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Comment by doctat | Hacker News Reader

The logical thing to do here is to simply rebuild it, right?

I mean all the infrastructure is there. Power, networking, housing, staff, etc., etc. Like there couldn’t ever be a more convenient place to drop a similar type of instrument, right?

And it seems that the towers are still up, surely the anchors for the cables are no worse for wear. The actual dish itself looks to be composed of a bunch of panels that are probably designed for easy replacement. And most of them seem to still be intact.

Just string up a newer, lighter weight, more powerful state of the art instrument array on a newer, stronger, lighter set of cables.

Or am I missing something obvious?

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There is no money for this. The National Science Foundation, the primary source of funding for Arecibo, has been trying to shut it down or offset its cost for years. NSF is a part of the US government, so it has been a victim of the cuts to public science that have affected universities and institutions across the US since the end of the Cold War and the Great Recession. You are right that it would be simple, but there was nobody willing to fund it until it was too late.

That is the real tragedy here, Arecibo was killed over the course of years.

>NSF victim of cuts to public science

Why is this completely erroneous fact believed by so many people? Other than a 1 time injection due to the 2008 crisis, NSF funding increases nearly every year and is currently at its second highest budget ever: https://dellweb.bfa.nsf.gov/NSFRqstAppropHist/NSFRequestsand...

Counterpoint: https://www.nsf.gov/about/budget/fy2019/pdf/40b_fy2019.pdf

In FY2019 NSF reduced its budget for Arecibo from $8M to $6.08M a 24% reduction in support for this instrument.

It's both true that the NSF a whole is getting an increased budget and that the NSF reduced its budget for this particular instrument.

Yes, but the GP comment was saying the NSF's budget was growing (which is also true) but the GGP's comment that NSF was reducing support for Arecibo is also correct. So for context I thought it might add a bit more depth to the question of "whether or not NSF was funding Arecibo or trying to get rid of it / defund it" idea.

And personally I was surprised that for $8M a year you could fund the program (presumably that was with a bunch of clearly needed maintenance being deferred). It really is too bad that some billionaire didn't just fund it. I'm wondering if Paul Allen helped out when he was alive.

Thank you for the correction. I had been following the news about Arecibo mostly and had not investigated NSF's total funding.

The NSF budget increased dramatically between 1951-2008 -- but when accounting for inflation in the figures you linked, has declined by about 10% in real terms since then.

(That is, the 2010 NSF budget of $7.045 B in 2010 is in real terms equivalent to about $8.413 B today, about a billion dollars more than the real 2020 budget of $7.066 B, using the inflation calculator at [1].)

[1] https://www.in2013dollars.com

The linked budget summary says it is in "Millions of Current Dollars". I interpret that to mean it is already inflation adjusted.

That is what I would have interpreted that to mean as well, but the numbers in the far right column don't really appear to be inflation-adjusted relative to the actual primary sources.

Here, for instance, is the actual appropriations bill for 1998 [1]. As you can see,

> "There are authorized to be appropriated to the Foundation $3,505,630,000 for fiscal year 1998."

For comparison, the value in the aforementioned table for FY1998 is $3,430.63 M. This is a bit off, presumably because in contrast to the bill the values in the table are " after supplemental appropriations, transfers, and reprogrammings".

I had missed, though, that the appropriations for the last two years were actually higher than the request, so some signs of recent growth.

[1] https://www.congress.gov/bill/105th-congress/house-bill/1273...

There is a footnote that specifically mentions some additional funding to repair Hurricane damage to what sounds like Arecibo.

Most radio astronomers would rather see the money spent on the SKA instead (https://en.wikipedia.org/wiki/Square_Kilometre_Array). Looking at the epoch of reionization is where the excitement is in low frequency radio astronomy these days. I know the SKA can't replace Arecibo's radar capabilities, but the SKA will do more interesting astronomy.

The U.S. is NOT one of the governments supporting the SKA.

Maybe now we can be?

It still absolutely blows my mind that Arecibo was able to be used as an active radar to survey planets and other objects in the solar system.

Well, one reason why it may not be worth bothering is because of the existence of FAST.

https://en.wikipedia.org/wiki/Five-hundred-meter_Aperture_Sp...

It's bigger, more steerable, and better in (almost) every way, although one could imagine reasons why its location in China could be problematic.

FAST cannot do radar astronomy, as it has no transmitting capability. Among other things, this means FAST is less useful for tracking near-earth asteroids.

I assume that due to the rotation of the earth that when Arecibo emits a radar beam that other radio-telescopes on earth collect? Otherwise only objects within Arecibo’s relatively narrow FoV (that are also very close to earth) would be detected - so wouldn’t a purpose-built (and steerable!) radar emitter be more useful?

Arecibo was steerable, that's what the receiver array was for.

Sort of, 5 degrees isn’t exactly a lot.

Nope, it transmitted and received. The range was limited to about Jupiter because the dish would move over the effective horizon before the signals returned.

Pretty incredible!

Unfortunately the skewed motivations of academia make rebuilding this instrument less attractive to scientists.

If you build a new and very different instrument you can churn out a lot of papers picking the long hanging fruit on the new instrument (just whatever you discover as soon as you turn it on), you can churn out a lot of papers about the technical challenges that come up in a new and different instrument.

A well understood, well established instrument type is more valuable for verifying results and discovering the things that take decades of consistent observations. ... but these don't generate many publications.

Last time I check it is the problem to have those old things there.

Like you I initially think just a repair job. Big one no though. But it seems those remaining could harm anyone who do the repair. It was not designed with only one less cable. And hence those remained can cut anytime and anywhere. The whole area could be a danger Zone.

Seems you need to demolish the whole site if the discussion along this line is true.

See whether any better information. But I guess the reason why the maintenance is not there to prevent it is also the reason it cannot be rebuilt.

I think the question is: is an arecibo big dish observatory still a better choice for future goals than arrays of smaller dishes or maybe even some other technology?

It was about to be demolished anyway: https://www.npr.org/2020/11/19/936677582/world-renowned-arec...

Large portions of the towers fell. Large portions of the dish are destroyed. And if you're going to effectively build over again, you might as well build a bigger one.

Topography is a major determinant of the size.

Of course. And that is part of my point: Arecibo may not be the most sensible thing to rebuild if it's not salvageable and larger antennas exist.

It was built in a natural sinkhole, and maybe this is what happens to sinkholes?

I've read a number of publications covering Arecibo. I've not read anywhere that subsidence or any other sinkhole related activity hastened it's demise.

This seems to have been much more a problem of ~60yo hardware, suffering decades of insufficient maintenance funding, compounded by multiple tropical events and at least one earthquake.

That's fair. Thanks for sharing.

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