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Author Topic: Arecibo Observatory dish suffers serious damage (failed suspension cable)  (Read 2863 times)

WLJ

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Re: Arecibo Observatory dish suffers serious damage (failed suspension cable)
« Reply #25 on: November 21, 2020, 12:18:41 PM »

We don't need no stinking radio telescope when all science is settled. That land is much more valuable as a wind or solar panel farm
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zxcvbob

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Re: Arecibo Observatory dish suffers serious damage (failed suspension cable)
« Reply #26 on: November 21, 2020, 04:48:00 PM »

I'm wondering if what they mean is, that's the total tension required on the cables or something like that.

When one refers to a tightrope walker, that rope has to be really, really tight.

  
 

I've forgotten how to do the calculations (high school, ~1955), but I know that even a small weight on a "tight" "rope" will deflect the rope substantially no matter how "tight" the rope is.

So it seems to me that large number (900 tons) might refer to the suspension cable tensions rather than the weight of the module.

Hawkmoon, what do  you think?

Terry, 230RN

Pic credits in properties.  The tightrope walker may not be an actual image.



You are correct, it doesn't take much weight to deflect the cable.  But that doesn't mean the cable tension increased all that much.  I used to know how to figure that...  (Disclaimer: I made a D in that class in college)
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ConstitutionCowboy

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Re: Arecibo Observatory dish suffers serious damage (failed suspension cable)
« Reply #27 on: November 21, 2020, 04:59:48 PM »

Eh. I don't get all the fuss. What's a hundred foot hole to a mile wide dish?   :old:

Woody

WLJ

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Re: Arecibo Observatory dish suffers serious damage (failed suspension cable)
« Reply #28 on: November 21, 2020, 05:02:11 PM »

Eh. I don't get all the fuss. What's a hundred foot hole to a mile wide dish?   :old:

Woody


It's pretty much falling apart and considered unsafe to attempt repairs

Worlds Largest Radar Astronomy Dish To Be Demolished!
https://www.youtube.com/watch?v=IEe4Wlc5Vp0
Never Underestimate The Power Of The Stupid Side

230RN

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Re: Arecibo Observatory dish suffers serious damage (failed suspension cable)
« Reply #29 on: November 21, 2020, 05:43:03 PM »

Woody, you're right about the size of the hole.  After all, they originally set it up as a spherical mirror and could correct for spherical aberrations by positioning the pod, so by comparison, it's sort of like a dust mote on your camera lens.

The problem (as I see it) is the fact that a cable broke and re-suspending the pod is beyond reasonable feasibility.

And looking at the suspension system in the aerial view, calculating those multiple cables would be a nightmare, and no wonder they were looking for the original calculations and specs for that.

(I would liken it to the complexities of calculating a three-element compound lens.  Any change of any element's refractive index, gapping between lenses, or a bit of curvature change and you've got to start all over.)

While the actual number-crunching could be done by computin' engines nowadays, it sounds like nobody knows how they set up the parameters any more.

And I guess most of the valuable results have already been obtained, so it ain't worth it.

That's my take on it anyhow.

Terry
« Last Edit: November 21, 2020, 06:05:05 PM by 230RN »

zxcvbob

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Re: Arecibo Observatory dish suffers serious damage (failed suspension cable)
« Reply #30 on: November 21, 2020, 05:52:25 PM »

Woody, you're right about the size of the hole.  After all, they originally set it up as a spherical mirror and could correct for spherical aberrations by positioning the pod, so by comparison, it's sort of like a dust mote on your camera lens.

Tje peoblem (as I see it) is the fact that a cable broke and re-suspending the pod is beyond reasonable feasibility.

And looking at the suspension system in the aerial view, calculating those multiple cables would be a nightmare, and no wonder they were looking for the original calculations and specs for that.

While the actual number-crunching could be done by computin' engines nowadays, it sounds like nobody knows how to set up the parameters any more.

And I guess most of the valuable results have already been obtained, so it ain't worth it.

That's my take on it anyhow.

Terry

Even tho' I made a D in that class 40 years ago, I could probably figure it out.  Sad! ;)  Whether it's worth fixing is an interesting question.
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ConstitutionCowboy

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Re: Arecibo Observatory dish suffers serious damage (failed suspension cable)
« Reply #31 on: November 21, 2020, 08:33:27 PM »

Woody, you're right about the size of the hole.  After all, they originally set it up as a spherical mirror and could correct for spherical aberrations by positioning the pod, so by comparison, it's sort of like a dust mote on your camera lens.

The problem (as I see it) is the fact that a cable broke and re-suspending the pod is beyond reasonable feasibility.

And looking at the suspension system in the aerial view, calculating those multiple cables would be a nightmare, and no wonder they were looking for the original calculations and specs for that.

(I would liken it to the complexities of calculating a three-element compound lens.  Any change of any element's refractive index, gapping between lenses, or a bit of curvature change and you've got to start all over.)

While the actual number-crunching could be done by computin' engines nowadays, it sounds like nobody knows how they set up the parameters any more.

And I guess most of the valuable results have already been obtained, so it ain't worth it.

That's my take on it anyhow.

Terry

Yeah, I get that too.

This reminds me of the miscalculated shape of the mirror on the Hubble Telescope that rendered it nearly unusable. I'm glad they were able to surmount it, though. It has contributed much to our knowledge just like Arecibo. With the advancements in drones and calculating prowess, maybe a little more can be squeezed out of Arecibo sort of like how they can send out a laser beam from the giant optical telescopes and calculate and flex the mirror(s) to compensate for atmospheric aberrations.

On an anecdotal note, I hope they used better cables on the Golden Gate Bridge ...

Woody

230RN

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Re: Arecibo Observatory dish suffers serious damage (failed suspension cable)
« Reply #32 on: November 21, 2020, 09:25:00 PM »

Well, things age just sitting there.  And they had a couple of goodly hurricanes over the decades.  I guess you can design for a hurricane, but I don't know how you design for N hurricanes.

I wonder, too, about the day-to-day economy of the surrounding area now that it will be closed down.  Maybe a tourist attraction?  But how many touristas might actually be interested in seeing it now.

Plug  up the drains and fill it as a swimming hole?

Terry, 230RN

ConstitutionCowboy

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Re: Arecibo Observatory dish suffers serious damage (failed suspension cable)
« Reply #33 on: November 21, 2020, 09:46:42 PM »

Well, things age just sitting there.  And they had a couple of goodly hurricanes over the decades.  I guess you can design for a hurricane, but I don't know how you design for N hurricanes.

I wonder, too, about the day-to-day economy of the surrounding area now that it will be closed down.  Maybe a tourist attraction?  But how many touristas might actually be interested in seeing it now.

Plug  up the drains and fill it as a swimming hole?

Terry, 230RN

Put it up for sale. Someone will buy it.

Woody

TommyGunn

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Re: Arecibo Observatory dish suffers serious damage (failed suspension cable)
« Reply #34 on: November 21, 2020, 10:58:47 PM »

Put it up for sale. Someone will buy it.

Woody

If you tack on the Brooklyn Bridge as a free add-on it will sell faster .....  [tinfoil] [popcorn]    .........  =D
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kgbsquirrel

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Re: Arecibo Observatory dish suffers serious damage (failed suspension cable)
« Reply #35 on: November 22, 2020, 02:26:19 AM »

It's pretty much falling apart and considered unsafe to attempt repairs

Worlds Largest Radar Astronomy Dish To Be Demolished!
https://www.youtube.com/watch?v=IEe4Wlc5Vp0

And supersized dishes have been supplanted by distributed arrays.  The big dish in question is also more limited in its field of view than a comparable array telescope.
« Last Edit: November 22, 2020, 03:30:47 AM by kgbsquirrel »

K Frame

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Re: Arecibo Observatory dish suffers serious damage (failed suspension cable)
« Reply #36 on: November 22, 2020, 09:00:05 AM »

OK, looks like I was wrong... They really do focus that thing in...
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Brad Johnson

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Re: Arecibo Observatory dish suffers serious damage (UPDATE: It's gone)
« Reply #37 on: December 01, 2020, 02:22:42 PM »

Gravity saved them the expense of demolition. Catastrophic cable failure early this morning. The mighty Arecibo dish is gone.





https://www.sciencemag.org/news/2020/12/arecibo-telescope-collapses-ending-57-year-run

https://www.youtube.com/watch?v=vchDbyIRP44


Double-unfortunate is the failure appears to have destroyed the cable decks on all three suspension towers, ending any hope of using the towers for future re-instrumentation.

Brad
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TommyGunn

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Re: Arecibo Observatory dish suffers serious damage (failed suspension cable)
« Reply #38 on: December 01, 2020, 02:25:08 PM »

If they patch the holes they might be able to get a swimming pool out of it .....  [tinfoil]  [popcorn]
MOLON LABE   "Through ignorance of what is good and what is bad, the life of men is greatly perplexed." ~~ Cicero

Jim147

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Re: Arecibo Observatory dish suffers serious damage (failed suspension cable)
« Reply #39 on: December 01, 2020, 03:06:47 PM »

Wonder if it still gets the playboy channel
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kgbsquirrel

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Re: Arecibo Observatory dish suffers serious damage (failed suspension cable)
« Reply #40 on: December 01, 2020, 03:10:21 PM »

Nature always wins in the end.

WLJ

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Re: Arecibo Observatory dish suffers serious damage (failed suspension cable)
« Reply #41 on: December 01, 2020, 03:15:15 PM »

Has anyone blamed Orange Man yet?
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K Frame

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Re: Arecibo Observatory dish suffers serious damage (failed suspension cable)
« Reply #42 on: December 01, 2020, 03:23:43 PM »

Rub some dirt on it. It will be fine.
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HankB

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Re: Arecibo Observatory dish suffers serious damage (failed suspension cable)
« Reply #43 on: December 01, 2020, 03:47:32 PM »

. . . I would liken it to the complexities of calculating a three-element compound lens.  Any change of any element's refractive index, gapping between lenses, or a bit of curvature change and you've got to start all over. . . .
Lenses like the Cooke Triplet (patented in 1893) are today considered simple - almost trivial. Whereas the old timers had to be really clever and rely on things like log tables and mechanical calculators, the programs that run on today's desktop computers allow a skillful optical engineer to move FAR beyond triplet lenses, and include things like aspheric surfaces, holographic optical elements, and gradient index materials.
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230RN

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Re: Arecibo Observatory dish suffers serious damage (failed suspension cable)
« Reply #44 on: December 01, 2020, 05:47:01 PM »

Well, things age just sitting there.  And they had a couple of goodly hurricanes over the decades.  I guess you can design for a hurricane, but I don't know how you design for N hurricanes.

I wonder, too, about the day-to-day economy of the surrounding area now that it will be closed down.  Maybe a tourist attraction?  But how many touristas might actually be interested in seeing it now.

Plug  up the drains and fill it as a swimming hole?

Terry, 230RN

Another skip-poster:

If they patch the holes they might be able to get a swimming pool out of it .....  [tinfoil]  [popcorn]

It's OK, I do that myself sometimes.  Just amusing to find I'm not the only one.

« Last Edit: December 01, 2020, 06:21:22 PM by 230RN »

Ben

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Re: Arecibo Observatory dish suffers serious damage (failed suspension cable)
« Reply #45 on: December 01, 2020, 05:53:10 PM »

If they put a liner over it, that would be an awesome spot for a giant swimming pool.
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230RN

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Re: Arecibo Observatory dish suffers serious damage (failed suspension cable)
« Reply #46 on: December 01, 2020, 06:03:22 PM »

If they put a liner over it, that would be an awesome spot for a giant swimming pool.

Holy cow, Ben.  Anyone else want to extend the swimming hole concept?

Lenses like the Cooke Triplet (patented in 1893) are today considered simple - almost trivial. Whereas the old timers had to be really clever and rely on things like log tables and mechanical calculators, the programs that run on today's desktop computers allow a skillful optical engineer to move FAR beyond triplet lenses, and include things like aspheric surfaces, holographic optical elements, and gradient index materials.

Oh, I'm pretty much aware of that.  But having a machine programmed to do the number-crunching does not change the complexities involved.  It's like saying the Roman Aqueduct or the Coliseum was easy to build because you had slaves to carry all that masonry up and down.

Somebody still had to work out the VLI + IV = L versus VLI + V = LI stuff in the first place.

Terrigula, CCXXX RN
« Last Edit: December 04, 2020, 01:13:02 PM by 230RN »

TommyGunn

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Re: Arecibo Observatory dish suffers serious damage (failed suspension cable)
« Reply #47 on: December 01, 2020, 07:56:24 PM »

If they put a liner over it, that would be an awesome spot for a giant swimming pool.

Yeah, liner!  It would definantly require that!!!    =D  I love you guys!  :lol:
MOLON LABE   "Through ignorance of what is good and what is bad, the life of men is greatly perplexed." ~~ Cicero

230RN

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Re: Arecibo Observatory dish suffers serious damage (failed suspension cable)
« Reply #48 on: December 01, 2020, 09:51:32 PM »

Could rhey stock it with bass?  The locals could make money renting bass boats and bass equipment for bass fishing contests.  Or would the water be too warm?

            

The trouble with making it a pool is there'd be no shallow end.  It's all deep end unless they put in artificial beaches.  You could lose a lot of little kids that way.

 
Pic credit in properties

ConstitutionCowboy

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Re: Arecibo Observatory dish suffers serious damage (failed suspension cable)
« Reply #49 on: December 02, 2020, 10:16:47 AM »

Could rhey stock it with bass?  The locals could make money renting bass boats and bass equipment for bass fishing contests.  Or would the water be too warm?

            

The trouble with making it a pool is there'd be no shallow end.  It's all deep end unless they put in artificial beaches.  You could lose a lot of little kids that way.

 
Pic credit in properties


I think stock it with mermaids for all us redneck "anglers".

Woody
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