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Drone Footage of Arecibo Observatory Collapse

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Re: Drone Footage of Arecibo Observatory Collapse

#51

Post by giantrobot »

_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?

Answering as a non-astronomer: Arecibo had two major advantages over synthetic aperture arrays. The first was the "seeing" power or total sensitivity. Because it's a large single dish it collects far more photons than multiple smaller dishes.

The receivers were also cooled with liquid helium IIRC so the noise floor was ridiculously low. Those features combined made for not just high resolution but high sensitivity observations. Most telescope arrays (to my understanding) have a higher noise floor.

The second feature was the ability to transmit. Arecibo has been used for decades as a radar to image asteroids and such. Many asteroids are too small and dark to effectively image with optical telescopes where Arecibo's radar is no problem. It also gets extremely accurate distance and rotation measurements.

Re: Drone Footage of Arecibo Observatory Collapse

#52

Post by petschge »

spenczar5 wrote: post #15
woeirua wrote: post #11

Is the loss of Arecibo a big blow to the scientific community? I was of the impression that Arecibo was long past it's heyday and in general that large arrays of smaller receivers were now considered superior.

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…

There was still way more requests for observing time and the total amount of time available in the last cycles. Also there is a lot of value to have long-term datasets that are recorded with the same instruments as it removes a lot of systematics. Nanograph is being badly bitten by that, as they use pulsar timing data over 10 or 12 years. (And were likely only 1 or 2 years away from results, which may now be delayed for several years if they have to switch to timing with another instrument.)

Re: Drone Footage of Arecibo Observatory Collapse

#53

Post by LeoPanthera »

Someone wrote: post #31
_verandaguy wrote: post #16

Earlier quoted context omitted.

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.

Though, as the linked article explains, you can’t use the entire 500m as a single aperture. You can only use 300m of it at a time, but you can “point” it in different directions by using different 300m windows.

Re: Drone Footage of Arecibo Observatory Collapse

#55

Post by yborg »

zaroth wrote: post #34
wyldfire wrote: post #2

The clip has two different vantage points, skip to the middle of the clip for the closeup where you can see the supports/guys snapping.

Seems like they knew exactly where it was going to fail.

And they must have known it was imminent, it seems unlikely they had a drone over it 24/7 given the available hover time.

Re: Drone Footage of Arecibo Observatory Collapse

#56

Post by luisjv »

yborg wrote: post #55
zaroth wrote: post #34

Earlier quoted context omitted.

Seems like they knew exactly where it was going to fail.

And they must have known it was imminent, it seems unlikely they had a drone over it 24/7 given the available hover time.

They were doing hourly inspections of the structure ever since the report came out a couple of weeks ago.

Re: Drone Footage of Arecibo Observatory Collapse

#57

Post by nuccy »

zaroth wrote: post #34
wyldfire wrote: post #2

The clip has two different vantage points, skip to the middle of the clip for the closeup where you can see the supports/guys snapping.

Seems like they knew exactly where it was going to fail.

Yes. The drone was accessing the tower where cable has snapped before, so other cables there were under highest load. The fact that drone was there in the "right" moment likely just a coincidence, probability of which was increased by the hourly inspections.

Re: Drone Footage of Arecibo Observatory Collapse

#59

Post by dylan604 »

IfOnlyYouKnew wrote: post #49
dylan604 wrote: post #41

So now, humans are going to be the intergalactic assholes of the universe who go and change their phone number without leaving a forwarding number. When our message sent from Arecibo is finally received, their response will go to a disconnected number. https://www.youtube.com/watch?v=2BVbyCZXc5s

"now" is doing a lot of work here... If I'm not mistaken, we have about a millennium or a hundred make arrangements.

the lack of interest in funding Arecibo at a level to even do maintenance to prevent this from happening suggests we won't bother within that millennium you are allowing.

Re: Drone Footage of Arecibo Observatory Collapse

#60

Post by jiofih »

lambda_obrien wrote: post #28
_verandaguy wrote: post #16

Earlier quoted context omitted.

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?

Arecibo was initially built to excite plasma balls in the atmosphere to study them, and was also used for other transmitter uses that required a super powerful transmitter, initially designed for that plasma use.

Built to “excite plasma balls” sounds like it would be creating plasma balls if it’s own. It was used as a scatter radar to study plasma in the upper atmosphere.
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