RIP Arecibo Radio Telescope

[lpetrich]

•  Arecibo Observatory
• Legendary Arecibo telescope will close forever — scientists are reeling
• 'A Magically Surreal Symbol of Human Ingenuity': Scientists Reflect on Arecibo’s Doomed Big Dish
• Arecibo observatory supporters ask White House to help save damaged radio telescope | Space

The Arecibo Observatory is a large radio telescope built into a natural sinkhole some 8 mi / 13 km south of the town of Arecibo, Puerto Rico, on the island's northern coast. It is a spherical dish about 1,000 ft / 305 m across, with an observation platform suspended above it with cables coming from three towers at the edge of the dish. The platform contains receivers and transmitters, the transmitters being used for radar astronomy.

Its designers originally wanted a paraboloidal dish, and while it would make a good focus, it would only be suitable for observations near the zenith, the local upward direction. Away from the zenith would make off-axis aberration or misfocusing. So they decided on a spherical dish. Though it has spherical aberration, it has the same aberration in all directions, and one can thus use it for observations well away from the zenith.

It was built in 1963, and it has been in operation ever since, until the disastrous events of recent months.

The Arecibo telescope has been involved in some big discoveries.

It was used to measure the rotation periods of Mercury and Venus with radar observations, showing that Mercury's sidereal or star-relative rotation period is 2/3 of its orbit period instead of its orbit period, as earlier believed. Equality of periods is common among the larger moons, including our planet's moon, and it seemed plausible for Mercury for a long time.

It was used to map Venus and some asteroids, also with radar observations.

It was used for observations of several pulsars, including the Hulse-Taylor binary pulsar.

But in recent years, disaster struck. It was damaged by Hurricane Maria in 2017, and also by earthquakes in 2019 and 2020.

On August 10, 2020, a support cable came loose from its socket on its support tower, and made a gash in the dish. The telescope's operators ordered a replacement, but before it arrived, a second cable broke in two on November 7, 2020, making more damage to the disk.

After considering the prospects for repairing the telescope, the National Science Foundation decided in November 19, 2020 to decommission it, doing a careful disassembly of it.

If the NSF goes ahead with that, then it may be possible to build a new one there, one that is much more hurricane-proof and earthquake-proof and corrosion-proof.

 

[Treedbear]

Since January 2020 there's been a bigger one named FAST in China. 1600 vs 1000 ft. diameter.

 

[Politesse]

Hardly surprising given its current condition, but the end of an era nonetheless. At a certain point, replacement is often cheaper than repair, especially as infrastructural technologies change. Realistically, scientific equipment and nostalgia can be awkward bedfellows, and potential sites for new telescopes can be a short list. Hope the construction of the new dish, if embarked upon, does not meet the same sort of political controversy as we saw at Mauna Kea.

 

[lpetrich]

Since January 2020 there's been a bigger one named FAST in China. 1600 vs 1000 ft. diameter.

A big problem with FAST: it does not seem capable of radar astronomy - its central platform can't hold the weight of a good transmitter, unlike Arecibo's.

 

[Rhea]

I hope they will rebuild this. It makes sense that rebuild at some point makes more sense than repair.

 

[Jokodo]

Since January 2020 there's been a bigger one named FAST in China. 1600 vs 1000 ft. diameter.

I'm pretty sure they don't measure it in feet in China.

 

[lpetrich]

FAST's diameter is 500 meters, Arecibo's is 300 meters.

 

[Treedbear]

Since January 2020 there's been a bigger one named FAST in China. 1600 vs 1000 ft. diameter.

I'm pretty sure they don't measure it in feet in China.

How many of us are in China?

 

[Jimmy Higgins]

FAST's diameter is 500 meters, Arecibo's is 300 meters.

FAST's is 500 meters and Arecibo's is 1000 feet. USA! USA! USA!!!!

 

[Jokodo]

Since January 2020 there's been a bigger one named FAST in China. 1600 vs 1000 ft. diameter.

I'm pretty sure they don't measure it in feet in China.

How many of us are in China?

Many of us are not in the US. When it comes to measuring stuff, China is not the weird kid who doesn't with the rest of the class, you are.

 

[Treedbear]

How many of us are in China?

Many of us are not in the US. When it comes to measuring stuff, China is not the weird kid who doesn't with the rest of the class, you are.

Your point is completely irrelevant to the OP. If you simply cannot tolerate inconsistencies in your world view I would be very pleased if you'd place me on your ignore list.

 

[Bomb#20]

How many of us are in China?

Many of us are not in the US. When it comes to measuring stuff, China is not the weird kid who doesn't with the rest of the class, you are.

 

[skepticalbip]

I kinda suspect Arecibo will be rebuilt. The thousand foot reflector part seems to still be intact. It is a hell of a reflector even though its diameter isn't as wide as the one Chinese Li diameter FAST or the 576 m of the RATAN-600 in Russia.

 

[Loren Pechtel]

How many of us are in China?

Many of us are not in the US. When it comes to measuring stuff, China is not the weird kid who doesn't with the rest of the class, you are.

And the scientific community generally goes metric even here.

 

[Jokodo]

How many of us are in China?

Many of us are not in the US. When it comes to measuring stuff, China is not the weird kid who doesn't with the rest of the class, you are.

Your point is completely irrelevant to the OP. If you simply cannot tolerate inconsistencies in your world view I would be very pleased if you'd place me on your ignore list.

If you can't tolerate nitpicks about things you consider irrelevant, or being made fun of for using a pre-18th-century system if measurements in the 21st century, maybe you shouldn't be posting on a forum full of nerds.

 

[Treedbear]

Your point is completely irrelevant to the OP. If you simply cannot tolerate inconsistencies in your world view I would be very pleased if you'd place me on your ignore list.

If you can't tolerate nitpicks about things you consider irrelevant, or being made fun of for using a pre-18th-century system if measurements in the 21st century, maybe you shouldn't be posting on a forum full of nerds.

I made my reply in a way that I thought most forum participants would comprehend most easily. Because that reflects an outdated system is not my fault and doesn't reflect my preference for how things are. I even provided a link to the reference I was citing that included both systems of measurement. You decided to make it a political issue by implying that I harbored some kind of bigotry towards China, which was self-evidently not the case. On the contrary, I was noting one of their advantages in the scientific field. When I suggested the reason for how I replied you attacked me with "China is not the weird kid who doesn't with the rest of the class, you are.", which is not even a proper sentence. But yeah, you then insulted me for the second time, and implied that it was proper for me to simply ignore other posters when they decide they have the right to put me in my place. As you please. I can do that. Easily.

 

[Angra Mainyu]

Since January 2020 there's been a bigger one named FAST in China. 1600 vs 1000 ft. diameter.

I'm pretty sure they don't measure it in feet in China.

But whether the telescope is 1600 feet in diameter (or approximately so) does not depend on what measure they generally use in China. For that matter, they do not generally speak in English, either, but that has no bearing on whether the telescope is 500 meters in diameter (or approximately so).

The point is: when we talk about China (or things in China, etc.), we do not have an obligation to speak Chinese, or to use the measure system used in China. It is okay to speak English (and it would be okay even if 95% of the world spoke Chinese as their only language), or to use another system (I use the metric system when it's up to me, by the way).

 

[Jokodo]

Your point is completely irrelevant to the OP. If you simply cannot tolerate inconsistencies in your world view I would be very pleased if you'd place me on your ignore list.

If you can't tolerate nitpicks about things you consider irrelevant, or being made fun of for using a pre-18th-century system if measurements in the 21st century, maybe you shouldn't be posting on a forum full of nerds.

I made my reply in a way that I thought most forum participants would comprehend most easily.

Think again. Most Americans (arguably all Americans who spend time on a "natural science" subsection of a nerd forum, given how the metric system is frequently used in technical/scientific contexts even in America) have a good idea of how long a metre is, while many non-Americans have to look up the length of a foot. So even if a majority of the people on this board are Americans (which may or may not be the case), the aggregate comprehension difficulty caused by using ft instead of m is almost certainly higher.

Because that reflects an outdated system is not my fault and doesn't reflect my preference for how things are.

I didn't suggest it was.

I even provided a link to the reference I was citing that included both systems of measurement. You decided to make it a political issue by implying that I harbored some kind of bigotry towards China, which was self-evidently not the case.

I implied no such thing. I merely ridiculed you for using a pre-18th century system of measurement only Americans are familiar with on an international board in the 21st century.

On the contrary, I was noting one of their advantages in the scientific field. When I suggested the reason for how I replied you attacked me with "China is not the weird kid who doesn't with the rest of the class, you are.", which is not even a proper sentence.

Pointing out that Americans, not the Chinese, are weird when it comes to measuring things is not an attack, its a factual statement.

But yeah, you then insulted me for the second time,

I didn't even insult you a first time, so it is logically impossible for me to have insulted you a second time.

and implied that it was proper for me to simply ignore other posters when they decide they have the right to put me in my place. As you please. I can do that. Easily.

Whatever floats your boat.

 

[Jokodo]

Since January 2020 there's been a bigger one named FAST in China. 1600 vs 1000 ft. diameter.

I'm pretty sure they don't measure it in feet in China.

But whether the telescope is 1600 feet in diameter (or approximately so) does not depend on what measure they generally use in China. For that matter, they do not generally speak in English, either, but that has no bearing on whether the telescope is 500 meters in diameter (or approximately so).

The point is: when we talk about China (or things in China, etc.), we do not have an obligation to speak Chinese, or to use the measure system used in China. It is okay to speak English (and it would be okay even if 95% of the world spoke Chinese as their only language), or to use another system (I use the metric system when it's up to me, by the way).

Sure, we don't have such an obligation. However, when writing on a science topic in an international forum, it is prudent to use the terminology science-minded people internationally are most likely to understand - which is the metric system. A mitigating factor would be if the object described is in a hold-out using a non-metric system of measurement.

I would react similarly if a Pakistani described Germany's population as 8 crore, though I might give them a pass if quoting Pakistan's population as 21 crore.

 

[Angra Mainyu]

But whether the telescope is 1600 feet in diameter (or approximately so) does not depend on what measure they generally use in China. For that matter, they do not generally speak in English, either, but that has no bearing on whether the telescope is 500 meters in diameter (or approximately so).

The point is: when we talk about China (or things in China, etc.), we do not have an obligation to speak Chinese, or to use the measure system used in China. It is okay to speak English (and it would be okay even if 95% of the world spoke Chinese as their only language), or to use another system (I use the metric system when it's up to me, by the way).

Sure, we don't have such an obligation. However, when writing on a science topic in an international forum, it is prudent to use the terminology science-minded people internationally are most likely to understand - which is the metric system. A mitigating factor would be if the object described is in a hold-out using a non-metric system of measurement.

I would react similarly if a Pakistani described Germany's population as 8 crore, though I might give them a pass if quoting Pakistan's population as 21 crore.

It's not the same in terms of immediate comprehension, as at least nearly everyone on this forum is familiar with feet. However, even in the case of "crore", it would not cause any problems, since looking that up takes seconds. We're not talking about someone posting in another language, but just using one word most people here (unlike "feet") are not familiar with.

By the way, it's not at all clear that the number of readers unfamiliar with feet - if any - exceeds the number of readers unfamiliar with meters - if any. I'd assign middling probability to that one. What's your probabilistic assessment on the matter, and why? (an non-scientific thread will a poll might provide anecdotal evidence).

At any rate, which system they use in China is irrelevant.