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Wed Dec 2, 2020, 08:54 AM

Tell me my idea is stupid...

Arecibo Observatory collapse and the pics gave me an idea, once the dish is repaired could the
instrument platform be a drone or a series of drones?

Modern drones can precisely hold their position and are used to measure antenna radiation patterns.
They can also carry heavy payloads but modern telescopes are mostly measuring electromagnetic waves.
Modern electronics are far superior and lighter than 57 years ago when Arecibo was built.
All results can be transmitted to the observatory by streaming over wifi.

Could this work? Could the dish itself be made up of an array of drones that could change shape to focus?




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Arrow 19 replies Author Time Post
Reply Tell me my idea is stupid... (Original post)
5X Dec 2020 OP
DonaldsRump Dec 2020 #1
5X Dec 2020 #2
DonaldsRump Dec 2020 #14
Galileo126 Dec 2020 #3
5X Dec 2020 #5
2naSalit Dec 2020 #4
eppur_se_muova Dec 2020 #6
5X Dec 2020 #8
eppur_se_muova Dec 2020 #10
5X Dec 2020 #11
eppur_se_muova Dec 2020 #16
5X Dec 2020 #17
William Seger Dec 2020 #7
5X Dec 2020 #9
William Seger Dec 2020 #13
Midnightwalk Dec 2020 #12
PoindexterOglethorpe Dec 2020 #15
Warpy Dec 2020 #18
NNadir Dec 2020 #19


Response to DonaldsRump (Reply #1)

Wed Dec 2, 2020, 09:12 AM

2. With my last idea, dish itself made up of drones and reflectors,

it could be anywhere and at any height that the drones could fly.

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Response to 5X (Reply #2)

Wed Dec 2, 2020, 12:13 PM

14. It isn't a stupid idea at all

It's using creativity to try to fix something that is heartbreakingly broken.

I'm not sure it would work since you'd have to have so many drones and a way to continuously power them and making sure that the power source didn't interfere with the signals to and from the reflectors. Then again, I am thankfully not a physicist or engineer! So, don't take my word for it.

Nonetheless, it's good to try to come up with something to save this. This is an international/interstellar tragedy.

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Response to 5X (Original post)

Wed Dec 2, 2020, 09:14 AM

3. ...and the NSF has given up funding before the collapse

So, they pulled the plug. Got a few 10's of millions for repairs? Not me...

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Response to Galileo126 (Reply #3)

Wed Dec 2, 2020, 09:19 AM

5. I sent the idea in a tweet to them,

I have done my part for the world.

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Response to 5X (Original post)

Wed Dec 2, 2020, 09:16 AM

4. Sound like interesting ideas...

I hope that some kind of facility will be constructed there as it is a prime spot for the type of data collection they do. There will be a gap in research until something is created to replace it.

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Response to 5X (Original post)

Wed Dec 2, 2020, 10:11 AM

6. Hmmm ... electric motor in drone ? RFI ? Maybe not. nt

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Response to eppur_se_muova (Reply #6)

Wed Dec 2, 2020, 10:23 AM

8. They are used now to evaluate existing antenna radiation patterns.

RFI can be shielded.

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Response to 5X (Reply #8)

Wed Dec 2, 2020, 10:42 AM

10. Below 10**-32 Watts?

That's the best (only -- *sigh*) figure I've been able to find re Arecibo's sensitivity.

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Response to eppur_se_muova (Reply #10)

Wed Dec 2, 2020, 10:48 AM

11. If you don't mind, could you share where you read that?

I would like to read up more.

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Response to 5X (Reply #11)

Wed Dec 2, 2020, 02:19 PM

16. 'Fraid there's not more to read -- this is from a PowerPoint for a college course in Astronomy ...

The largest radio transmitter/receiver on Earth is the 300m diameter Arecibo radio telescope. {no longer true}
The strongest signal it can produce is around 107W.
Arecibo can detect a signal of this strength, produced using a similar antenna, up to 1000 Ly away.
This corresponds to a signal strength at Earth of 10-32W.


http://www.astro.uvic.ca/~jwillis/teaching/astr201/astr201.lecture11.pdf (scroll to p.14)

the author: http://www.astro.uvic.ca/~jwillis/

You'd think the question "how sensitive is the Arecibo receiver" would get a simple answer, but this is the best Google could come up with. News stories about the collapse swamp any search w/the term Arecibo. Similar searches for just radio astronomy signals reveal a reluctance to print actual numbers. The best alternative I could come up with is the estimate that the entire Earth receives about 1 picowatt total radio energy from outer space. Honestly, what numbers I'm seeing are even smaller than I expected.

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Response to eppur_se_muova (Reply #16)

Wed Dec 2, 2020, 02:47 PM

17. You would think would such a sensitive reciever it would pick up earth signals only.

Thanks for the link. I was finding the same kind of non-results googling.

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Response to 5X (Original post)

Wed Dec 2, 2020, 10:16 AM

7. Yeah, I get ideas like that after a good bong hit, too

But upon further reflection, I prefer to call them "impractical" rather than stupid. If the new receiver is light enough to be carried by a drone, it wouldn't take much to hang it from new cables, which would be far less maintenance and much more reliable.

Anyway, drones do drift a bit since they depend on GPS, and i don't think they could hold position well enough to do what you propose. Civilian GPS these days (which typically also uses Russian GLONASS satellites) is only accurate to about 2 meters, and military GPS is probably accurate to about a foot. Commercial drones have infrared sensors that can measure altitude accurately when they're near the ground, but at higher altitudes they depend on barometric pressure sensors, so they can drift in altitude, too.

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Response to William Seger (Reply #7)

Wed Dec 2, 2020, 10:31 AM

9. Drones are used now to fix position of radio telescopes by being the fake reference star used to

steer the scope. There must be ways to correct for this drift electronically.

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Response to 5X (Reply #9)

Wed Dec 2, 2020, 11:22 AM

13. I don't know if that system is operational yet, but...

I've read a paper that proposed several ways to know how much a drone is drifting and compensating for that while guiding a telescope, but that isn't the same as being able to make it hold a position accurately.

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Response to William Seger (Reply #7)

Wed Dec 2, 2020, 10:49 AM

12. Track the drone distance from a central spot on ground

Could you correct for the drift doing that? I would think you could track to a central receiver on the ground very accurately.

I know nothing about what it takes to make multiple small attenae work as well as a single large one. I think thatís what youíd have to understand to be able to tell if it works.

The other problem could be how long would they have to hover? How long would do exposures have to be? I know military drones can fly for hours, but they are large and expensive. How cheap do these need to be and can they hover long enough? Would wireless power transmission work for this type thing so you donít need dangling wires? That would allow the drones to be further apart.

If the tracking idea above worked, I guess the drones could be a kilometer or more apart, each tethered to a ground mini station.

Probably all bs on my side, but fun to speculate. As you said, donít worry about dumb ideas. Exploring them sometimes teaches you something. Once in a while they actually work.

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Response to 5X (Original post)

Wed Dec 2, 2020, 01:56 PM

15. Actually, there are more telescopes in space

than most people realize, and many of them were up by other countries.

The radio stuff Arecibo did is easily taken up by the many other radio telescopes around the world, according to My Son The Astronomer. Arecibo did also do radar stuff, of which there is only one other telescope, in California, doing that stuff. There are three or four others around the world that also do that.

Often a telescope remains trained on the same spot in the sky for several hours to make its observations. Not sure if drones could do that as well and as accurately.

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Response to 5X (Original post)

Wed Dec 2, 2020, 05:57 PM

18. It won't be repaired, it will have to be rebuilt

The dish itself was badly damaged when the cables snapped, and most likely the other cables are in bad shape, too. Collapse was inevitable.

The problem with using drones is the constant back and forth radio signaling that would be needed to keep them in position and that would likely mask some signals a new dish would need to collect.

What new construction will have to include is a way of removing and replacing cables every few years if it is to be located at Arecibo, as years of wind driven salt water was likely a big factor in damaging the cables.

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Response to 5X (Original post)

Wed Dec 2, 2020, 11:23 PM

19. The inherent drift of drones would almost certainly make doppler shift measurements useless. n/t.

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