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Drone Footage of Arecibo Observatory Collapse

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Re: Drone Footage of Arecibo Observatory Collapse

#31

Post by Someone »

_verandaguy wrote: post #16
spenczar5 wrote: post #15

Earlier quoted context omitted.

I work at UW astronomy. It’s mostly symbolic. The main capability loss is that Arecibo was able to transmit, which is unique at its size. As an example, that was useful to rescue the ISEE-3 explorer when it passed through a comet trail in the 1980s. Only Arecibo was powerful enough to blast a radio message through the comet trail. (PDF reference: https://ipnpr.jpl.nasa.gov/progress_report/42-84/84T.PDF ) Arecibo was…

Asking as a non-astronomer: my understanding is that other telescopes in this class are synthetic/multiple aperture, and not single-aperture like Arecibo (with a small number of exceptions, like FAST). Is there any science you can do on extremely-large single-aperture telescopes that you can't do on comparable synthetic/multiple aperture telescopes?

For those interested: FAST has a diameter of 500m, compared to 300m for Arecibo (https://en.wikipedia.org/wiki/Five-hundred-meter_Aperture_Sp...)

There’s also https://en.wikipedia.org/wiki/RATAN-600, with a diameter of 575m, but that isn’t a fully filled dish.

Re: Drone Footage of Arecibo Observatory Collapse

#32

Post by soneil »

bob1029 wrote: post #12
lgrebe wrote: post #6

Why were they filming? As in why was the drone in place and looking at a close-up of the cable?

This is quite the coincidence. The drone operator seemed prepared for exactly what was coming.

There's probably a lot more warning than the video makes it look like. For example, the cables flaking significant chunks of paint could be a clue that the cable's changing geometry.

It seems fairly logical that it was being inspected precisely because this was anticipated. It's not like it was a surprise, it's exactly why they said they couldn't put manpower on it.

Re: Drone Footage of Arecibo Observatory Collapse

#33

Post by dylan604 »

blhack wrote: post #17

Is there any chance at all that this gets rebuilt? Is anybody even putting the costs requirements together to do it, or is this just a total loss? This is so unbelievably sad to see. It reminds me of seeing Notre Dame burning last year.

I think it has 2 chances: Slim and none, but slim just left town.

Then again, it could have a snowball's chance in hell.

However, those all imply a > 0% chance which I honestly believe to be way too high.

Re: Drone Footage of Arecibo Observatory Collapse

#37

Post by blake8086 »

ilamont wrote: post #30

The instrument platform was listed at 900 tons. The maximum takeoff weight of a Boeing 787 is just over 500,000 pounds, or 250 tons ... is it fair to say the instrument platform was the equivalent of three fully loaded 787s, plus two M1A1 tanks piled on for good measure? That's a lot of weight for those cables to support.

I always think it's funny when people use large planes as a reference for heavy weights, since they're designed to be as light as possible for the volume.

Re: Drone Footage of Arecibo Observatory Collapse

#38

Post by dylan604 »

NikolaeVarius wrote: post #18

I wonder whats going on with the cable when it fails. It seems to be snapping/frays at first, but then it seems like it was pulled out of its base

There is a lot LOT LOT of tension on these cables. So if something seemingly small snaps, then the strength of the rest of the cable is compromised. Each of the strands in the cable is rated for a specific amount of weight/tension. I'm sure there was some tolerance/over-engineering in the amount the cables could support, but as the individual strands started to pop, it was only a matter of time.

>seems like it was pulled out of its base

That's pretty much what happened. All of that weight on the cable pulled it away from its support structure on that tower. Gravity did the rest.

Re: Drone Footage of Arecibo Observatory Collapse

#39

Post by waiseristy »

blake8086 wrote: post #37
ilamont wrote: post #30

The instrument platform was listed at 900 tons. The maximum takeoff weight of a Boeing 787 is just over 500,000 pounds, or 250 tons ... is it fair to say the instrument platform was the equivalent of three fully loaded 787s, plus two M1A1 tanks piled on for good measure? That's a lot of weight for those cables to support.

I always think it's funny when people use large planes as a reference for heavy weights, since they're designed to be as light as possible for the volume.

Probably best to compare Arecibo to a suspension bridge instead

Re: Drone Footage of Arecibo Observatory Collapse

#40

Post by dylan604 »

dvtrn wrote: post #10
lgrebe wrote: post #6

Why were they filming? As in why was the drone in place and looking at a close-up of the cable?

To aid in future investigations of the structural failures I would imagine? As I understand it from reading various news reports and a video from one Scott Manley, the damage from the recent earthquake had this collapse in the “when” column not “if”.

Just squeezing one last bit of science out of the place. Sure, it's not the science it was designed to for, but science none-the-less
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