
Professional astronomers are calculating the cost of the Starlink constellation - ColinWright
https://twitter.com/cgbassa/status/1132555579988303872
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ldenneau
This issue astronomers have with Starlink is not with increased light
pollution per se, where the effect is negligible, but with the fact that when
there are 10,000 of these in the sky at one time, it will be much more
difficult to point a telescope and not have one of your exposures contaminated
by a Starlink satellite passing through. Some telescopes will sit on a source
for hours for the faintest objects and the odds of encountering one of these
becomes worrisome.

Anything visible to the naked eye or even binoculars is honking bright to
modern astronomical telescsopes, which are sensitive to sources millions of
times fainter. Even if they're not directly in the field, off-axis reflections
and glints can contaminate exposures. A train of these moving through the
field would be a total disaster.

For those saying let's just build space-based telescopes, sure, but it's
10-100X more expensive, and even modest ground-based facilities produce
100GB/night these days, and you can't do that from space (yet).

~~~
chr1
On the bright side Starlink is something that can help to solve both of this
issues by helping to lower the price of rockets and by improving the antennas.

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privong
The twitter thread (and most of the discussion here) is focused on the optical
impact of these satellites. As @watersb mentions in a reply[0] these
satellites will likely have an impact on radio telescopes. I've found
conflicting information on the frequency bands starlink will use, but all of
them would put the emission in the 10s of GHz regime, which is in the middle
of commonly used bands by current radio telescopes (e.g., the Very Large
Array), future expansions of existing telesopes ("Band 1" for the Atacama
Large Millimeter Array), and future radio telescopes (High-frequency Square
Kilometer array, Next Generation Very Large Array). Surely these are outside
of the "protected" radio frequency bands, but they may still affect the
measurements made by the sensitive electronics of radio telescopes.

The linked twitter feed notes that 84 satellites would be in the sky at any
time. I don't know how colimated their radio transmissions would be, but it's
possible more of them would be "visible" in the radio, compared to the
optical. So it could be a significant effect on radio astronomy.

[0]
[https://news.ycombinator.com/item?id=20016619](https://news.ycombinator.com/item?id=20016619)

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mhandley
I don't think I've seen anyone simulate the full Starlink constellation
including the ~7500 VLEO satellites. For your amusement, here it is:
[https://youtu.be/bKj4GDNhH0Q](https://youtu.be/bKj4GDNhH0Q)

No-one can say that SpaceX lacks ambition.

~~~
jjeaff
Wow, at first glance, that seems like a nightmare scenario, but then one must
realize that the animation is not to scale. For it to end up seeming as
crowded as that animation looks, each satellite would likely have to be the
size of a small city.

The vastness of just the Earth is hard to comprehend sometimes. In comparison,
if you put mountains, to scale, on a table top globe, Mount Everest would be
about the height of a grain of sand.

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booleandilemma
Let’s be thankful we don’t have giant flying illuminated billboards up there
(yet).

~~~
jarfil
There is a startup trying to do just that:
[https://astronomy.com/news/2019/01/billboards-in-
space](https://astronomy.com/news/2019/01/billboards-in-space)

~~~
bschwindHN
Wow, I sincerely hope their project fails miserably, what an awful idea.

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Paul-ish
Is the concern here that they will add to light pollution and make
astronomical observations more difficult?

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avmich
Can we make satellites with materials which don't emit or reflect in
frequencies which pass the atmosphere? So those satellites won't send energy
which would reach ground-based observers?

~~~
watersb
Radio astronomy relies upon internationally-recognized protection from
transmission on certain frequencies. Even when satellites comply with these
restrictions, these things have gotten so powerful they often overwhelm the
telescopes.

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pooya13
The article doesn’t provide any luminosity estimates. It is entirely possible
that when they claim up to 70 satellites would be “visible” that they mean in
a low light pollution area when you can see thousands of stars. On the other
hand if they mean the satellites would be visible with high luminosity, I
would be skeptical of that until they show their estimates of the size and
matterial since these are very small and mostly under Earth’s shadow.

------
jeffm3
Was hoping this would be a calculation of a financial cost. Any idea how much
that could be and how much would the consumer have to pay so that Starlink is
profitable?

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hairytrog
The only reason we can see them is the solar panels - right? Well, let this
generation of Starlinks go up as they are, and once they are out of commission
in about 5 years, send up the next generation. Instead of using solar panels,
they will use small nuclear reactors that will enable much higher power,
potentially higher orbits, higher bandwidth, longer life etc. If you want to
go NIMBY on the light, you should embrace nuclear power sources.

~~~
semi-extrinsic
I don't see any reason why we should allow these satellites, if we're talking
about literally mass polluting the night sky.

What they provide is a service that's already widely available in first world
countries, and is seeing rapid increase in availability in third world
countries (well, most of them, the US seems to be stagnant).

~~~
flyinglizard
Starlink could provide global connectivity that can’t be censored or regulated
in most countries - and that’s huge.

~~~
_Microft
Starlink would have to comply with what the country they are transmitting to
permits or doesn't if they don't want to get in all sorts of trouble. An
effect that Starlink could have though, is, that people might protest
censorship more because all that stands between them and freely accessing the
internet is their government allowing import of receivers (instead of no cable
or mobile available at all, ISPs, government, ...).

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teslabox
People in cities can’t see stars anymore, so this complaint about the new
satellite constellation is almost academic.

In decades past, people began to be concerned about light pollution. The city
of Phoenix, Arizona passed its first lighting ordinances around 1983. One of
the goals was to reduce sky glow.

After all those politicians retired LED lighting came out. Because the
politicians who worked on the sky glow problem were two generations back, the
current politicians didn’t realize there are very good reasons for using amber
low pressure sodium bulbs for the street lights, and replaced those lights
with white LEDs. The quality of light from the LEDs is terrible, but the city
saves a few pennies a year (electricity, maintenance), so they probably won’t
be fixing the problem.

My friend told me of how she takes her grandkids out to look at the phases of
the moon, and how sometimes they find a single star in the sky.

~~~
ColinWright
> _People in cities can’t see stars anymore, so this complaint about the new
> satellite constellation is almost academic._

There are designated areas of dark skies, and around observatories there are
limits as to the lighting that can be used around.

But all that is being rendered irrelevant - there are no areas that won't be
affected by these satellites - that's the whole point, they will cover pretty
much everywhere.

And these are professional astronomers saying that they are affected. The fact
that you, and others, don't really care and aren't affected isn't the point.
There's a very real risk that these satellites will kill Earth-based
professional astronomy, and large scale space astronomy isn't cost-effective.

~~~
teslabox
The point of my post was supposed to be that people who care about earth-based
astronomy really need to resist the proliferation of white led streetlights.
Kids who grow up without ever seeing stars aren’t likely to care about the
night sky.

~~~
stcredzero
Neil DeGrasse Tyson has a story about going to a planetarium as a child and
seeing a realistic depiction of what the night sky looks like in the
countryside. His immediate reaction: Fake!

