How bad are satellite megaconstellations for astronomy?

https://www.leonarddavid.com/blinded-by-the-light-megaconstellation-clash-with-astronomical-peer-groups/

by belter • 2 years ago

108 176 2 years ago

tetris11• 2 years ago

I know it's a blessing for people who live out in the sticks to have internet.... but is that really such a large use-case to justify entire fleets of these things?

How hard is it to run km of wire from the nearest town?

To me, these were built for the sole purpose of surveillance, and internet is an afterthought.

Edit: yes yes it's expensive, but the easiest solution the world came up with was for some guy to invest billions in a satellite program?

philomath_mn• 2 years ago

How hard is it to run km of wire from the nearest town?

Very hard, especially when the towns are much more dispersed than a km apart.

Turing_Machine3• 2 years ago

Yeah, no one is going to "run a wire" out to Umiat, Alaska.

In places like that it's satellite or nothing.

astrodust• 2 years ago

The hardest part is not the cable, or even the installation thereof, it's finding a contiguous right-of-way you can install it on, or having to fuss around with thousands of land owners who want their cut for the rights.

This is why most cables are laid alongside train tracks, not unlike telegram wires of years past. You negotiate with a handful of entities and can get permission relatively easily.

Of course, this presumes there's tracks, which is less and less likely as they keep getting ripped out.

If there's anything modern infrastructure build needs, it's more right-of-way access where you can provision dark fibre without getting mired in the legal issues.

LeoPanthera2• 2 years ago

How hard is it to run km of wire from the nearest town?

If it's not hard, why hasn't it happened already?

oh_my_goodness4• 2 years ago

To be fair, people are already using wire.

digging• 2 years ago

(in the US) It may be hard for a new company but easy for existing telecom giants. But existing telecom giants don't give a shit about national internet infrastructure quality, so if connecting rural customers simply appears less profitable* than focusing on current operations[1], they won't do it.

[1] Current operations include the obviously profitable "send monthly marketing materials via mail, email, and live salespersons to homes who canceled your services the day they had an alternative," among other idiotic practices.

FredPret6• 2 years ago

Super hard.

You have to dig a trench or span the wire. Either way you need to clear it with numerous property owners over a vast distance, get approval from dozens of authorities along the way, coordinate work crews, and then do maintenance on the whole thing for decades.

And then you discover that the wire used 50 years ago contained lead and we don't like that anymore, so now you have to pay for massive lawsuits (look up AT&T & Verizon) and rip up all that wire. More coordinating work crews and property owners!

And then they invent a new kind of wire and you have to do it all again.

Launching 1000's of satellites isn't easy but I can see wanting to do that rather than wire up the whole planet.

ajford2• 2 years ago

Because telecoms keep pocketing the money instead of actually building out broadband. https://www.huffpost.com/entry/the-book-of-broken-promis_b_5...

ericd2• 2 years ago

Yeah, I’m not sure why trenching is so expensive, I think PG&E was quoting something silly like millions per kilometer. I’m planning on doing like a tenth of a kilometer in a day with a $400 trencher rental pretty soon. I’m sure it’s not apples to apples, but the delta there seems pretty baffling.

For me, the biggest hang up has just been that I’m required by the state to get it inspected before I put in the conduit, and that ramps up the complexity of coordinating things quite a bit, because I’d rather not leave it open too long. If they have to deal with a bunch of bureaucratic coordination, then I could see the actual labor becoming a relatively tiny part of the difficulty/cost.

iwontberude• 2 years ago

It might cost money to figure out where to prioritize resources

oh_my_goodness4• 2 years ago

Hard enough that some people are putting up satellites instead.

EDIT: Say there's some way to put in fiber at $10k per km. Even then, ten million users at 1km per user makes $100 billion.

bmitc11• 2 years ago

To me, these are capitalistic solutions looking for problems. It's the whole startup mentality. Let's just throw a bunch of shit in space and see if it ends up being useful for anything. This idea of connecting the world is as false as the other hundred millions times that's been sold.

downWidOutaFite• 2 years ago

ISPs were paid billions to do this in the US and then stole the money and didn't do it thanks to regulatory capture.

shadowgovt5• 2 years ago

In many cases, the issue isn't cost to run but cost to maintain.

Consider South Africa, where the largest threat to installation deployment is inability to police the entire deployment coupled with massive wealth inequality... People just dig the cables out of the ground for the copper. Cellular radio has ameliorated the issue some (harder to steal the repeater antenna out of the back yard of a shotgun-owning resident), but Internet can still be a challenge.

Turing_Machine3• 2 years ago

That specific problem should go away as more lines get replaced with fiber, which has minimal scrap value compared to copper.

pfdietz3• 2 years ago

It's getting to the point it's not even worthwhile to run power lines to remote locations.

palata7• 2 years ago

To me, these were built for the sole purpose of surveillance, and internet is an afterthought.

Growth! Growth no matter the cost! Why would anyone question the need for always faster internet connections everywhere? /s

Turing_Machine3• 2 years ago

Let us know when you switch back to a 300 bps audio modem.

delichon3• 2 years ago

On the one hand the constellations are doing considerable damage to surface based astronomy. On the other hand they are funding an enormously lower cost of access to orbit and beyond for astronomy up in the sky.

marcosdumay2• 2 years ago

Yes, the future of astronomy is in space.

If the satellites don't disrupt it, light pollution will anyway, or best case, it will be disrupted by atmospheric pollution.

There's no lack of clear skies in space.

DiogenesKynikos3• 2 years ago

The future of astronomy is both on the ground and in space.

There are so many things that you can only conceivably do from the ground. You can build vastly larger telescopes on the ground, you can install far heavier instruments (like cameras and spectrographs) on them, you can upgrade and repair components much more easily. You can build massive arrays of radio telescopes. You get the point.

There are some things you can only do from space, or that are better in space, but saying that everything will be done in space is like saying we only need laptops and don't need datacenters. You need both.

ketralnis• 2 years ago

A: yeah we're hurting you but if we didn't, B & C would

B: yeah we're hurting you but if we didn't, A & C would

C: yeah we're hurting you but if we didn't, A & B would

I guess it’s nobody’s fault then

bmitc11• 2 years ago

That needs some citations. The James Webb Telescope's mirror is 6.5m in diameter. It took decades and billions of dollars of overruns and a prayer to launch and work correctly. There is no hope of most hardware repairs.

That mirror size pails in comparison to what can be accomplished via ground based observatories for much, much cheaper.

And the available modes of operation are completely different between space and ground. For example, space observatories are using decades old instrumentation techniques, hardware, and software. And that's just for starters.

We cannot do astronomy via space exclusively.

For me personally, I never wanted to see something like Starlink with my bare eyes, and I have several times. It's beyond annoying to me that a company has been able to unilaterally pollute the Earth's sky.

Almondsetat• 2 years ago

Exactly my thoughts. Scientists drool at the few telescopes we have in orbit. If we could launch more of them for less money at the expense of a busier night sky I don't think they would want to miss on that

Cacti• 2 years ago

Is this something we have evidence for, or is this just in theory?

delichon3• 2 years ago

SpaceX built the biggest constellation to date, and is using the profits to build Falcons while designing Starships. Check out the resulting cost per kilo to orbit:

https://ourworldindata.org/grapher/cost-space-launches-low-e...

That's pretty good for theory.

harimau777• 2 years ago

It seems to me that one problem is that regular people who are interested in astronomy don't have access to space based telescopes. I'm not sure I'd want to live in a world where there's that degree of class divide between astronomers who do and do not have access to that kind of funding.

sandworm101• 2 years ago

From the paper:

> Astronomy is also engaged in the search for extraterrestrial intelligence, a classic example of a program that might proceed for many years with little or nothing of interest to report, but that might someday provide one of the most profound discoveries in human history

That is all well and good. Most HN readers are probably well aware of that project. But if you want to alter policy at a national or international level, don't talk about extraterrestrial intelligence. It stirs the hornets next of faith, politics and cultural conflict. It opens the door to ridicule. Talk about the search for life, the search for a second life-supporting world. And maybe some of that life runs a radio station. Just avoid mentioning ET by name.

jonplackett2• 2 years ago

Is this a bit of a temporary problem, in the the very technology causing the issue - substantially cheaper access to space - will presumable ultimately put a frikkin massive telescope, or many massive telescopes into orbit where they’ll also not have to deal with the many other issues ground telescopes have to deal with.

I get that this still sucks for any individual with a Telescope though.

runeofdoom2• 2 years ago

It's not just "any individual with a telescope" though. It's stuff like the Simonyi Survey Telescope, a set to map the southern sky down to below 27th magnitude that's in trouble.

jonplackett2• 2 years ago

How would a telescope like that compare to Webb or Hubble in its capability? Eg, if we had to trade the loss of that for many Webb scale telescopes, or presumably something much much bigger once starship can start launching - is that worth the trade?

joshuakogut2• 2 years ago

put a frikkin massive telescope, or many massive telescopes into orbit

See: Hubble, JWST, and more to come

edit: JWST is in a different point from LEO but still counts

Havoc2• 2 years ago

As much as I sympathize this feels like a necessary evil to me in a sense vaguely accerlationism like.

I do think starlink can do more to help the situation though. Sure they tweaked some of the satellites to minimise it, but they could do more. Presumably the know the precise location and orientation of each sat. Surely that can be packaged into a data stream that helps unfk the images? Maybe with a sprinkling of that AI musk has going? Astronomers is a pretty small crowd...can't be that hard for someone like musk to throw them a bone that acknowledges that they're getting the short end here

LeoPanthera2• 2 years ago

There's no need to predict them in advance. Astronomy photos taken from the ground aren't one long exposure. They're lots - hundreds even - of short ones, which are then "stacked" to reduce noise and increase dynamic range of the final image.

It should be trivial to identify streaks in the stack and just throw out those images. I'd be surprised if they're not already doing that for the older satellites up there, and things like planes flying across the shot.

throw_pm23• 2 years ago

When you are driving towards a wall or a cliff you don't necessarily want to accelerate.

Havoc2• 2 years ago

You do if you think the gap between this cliff and the next can be jumped

schiffern7• 2 years ago

  >they could do more. Presumably the know the precise location and orientation of each sat. Surely that can be packaged into a data stream

SpaceX already does that.

https://youtu.be/MNc5yCYth5E?t=1717

https://arxiv.org/abs/2305.11123

trothamel• 2 years ago

30 years ago, it was possible to be lost - not because you wanted to be, but because you had no way of figuring out where we are. GPS and other GNSS networks have solved that problem.

It used to be possible to not have high-speed internet, and now high-speed Internet is available everywhere in the world that has an amenable government.

Right now, it's possible to be in a location where it's impossible to call for help. In a few years, when LTE-in-space is available and the 911 mandate applies to it, anyone with a charged phone will be able to get contact.

SpaceX has been working to mitigate how its satellites affect astronomy - see https://api.starlink.com/public-files/BrightnessMitigationBe... and https://new.nsf.gov/news/statement-nsf-astronomy-coordinatio... .

But fundamentally, to limit space to astronomy will be to limit the benefits it can give all mankind. a

shadowgovt5• 2 years ago

Including, notably, better astronomy.

Imagine a radio telescope as a satellite constellation, with an aperture the diameter of the orbit if you can synchronize the incoming signal with the right math...

StellarScience2• 2 years ago

There certainly is a real concern for astronomers, but the photo illustrations used in the article are selected to make things seem worse than they really are. They're wide field of view, long-duration exposures. That used to be the way astronomers imaged space, with film systems a century ago. But these days astronomical telescopes tend to have much narrower fields of view (like tiny soda straws peering into one particular spot in space) and use image stacking, a technique where many individual images are processed to form the final image (very simplistic overview: https://www.skyatnightmagazine.com/astrophotography/astropho... .) Using image stacking and armed with accurate catalogs that predict precisely where every satellite will be at any time, enables the removal of satellites during the image stacking process. Or they can just use that information for better scheduling: wait a minute or two to image a particular spot, so there won't be satellites in the field of view.

The article definitely gets this part right:

“Some astronomers see this as a true ‘hair on fire’ emergency, heralding irretrievable losses to space science; others present a more sanguine face, depicting this as yet another challenge to be surmounted in surveying a decreasingly pristine sky,” Koplow remarks.

Being involved in both space and astronomy plants me squarely in the latter camp. It takes a bit more work and software, but having so many satellites in space is a surmountable challenge for terrestrial astronomers. (Not to mention, these days some of the best astronomy is performed by telescopes in space, so astronomy overall benefits by having easier access to space.)

shadowgovt5• 2 years ago

Forget satellites; you can't do raw long-exposure for "serious" terrestrial-based astronomy anymore because you'll get planes in the way.

gammarator• 2 years ago

They're wide field of view, long-duration exposures. That used to be the way astronomers imaged space,

Sorry, but one of the two example images (https://noirlab.edu/public/images/iotw1946a/) is a single 333-second exposure with a modern survey camera, the Dark Energy Camera. This is not particularly long nor does it represent some outmoded observational strategy. Large, wide-field imaging sky surveys (such as the upcoming Rubin Observatory) are among the highest-profile ground-based astronomy projects today.

Masking and stacking can mitigate the problem but it does not of course compensate for the lost area and sensitivity. And the brightest satellites (like BlueWalker) saturate the readout electronics and spoil the whole exposure.

Narrow field instruments (such as spectrographs) have less geometric chance of seeing a satellite but tend to take longer exposures (tens of minutes), so there is a greater loss of telescope time when a streak does happen.

Even space telescopes are affected by streaks (https://www.space.com/hubble-images-spoiled-starlink-satelli...).

It takes a bit more work and software

Equivalently, it takes more money and time. That just means less science, given flat to declining funding from Congress.

nomel• 2 years ago

Masking and stacking can mitigate the problem but it does not of course compensate for the lost area and sensitivity. And the brightest satellites (like BlueWalker) saturate the readout electronics and spoil the whole exposure.

Is this only a problem in systems that aren't aware of where the satellites will be? I naively assume that, if the system knew, it could start exposing in the next clear window. I naively assume that the window is almost always clear, especially for an individual sensor.

malfist6• 2 years ago

Where do you see that the full well of those CCDs are fully saturated by a single satellite streak?

Even if that was the case, that seems a very poor design for a sensor and not really an issue of satellites. If a satellite streak can saturate your well, then so could a decently dense star field.

Do they blow out the individual pixels? Sure. But you just stack.

You don't lose sensitivity just because your stack rejected pixels, that's not how stacking works. You wind up with a tiny bit more noise, how much more depends on your capture. But not lower sensitivity, stacking isn't just average an area

dheera• 2 years ago

the photo illustrations used in the article are selected to make things seem worse than they really are

Exactly. I do a LOT of astrophotography and satellite trails are actually very easy to get rid of. Even the stupidest, most naive outlier rejection techniques, such as taking a stack of tracked images, finding their mean and standard deviation, throwing out any data points outside of 2 standard deviations, and then re-averaging, will get rid of the satellites very cleanly. You can go to more advanced techniques such as doing linear fits and RANSAC and whatnot, but you get the idea.

NOT doing any outlier rejection, just taking the mean of all the images will show the satellite tracks, but very dimly. The people who are trying to make noise on social media deliberately and disingenuously take the max() instead of the mean() to make the problem seem worse than it is.

That said -- in all of my imaging sessions, aircraft are a much, much, much bigger problem than satellites, and still easy to deal with. Yet nobody makes any noise about aircraft.

malfist6• 2 years ago

Seriously, any time you have >3 images to stack satellites and planes are a complete non issue. The median pixel value is always going to exclude those. Five images is enough to eliminate any trails even if they overlap between images.

thayne3• 2 years ago

Taking pretty pictures, and collecting scientific data are very different.

If a satellite is anywhere close to your target object in a frame you are using for photometry (measuring the amount of light), the frame is ruined, because it adds noise.

thayne3• 2 years ago

If you are looking for short period events, losing a single frame can mean losing critical data.

Or they can just use that information for better scheduling: wait a minute or two to image a particular spot, so there won't be satellites in the field of view.

Which means more time and effort, and ultimately money needs to be spent on scheduling observations to avoid the thousands of these satellites.

And sometimes it isn't an option. What if a GRB happens in the same field of view as one of these satellites and you want to observe it as soon as possible?

Now there are some types of observations that won't be impacted that much. If you can tolerate scheduling around it, or throwing away some of your frames it is just a minor annoyance. But a lot of observations are also more sensitive to such disruptions.

serial_dev• 2 years ago

What if a GRB happens

Yeah, what if? I mean, you probably missed the GRB, sure, but apart from that, you'll be fine and you can wait for the next one, or find a data from somewhere else.

lifeisstillgood• 2 years ago

GRB - Gamma Ray Burst (I am guessing)

whoopdedo• 2 years ago

these days some of the best astronomy is performed by telescopes in space, so astronomy overall benefits by having easier access to space.

Public access satellites. The FCC requires broadcast licensees to demonstrate that they're acting "in the public interest". Should private rocket launches have to give a minimum amount of their payload to research and non-profit purposes?

labcomputer7• 2 years ago

Sure, why not? A Hubble-sized telescope is only about 12 tons, which is only about 70% the mass of what a Falcon 9 can deliver to low earth orbit, and SpaceX does that 100x per year (it's only May and they've launched 47 so far this year). For reference, Spitzer is 1 ton and Chandra is 6 tons.

The elephant in the room is that launching one Hubble per year to a Hubble-like orbit only uses about 1% of SpaceX's current annual demonstrated launch capacity, and the actual reason people are upset has little to do with the actual impact on astronomy and more do with wanting to punish a certain CEO. One new space telescope every year would completely revolutionize the field, yet he'd barely notice. Better think of something else.

sitkack3• 2 years ago

You ignore the entirety of the LSST which will take more image data in its first year than all of humanity.

It is wide field, and these constellations cannot just be stacked out.

You think you are more informed than you are.

fecal_henge• 2 years ago

Why is stacking not possible in this case?

sitkack3• 2 years ago

You ignore the entirety of the LSST which will take more image data in its first year than all of humanity.

It is wide field, and these constellations cannot just be stacked out.

You think you are more informed than you are.

malfist6• 2 years ago

OP is not wrong, there is no satellite constellation that can't be "stacked out" That's precisely what stacking does.

Trust me, I'm an astrophotographer, you can check my website in my profile, I know what I'm talking about here.

WithinReason2• 2 years ago

Not to mention this only happens at dusk and dawn when the satellites are in sunlight.

shadowgovt5• 2 years ago

I'm sure it's inconvenient, but it's hard for me to believe that this isn't a solvable problem.

Satellites have extremely predictable paths and are very well-tracked by every government with a space program. If you can know a source of noise is there, you can trim the noise out of the signal. Sure, this impacts the fidelity of your signal for the three-dimensional coordinates of image where the noise was present, but "We're getting less science per day" isn't a reason to stop the low-orbit satellite boom.

What am I missing here? Can we not do the signal-subtraction? Is the problem unsolved or unsolvable? And if it's unsolved... Where are the grants to solve it?

SaberTail• 2 years ago

When counting photons, the noise in your signal scales with the square root of the total count. If the satellite is dumping 100 ± 10 photons in every pixel it passes through, you can no longer distinguish objects so faint that they'd only leave 10 photons in a pixel during your exposure.

shadowgovt5• 2 years ago

But in two dimensions of space and one of time, that's only a momentary occlusion right?

FredPret6• 2 years ago

It'd be so cool if we can put up a huge antenna / scope on the far side of the moon. You'd be completely shielded from all human noise

amelius• 2 years ago

Until we put satellites around the Moon.

FredPret6• 2 years ago

I wonder if it could be made practical to have a radio interferometer made up of several spacecraft flying in various directions.

martinky242• 2 years ago

Doesn’t the moon rotate

ooterness• 2 years ago

No. The moon is tidally locked to the Earth, so its rotation exactly matches its orbital period. If you put a telescope on the far side, it'll always be pointing away from Earth.

rickydroll5• 2 years ago

1) Most research is performed on the thousands of smaller telescopes (0.5-2 m.) scattered worldwide at private and public institutions. Even with the multitude of telescopes in the size range, there is still significant contention for scope time.

2) Space telescopes will never be disposable and will always require some form of service, even with high-reliability construction.

3) low Earth orbit is a limited resource and should be managed as a worldwide Commons. Allowing private corporations to occupy space is another way to privatize profit and push losses onto the public purse. Do you think any of these private companies will clean up the orbital messes they create, or will they act like they have to date?

4) Satellite Internet solves the billionaire's problem of extracting more money from users. Terrestrial methods for Internet access are good enough in all but the most remote communities. The main problem with terrestrial Internet is funding buildout Via private companies in a natural monopoly environment.

29athrowaway• 2 years ago

Now we are left without a way to detect if an asteriod is coming our way.

bythreads2• 2 years ago

I always thought spacex should stick a 5 dollar webcam to each sattelite pointing upwards and create the worlds largest telescope to just shut everybody up

martinky242• 2 years ago

Can you expand on how sticking a $5 webcam on each starlink satellite would quell concerns?

I’m in the astronomy community and I can’t quite figure it out. If you could expand on what you’re thinking and some of the science behind it, that’d be great.

bythreads2• 2 years ago

Half baked for sure, but : I thought given the ultra precise location and clocks, combined with the laser coms you could build a large array, or a inferometer with a baseline the size of the leo orbit.

Could be used for whole sky surveys, transient detections, wide angle monitoring, and high res imaging (granted this last one might require more operational finesse than a 5 dollar webcam c ould give you since you'd need fractional wavelength accuracy (right?). A radio antenna pointing outwards would in all honesty probably be better.

But 42.000 x X mega pixels in orbit pointing outwards at least will give you some nice big piles of data to play woth - and the downlink is baned in

briandw• 2 years ago

Mega-constellations also mean that access to space is getting cheeper. Bigger and more plentiful space telescopes should offset the loss from ground based astronomy in the long run. It's no consolation in the near term. But imagine the possibilities for a Starship sized telescope, or many of them.

How bad are satellite megaconstellations for astronomy?

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