11 ms·

Why rebuild it? While cutting-edge when it was originally built, my understanding is that computationally combined arrays of smaller dishes are today considered

Why rebuild it? While cutting-edge when it was originally built, my understanding is that computationally combined arrays of smaller dishes are today considered superior to what Arecibo was, for radio astronomy. I’d be interested to hear from folks with expertise whether that is right or wrong.

rahen 4y ago
It was supposed to be rebuilt as a phased array of about a thousand 10m dishes mounted on a steerable plate about 300m wide. That would have been some colossal engineering. Have a look: https://www.youtube.com/watch?t=518&v=2qiu86-ZZdU https://www.youtube.com/watch?t=518&v=2qiu86-ZZdU
sigmoid10 4y ago
The thing is, even by rebuilding Arecibo the US (or more specifically, the NSF) would no longer own the largest radio telescope. China's 500m telescope [1] is already operational and while there are some minor differences when it comes to frequency range and field of view, there isn't much to justify the expenditure for another telescope in the US beyond mere political indulgences. From a strictly science based point of view, a new Arecibo is very hard to sell considering the implied costs. [1] https://en.wikipedia.org/wiki/Five-hundred-meter_Aperture_Spherical_Telescope https://en.wikipedia.org/wiki/Five-hundred-meter_Aperture_Sp...
- onlyrealcuzzo 4y ago
  How much does it cost? I see it was built for $9.3M in 1960. Now they're estimating the cleanup cost alone to be $50M. Inflation adjusted - it should cost ~$95M to re-build. I'm not sure how if you'd need to include the total $50M cleanup on top of that. Either way - if it can be re-built for $95M - that seems like a better deal than spending $50M to clean it up.
  - jws 4y ago
    There are 38,000 1mx2m perforated aluminum panels out there. I would pay a nice premium for them as a wall covering. Maybe not $50m/38000, but a good chunk of that. Having a section of the iconic telescope would be worth it. Now, are there thousands of people like me to make it work at scale?
  - cma 4y ago
    Need to adjust for Puerto Rico's change in something like purchasing power parity since then, not just US inflation, depending on the mix of labor that was involved.
  - bee_rider 4y ago
    It is a big fiddly science instrument that requires constant maintenance, the benefit of cleanup is to get rid of that obligation. If we want to turn it into a museum or something, that might be worth considering. But that will require getting it into a safe state which is presumably lots of the cleanup cost.
  - echelon 4y ago
    $50M is a lot to spend for nothing. Can't the site just be fenced off (assuming it doesn't contaminate groundwater or endanger in-use facilities)? If a private developer wants to take it over and turn it into a tourist destination, let them spend their own money. Throw them some tax incentives, maybe. $95M would be a great deal to new science projects. India put an orbiter around Mars for less. We could start studying a distributed array approach to whatever comes after JWST.
    - nullc 4y ago
      The cost of cleanup (which includes restoring the forrest to its natural state) is really what kept it running for a long time-- basically within the budget horizon it was cheaper to keep it running at limp-along levels (which presumably contributed to the failure) than to shut it down. I've long assumed that complete restoration being an assumed mandatory consequence of shutdown was itself a successful gambit from parties that wanted to keep the instrument operational. :)
      - onlyrealcuzzo 4y ago
        Why does it need to be cleaned up? I thought telescope mirrors had to be absurdly pure. It seems like it would make for a super cool museum.
        nullc 4y ago
        Arecibo was a radio telescope, like a satellite dish. The 'mirror' is a great big metal mesh hemisphere covering 18 acres of land in a mountain valley. It's not an ideal museum location in and of itself because it's almost an hour drive out of the city across some not-sutiable-for-high-traffic mountain roads (see the beginning of the movie Contact for a pretty reasonable view of what the trip out and in is like). Presumably the idea is that if we go around building stuff and just abandoning it we're doing unnecessary harm to nature as well as creating hazardous environments, e.g. when people go in to take the scrap metal and have stuff collapse on them.
        haneefmubarak 4y ago
- shagie 4y ago
  The 500m telescope lacks transmitters - this is an important distinction. > Fifth, Arecibo's larger secondary platform also housed several transmitters, making it one of only two instruments in the world capable of radar astronomy. ... The NASA-funded Planetary Radar System allowed Arecibo to study solid objects from Mercury to Saturn, and to perform very accurate orbit determination on near-earth objects, particularly potentially hazardous objects. China's 500m telescope wouldn't be able to capture https://www.planetary.org/space-images/radar-images-of-asteroid https://www.planetary.org/space-images/radar-images-of-aster... because it can't send a pulse. https://ui.adsabs.harvard.edu/abs/2010DPS....42.1317B/abstract https://ui.adsabs.harvard.edu/abs/2010DPS....42.1317B/abstra... > We report Arecibo (2380 MHz, 13 cm) and Goldstone (8560 MHz, 3.5 cm) delay-Doppler radar observations of binary near-Earth asteroid (NEA) 65803 Didymos (1996 GT) obtained on five dates between November 14-26, 2003 during the asteroid's approach within 0.048 AU. You'll note the Goldstone mention there and the "making it one of only two instruments in the world" from the wiki link on the 500 meter article https://en.wikipedia.org/wiki/Radar_astronomy https://en.wikipedia.org/wiki/Radar_astronomy > There is one remaining radar astronomy facility in regular use, the Goldstone Solar System Radar.
  - snowwrestler 4y ago
    Thanks for a substantive and well-sourced comment. There is a comment lower down saying Green Bank might add radar: https://news.ycombinator.com/item?id=33233119 https://news.ycombinator.com/item?id=33233119 I’m not in a position to confirm whether that is true though.
    - shagie 4y ago
      https://greenbankobservatory.org/future-of-earths-defense-is-ground-based-planetary-radar/ https://greenbankobservatory.org/future-of-earths-defense-is... > The National Science Foundation has awarded funds for the conceptual design of a higher-power radar system on the GBT – one that would be nearly 1,000 times more powerful than the proof of concept. In addition to a more powerful transmitter, NRAO and GBO, working with industry partners, will leverage new, solid-state amplifier and array receiving-system technologies to maximize the effectiveness of the new system. In parallel to this, as additional funding is allocated, the team plans to move to final design and construction activities, beginning in 2023. > The GBT’s new radar capabilities will introduce a tool that astronomy has not had before, collecting data at higher resolutions and at wavelengths not previously available. NRAO and GBO also are developing advanced data reduction and analysis tools that have not been available before. The flexibility and increased performance of this new system will fill an important need for planetary defense, and also allow astronomers to observe asteroids, comets, planets and moons. The versatility of this system will contribute to many areas of science.
- deleted 4y ago
  [deleted]
deleted 4y ago
[deleted]
arbalasquide 4y ago
It goes beyond being a state of the art tool. It is a part of our culture having this observatory. As a child, I loved going there and its the earliest part of my childhood that I remember something motivating me to pursue science/math. Even in my later part of my life I was able to do some research with the observatory which kick started my current career. The island already suffers from a lack of funding in education, thus I fear the youth might miss out on this sense of awe and curiosity I was lucky enough to have as a child. Another issue is that we have our brightest minds leaving the island because there's no fulfilling or well paying work to be done. The lack of this observatory is another reason more people will leave. Here's a white paper the people in the observatory wrote about a new dish. It contains reasoning, beyond my socio-cultural observations, for having a new one. http://www.naic.edu/NGAT/NGAT_WhitePaper_v2_01022021.pdf http://www.naic.edu/NGAT/NGAT_WhitePaper_v2_01022021.pdf
- rahen 4y ago
  They also published a video with some renders of the NGAT: https://www.youtube.com/watch?t=518&v=2qiu86-ZZdU https://www.youtube.com/watch?t=518&v=2qiu86-ZZdU I really wish it had been built.
- ApolloFortyNine 4y ago
  >As a child, I loved going there and its the earliest part of my childhood that I remember something motivating me to pursue science/math. Even in my later part of my life I was able to do some research with the observatory which kick started my current career. Honestly seems like this is what they considered most when deciding to turn it into an education center.
- MichaelZuo 4y ago
  Funding for local projects is competitive at the federal level from what I understand. If it doesn't serve a primary scientific purpose, then why would Puerto Rico be put at the front of the line? i.e. there's 50 other states and D.C. competing to be the most attractive to big ticket project funding, which also deliver education, youth initiatives, high paying jobs, etc.
rtkwe 4y ago
A single large collecting area still has sensitivity advantages vs arrays of smaller dishes. It was also used for radar and measuring distances to various objects in the solar system and the beam pattern from a single source there is vastly simpler than trying to use a phased array for the same task.
aardvarkr 4y ago
The main purpose was militaristic and science benefited as a result. Like others have said, the technology has advanced to the point where it didn’t have much scientific value and we no longer need it to spy on the Russians so I highly doubt anyone is willing to pony up the billions just to have something cool and inspirational when it won’t even be cutting edge anymore
- jjk166 4y ago
  Arecibo was never intended to spy on the Russians, nor is it capable of doing so - it's facing completely the wrong way. Arecibo did receive military funding, but that was because the military was interested in the behavior of the ionosphere. It was always a general science and technology development platform.
  - nomel 4y ago
    https://news.ycombinator.com/item?id=33234109 https://news.ycombinator.com/item?id=33234109 Soviet tech allowed members, and equipment, to cross the borders of the country. ;)
    - jjk166 4y ago
      Again, this doesn't stand up to scrutiny. To pick up radar transmissions reflected off the moon, the moon has to be in line of sight for both the emitter and detector. Puerto Rico is just about the worst positioned place in the US for something to have the moon in line of sight at the same time as the soviet union, and the particular design of Arecibo further limits the angles it can be directed at, so it can't even look towards the horizon where it might conceivably stand a chance. It's fine for a telescope as the rotation of the Earth allows it to look at different parts of the sky at different times, but there's a reason no radio receivers for terrestrial communication are built that way. Further, Arecibo works at frequencies of 10-40 MHz, substantially lower than even the lowest frequency radars. With secondary reflections you might be able to detect that a radar pulse had been detected, but determining where it came from or even what emitted it would be extremely challenging. I suppose perhaps Cuba could have been spied upon with it, but again it's just the worst design for the application.
magnat 4y ago
It could transmit at 22 TW EIRP, a feature quite rare in smaller arrays.
uplifter 4y ago
While combined arrays can have equivalent reception resolution, I don't believe they are equivalent for transmission. I recall reading in a Carl Sagan book that one Arecibo could transmit and receive messages from another Arecibo anywhere in the galaxy.
mandevil 4y ago
Arecibo had an active capability: radar mapping Venus most famously, that really can't be substituted with synthetic approaches. You can use aperture synthesis (from VLBA all the way to IVS) for greater resolving power, but they don't solve the coherent output problem.
bdamm 4y ago
The unique capability is active radar. As far as I know, combined arrays of smaller dishes can't pulse out a radar beam, they can only sense via interferometry. Unless there have been some advances in large scale wave forming, a giant dish is the only way to beam out powerful radar.
- aqfamnzc 4y ago
  Could a large-scale array not transmit in the same way a phased array would on, for example, a Starlink antenna? https://en.wikipedia.org/wiki/Phased_array https://en.wikipedia.org/wiki/Phased_array

rahen 4y ago

It was supposed to be rebuilt as a phased array of about a thousand 10m dishes mounted on a steerable plate about 300m wide. That would have been some colossal engineering. Have a look: https://www.youtube.com/watch?t=518&v=2qiu86-ZZdU https://www.youtube.com/watch?t=518&v=2qiu86-ZZdU

sigmoid10 4y ago

The thing is, even by rebuilding Arecibo the US (or more specifically, the NSF) would no longer own the largest radio telescope. China's 500m telescope [1] is already operational and while there are some minor differences when it comes to frequency range and field of view, there isn't much to justify the expenditure for another telescope in the US beyond mere political indulgences. From a strictly science based point of view, a new Arecibo is very hard to sell considering the implied costs. [1] https://en.wikipedia.org/wiki/Five-hundred-meter_Aperture_Spherical_Telescope https://en.wikipedia.org/wiki/Five-hundred-meter_Aperture_Sp...

onlyrealcuzzo 4y ago
How much does it cost? I see it was built for $9.3M in 1960. Now they're estimating the cleanup cost alone to be $50M. Inflation adjusted - it should cost ~$95M to re-build. I'm not sure how if you'd need to include the total $50M cleanup on top of that. Either way - if it can be re-built for $95M - that seems like a better deal than spending $50M to clean it up.
- jws 4y ago
  There are 38,000 1mx2m perforated aluminum panels out there. I would pay a nice premium for them as a wall covering. Maybe not $50m/38000, but a good chunk of that. Having a section of the iconic telescope would be worth it. Now, are there thousands of people like me to make it work at scale?
- cma 4y ago
  Need to adjust for Puerto Rico's change in something like purchasing power parity since then, not just US inflation, depending on the mix of labor that was involved.
- bee_rider 4y ago
  It is a big fiddly science instrument that requires constant maintenance, the benefit of cleanup is to get rid of that obligation. If we want to turn it into a museum or something, that might be worth considering. But that will require getting it into a safe state which is presumably lots of the cleanup cost.
- echelon 4y ago
  $50M is a lot to spend for nothing. Can't the site just be fenced off (assuming it doesn't contaminate groundwater or endanger in-use facilities)? If a private developer wants to take it over and turn it into a tourist destination, let them spend their own money. Throw them some tax incentives, maybe. $95M would be a great deal to new science projects. India put an orbiter around Mars for less. We could start studying a distributed array approach to whatever comes after JWST.
  - nullc 4y ago
    The cost of cleanup (which includes restoring the forrest to its natural state) is really what kept it running for a long time-- basically within the budget horizon it was cheaper to keep it running at limp-along levels (which presumably contributed to the failure) than to shut it down. I've long assumed that complete restoration being an assumed mandatory consequence of shutdown was itself a successful gambit from parties that wanted to keep the instrument operational. :)
    - onlyrealcuzzo 4y ago
      Why does it need to be cleaned up? I thought telescope mirrors had to be absurdly pure. It seems like it would make for a super cool museum.
      - nullc 4y ago
        Arecibo was a radio telescope, like a satellite dish. The 'mirror' is a great big metal mesh hemisphere covering 18 acres of land in a mountain valley. It's not an ideal museum location in and of itself because it's almost an hour drive out of the city across some not-sutiable-for-high-traffic mountain roads (see the beginning of the movie Contact for a pretty reasonable view of what the trip out and in is like). Presumably the idea is that if we go around building stuff and just abandoning it we're doing unnecessary harm to nature as well as creating hazardous environments, e.g. when people go in to take the scrap metal and have stuff collapse on them.
      - haneefmubarak 4y ago
shagie 4y ago
The 500m telescope lacks transmitters - this is an important distinction. > Fifth, Arecibo's larger secondary platform also housed several transmitters, making it one of only two instruments in the world capable of radar astronomy. ... The NASA-funded Planetary Radar System allowed Arecibo to study solid objects from Mercury to Saturn, and to perform very accurate orbit determination on near-earth objects, particularly potentially hazardous objects. China's 500m telescope wouldn't be able to capture https://www.planetary.org/space-images/radar-images-of-asteroid https://www.planetary.org/space-images/radar-images-of-aster... because it can't send a pulse. https://ui.adsabs.harvard.edu/abs/2010DPS....42.1317B/abstract https://ui.adsabs.harvard.edu/abs/2010DPS....42.1317B/abstra... > We report Arecibo (2380 MHz, 13 cm) and Goldstone (8560 MHz, 3.5 cm) delay-Doppler radar observations of binary near-Earth asteroid (NEA) 65803 Didymos (1996 GT) obtained on five dates between November 14-26, 2003 during the asteroid's approach within 0.048 AU. You'll note the Goldstone mention there and the "making it one of only two instruments in the world" from the wiki link on the 500 meter article https://en.wikipedia.org/wiki/Radar_astronomy https://en.wikipedia.org/wiki/Radar_astronomy > There is one remaining radar astronomy facility in regular use, the Goldstone Solar System Radar.
- snowwrestler 4y ago
  Thanks for a substantive and well-sourced comment. There is a comment lower down saying Green Bank might add radar: https://news.ycombinator.com/item?id=33233119 https://news.ycombinator.com/item?id=33233119 I’m not in a position to confirm whether that is true though.
  - shagie 4y ago
    https://greenbankobservatory.org/future-of-earths-defense-is-ground-based-planetary-radar/ https://greenbankobservatory.org/future-of-earths-defense-is... > The National Science Foundation has awarded funds for the conceptual design of a higher-power radar system on the GBT – one that would be nearly 1,000 times more powerful than the proof of concept. In addition to a more powerful transmitter, NRAO and GBO, working with industry partners, will leverage new, solid-state amplifier and array receiving-system technologies to maximize the effectiveness of the new system. In parallel to this, as additional funding is allocated, the team plans to move to final design and construction activities, beginning in 2023. > The GBT’s new radar capabilities will introduce a tool that astronomy has not had before, collecting data at higher resolutions and at wavelengths not previously available. NRAO and GBO also are developing advanced data reduction and analysis tools that have not been available before. The flexibility and increased performance of this new system will fill an important need for planetary defense, and also allow astronomers to observe asteroids, comets, planets and moons. The versatility of this system will contribute to many areas of science.
deleted 4y ago
[deleted]

deleted 4y ago

[deleted]

arbalasquide 4y ago

It goes beyond being a state of the art tool. It is a part of our culture having this observatory. As a child, I loved going there and its the earliest part of my childhood that I remember something motivating me to pursue science/math. Even in my later part of my life I was able to do some research with the observatory which kick started my current career. The island already suffers from a lack of funding in education, thus I fear the youth might miss out on this sense of awe and curiosity I was lucky enough to have as a child. Another issue is that we have our brightest minds leaving the island because there's no fulfilling or well paying work to be done. The lack of this observatory is another reason more people will leave. Here's a white paper the people in the observatory wrote about a new dish. It contains reasoning, beyond my socio-cultural observations, for having a new one. http://www.naic.edu/NGAT/NGAT_WhitePaper_v2_01022021.pdf http://www.naic.edu/NGAT/NGAT_WhitePaper_v2_01022021.pdf

rahen 4y ago
They also published a video with some renders of the NGAT: https://www.youtube.com/watch?t=518&v=2qiu86-ZZdU https://www.youtube.com/watch?t=518&v=2qiu86-ZZdU I really wish it had been built.
ApolloFortyNine 4y ago
>As a child, I loved going there and its the earliest part of my childhood that I remember something motivating me to pursue science/math. Even in my later part of my life I was able to do some research with the observatory which kick started my current career. Honestly seems like this is what they considered most when deciding to turn it into an education center.
MichaelZuo 4y ago
Funding for local projects is competitive at the federal level from what I understand. If it doesn't serve a primary scientific purpose, then why would Puerto Rico be put at the front of the line? i.e. there's 50 other states and D.C. competing to be the most attractive to big ticket project funding, which also deliver education, youth initiatives, high paying jobs, etc.

rtkwe 4y ago

A single large collecting area still has sensitivity advantages vs arrays of smaller dishes. It was also used for radar and measuring distances to various objects in the solar system and the beam pattern from a single source there is vastly simpler than trying to use a phased array for the same task.

aardvarkr 4y ago

The main purpose was militaristic and science benefited as a result. Like others have said, the technology has advanced to the point where it didn’t have much scientific value and we no longer need it to spy on the Russians so I highly doubt anyone is willing to pony up the billions just to have something cool and inspirational when it won’t even be cutting edge anymore

jjk166 4y ago
Arecibo was never intended to spy on the Russians, nor is it capable of doing so - it's facing completely the wrong way. Arecibo did receive military funding, but that was because the military was interested in the behavior of the ionosphere. It was always a general science and technology development platform.
- nomel 4y ago
  https://news.ycombinator.com/item?id=33234109 https://news.ycombinator.com/item?id=33234109 Soviet tech allowed members, and equipment, to cross the borders of the country. ;)
  - jjk166 4y ago
    Again, this doesn't stand up to scrutiny. To pick up radar transmissions reflected off the moon, the moon has to be in line of sight for both the emitter and detector. Puerto Rico is just about the worst positioned place in the US for something to have the moon in line of sight at the same time as the soviet union, and the particular design of Arecibo further limits the angles it can be directed at, so it can't even look towards the horizon where it might conceivably stand a chance. It's fine for a telescope as the rotation of the Earth allows it to look at different parts of the sky at different times, but there's a reason no radio receivers for terrestrial communication are built that way. Further, Arecibo works at frequencies of 10-40 MHz, substantially lower than even the lowest frequency radars. With secondary reflections you might be able to detect that a radar pulse had been detected, but determining where it came from or even what emitted it would be extremely challenging. I suppose perhaps Cuba could have been spied upon with it, but again it's just the worst design for the application.

magnat 4y ago

It could transmit at 22 TW EIRP, a feature quite rare in smaller arrays.

uplifter 4y ago

While combined arrays can have equivalent reception resolution, I don't believe they are equivalent for transmission. I recall reading in a Carl Sagan book that one Arecibo could transmit and receive messages from another Arecibo anywhere in the galaxy.

mandevil 4y ago

Arecibo had an active capability: radar mapping Venus most famously, that really can't be substituted with synthetic approaches. You can use aperture synthesis (from VLBA all the way to IVS) for greater resolving power, but they don't solve the coherent output problem.

bdamm 4y ago

The unique capability is active radar. As far as I know, combined arrays of smaller dishes can't pulse out a radar beam, they can only sense via interferometry. Unless there have been some advances in large scale wave forming, a giant dish is the only way to beam out powerful radar.

aqfamnzc 4y ago
Could a large-scale array not transmit in the same way a phased array would on, for example, a Starlink antenna? https://en.wikipedia.org/wiki/Phased_array https://en.wikipedia.org/wiki/Phased_array