the conspiracy theories commence.....It's a cover-up! The dish was destroyed to protect US government secret meetings with aliens at area 51! You can clearly see the white puffs of smoke from the explosives used to bring down the towers!

    It's a sad loss to the scientific community as a whole, RIP Arecibo. Hope to hear that they have plans (And hopefully funding...) to build something new at the site to continue the great work started there over half a decade ago.

  • Look,we all know engineers of all stripes are Pinheads,,Pocket protector loving dweebs, nerds,geeks,weirdos....ummm, yeah. So,why in the hell are they soooo very very short sighted? 900 tons or tonns,tons, tonnes. A few million rolls or yarn is a waste! You should have brought in a Physicist or a better one as the case may be to have projected 500-1,000 yrs. out the tensile strength of every individual cable to guage it's strength then compared to when it was first erected. Don't be satisfied with the single strength, double strength...try 3x as strong, 4x as strong. The dopes who were responsible for erecting the dish as just a guilty as the dopes who, after the strand broke thought is was okay. You want to checkmate the pull of gravity? Do what those who've seen combat do,be secured 6 ways to Sunday. Multiple long guns,pistols, grenades,knives etc.

  • This is one of the best recordings I ever read. The videos were outstanding. Thank you for making things interesting. The basketball information of the lakers was excellent.

  • It is so sad to see such an iconic landmark come down in a matter of seconds. As a native Puerto Rican, who has visited the site many times, I'm heartbroken. Puerto Rico has lost an Iconic Visitor Attraction. I hope it can be rebuilt as we need this site to once again be a part of the World's Science exploratory site.
    Arecibo , You will be resurrected one day soon. Keep the faith. You were the strongest and you WILL live on..

  • Just wondering....did they really fly a drone 24/7 to watch the equipment and the specific cable that failed?...kind of strange.

    • Only conspiracy theory that I would support is the most obvious. This facility was too old, outdated ( in comparison to the Chinese ) too far away from USA and expensive to operate. We can romanticise and cry over it's sad destiny ( similar we did with space shuttle ) but i can bet you that in less than a year we will have a proposal to build much larger dish and facility somewhere in continental USA!
      possibly privately owned and leased to USA research.

      You see, it's all about money and power.

  • Someone said make it 4x as strong. That's easy to say but your TAX dollars pay for this and you and people like you get outraged when the government asks for more TAXES to pay for things like this. Everybody wants the moon and stars. But nobody wants to pay for it. And in any case, projects like this have to ask for funding from Congress and they DO ask for the money they need, but Congress often comes back with a fraction of the money requested, like 20-30%, or sometimes zero money. So projects like this end up operating on shoestrings and donations and gift shop profits. So sure, make it 4x stronger than needed. But who pays for that? This particular site will be cleaned up and that's it. They won't rebuild. And they won't even have money for the clean-up.

  • If you look at the coloumn at the back ....there seems to me either some sort of electrical charge or something the film in slow motion focusing on the black column at the back

    • *Facepalm* Please don't encourage conspiracies. Rewatch all of it, and using critical thinking skills digest what you've seen. That tower you mention is the one the drone was watching. What you saw was the cables snapping, which when cables of their stature breaks, it is quite a sight.

National Science Foundation

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