
Gigantic Chinese telescope opens to astronomers worldwide - bookofjoe
https://www.nature.com/articles/d41586-019-02790-3
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latchkey
Found it on Google Maps:

[https://www.google.com/maps/place/Dawodang,+Pingtang,+Qianna...](https://www.google.com/maps/place/Dawodang,+Pingtang,+Qiannan,+Guizhou,+China/@25.6516267,106.855364,1440m/data=!3m1!1e3!4m5!3m4!1s0x36b892572079a627:0x196fc74e04c60688!8m2!3d25.650706!4d106.860469)

~~~
milankragujevic
There's a cool 360 image --
[https://goo.gl/maps/v4VkHhGmp5mfFk457](https://goo.gl/maps/v4VkHhGmp5mfFk457)
\-- from the (near) center of the telescope.

~~~
GrumpyNl
Great image, but i expected a clear sky.

~~~
simcop2387
Buying or opening a new telescope is known to all astronomers to cause cloudy
nights for weeks.

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arbuge
Previous record holder was the well-known Arecibo telescope at 305m diameter:

[https://en.wikipedia.org/wiki/Arecibo_Observatory](https://en.wikipedia.org/wiki/Arecibo_Observatory)

500m may not seem like a huge improvement over that but here's a picture that
puts it in perspective:

[https://en.wikipedia.org/wiki/Five-hundred-
meter_Aperture_Sp...](https://en.wikipedia.org/wiki/Five-hundred-
meter_Aperture_Spherical_Telescope#/media/File:Comparison_FAST_Arecibo_Observatory_profiles.svg)

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ajross
Lost in the announcement is the fact that they're opening this for global
research because... they don't really have anything queued up yet. High-
aperture radio astronomy doesn't really have a hook right now.

Arecibo was built half a century ago now, and ever since has remained (by far)
the most sensitive radio telescope available. Yet... it hasn't found much that
we didn't already know about. FAST seems likely to sit in the same realm:
it'll be able to see known phenomenon farther away, but that's about it.

We have plenty of radio sensitivity right now, what we need is broader
coverage to pick up transient things like FRB's, and (as always) longer
baselines for VLBI work (e.g. the Event Horizon "Telescope"), both of which
which mean more dishes, not one giant dish.

~~~
tremulens
Is there anything preventing them from tuning up FAST so it's as or even more
sensitive than Arecibo? Like, is it just a matter of better sensors or dish
design? Maybe we don't need it, but cleaner data would be nice at least.

~~~
ajross
FAST will surely be better than Arecibo, absent some kind of terrible
technical glitch. The point was more that, post-Arecibo (and again we're
talking the 1970's here) there has been no rush to build more Arecibo-style
dishes, because the perceived scientific benefit is low.

~~~
tremulens
I see. Curious they just spent a big wad of cash on it, though I suppose
they've been doing lots of construction work with marginal utility.

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tempestn
Sorry, I couldn't help myself.

Real missed opportunity there to name it the Five-hundred-meter Aperture Radio
Telescope. Bonus points if they detect an interesting pulsating signal and do
as was done with the gravitational waves, shifting it into the audio band...

~~~
peterlk
I'm hopeful that the scientific community will be happy to colloquially refer
to this as the FARTiscope

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Ididntdothis
”The 1.2-billion-yuan (US$171-million) telescope,”

This price is surprisingly low compared to other big science projects.

~~~
bigpumpkin
I wonder whether this is because they don't need to have a highly specified
lens found in conventional telescopes?

~~~
kayaeb
Not sure why you're being downvoted.

This is correct to an extent, the surface of a mirror needs to be polished to
a degree such that abnormalities in the lens are small relative to the
wavelength being observed (I think it's the diffraction limit equation, not
positive atm). Radio telescopes (with cm wavelengths) require much less
precision than optical ones (with sub-micron wavelengths). This telescope,
FAST, actually is made out of a collection of triangular (I think) sheets
arranged into a kind of dome, if it were observing optical it would act like a
disco-ball instead of a parabolic mirror. Arecibo is literally a hole in the
ground with rocks and crap on the reflector.

This thing actually had "first light" observations with several holes in it
from triangular sections that were fritzing just kind of fluttering in the
breeze. The first radio telescopes were literally built out of post-coldwar
trash just kind of rigged up in the back-yard. There's a major array going in
in south Africa where the antennas are like christmas tree wires that are just
kind of hammered into the ground, one of the PIs showed video at a colloquium
I attended of his 10 year old kids setting them up. If anything in modern
science can be called "low specification" it's radio telescopes.

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forgingahead
Meanwhile, TMT is still facing tons of opposition:
[https://www.hawaiinewsnow.com/2019/09/26/solidarity-mauna-
ke...](https://www.hawaiinewsnow.com/2019/09/26/solidarity-mauna-kea-spread-
oregon-europe/)

~~~
CharlesColeman
> Meanwhile, TMT is still facing tons of opposition

Which is one of the things that makes democracy and civil rights great:
different people can express different perspectives and influence the
decisions made.

~~~
bart_spoon
People expressing different perspectives and influencing decisions isn't an
absolute good. It certainly can be positive and desireable in many situations.
In others it can be utterly destructive, such as the the anti-vax movement or
climate change skeptics.

~~~
cgriswald
I don't think it is utterly destructive in the anti-vax movement. Dangerous
and stupid, sure, but what if the government was trying to force you to put
something else in your body that you thought was not in your best interests or
that of your child? Isn't it an absolute good that you're able to speak up and
resist?

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echelon
> force you to put something else in your body that you thought was not in
> your best interests or that of your child?

It's not in the best interest of _other_ children to let your children not be
immunized.

One of the reasons immunizations work so well is because of herd immunity. The
entire population doesn't need to be inoculated against every random mutation
the virus will take. Enough of the population has good enough immunity that
the virus can't take a foothold. But once you dip below a certain percentage,
the virus gets free rein to spread and evolve again.

Effective immunization requires that we all mostly get immunized.

~~~
cgriswald
You don't have to convince me. I know all this and I'm not an anti-vaxxer.

> It's not in the best interest of other children to let your children not be
> immunized.

This doesn't change my point at all.

First, the idea that my child should be subjected to something harmful because
it's better for other children doesn't fly with me. I doubt it flies with
anyone. I vaccinated my kid for her benefit and for everyone else's, but if
the choice is "everyone else" or "my kid"... I don't think you have to be a
parent to see how that one shakes out.

Second, that's not how anti-vaxxers see it. They see it as bad for those
children as well.

~~~
authoritarian
>the idea that my child should be subjected to something harmful because it's
better for other children doesn't fly with me

They aren't being subjected to something harmful, they falsely believe that
it's something harmful because they saw an infographic on facebook

>that's not how anti-vaxxers see it. They see it as bad for those children as
well.

Yes, and this kind of toxic stupidity should not be tolerated as it puts
everyone else at risk

~~~
cgriswald
If you want to boil this down to black-and-white you need to compare the past,
present, and future deaths of the anti-vax movement against the solution of
'not tolerating' anything that doesn't meet your utilitarian ideal. And that's
aside from the moral aspects.

~~~
katbyte
It is black and white. Everyone who can needs to vaccinate otherwise we loose
herd immunity. Full stop. Vaccines benefit far more people then they
negativity affect.

~~~
cgriswald
You and authoritarian seem to be saying "anti-vaxxers are completely bad!"
Well, congratulations. You're right. But no one here is arguing with you.

The issue is whether allowing people voice in influencing policy in a
democracy is an absolute good if it means people like anti-vaxxers can still
influence policy. I argued that _from the point of view of an anti-vaxxer_
they are doing good, and that, _you_ might find yourself in such a position
one day. That's irrespective of whether the anti-vaxxers are right or wrong
and if the hypothetical you is right or wrong.

And if it's not clear by now, (which it should be for anyone who read the
thread): I'm not an anti-vaxxer; I'm not in favor of them; and nothing I've
said here is in support of them.

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chongli
Surprised to see no mention of tourists or cellphones. We learned about this
telescope in astronomy class on Tuesday and our professor said the place was
inundated with so many tourists that it was impossible to get any useful data
due to the noise generated by all the cellphones. Part of the reason the
telescope was built in such a remote area was to reduce the amount of radio
noise from terrestrial sources.

~~~
mp8
That's surprising. I went there recently, and you aren't permitted to bring
any electronic devices whatsoever - you have to leave them in a locker and
then take a ~30 minute bus ride to the telescope.

They're also very strict about checking: you have to go through two different
x-ray machines to check you didn't sneak any electronics through.

~~~
janekm
Perhaps the no-devices policy was introduced after the interference issues
were encountered?

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SiempreViernes
No, the no devices policy would have been there from the start, its as basic
as forbidding open flames at a petrol station.

The need for X-ray machines due to tourists ignoring the ban is a more likely
development.

~~~
guenthert
Are those truly x-ray machines? Not just magnetic coils? Seems overkill and
I'd object to being exposed to ionizing radiation just for the purpose of
validating my claim that I don't carry any electronic communication devices.

~~~
janekm
It's actually a pretty standard setup in China anyway... Pretty much anytime
you go onto an inter-city bus / train or into a crowded space (museum /
exhibition centre) you will go through a metal detector and your bag through
an x-ray machine. So it makes sense that they'd just use the standard setup
that the local security company would be used to.

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yawz
Did they build a football/soccer field next to it so that we can realize how
gigantic it is by looking at the pictures?

~~~
benburleson
More likely so the workers had some recreation while on assignment!

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godelski
This is a smart move by China. There are a lot of reasons to do big science
projects other than accomplishing the science itself. One of the biggest is
that you get a lot of the smartest minds around the world in the same place as
one another. The country that is hosting them will receive more benefits than
the other countries participating (though everyone wins in some way). You also
are more likely to get the spinoffs that always come off from working on
difficult projects.

China is also building a super collider that's larger than CERN. The big
question though is if they plan on doing an international effort (and if so,
can they attract international scientists while operating an authoritarian
state?) or if they plan on doing it only nationally (seems much harder to do
and not as effective).

~~~
kayaeb
FAST is actually having difficulty hiring (on-site specialists like operations
director) the smartest minds because it's in a jungle in small-town China.

But yes, overall China is executing an excellent "brain drain" (not meant in a
negative sense) by being willing to invest in these "keystone" projects when
other countries are tightening budgets.

~~~
godelski
Telescopes generally have this problem though. Because it sucks to live out in
the middle of nowhere and you typically want to bring your family (which means
you need cities to support things like schools and recreation. Most
labs/research sites I know are like this. China Lake is an exception. But even
Groom Lake has has Vegas near it).

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aritmo
What is the percentage of the sky it can observe? Should be fairly small.

~~~
Iv
This telescope moves the sensor head across the surface, changing the actual
angle of the observation. The big poles around it are what suspends the head
over the surface. It has actually a huge angle of observation. According to
WP, 60° in its small 200 m aperture and 26.4° in its 300m aperture.

~~~
kayaeb
FAST can also move it's "mirror," the shell has some huge number of triangular
sections on wires, so it should be able to point even more than arecibo which
has an immutable reflector. Both have adjustable focal points (sensor head) on
wires like you describe.

