The end of the line for the Arecibo radio telescope

[Homer J Simpson]

Tour of Arecibo from 2017.

[TerraHertz]

My son is in Puerto Rico atm, and sent this drone footage he took. Shows state of the cleanup at Arecibo.

https://youtu.be/N9U_i4ktPr8

Road tripping through Puerto Rico and realized we would be passing nearby here this morning. We couldn't get in to see it in person but luckily we had a drone with us...
Would've loved to be able to fly lower but we had to take off from pretty far away so would have lost signal.

[coppercone2]

giant pizza

[cdev]

Gorgeous solid video. Does he use GPS to control/take it? He must. How does that work? Could you share anything about his drone setup?

Such a beautiful area too. That must be beautiful. scenery there. .

[cdev]

Before the Arecibo site could be reused, there's a lot of work to be done scrapping the failed platform, and probably the reflector, though some of it may be salvageable.   However its all near-ground so wont require more than ordinary heavy plant to do so, and could be undertaken with local labor, which would obviously benefit the local community.

If a rebuild was funded internationally by a coalition of universities and other academic bodies its likely the funding would be more stable than if it relied on US government funding subject to short-term political pressures.

International procurement rules probably apply which puts local firms at a huge disadvantage. They would have to underbid firms from countries where workers are paid almost nothing. And they would probably underbid to get a job like that they they could use in their advertising.

[Ian.M]

International procurement rules probably apply which puts local firms at a huge disadvantage. They would have to underbid firms from countries where workers are paid almost nothing. And they would probably underbid to get a job like that they they could use in their advertising.

It would be very difficult for companies using 'slave wage' foreign workers to use them on a contract in Puerto Rico.  Its a US territory under US visa rules, and they'd need to get H-2B visa for all their 'grunts'.   A company can certainly bring in a core of specialists, but they'd have to recruit the 'grunts' locally or from the USA. 

[cdev]

The banks want the real estate. (in Puerto Rico) And so do the real estate speculators. The land in Puerto Rico is beautiful, too beautiful for it's poor people, thats how they think. If they lend money to poor people and they default, they get to foreclose on it all in most states here, the borrowers lose their entire investment. . This is the divine right of capital, that's how it works. the coronavirus is causing a lot of families to fall off the edge of the economic map.; And likely, windfall profits for banks, wealthy investors, and many others. Just yesterday I read the story of Poshawn Brown. It's heartbreaking. She probably had cryptic covid-19 and didnt know it. She worked for Amazon. At a large warehouse they have in Virginia. They had tasked her with giving COVID tests to other workers. She has no medical training at all but she knew it was a risky situation. But they didn't give her adequate PPE. She should have said no, but she had a daughter so she just did what they asked her to. They could not even afford an autopsy for her. She leaves an 8 year old daughter. 

Even there is a money and interest, whats the point ? The whole Puerto Rico island was destroyed by hurricane Maria 3 years ago is still abandoned by mainland federal government with no help what so ever, the basic and major infrastructure still heavily damaged, the money better use to help these poor people 1st, and a telescope has much lower priority.

Youre right. They created all kinds of rules that make it so banks cant be restrained. And extreme weather means natural disasters like hurricanes are becoming the norm.

Unless those Puerto Ricans are 2nd grade US citizen. Just read this carefully -> Reference Not being a state, they basically are left without adequate representation.Its not a good situation. Wages are significantly lower there.

Its like watching a poor African countries that is still struggling on basic need, but want to build rocket to send their astronaut to the moon. 

  Are you talking about India? There is a lot of hype revolving around AFrca and the coming years. Africa is supposed to be the big growth stoy of the coming decade. Lots of companies are hoping to invest lots there. Because of the low wages, and large families. Americans and Europeans are not having children. (We often can't afford to)

Self esteem will become a huge problem as jobs become hard to find. Especially for young people. So all the stuff like that is helpful with that. They cant afford the substantiative things they say. They will just make young people want a future they cant have. Still, science is good for our sanity. Science creates stable jobs that wont be outsourced. Its a good investment.

I agree, looking in from the outside, talking to relatives and friends in the US, the 'American dream' looks like a nightmare for an awful lot of people and it all stems from a basic lack of humanity in the belief that, to quote a fictional character, "greed, for lack of a better word, is good. Greed is right. Greed works. Greed clarifies, cuts through, and captures the essence of the evolutionary spirit."

 I don't think we Americans fall for that greed hype. nor do we worship at the altar of their so called  "invisible hand" .  We do understand the best wealth creator, the importance of quality and value. we know fluff when we see it.

[cdev]

As we agreed to let them bid, its part of the WTO, its quite likely we'll have to let them actually perform the work if they win.


This is the subject of a WTO dispute. Its estimated by Princeton economist Alan Blinder that 26% up to perhaps as many as half - yes half or more of the jobs in the US and the EU are outsourceable and may be outsourced within the coming years. The financial incentive is huge. Trillions of dollars a year. So I stand by my statement. I'm not saying that foreign firms have anything wrong with them. They want the work and they are having riots over the lack of jobs. SO there is no doubt that they need them. They have large numbers of workers with engineering training, more than the US. They speak excellent English. Also, we made a deal. We now have a debt in many kinds of jobs we must repay. If they bid the lowest, they get the jobs, its an entitlement. you bring up an important issue, wage parity. Do we have a right to demand that they pay wokers a legal US wage before they come here to work, typically for a period like six years. This dispuite is - the important issue has quite a history. Recently, the US government ruled that they must pay workers at least a legal US wage for the area whee they were supposed to work. which in this case was more than eight dollars an hour. USCIS ruled that paying a quality control engineer supposed to work in the Portland area the equivalent of around $6:50 an hour in a foreign currency was too little.   This is what globalization is all about, trade in services agreements. Its the main goal, vastly lowering wages and increasing profits internationally.

International procurement rules probably apply which puts local firms at a huge disadvantage. They would have to underbid firms from countries where workers are paid almost nothing. And they would probably underbid to get a job like that they they could use in their advertising.

It would be very difficult for companies using 'slave wage' foreign workers to use them on a contract in Puerto Rico.  Its a US territory under US visa rules, and they'd need to get H-2B visa for all their 'grunts'.   A company can certainly bring in a core of specialists, but they'd have to recruit the 'grunts' locally or from the USA.

Thats not how I feel at all. I think we should pay everybody a living wage. I don't agree with neoliberal dogma which doesnt accept the concept of a 'living wage' .

also indeed, the people they bring in have to have special knowledge, and they also have to prove that they tried to find local workers they typically do this by placing an ad online and having local workers interview for a job, even if they already have somebody in mind. I have placed these ads and had their purpose explained to me.

The use of workers from back home in their most expensive positions saves them millions, even billions of dollars. Otherwise it would be much less profitable working in the US, and of course thats the most important thing.

This all goes to show the near-futility of some kinds of regulation in the face of trade agreements. Such as minimum wage laws and laws on overtime and working conditions. When they become the subjects of trade agreements they are toast.

[nctnico]

Compared to space missions rebuilding the dish would be relatively cheap. The tricky part could be more  like getting the funding for the ongoing costs, so we don't get the next collapse by 2050. A chance would be if NASA decides to forgets about maned space missions - lots of money to set free.

Late reaction but from some indirect interactions with the radio atronomy community I understand that they are no longer into building really big dishes but are going to link up many smaller dishes. The advantage is that this also allows to be able to pinpoint from where signals are coming from.

[james_s]

Gorgeous solid video. Does he use GPS to control/take it? He must. How does that work? Could you share anything about his drone setup?

Such a beautiful area too. That must be beautiful. scenery there. .

There's a huge amount of information out there about multirotor UAVs. This stuff is widespread and complete ready to fly "drones" capable of this sort of video footage have been available off the shelf for close to a decade if not more. You can walk into any hobby store and buy one for a few hundred bucks. 

[coppercone2]

Compared to space missions rebuilding the dish would be relatively cheap. The tricky part could be more  like getting the funding for the ongoing costs, so we don't get the next collapse by 2050. A chance would be if NASA decides to forgets about maned space missions - lots of money to set free.

Late reaction but from some indirect interactions with the radio atronomy community I understand that they are no longer into building really big dishes but are going to link up many smaller dishes. The advantage is that this also allows to be able to pinpoint from where signals are coming from.

I think you will have a lower bandwidth though. But the minimum they measured is 300MHz which is only 1 meter, so this is fine. But if I recall, they had low frequency transmitters on there. 5MHz. The VLA can do 90MHz.

The 300 meter dish is 22 dB at 5MHz.

If you have a bunch of small dishes how does the math work out with that? Not sure if its identical.

[David Hess]

Late reaction but from some indirect interactions with the radio atronomy community I understand that they are no longer into building really big dishes but are going to link up many smaller dishes. The advantage is that this also allows to be able to pinpoint from where signals are coming from.

The huge amounts of cheap digital processing available now allow aperture synthesis unlike back when Arecibo was built.  Integration makes individual transceivers inexpensive.

[fourfathom]

A single large dish will have a lower noise floor than an array of smaller dishes.  This is because a small dish has lower gain before the preamp.  In an array, each dish/preamp sends the amplified signal to a delay/combiner stage where the Synthetic Aperture beam steering is done.  Assuming similar amplifier noise figures, the higher-gain antenna will have better sensitivity.  But a very large array can create a smaller beam angle than a practical big dish, reducing the cosmic background noise and other off-angle pickup.  The large arrays have significant operational performance advantages, just not for very weak signal work.

This reminds me of a discussion I had regarding radar reflectors (used on boats), and how they compare to optical reflectors (mirrors).  An X-band radar runs around 10 GHz.  My 12" diameter octahedral radar corner reflector compares (in wavelengths) to an optical light mirror about 2.5 miles x 2.5 miles.  There's probably some analogy here to the angular resolution of radio astronomy antennas vs optical telescopes.

[edit: I got these backwards.  My 12" radar reflector is wavelength-equivalent to an optical mirror 0.000188" in dia.  Or, taking my 2x3" emergency signaling mirror and scaling up to radar wavelengths would give a radar reflector 2 miles x 3 miles. ]

[CatalinaWOW]

A single large dish will have a lower noise floor than an array of smaller dishes.  This is because a small dish has lower gain before the preamp.  In an array, each dish/preamp sends the amplified signal to a delay/combiner stage where the Synthetic Aperture beam steering is done.  Assuming similar amplifier noise figures, the higher-gain antenna will have better sensitivity.  But a very large array can create a smaller beam angle than a practical big dish, reducing the cosmic background noise and other off-angle pickup.  The large arrays have significant operational performance advantages, just not for very weak signal work.

This reminds me of a discussion I had regarding radar reflectors (used on boats), and how they compare to optical reflectors (mirrors).  An X-band radar runs around 10 GHz.  My 12" diameter octahedral radar corner reflector compares (in wavelengths) to an optical light mirror about 2.5 miles x 2.5 miles.  There's probably some analogy here to the angular resolution of radio astronomy antennas vs optical telescopes.

I think you got your optical/radar comparison backwards.  A 12 inch optical reflector is roughly the same number of waves across as a 2.5 mile radar reflector.  Or said another way the two reflectors would have comparable beam patterns.

[fourfathom]

I think you got your optical/radar comparison backwards.  A 12 inch optical reflector is roughly the same number of waves across as a 2.5 mile radar reflector.  Or said another way the two reflectors would have comparable beam patterns.

Yes, thanks for catching that.  I was grabbing quotes from a previous conversation and got things scrambled.  Speaking of scrambled, I realized my error while I was eating breakfast, and rushed back here to discover that you had already found it.  (I hoped I could sneak in and fix it before anybody noticed!)

[MathWizard]

Anyone remember the early X-files episode where they went to Arecibo ?

[coppercone2]

is reflector effiency and everything constant when dish size decreases?

I.e. 5MHz is 60 meters, the dish is 300 meters, so it is large in comparison to the wavelength.

If your dish is too small for the wavelength what happens? But what is the deal with that telescope, it transmits on 5Mhz but only picks up a minimum of 300MHz?

[CatalinaWOW]

is reflector effiency and everything constant when dish size decreases?

I.e. 5MHz is 60 meters, the dish is 300 meters, so it is large in comparison to the wavelength.

If your dish is too small for the wavelength what happens? But what is the deal with that telescope, it transmits on 5Mhz but only picks up a minimum of 300MHz?

There is no simple answer for these questions.   Reflector efficiency (a term that needs some definition if you want to get down to details) tends to drop as reflector size gets small wrt wavelength.  Small also requires some definition.  For a visible optics person a reflector that is only five wavelengths across is extremely tiny.  But at 60 meters it is actually huge.  The simplest way I know to think of it is this.  The beam reflected from a parabolic dish goes to a point in the ideal case.  Reflectors hundreds or thousands of wavelengths across approach this ideal, with the differences from ideal often being dominated by imperfections in the geometry of the reflector (remember the Hubble kefluffle).   As reflector to wavelength ratio drops the reflected wave is diffracted and departs significantly from the ideal case, even if the reflector has perfect geometry.  Soon that point from the ideal case becomes a blob approaching the size of the reflector.  You start to have to trade collecting the reflected energy against blocking incoming energy from getting to the reflector.

I suspect you have mis-interpreted some of the publicity sheets.  I am sure the active radar function of Arecibo sent and received at the same frequencies.  Perhaps as low as 5 MHz, but it seems likely to me that higher frequencies were used, if for no other reason than to penetrate the Heaviside layers.  Arecibo was also operated as a passive receiver for radio astronomy.  No reason for that function not to have different operating bands than the active radar.