Iconic Puerto Rico telescope to be dismantled

[Notebook]

Iconic Puerto Rico telescope to be dismantled amid collapse fears - BBC News

 

[jedidia]

Well, that sucks!

 

[Notebook]

Yes, big shame. Big structure though, a lot of money for maintenance, especially in that climate.

 

[BenSisko]

Tragic! What effect will that have on the quality of radio astronomy and astronomical research?

 

[kuddel]

Sad news.
I understand however that is would be irresponsible to let people work on it to fix it, when there is a high degree of uncertainty regarding their safety.
I still hope that some alternative idea for a fix could be made...like robotic removal of the underlying "dish-plates", so that the gondola can be lowered without the thread of injuring people...

 

[DaveS]

Sad news.
I understand however that is would be irresponsible to let people work on it to fix it, when there is a high degree of uncertainty regarding their safety.
I still hope that some alternative idea for a fix could be made...like robotic removal of the underlying "dish-plates", so that the gondola can be lowered without the thread of injuring people...

The problem is isn't the dome-shaped reflector, but the big suspended Instrument Platform hanging above it. It weighs 900 tonnes and is suspended by a set of cables attached to three towers. The problem is that two of the main cables have broken from one of the towers and they're not sure how long the remaining main cables can hold on to the IP. Having workers with tools and equipment moving across the IP could upset things to the point of remaining cable failure which would lead to the IP coming crashing down at a high speed injuring/killing alot of workers. The reflector itself is in fine condition.

 

[kuddel]

@DaveS : I know.
My thought was: Lowering the IP controlled from the side-posts can be managed without endangering workers - I think.
But removing the dish-plates below the IP beforehand with people poses the thread of a falling 900 tonnes object.
Again, this is just one idea I had - possibly not the best

 

[Notebook]

How do they get 900 tons on the Instrument Platform?

 

[Urwumpe]

How do they get 900 tons on the Instrument Platform?

The whole platform is lots of good steel and heavy machinery suspended on heavy cables, which also carry old wave guides (that had not been used for many years). For example, it also has to carry a counterweight structure to compensate for the mass of the gregorian dome, that can be moved along rails.

 

[Linguofreak]

One question in my mind is, if the remaining cables on that tower fail, what will actually happen? The IP will be off center from the other two towers, so it won't drop straight down. How far from the center of the dish can we expect it to hit? When it hits, it will almost certainly make a hole in the dish at impact, but will its weight be enough to widen the hole and slide downhill towards the center?

 

[GLS]

One question in my mind is, if the remaining cables on that tower fail, what will actually happen? The IP will be off center from the other two towers, so it won't drop straight down. How far from the center of the dish can we expect it to hit? When it hits, it will almost certainly make a hole in the dish at impact, but will its weight be enough to widen the hole and slide downhill towards the center?

Probably cascade failure of the remaining cables. The order of cable failure (and speed of the whole event) would determine where the platform hits, but I'd say it would be towards the 2 "good" towers.
The dish looks quite "light", so the platform should "crash-thru" without sliding, like the failed cables did.
I think the big issue is: what will the snapped cables do? Their "range of impact" is probably much larger than the platform and they can move much faster than a free-falling object, as seen in this video containing colourfull language:

Spoiler

 

[Notebook]

Australian scientists map millions of galaxies with new telescope - BBC News

Australian scientists say they have mapped a million new galaxies using an advanced telescope in the desert.
The CSIRO, the national science agency, said its new telescope had created "a new atlas of the universe" in record time - showing unprecedented detail.

 

[DaveS]

The Instrument Platform just fell down according to this tweet:

https://twitter.com/i/web/status/1333741751069192195

 

[DaveS]

Follow-up tweet with comparison photo that shows the IP still in place:

https://twitter.com/i/web/status/1333747356605571072

 

[jedidia]

 

[Thunder Chicken]

I am so glad I was able to see it in person in 2017.

It seems that it was structurally weaker than expected and so repairs of the damage last month would not be possible. This collapse may make remaining decommissioning work safer and more feasible.

It survived 57 years in the tropics and gave us a lot of great science.

 

[GLS]

https://twitter.com/i/web/status/1333806230125604867

 

[GLS]

More aerial images https://www.noticel.com/galeria/202...ivas-del-colapso-del-observatorio-de-arecibo/

 

[Urwumpe]

Ok, the Instrument Platform came further than I expected... what a huge tension in those cables, thankfully nobody was injured by that energy.

 

[kuddel]

Scott Manley on this: