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Decommisioning of Arecibo Radio Telescope




 
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Author Topic: Decommisioning of Arecibo Radio Telescope  (Read 6962 times)
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W1RKW
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« Reply #25 on: December 04, 2020, 03:19:58 PM »

So that drone just happened to be in  the air during the collapse?  great pictures...the guy taking the pictures must have felt helpless to do anything..

I think they knew where the failure point would be and were monitoring it on a regular basis and just edited out any preceding footage. If not, if you look at the failure mode at the attachment points of the cables, at about 0:41 seconds and going forward, I think they knew something was up based on the first cable that snapped. The first cable, prior to snapping, was absent of paint and clean and shiny at that point in time.   Paint is blown off from additional tension or stretching. then on the first cable you can see when one strand snaps more paint comes off then it escalates from there. Then just before the time the other cables snapped they lose paint as well.

The suspension cables that suspend the 900ton platform would have to have precisely equal tension to maintain integrity. If one cable fails or tension drops considerably in one cable suddenly for whatever reason the other cables end up being over stressed.  Almost seems like the design did not have enough redundancy or headroom built in for such a situation.

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« Reply #26 on: December 05, 2020, 07:06:29 AM »

slow motion video
https://www.youtube.com/watch?v=59WQIRvezzI&feature=youtu.be
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Bob
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Sam KS2AM
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« Reply #27 on: July 26, 2021, 07:54:03 PM »

Really interesting detail on Arecibo and what happened.

https://www.youtube.com/watch?v=3oBCtTv6yOw
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« Reply #28 on: July 27, 2021, 09:58:17 AM »

It appears that there is work going on there now.
I saw a vid of scaffolding put up on a tower.

It may be that they are rebuilding it... dunno.

                    _-_-bear
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« Reply #29 on: July 28, 2021, 12:12:04 PM »

It appears that there is work going on there now.
I saw a vid of scaffolding put up on a tower.

It may be that they are rebuilding it... dunno.

                    _-_-bear


Here is an article from six days ago ;   Space.com says  it would cost $454 million to rebuild.  The US govt should peel this off from their $Trillion slush fund.

Personally, I would like to see it rebuilt, but with a different design.  Use the same dish but build a strapping center pillar to support the RF secondary dome in the middle.  That cables-supported method was so JS and mechanically a nightmare.   A free-standing tower/pillar in the center with the dome offset with full rotation in 2 axis' would do the job FB and get rid of all cables and side tower supports. The obstruction field filled with cable RF reflection artifacts would be eliminated too.  

T





https://www.space.com/arecibo-telescope-replacement-process-and-designs
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« Reply #30 on: July 29, 2021, 10:21:18 AM »

The RF dome was slidable in declination as well as a little in hour angle.  It depended on earth's rotation for primary hour angle.  Rotation of the RF dome receivers required for proper R.A. alignment in essentially an alt. / az. mount.

A central column may be just as shadowing and vibration at apex prone as the three dimensional, three point stressed cable array.   -( 3 point stressed catenary structure.)

Interesting that the larger Chinese copy uses six peripheral towers of same design instead of three.
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RICK  *W3RSW*
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« Reply #31 on: July 29, 2021, 10:52:26 AM »

Interferometer Radio telescopes of many smaller antennae spaced on tracks or time sequenced with far larger base lines have pretty much superseded single, large single dishes.  This is the biggest reason that  single dish antennae have lost funding.

The Chinese just have to have the latest/greatest even if the usefulness is limited, in this case to shear single antenna power illumination at a slight increase of resolution compared to the once world's largest.

The large, fully steerable single dish antenna in WVA ( a radio quiet zone, AM included  Grin ) is kept operable pretty much because it is fully steerable and not dependent on earth's rotation for R. A.   Even at that it's future is questionable.    Because of the recent orders of magnitude in time base with even relativity corrected precision, interferometer radio telescopes of planetary orbit Lagrange point distances are now feasible. 
 
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RICK  *W3RSW*
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« Reply #32 on: July 29, 2021, 12:37:56 PM »

Interferometer Radio telescopes of many smaller antennae spaced on tracks or time sequenced with far larger base lines have pretty much superseded single, large single dishes.  This is the biggest reason that  single dish antennae have lost funding.

The Chinese just have to have the latest/greatest even if the usefulness is limited, in this case to shear single antenna power illumination at a slight increase of resolution compared to the once world's largest.



Good points, Rick.

Maybe it's time to look ahead to newer technology instead of rebuilding in the 60's.   Get Elon Musk involved to orbit an array of interferometer radio dishes past Earth orbit, into solar orbit, synchronous to the Earth..  Lots of them spaced as far apart as possible.   Aside from maintenance problems, it would be the next logical step in greatly meaningful progress. But what a project in complexity!

T
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Use an "AM Courtesy Filter" to limit transmit audio bandwidth  +-4.5 KHz, +-6.0 KHz or +-8.0 KHz when needed. 

Nothing like a new homebrew rig. Come into the shack, flip on the switches and everything works perfectly.

And, nothing like an old dog.
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« Reply #33 on: July 29, 2021, 03:13:43 PM »

Yeah, I got a little stuffy there.
 Your right. Instead of sending up perfectly good Teslas, a better choice would’ve been at least one or two interferometer antennas.  Probably need another stage for synchronous orbit though.

Gotta admit though, that car had a gorgeous color scheme against the earth’s and starry background.
I think it was red and black two tone, but you know how memory is,
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RICK  *W3RSW*
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« Reply #34 on: July 29, 2021, 04:04:27 PM »

Teslas LOL That guy lost my ground vehicle biz when he reneged on accepting BTC for that electric pickup truck..
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« Reply #35 on: July 29, 2021, 05:51:39 PM »

NM already has a biggie, the VLA in Magdelena.

Giant dishes on Railroad tracks to allow focusing movement.

Run by the National Science Foundation, the tours are great.

73DG
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« Reply #36 on: August 01, 2021, 12:37:11 AM »

You may need a Facebook account to see the vid, don't know where else to find it.
Work going on there, now.

https://www.facebook.com/PuertoRicoWire/posts/4693721633990240
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