Arecibo observatory to be demolished

[JIMMY_the_DOG]

Oh no! This is terrible!

[AlamoVampire]

Perhaps a new and better one can be built in a better location. Arecibo will be gone, never forgotten.

 

220411232020

[kerbiloid]

Destroyed by the SETI message recoil.

[RCgothic]

Arecibo just collapsed completely.

 

 

 

[cubinator]

 

[adsii1970]

Sure, it may be the ending of an era since Arecibo Observatory collapsed. But consider this - it was over 50 years old and there are numerous articles where decommissioning it was already being discussed. There have been other facilities which have similarly collapsed - and some without warning. Before Arecibo, the most recent one was Green Bank Observatory in West Virginia in November of 1988. It was replaced and the replacement went into operation in 2003.

Will Arecibo be replaced? There's already discussion about replacing it with another observatory. The question is actually will the replacement be built on that particular site or somewhere new.

[RealKerbal3x]

15 minutes ago, adsii1970 said:

Will Arecibo be replaced? There's already discussion about replacing it with another observatory. The question is actually will the replacement be built on that particular site or somewhere new.

They should build Arecibo 2.0 on the far side of the Moon.

[Shpaget]

Perhaps it's for the best that it collapsed, since controlled demolition would have been dangerous. At least now it's much safer to clean up.

[Clamp-o-Tron]

It's pretty bad. RIP Arecibo.

Before:

After:

Edited December 1, 2020 by Clamp-o-Tron

[RCgothic]

4 hours ago, RealKerbal3x said:

They should build Arecibo 2.0 on the far side of the Moon.

It requires megawatts of power for the radar function. Supplying that on the moon would be challenging.

I hope they rebuild it on the same site.

[GluttonyReaper]

3 hours ago, Shpaget said:

Perhaps it's for the best that it collapsed, since controlled demolition would have been dangerous. At least now it's much safer to clean up.

Really? I would've assumed it was the other way around - unless it does totally collapse in the near future, I'd think it'd make it more dangerous, given further collapse could happen at any moment.

[RyanRising]

38 minutes ago, GluttonyReaper said:

Really? I would've assumed it was the other way around - unless it does totally collapse in the near future, I'd think it'd make it more dangerous, given further collapse could happen at any moment.

I think this is the total collapse. There's nothing left to come crashing down - I guess some parts of the dish could fall a couple meters? The towers don't have the load of the platform anymore, so I don't think there's any risk of them falling.

[Shpaget]

Yeah, it was the instruments pod thing that was freakishly massive (900 tons) and the cables that were in tension, ready to snap and cut in half whatever and whoever happens to be in the way that were the dangerous bits. All of that is now safely at the bottom of the valley. Sure there are probably some bits of the dish itself that are damaged and still may be dangerous, but that is a problem much easier to solve. The pylons that were holding the instruments platform are no longer stressed and can probably be demolished with standard demolishing procedures.

In any case, the loss of the instrument is sad enough, I'm just glad there were no injuries on top of it.

Edited December 2, 2020 by Shpaget

[AHHans]

9 hours ago, Shpaget said:

In any case, the loss of the instrument is sad enough, I'm just glad there were no injuries on top of it.

That!

Still sad though!

[Gargamel]

14 hours ago, RCgothic said:

It requires megawatts of power for the radar function.

That's the rub here.   There was no other radar telescope that came close to it's power.  Even the bigger one in China, FAST, is far less powerful when it comes to radar astronomy.  While there are better radio telescopes out there, nothing else really came close in radar astronomy. 

[Scotius]

It is a sad day indeed. For decades Arecibo Observatory was a defining image presenting astronomy to the masses. It was iconic enough to filter into pop-culture as a setting for multiple movies and games.

And now it's gone.

Only time can tell if there is will and funding to rebuild it. Bigger, better and again bleeding edge of technology.

[wumpus]

19 hours ago, GluttonyReaper said:

Really? I would've assumed it was the other way around - unless it does totally collapse in the near future, I'd think it'd make it more dangerous, given further collapse could happen at any moment.

Somebody would have to climb each tower and place pyrotechnics at each cable for a controlled demolition, all the while one could snap and whip around in arbitrary directions.  Assuming nobody was around, this is far better.  After the second cable snapped, any possibility of repair became extremely difficult (and apparently futile, as you'd be unlikely to get it sufficiently supported before today).  Scott Manley has a video (of course.  And probably one for today as well).

[YNM]

21 hours ago, Gargamel said:

 Even the bigger one in China, FAST, is far less powerful when it comes to radar astronomy.

FAST cannot transmit anything at all. It can't do active radar imagery the way Arecibo was able to.

On 12/1/2020 at 10:01 PM, adsii1970 said:

But consider this - it was over 50 years old and there are numerous articles where decommissioning it was already being discussed. There have been other facilities which have similarly collapsed - and some without warning. Before Arecibo, the most recent one was Green Bank Observatory in West Virginia in November of 1988. It was replaced and the replacement went into operation in 2003.

Honestly, as someone who's studying civil engineering, the fact that important scientific instruments can be in terrible condition while in full swing of operation is alarming... You don't want schools to collapse around the world, and while scientific instruments don't really possess much of a danger when collapsing unlike a school (schools are also often used as refuge in times of disaster), there must've been considerable amount of funds that could've been saved otherwise if it didn't fail in such a sudden manner.

Although, yeah, 50 years is a long enough time (it is the standard timescale we expect buildings to last when designing them), but I'm more puzzled that no-one seems to be wanting to close it once it nears 50 years of age in a controlled manner, at least we could've powered down and removed the important instruments and everything out before the structure goes to waste.

Edited December 3, 2020 by YNM

[kerbiloid]

17 hours ago, wumpus said:

Somebody would have to climb each tower and place pyrotechnics at each cable for a controlled demolition, all the while one could snap and whip around in arbitrary directions.

Or attach three cables bound to the trusses to a rotating drum in the center and pull them inside...

Spoiler

...and release.

***

Anyway, now the earthlings need a new emitting radiotelescope to let the interplanetary rockets with semi-active guidance system aim the approaching fleet of interstellar invaders.

Edited December 3, 2020 by kerbiloid

[tater]

 

[GuessingEveryDay]

Oof.

[Elthy]

There is also video from the cable as it snaps. At least we got two fine videos of this destruction, something positive. Would be a real shame if noone filmed this.

[YNM]

7 hours ago, Elthy said:

At least we got two fine videos of this destruction, something positive. Would be a real shame if noone filmed this.

I'm quite surprised on the cables. Thought there'd be a sheath much like bridge cables but it's all unsheathed bar some paint...

Well, one to add to the "what happens if you don't inspect closely during lifetime" list.

Though, for an interesting look at how the towers fail : you might notice that the tower where the cables had been failing first were toppled outwards while the rest toppled inwards. This is in line with the temporal increase in stress - on the place where it first collapsed, the outer cables now have nothing to hold onto other than bending the towers out, while on the other two now they suddenly have to tow in the massive platform structure by itself. Towers seems not really designed to handle much bending, given the stepped cross-section. Cables be cables, they do fail catastrophically in tension, once thinning (and necking) has set in there's not much else to do given constant loading.

 

EDIT : Seen this news release from the NSF, dated from Nov 19, 2020.
What interests me more was the attached recommendation of actions from the Engineer of Record, dated Nov 12, 2020.

To be short : They knew it was hopeless after the second cable breakage, none of the safety factors calculated for remediation actions were even above the original limit set in during construction in the 60s (let alone the SF set during upgrade in the 90s), even using the predicted (not observed) strength. The most damning part however was the fact that no one knew how deteriorated it has actually really become... which is the sad part to me, more than the eventual collapse.

The only course of action recommended was immediate demolition... and we kind of get it.

Edited December 4, 2020 by YNM

[sevenperforce]

R.I.P.

[RCgothic]

I almost suspect that a thorough appraisal of the site's condition might have caused it to be condemned even before the first cable failed.

Replacing all the degraded parts would have been a major undertaking, and if the safety factors aren't there for the work then that's the end right there, even before thinking of things like budget.