RIP Arecibo

[gmax137]

https://www.theverge.com/2020/11/19...-decommission-structural-collapse-cable-break


The world-famous Arecibo Observatory in Puerto Rico, known for helping scientists peer into deep space and listen for distant radio waves, is set to be decommissioned and demolished after engineers concluded that the facility’s structure is at risk of a collapse. While teams will try to salvage some parts of the observatory, the decommission will bring an end to the popular 57-year-old telescope, which has been featured in numerous films and television shows.

The decision comes after two major cables failed at the facility within the last few months, causing significant damage to the observatory.

 

[russ_watters]

Wow, that sucks -- I'm glad I got to see it during a visit a couple of years ago.

 

[gmax137]

I wanted to go last time I was in PR, maybe 5 years ago, but it was closed for ongoing construction / repair work

 

[mcastillo356]

Very bad news, but relieving from my point of view, after watching the photo. I truly believe that we will manage to build another one.

 

[DaveE]

It is sad, but most scientific instruments have a limited useful life. Of course if it was in good shape it would still be useful. However, I don't think rebuilding it would be the best use of astronomy dollars.

 

[hutchphd]

The story I remember hearing at Cornell was that the origin of the dish was Air Force money to look at the ionosphere to support long range bomber operations (this was all hear say, you understand). Along the way they seemed to have overdesigned it some and with the switch to ICBMs left Cornell with a big dish that maybe could be converted to Astronomy! How fortunate!
If anyone can document the history with actual authority I would love to know the reference.
" Golly we have this big dish pointing at the sky...what will we do now?"
So we should probably celebrate its relative longevity and cost effectiveness. RIP

 

[nsaspook]

https://www.naic.edu/history_gal/historicgal.html

courtesy of the NAIC - Arecibo Observatory, a facility of the NSF

 

[mfb]

Edit: Missed that there was a thread in a different forum. This was a stand-alone post initially.

In August a support cable got loose. While engineers were still discussing how to fix it another cable broke earlier this month. There is no way to repair this without putting people on site in danger, and there is no money to largely rebuild it, so NSF decided to decommission the Arecibo telescope.
For a long time Arecibo was the largest single-dish telescope in the world, and it was by far the largest one for radar astronomy. FAST is larger but it's unclear when/if it can start doing radar astronomy. But even beyond its unique capabilities: It helped with the chronic overbooking of large radio telescopes, which will get worse now.

News articles: Nature, SpaceNews

 

[Wrichik Basu]

Sad news, 2020 claims another victim. From the photo, it seems to me that there was a lack of maintenance. There are structures in the world that are far older than this telescope, but are in good condition due to proper maintenance.

 

[nsaspook]

Sad news, 2020 claims another victim. From the photo, it seems to me that there was a lack of maintenance. There are structures in the world that are far older than this telescope, but are in good condition due to proper maintenance.

Location, location, location. Being exposed to hot humid tropical conditions with earthquakes and hurricanes in the mix takes a toll.

Mother Nature limited its lifetime IMO, not a maintenance crew.
https://www.universetoday.com/10928...gency-repairs-after-earthquake-causes-damage/

The Arecibo Observatory’s 305 meter (1,000 ft) radio telescope is undergoing emergency repair after being damaged during a 6.4 magnitude earthquake on January 13, 2014. A large cable that supports the telescope’s receiver platform had “serious damage,” according to Bob Kerr, the Director of the Arecibo Observatory.

“A protocol structural survey following the January 13 earthquake revealed serious damage to [a] short cable section, with apparent breach of several cable strands,” Kerr told Universe Today via email. “An experienced structural engineering firm was brought to assess the damage, and to consider repair options.”

https://www.space.com/arecibo-observatory-puerto-rico-earthquake.html

The earthquake swarm arrived just as Arecibo Observatory was preparing to embark on a year full of repairs to damage caused by Hurricane Maria, which battered Puerto Rico in 2017. The observatory has been conducting science work in the wake of the storm, but the new data has not been of the same quality as that gathered before the hurricane.

 

[jasonRF]

The story I remember hearing at Cornell was that the origin of the dish was Air Force money to look at the ionosphere to support long range bomber operations (this was all hear say, you understand). Along the way they seemed to have overdesigned it some and with the switch to ICBMs left Cornell with a big dish that maybe could be converted to Astronomy! How fortunate!
If anyone can document the history with actual authority I would love to know the reference.
" Golly we have this big dish pointing at the sky...what will we do now?"
So we should probably celebrate its relative longevity and cost effectiveness. RIP

Not quite. It was designed for incoherent scatter measurements of the ionosphere. However, the theory wasn’t developed yet so it was oversized for that task. Basically, they assumed the scattering would be from individual electrons, but in reality the scattering is from thermal fluctuations of plasma waves. Anyway, the extra capability did make it more useful for astronomy, and my understanding is that it was used more for astronomy than ionospheric research.

here is an article with some of the history
https://authors.library.caltech.edu/17042/

and here is a tribute to William Gordon, the driving force behind it:
https://www.nature.com/articles/464502a

jason

 

[hutchphd]

Thanks for the references. Really a good read. I think it is pretty clear from the article that there was a group at Cornell who managed to get AARPA to buy them a big toy. This is in the best spirit of American ingenuity and I cast no aspersions: there was good and useful information provided to the cold war efforts...and so much more. Perhaps the useful overestimates of the size required were unwitting at the outset...clearly less so at the end.
One of the great bargains in our scientific history. I wish these detailed machinations were better known because it makes the endeavor all the more interesting.

 

[DaveC426913]

So sad. Glad I had the chance to visit it in '90. Kind of a retroactive Bucket List item.

 

[gmax137]

https://weather.com/news/news/2020-12-01-arecibo-observatory-radio-telescope-collapses

The renowned Arecibo Observatory radio telescope in Puerto Rico, closed because of damage, completely collapsed Tuesday morning.

"Friends, it is with deep regret to inform you that the Arecibo Observatory platform has just collapsed," tweeted Deborah Martorell, a senior meteorologist for WAPA-TV and El Nuevo Dia in San Juan, Puerto Rico.

Martorell, who was at the observatory on Monday, received a call from a scientist at the site Tuesday saying the giant reflector dish and the Gregorian Dome that held instruments above it had both collapsed, El Nuevo Dia reported...

 

[russ_watters]

Also:

Ramon Lugo, director of the Florida Space Institute at the University of Central Florida, which manages the 57-year-old radio telescope for the National Science Foundation (NSF)...

He believes it was because of a failure of one of the remaining cables connecting the platform to one of three support towers. These cables were carrying extra stress following the two previous failures. And since the Thanksgiving holiday, Lugo says, wires were breaking in these remaining cables at a rate of about one a day. He says he told NSF the structure only had a week or two remaining before it would collapse.

 

[nsaspook]

 

[nsaspook]

Better times.

 

[mfb]

Here is a video of the collapse

Extra drone video

 

[Wrichik Basu]

Here is a video of the collapse

Extra drone video

Did they anticipate the collapse and hence put up the drone?

 

[mfb]

Yes. It looks like coincidence that the drone was in the air just as the last cables snapped, but the collapse in the very near future (days) was expected and they wanted to monitor the cables.

 

[nsaspook]

Yes. It looks like coincidence that the drone was in the air just as the last cables snapped, but the collapse in the very near future (days) was expected and they wanted to monitor the cables.

Unfortunately it failed exactly like expected. To get an idea of the forces balanced with the cables notice that all three towers also snapped near the top from unbalanced loads before the deck actually hit bottom.

The towers are in compression tension with balanced forces from the wire anchors to the weight of each leg of the lifted deck. When one of the three sides snap, the anchor forces snap that tower backward. The deck would swing down pulling the tops of the other two towers off as the deck crashes offset to that side..

 

[BillTre]

The drone was being used to inspect cables when they broke.
It than panned to a larger view of things.
Nice reaction by the drone operator.

This looks to be the same video as @mfb linked to.