Nighttime view of the Arecibo Radio Telescope’s transceiver array under a clear sky and during better times
This is a follow-up story to recent developments at Puerto Rico’s Arecibo Radio Observatory.
At 7:53:50 AM EST, December 1st, the observatory’s radio transceiver superstructure, suspended above the 305-meter spherical radio dish, collapsed and fell to the dish below (watch video at the foot of this article). The NSF news release reporting the event follows:
The instrument platform of the 305-meter telescope at Arecibo Observatory in Puerto Rico fell at approximately 7:55 a.m. Atlantic Standard Time Dec. 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 Nov. 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.
“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.
NSF will continue to release details as they are confirmed. Additional information, including engineers’ assessments of the structure, can be found in NSF’s Nov. 19 news release.
Background
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 Nov. 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 Nov. 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 Nov. 30 while another showed about eight. Each cable is made up of approximately 160 wires.
-NSF-
Significant in the press release is the following:
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.
This tragic end to the unique and iconic scientific landmark closes out the current chapter of the 57-year-old radio observatory, made famous by the 1997 feature-length Hollywood Production Contact.
It is important to note that a “Public-Private” partnership was entered into in 2018 to manage the observatory between the University of Central Florida, The National Science Foundation and “Yang Enterprises“, a for-profit government contractor with Democratic Senator from Florida Bill Nelson having secured $20M in federal repair money to repair damages to the observatory sustained during Hurricane Maria’s 2017 rampage across the island.
The question begs asking, how is it possible that the facility has prevailed during many hurricanes since 1963 as well as surviving two upgrades, the first in 1974 and another in 1997, with the later adding much additional mass and corresponding engineering upgrades to the support cables, towers and infrastructure. Now, how is it that, having received $20M in public repair money in 2018, the main radio transceiver superstructure support cables suffer a general failure, causing catastrophic collapse and rendering any future discussions of “repair/upgrade” as moot? Where did the $20M go? Was it ever used? Was more money needed and who made the determination of how much was enough? These are legitimate questions that need to be asked.
Rather than lament over how this tragedy could have been prevented (and it could have been prevented if the observatory’s benefactors were determined to do so), let’s focus on what it has accomplished over the intervening 57 years since its commissioning and look forward to new possibilities as expressed here:
Here is the view of The Arecibo Observatory. A sad day for science, for Puerto Rico, and for the entire world. We will not rest until we #RebuildAreciboObservatory. Now we will fight faster and stronger. We can’t lose our Observatory forever. @SaveTheAO @NAICobservatory pic.twitter.com/AvCPO2bmbm
— Wilbert Andrés Ruperto (@ruperto1023) December 1, 2020
For starters
- The observatory was instrumental in the Exploration of Black Holes begun by this Year’s Nobel Prize Winners in Physics.
- Completed in 1963 and stewarded by U.S. National Science Foundation since the 1970s, Arecibo Observatory has contributed to many important scientific discoveries, including the demonstration of gravitational waves from a binary pulsar, the first discovery of an extrasolar planet, composition of the ionosphere, and the characterization of the properties and orbits of a number of potentially hazardous asteroids.
- The only Radar Equipped (planetary radar system) instrument in its class, allowing for detailed [radar] studies of the surfaces of Mercury, Venus, Titan, the mapping in real time of various asteroids of recent note as well as other solar system objects. Along with other accomplishments, details of all these studies can be found at the observatory’s web portal here.
Arecibo observed near-Earth asteroid (505657) 2014 SR339 using its planetary radar system on February 9, 2018. Radar images reveal 2014 SR339 to have a lumpy, elongated shape at least 1.5 km long and a rotation consistent with the 8.7 hour period determined from optical lightcurves (B.D. Warner).
4. Arecibo and Cassini collaborate to resolve a bright radar reflection anomaly on Saturn’s large moon Titan.
5. Arecibo was a member node in the VLBI (Very Large Baseline Interferometer)
6. Extensive observations and studies of PULSARS conducted at Arecibo.
7. Arecibo Observatory Helps Test Einstein’s Theory of Relativity for Heavy Objects
8. To celebrate and commemorate the first of these upgrades, a 450 Kw (kilowatt) signal was beamed at a frequency of 2.4 Ghz towards the core of the great globular star cluster M-13 in Hercules, 25,000 Light years distant on 16 November 1974. The message contained basic information about humanity, our biology, our location in the galaxy and our home planet. The transmission, with a duration of 3 minutes, was meant more as a demonstration of human technical prowess rather than a real attempt to begin a conversation with extraterrestrials.
The “Legacy Discoveries” page lists many notable items with a few of the more noteworthy below:
- Arecibo discovered two extremely strange pulsars
- VLBI observations of quasar 3C273 revealed a brightness temperature greater than 1013 K.
- Arecibo discovered the first ever repeating Fast Radio Burst (FRB).
The Physics Involved
We’ve received inquiries as to why the support system experienced a general failure “all at once”.
Regarding the general failure of the transceiver superstructure support cables falling all at once and why one of the support masts also failed and why didn’t the remaining 2 masts sustain the falling transceiver?
The support masts were never designed to support the falling transceiver and once that began, a whole new set of dynamics came into play.
To suspend the structure is one thing but to stop it once it begins falling is a whole new problem. Newton’s second law informs us that the force required to stop it, once in motion, is not the same as suspending it above the dish; this force would be tremendous. Once it started to fall, the other cables, already compromised, would quickly fail, bringing with them the section of one of the masts and thus, we have the tragedy witnessed. This is why “they all seemed to fail at once“.
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