Friday, November 20, 2020

A Very Sad Day For Radio Astronomy

 The Arecibo Radio telescope is being shut down.


Not just shut down, but decommissioned and dismantled.

The installation had suffered damage from the hurricanes and tropical storms, causing one of the feeds (the 70cm "Line Feed") to break loose, fall, and damaging about 30 out of the 38,000 aluminum panels used for the reflecting surface.

Then in August, one of the suspension cables broke, causing a 100' long gash to the reflector. Then in early November, a second cable snapped, causing much more extensive damage.



So rather than spend the money to repair and upgrade the facility, they're going to tear it down.

This is just as sad as when the 300' Green Bank Telescope collapsed.



I suppose you could say these "Old Dinosaurs" of Science are obsolete, but Very Large Aperture Antennas are extremely useful devices at radio frequencies. Unless you're a Radio Geek, or you grew up watching the transition from analog to digital electronics, you might not "get it". Yes, with today's Digital Signal Processing techniques applied to Very Long Baseline Interferometry, you can use hundreds (or thousands) of smaller dish antennas, and combine them into one extremely large Synthetic Aperture. Yes, the numbers are astounding, but I can't help but wondering what we've given up to get these extraordinary sensitivities and resolutions. Car and Driver recently comparison tested the new Corvette with a new Porsche Cayman. The Corvette generated staggering numbers on the track and in testing, but the drivers said it felt cold and antiseptic doing it, like it had sold it's soul for performance, while the Porsche seemed alive and worked with you so you both did your best. It's what I call "An Analog Thing", and I get it entirely. Maybe even grok it. That Porsche manged it pull it off in a car packed with more electronics than the Apollo Command Module is a very admirable thing.

Anyway.....it's too bad that it's being dismantled. It was a very useful instrument, and it will be missed.

14 comments:

  1. I read about the Arecibo debacle earlier today. Thanks for the pix and descriptions.

    I had forgotten about the Green Bank collapse. Both are tragic incidents.

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    1. Green Bank was a structural failure of a key gusset plate in one of the main box-girder beams. Possibly they made it a bit too light in construction?

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    1. The National Science Foundation was in charge of the Green Bank facility when the antenna collapsed in 1988.

      Arecibo was managed by Cornell (Carl Sagan's alma mater) from when it was built in 1963 until 2011 when it was transferred to a partnership led by SRI International. As of 2018 it was run by a consortium with the University of Central Florida, but still funded by a division of the NSF. The NSF has been whacking the budget back steadily since 2006, and I'm sure maintenance got back-burnered.

      Big metal structures in a tropical environment like that tend to need constant maintenance. It's not as bad as sea going equipment, but far, far worse than the environment here. Even in Long Beach and San Pedro we had constant maintenance battles with corrosion. Aluminum will eventually just go back to Mother Nature if it's not painted or oiled. All the humidity and salt in the air just makes things disappear after a few years.

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  3. Well, to be fair, between 1994 and 2000, and 2008 to 2016, much needed repairs didn't get done. And the middle section? Not much done as monies went to the GWOT. Arecebo's been looking shabby for a long time.

    Not to mention, for some strange reason, the Dems don't seem to want to actually fund actual science, as they would rather lavish our funds on pseudo-science (where they can also rake in the kickbacks.)

    And now only the Chinese have a large aperture radio telescope. Yay. Skippy. We trust them to share real science with the rest of the world? Um... nope.

    But, yeah, sad day for the world now. But if you don't maintain the structures (like bridges, telescopes, ships) eventually they will fail. And most likely kill people or dreams or both.

    But then again, I expect to see some serious telescopes being boosted once Starship Cargo comes online. It may be a minor setback before we go all space.

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    1. We still have the largest fully-steerable dish, but it's "only" 100m in diameter. Signals from ET gets lots of press, but if you don't keep corrosion at bay, you won't have an antenna.

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  4. Entropy. The recent election is a metaphor for the situation with very large aperture antennas.

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    1. Well at least they haven't shut down Fermilab and filled the tunnels with concrete...

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  5. As others have said, the VLAAs are literally a 'dying' breed. Old tech, no longer viable, supposedly... But they worked and worked well for many years. Sad to see them go.

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    1. These old arrays made many discoveries in their prime. Just too big to stick in a museum somewhere....

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  6. There's a hidden problem with Very Large Arrays of small telescopes. Spread out along a line, they only simulate a large aperture in the direction of the line of antennas. They can't simulate the perpendicular direction because there's no data. They make Y or Delta configurations, but you know physics is a bitch and won't let you get something for nothing. You have no idea what's going on where there are no antennas, so the data has holes in it.

    We assume that the wavefront is continuous and nothing is going on there, but you also know the most important things in science are the "that's funny" moments. The unexpected things that reveal more when you look deeper.

    I'm sure you heard the story of guys from KP4-land working moonbounce a few times with Arecibo when it was unused. I want to see that with a VLA.

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    1. Ah, yes, those "Gee, that's funny" moments. It's like when Mother Nature whispers one of her secrets to you, or does something that gets your attention. Sometimes the holes in the data are as interesting as what you first started looking for.

      Jansky started out by looking at the noise that was interfering with Trans Atlantic Radio Telephone calls on 14MHz. Who would have thought he'd discover an entirely new field of Astronomy?

      I remember reading in the 1960's in QST about the first moonbounce activities from there. Really inspired a young Ham back in Illinois to continue his career.

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  7. Years and years ago, one of my Electronics College professors knew someone that worked at Greenbank, and got us a field trip to spend a few days out there. We used one of the older scopes to poke the heavens and while not something exciting to do, loved the site, the tour, seeing their internal electronics shop for their in house component builds.

    It was an experience I wont forget.

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    1. The first big scientific research installation I ever went to was Fermilab in Northern Illinois. I went there for a job interview, and wound up hanging around for three years.

      While the size of the accelerator was most impressive, the Real Science took place several miles from where I worked, out on the "Beam Lines", where they used the high energy protons I helped deliver.

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Keep it civil, please....