[HN Gopher] A new era for Arecibo
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A new era for Arecibo
Author : gmays
Score : 116 points
Date : 2023-09-29 14:45 UTC (8 hours ago)
(HTM) web link (www.nature.com)
(TXT) w3m dump (www.nature.com)
| markhahn wrote:
| what would it cost to really begin it's next phase (rebuilding,
| not what amounts to a mausoleum that runs some classes)?
| jameshart wrote:
| Struck by this part about the island's sense of loss of the
| telescope:
|
| > Arecibo's prowess at astronomy was a source of pride in Puerto
| Rico, and many have been disappointed with the NSF's decisions.
|
| Such a contrasting view compared to the long fight in Hawaii over
| the Thirty Meter Telescope project [1], where locals have
| continually fought and protested. It's tied up in the Hawaiian
| sovereignty movement, and a lot of cultural connotations, but I
| can't help feeling like the Arecibo case should be a lesson for
| the TMT movement: you'd miss the telescopes if they went away.
|
| [1] https://www.npr.org/2022/07/31/1114314076/hawaii-mauna-
| kea-t...
| petsfed wrote:
| Insofar as I'm aware, Arecibo is not a sacred site to
| indigenous Puerto Ricans. Nor was there any concern about
| barring local access to the site, which had been available for
| literally centuries (excepting, of course, the historic bans of
| all but the most senior members of Hawaiian society - again
| _sacred_ site).
|
| I'm generally pro-telescope, and I've worked with people who
| have spent a lot of time at Mauna Kea (Keck, especially). But
| the more I learn about this, the more the Mauna Kea telescopes
| feel an awful lot like Mt. Rushmore: colonists moving in and
| saying that the natives' claim to a place is less legitimate
| than whatever "progress" the colonists have planned.
| coldbrewed wrote:
| I'm really torn about this. Mauna Kea is the best place on
| the entire planet to observe the galactic center; it has the
| best seeing (minimal humidity and low atmospheric turbulence)
| that's not matched in the northern hemisphere. The ESO
| already has an equivalent observatory planned in the southern
| hemisphere so there's less value in relocating the TMT down
| to Chile, so effectively either Mauna Kea or nowhere.
|
| Simultaneously, Hawaii has an ugly history of colonization
| that's not talked about enough. The area is sacred to native
| Hawaiians and indigenous people deserve say in how their
| ancestral land is used. The TMT is also a comparatively easy
| target for activists to push back on colonization compared to
| large corporations with continents of lawyers, or the tourism
| economy that provides revenue for the island. Folks know that
| chaining elderly folks across construction access works, and
| it would be a PR nightmare to forcibly remove them.
|
| Scientific progress should be something that transcends
| politics but we're stuck with the legacy of colonization, and
| that makes us all a little poorer.
| jameshart wrote:
| Torn is right.
|
| Mauna Kea is sacred to the world's scientists too - it's a
| perfect observing site; a spectacular volcano; a unique
| glacial environment; an isolated habitat for plant and
| animal life; it feels like there ought to be some way to
| share the gift of this improbable piece of land with the
| world.
|
| But yes, the way things have been done in the past affect
| the relationships we can have now.
| aylmao wrote:
| > you'd miss the telescopes if they went away.
|
| This is simplifying the issue too much. Mauna Kea is the most
| sacred mountain in Hawaiian culture, Arecibo wasn't built in
| particularly special land as far as I know.
| Hooray_Darakian wrote:
| > where locals have continually fought and protested. It's tied
| up in the Hawaiian sovereignty movement
|
| A vocal minority of locals. There are less noisy groups in
| favor of the TMT https://www.imuatmt.org/
| TaylorAlexander wrote:
| > I can't help feeling like the Arecibo case should be a lesson
| for the TMT movement: you'd miss the telescopes if they went
| away.
|
| Generally when people are fighting for their sovereignty I
| don't presume to know what is best for them. That's kind of the
| whole point of fighting for one's sovereignty.
| jameshart wrote:
| Oh, I get it. I just find the parallel stories draw attention
| to the different experiences of Hawaii and PR (as the sibling
| post elucidates).
| burkaman wrote:
| > It's tied up in the Hawaiian sovereignty movement, and a lot
| of cultural connotations
|
| I mean I think this is underselling it a little. It seems like
| the main difference is that Puerto Rican colonization and
| subjugation started like 350+ years before Hawaiian overthrow
| and annexation, so there are just very few descendants of
| indigenous people left in Puerto Rico. Conversely, a
| significant portion of Hawaii is descended from indigenous
| people, and some of them probably had grandparents who grew up
| in an independent nation and remember them talking about it.
| The wound is still relatively fresh.
|
| I think what happened with TMT would have also happened with
| Arecibo if the Spanish hadn't already killed nearly all of the
| indigenous people, to be blunt. It's definitely about
| sovereignty and not about a distaste for telescopes. There's a
| lot of infrastructure I'd like to see built in my own country,
| but that doesn't mean I want another country to invade and then
| build it.
| jgalt212 wrote:
| Maybe it's because the Hawaiians are rich enough to turn away
| business and the the Puerto Ricans are not.
| dotancohen wrote:
| Where should I read more about how the US invaded Hawaii?
| j-bos wrote:
| If you like videos/audio this is is high level view with
| detailing: https://youtu.be/_H7xl9X3G8U
| burkaman wrote:
| Wikipedia is pretty good, I'd start here: https://en.wikipe
| dia.org/wiki/Overthrow_of_the_Hawaiian_King...
|
| I'm sure there are plenty of good books on the subject but
| I don't have any recommendations unfortunately.
|
| Edit: Actually maybe the US government's own account is a
| better place to start: https://www.govinfo.gov/content/pkg/
| STATUTE-107/pdf/STATUTE-...
|
| > Whereas, in pursuance of the conspiracy to overthrow the
| Government of Hawaii, the United States Minister and the
| naval representatives of the United States caused armed
| naval forces of the United States to invade the sovereign
| Hawaiian nation on January 16, 1893, and to position
| themselves near the Hawaiian Government buildings and the
| lolani Palace to intimidate Queen Liliuokalani and her
| Government;
| jameshart wrote:
| And while you're learning about this stuff, make sure you
| follow the rabbit trail far enough to get to this little
| historical backstory:
|
| > In 1899, industrialist James Dole moved to Hawaii.
| James was the cousin of Sanford B. Dole, who had helped
| overthrow the Kingdom of Hawaii in 1893, and became the
| governor of Hawaii in 1898. Two years after James Dole's
| arrival, he formed the Hawaiian Pineapple Company (HPC).
|
| https://en.wikipedia.org/wiki/Dole_plc
| VHRanger wrote:
| Fucking with sovereign nations in the name of fruit
| companies is US heritage at this point
| buildsjets wrote:
| Indeed fruit companies have been a major force of
| colonization. The house I grew up in was built on the
| former estate of Minor Cooper Keith, one of the founders
| of the United Fruit Company, now known as Chiquita.
|
| The term "Banana Republic" refers to UFC's complete
| domination of most South American governments through
| criminal activity.
|
| https://en.wikipedia.org/wiki/United_Fruit_Company
| runako wrote:
| This isn't confusing. It's totally rational to not want
| limited, unspoiled land to stay that way on the one hand, and
| then on the other hand having lost that battle it's fair to
| prefer a working telescope over the wreck that's at Arecibo
| now. It's not an obvious conclusion from those two perspectives
| that one would therefore prefer to have a pristine environment
| spoiled with concrete.
| jameshart wrote:
| There are 13 telescopes on Mauna Kea already - and some are
| already due to be decommissioned. It's not unspoiled and
| pristine. If they don't continue to develop the site, the
| telescopes there will fall into obsolescence, and ultimately
| disuse. Pushing back against continued development on the
| site is, ultimately, pushing for it to go the way of Arecibo.
| petsfed wrote:
| Or they could perform an explicit reclamation project, to
| try to restore the land as best they could to the way it
| was prior to 1893.
|
| There are more options than just "build more telescopes" or
| "let the existing telescopes rot". Of course, just letting
| them rot would be playing to the standard colonial practice
| of extracting value, then leaving consequences of that
| extractive effort to the remaining indigenous people.
| jjav wrote:
| > Such a contrasting view compared to the long fight in Hawaii
|
| In Hawaii the location is the top of the mountain and
| considered sacred land.
|
| The small natural dip where the Arecibo telescope was built did
| not have particular society-wide historical significance so
| it's not comparable.
| aidenn0 wrote:
| How does a large single dish antenna compare to an array of
| smaller dish antennas? Like e.g. the VLA in New Mexico.
| tpmx wrote:
| That Arecibo scene from Contact (1997):
|
| https://www.youtube.com/watch?v=zfiOT14MyaQ
| guender wrote:
| [dead]
| spiritplumber wrote:
| Looks like it'll become a museum of itself :(
| elil17 wrote:
| When I visited Arecibo (which I highly recommend but the way -
| one of the coolest things I've ever seen), the intern giving me a
| tour told me that Arecibo was essentially the main way we had to
| detect asteroids that might hit earth. Without it, we may not
| have enough time to launch an asteroid redirect mission.
|
| If that's accurate, it seems penny wise and pound foolish to have
| spent ~$300 million on the DART test but then not spend the extra
| ~$50 million needed to actually detect an asteroid coming towards
| us.
| _kst_ wrote:
| The Arecibo dish was not steerable, so there are large parts of
| the sky that it couldn't see.
|
| China built a similar radio telescope that went into service in
| 2016. https://en.wikipedia.org/wiki/Five-hundred-
| meter_Aperture_Sp...
| jamesmaniscalco wrote:
| Are you sure? I recall that the dish was spherical, not
| parabolic, and had a movable receiver mounted on cables;
| moving the receiver adjusts the direction from which signals
| can be received. Indeed, Wikipedia claims that it was
| steerable [0].
|
| [0] https://en.wikipedia.org/wiki/Arecibo_Observatory
| ben_w wrote:
| You're kinda both right; the dish itself was fixed, but the
| system as a whole still had limited steerability because it
| was (spherical?) instead of parabolic, allowing 20deg of
| the zenith.
|
| This was still a lot more limited than the horizon-to-
| horizon of the other iconic radio telescope type: https://c
| ommons.wikimedia.org/wiki/File:CSIRO_ScienceImage_8...
| DiogenesKynikos wrote:
| Most of the large (more than a few hundred meters) potentially
| hazardous asteroids are thought to have been found. However,
| there are some locations (relative to Earth's orbit) that are
| difficult to view from the ground, because you can only observe
| them at twilight. The best way to find those last remaining
| potentially hazardous asteroids would be to launch a space
| telescope to the Earth-Sun Lagrange Point 1.
|
| In the grand scheme of things, this type of mission wouldn't
| cost that much, but so far, nobody has made the decision that
| making sure Earth doesn't get hit by an asteroid is worth an
| investment of a few hundred million dollars.
| dotancohen wrote:
| It seems that Starship well greatly upend these calculations
| and considerations. When launching 100 tons of payload costs
| $10 million, we should start seeing a lot more science being
| launched.
| DiogenesKynikos wrote:
| We really just need one telescope at L1. That's all.
| jameshart wrote:
| With 'large potentially hazardous asteroids', thinking we
| have found most of them doesn't really seem that reassuring.
|
| Like the mayor giving a press conference in front of the zoo
| saying "Most of the large, maneating lions are thought to
| have been located".
| elil17 wrote:
| > nobody has made the decision that making sure Earth doesn't
| get hit by an asteroid is worth an investment of a few
| hundred million dollars.
|
| This is not true. NASA spent over $300 million to test DART,
| an anti-astroid planetary defense system.
| DiogenesKynikos wrote:
| And yet, a straightforward mission that would identify all
| remaining potentially hazardous asteroids hasn't gone
| forward. DART is great, but it's useless if you don't see
| the asteroid coming long in advance.
| dheera wrote:
| The problem is most people with $300 million aren't willing to
| spend it on this. They're more worried about how to get another
| $300 million. That mentality how they turned $150 million into
| $300 million in the first place.
|
| Government spending on the other hand, is mostly decided by
| poor people (majority of voters) who are more worried about
| tomorrow than 1000 years from now.
| hotnfresh wrote:
| > Government spending on the other hand, is mostly decided by
| poor people (majority of voters) who are more worried about
| tomorrow than 1000 years from now.
|
| I'm fairly sure studies of voter sentiment & positions vs.
| legislative activities and executive priorities do not back
| up this guess.
| elzbardico wrote:
| Yeah, I am sure poor people prefer to give dozens of billions
| every year to Lockheed Martin, Boeing, Northrop, General
| Dynamics, BAE et caterva instead of affordable public housing
| and public health.
|
| I see the homeless living on their tents, the inner city
| blacks and the white unemployable rednecks gnashing their
| teeth in unison: "Don't you dare buy a single F-35 less to
| give us some fucking stinking doctors!"
|
| That's exactly how it is, a perfect democracy.
| TaylorAlexander wrote:
| > Government spending on the other hand, is mostly decided by
| poor people (majority of voters)
|
| Government spending is decided by Congress and the President,
| who are not poor people. There is a convoluted selection
| process in which rich people (donors) select the pool of
| candidates from a group of rich people, and then they let
| poor people vote on which of the rich people selected by
| other rich people they would like to have make decisions for
| us.
|
| On a practical matter it is clear poor people do not make
| decisions because poor people want things like universal
| health coverage, but we do not have that.
| user3939382 wrote:
| > Government spending on the other hand, is mostly decided by
| poor people (majority of voters)
|
| Government spending is mostly decided by huge corporations,
| firstly the arms industry. If poor people controlled our
| budget we wouldn't have throngs of homeless people in every
| city in the country.
| 0x5345414e wrote:
| Education centre seems like a strange choice given that it's in
| the middle of nowhere...
| mikhailfranco wrote:
| Arecibo is d-e-a-d.
|
| Passing the baton...
|
| https://en.m.wikipedia.org/wiki/Five-hundred-meter_Aperture_...
| jasonkester wrote:
| Arecibo is really awkwardly placed for being anything but what it
| was. It's at the end of a long windy narrow road up the side of a
| mountain in the jungle. And when you get there, there's just
| about enough room for a little building perched on the side of a
| pit.
|
| They can fit a lot of biology and computer science schools at the
| base of that road, I bet.
| orev wrote:
| Its location in a remote area made it good for what it was, a
| telescope with relatively little surrounding radio
| interference, but it really isn't suited for other uses that
| bring in more people.
|
| It's unfortunate since there's a lot of pride about what it
| used to be on the island, but I feel like this is more of an
| emotional grasp than something that actually requires that
| site.
| lacker wrote:
| There has also been more and more radio interference at that
| site over time. It isn't _that_ remote. Sites that are really
| out in the middle of nowhere in empty desert, like the VLA in
| New Mexico and MeerKAT in South Africa, have far less radio
| interference.
| an-allen wrote:
| Having made the trek myself, and seeing one, in my opinion, of
| the great wonders of the modern world... I can certify that i
| would not drive there to just experience science museum stuff.
| Driving in puerto rico is terrifying, and up that hill to
| Aribaco... never again.
| chasil wrote:
| ...and that long, windy road is one-lane, and I don't remember
| high-quality pavement.
|
| Some of that money would have to be spent on the road, right
| away, if there is any hope of it to be a general attraction.
| ajford wrote:
| Yep. Parking for visitors (and staff) was an absolute nightmare
| the entire time I worked there. I can only imagine how much
| worse it'll be if the revamp the visitor center.
|
| There's almost no space on-site for more parking without
| tearing up more of the natural environment. Though perhaps
| without the need to maintain the superstructure any more they
| could repurpose the Physical Maintenance yards into more
| parking.
| digging wrote:
| Although expensive, seems that vertical building (underground
| and above) should be a priority then.
| deepsun wrote:
| Why didn't they made a shuttle?
| ajford wrote:
| Wasn't a priority. It was an active scientific facility, so
| the priority was on producing science. The site was chosen
| for being remote and shielded from the outside by
| hills/mountains, so it really is a long winding road to the
| entrance gate.
|
| I can't really think of a suitable site for parking within
| say 10min of the site, so it'd be a long shuttle ride.
| user3939382 wrote:
| This is how we solve it in Manhattan
| https://i.imgur.com/qLYlbya.png
| jedberg wrote:
| Given that they don't need the antenna anymore, can't they
| repurpose the entire pit for buildings?
| squarefoot wrote:
| Sad to see it go away, but for starters they could sell the
| remaining reflector tiles and make some money for other
| science related uses.
| wkat4242 wrote:
| That's ideal for a radio telescope, especially considering how
| reliant modern society is on radio equipment
| garba_dlm wrote:
| nonetheless astronomy is doing fine
| https://english.news.cn/20230928/5929e14fe40b4c939c1f8194e0b...
| 1970-01-01 wrote:
| Great news, but I'm still sad due to the lack of interest in
| funding a replacement. To put it in perspective, the cost of just
| one football (Premier League or NFL) stadium would pay for an
| entire radio array.
| world2vec wrote:
| Very sad that its next phase is not as a bigger, better
| observatory. RIP.
| oh_sigh wrote:
| Do these massive telescopes have a future, when we could just
| build smaller ones and use aperture synthesis to pretend like
| we have a really really big telescope?
| mandevil wrote:
| For receive only, yes, aperture synthesis (like the VLA and
| the GVLBI) is capable of resolving more precisely than even
| Arecibo could. But Arecibo also did a bunch of active radar
| mapping of things within the solar system, which aperture
| synthesis cannot replace. You can't solve the coherent beam
| problem without actually having an antenna that really is
| that big.
| echelon wrote:
| > You can't solve the coherent beam problem without
| actually having an antenna that really is that big.
|
| What's the tl;dr on the math here?
| madengr wrote:
| You know how Nyquist says you must sample at minimum
| twice your highest "frequency" or your get aliasing in
| your spectrum? It's the same with antennas except you
| must sample at least 1/2 your wavelength or you get
| grating lobes (the equivalent of aliasing) in you far
| field pattern; it's all the same math. A sample in time
| is equivalent to an antenna element sampling space. A big
| reflector is equivalent to sampling everything at once
| with no gaps; it's bandwidth independent. You can only
| put array element so close together, limited by the size
| of the element (itself is limited to a fraction of the
| lowest wavelength), electronics, and unwanted inter-
| element coupling (though there are tricks to take
| advantage of this coupling and make very wideband
| arrays).
|
| If you leave "gaps" in your array elements, that's not a
| problem receiving strong, periodic signals. You can
| physically move the elements to fill in the gaps to
| remove those lobes; the equivalent of an equivalent time
| oscilloscope or a synthetic aperture radar. The problem
| is you can't do that when transmitting since you only
| have one opportunity to send something (non-periodic).
|
| There are other disadvantages with phased arrays. Each
| amplifier has to be matched in amplitude and phase. I've
| had to bin lots of amplifiers as some have phase
| compression and some phase expansion over amplitude. That
| distorts the pattern over the pulse.
|
| On the receive side, each receiver has thermal noise un-
| correlated with the others. So for N antenna elements,
| you received signal-to-noise scale proportional to
| sqrt(N) instead of N like you have on transmit, or with a
| big reflector. This is why arrays suck for very weak
| signals. Notice NASA keeps building big dishes for their
| DSN instead of "cheaper" arrays.
|
| Then there's the whole timing and phase noise issue with
| distributing an oscillator.
|
| Tough you can only make a reflector with about 100 dB
| gain.
| markhahn wrote:
| huh? wouldn't all the planes with AESA radar dispute this
| characterization?
| mcpackieh wrote:
| https://en.wikipedia.org/wiki/Thinned-array_curse
|
| > _The thinned-array curse (sometimes, sparse-array
| curse) is a theorem in electromagnetic theory of
| antennas. It states that a transmitting antenna which is
| synthesized from a coherent phased array of smaller
| antenna apertures that are spaced apart will have a
| smaller minimum beam spot size, but the amount of power
| that is beamed into this main lobe is reduced by an
| exactly proportional amount, so that the total power
| density in the beam is constant_
|
| So you can transmit with a sparse array, but the power
| you can deliver with it (for a set synthetic aperture
| size) decreases with the degree of sparseness. No free
| lunch.
| adgjlsfhk1 wrote:
| massive telescopes still win in terms of light sensitivity
| per dollar. apature synthesis/VLBI are the clear way to go
| for angular resolution but for bigger fainter objects, you
| care more about area where a big dish does better.
| madengr wrote:
| It had a powerful transmitter for radar work, and there are
| advantages to having a single, giant aperture when it comes
| to maintaining low sidelobes, power amplifier coherency, etc.
| skymast wrote:
| [dead]
| srean wrote:
| Its such a strange coincidence that a few hours earlier I was re-
| reading this beautiful short by Ted Chiang https://nautil.us/the-
| great-silence-237510/
| geocrasher wrote:
| Oh goodness... I didn't expect to shed a tear at the end of
| that. What a gorgeous bit of writing. I can only aspire to be
| such a powerful storyteller as Mr. Chiang. Thanks for sharing.
| srean wrote:
| Am happy you liked it.
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