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How satellite ‘megaconstellations’ will photobomb astronomy images

nature.com

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Re: How satellite ‘megaconstellations’ will photobomb astronomy images

#161

Post by aga98mtl »

jeroenhd wrote: post #112
reitzensteinm wrote: post #42

Earlier quoted context omitted.

I personally believe that pervasive high speed internet even in remote locations will do more for humanity than the scientific cost of these satellites. However, this conversation has basically been skipped over. Maybe you're right and I'm wrong. The constellations are being launched, and there's zero chance of shutting them down once they're serving a commercial role. Considering the abundant red tape in the modern…

> I personally believe that pervasive high speed internet even in remote locations will do more for humanity than the scientific cost of these satellites. Perhaps in the US, but other countries, even poor ones, manage to do rural internet fine without cluttering the night sky. I, for one, am not stoked about the implications of an American ISP forcing worldwide coverage for themselves. Their shady business practices…

>Perhaps in the US, but other countries, even poor ones, manage to do rural internet fine without cluttering the night sky.

Most of sub-saharan Africa has slow and expensive internet. I would guess there is 1 billion people who will have access to the internet via mobile tower with starlink & competitors backhaul in a few years. This is enormous.

Re: How satellite ‘megaconstellations’ will photobomb astronomy images

#162

Post by welterde »

0-_-0 wrote: post #158
welterde wrote: post #149

Earlier quoted context omitted.

Sure. And for small field of view things that might be the future. But if you are looking at large chunks of the sky at some point with enough satellites the shutter will have to stay shut for the whole duration of the exposure.. so not really a good solution for that.

What if SpaceX funded research into shutters that cover part of the CCD? Is that a possible solution?

Shutters for astronomical instruments are specifically designed to open and close evenly, so that each pixel of the detector receives the same amount of exposure time (as good as is possible). Otherwise it becomes very difficult to calibrate the image, since some parts of the image received more light than others.

Even opening and closing the shutter multiple times during one exposure will cause issues - but probably still possible to get under control. But covering parts of the detector will create significant variants that will be extremely hard to control for. Keep in mind we don't really want pretty pictures, but we use these images to measure the brightness of objects in those images (photometry).

Re: How satellite ‘megaconstellations’ will photobomb astronomy images

#163

Post by 0-_-0 »

welterde wrote: post #149
0-_-0 wrote: post #140

Earlier quoted context omitted.

Can you move the shutter in front of the receiver when you know a satellite will transit?

Sure. And for small field of view things that might be the future. But if you are looking at large chunks of the sky at some point with enough satellites the shutter will have to stay shut for the whole duration of the exposure.. so not really a good solution for that.

(can't reply below) If you had a localised shutter covering pattern X for 6 seconds, could you compensate for that by covering the inverse pattern of X for 6 seconds to get the same exposure for all pixels? So if you covered 3 satellite streaks of 6 seconds each using non-verlapping patterns (A,B,C) you could compensate for that by ending your exposure with covering the inverse of A+B+C for 6 seconds, adding only 6 seconds to your total exposure time and get uniform exposure.

Re: How satellite ‘megaconstellations’ will photobomb astronomy images

#164

Post by simion314 »

BurningFrog wrote: post #159
simion314 wrote: post #45

Earlier quoted context omitted.

Will those american billionaires pay say for more European satellites to compensate? What if this were Chinese satellites would you have the same opinion? It would be great if this billionaires would also launch scientific satellites payed from their pocket to compensate, then I would change my mind.

SpaceX is lowering satellite launch cost by 90% for anyone, Chinese or otherwise. This should start a golden age of space astronomy, even if Elon doesn't give away some telescope launches as PR.

The launch costs is just a small part of the total costs.

You destroy my house and I should be happy you offer me a discount when I buy new blueprints from you.

Re: How satellite ‘megaconstellations’ will photobomb astronomy images

#165

Post by welterde »

0-_-0 wrote: post #163
welterde wrote: post #149

Earlier quoted context omitted.

Sure. And for small field of view things that might be the future. But if you are looking at large chunks of the sky at some point with enough satellites the shutter will have to stay shut for the whole duration of the exposure.. so not really a good solution for that.

(can't reply below) If you had a localised shutter covering pattern X for 6 seconds, could you compensate for that by covering the inverse pattern of X for 6 seconds to get the same exposure for all pixels? So if you covered 3 satellite streaks of 6 seconds each using non-verlapping patterns (A,B,C) you could compensate for that by ending your exposure with covering the inverse of A+B+C for 6 seconds, adding only 6 s…

If the conditions are quite stable that might work (or if one can live with limited accuracy), but conditions tend to change over time (moon position, thin clouds and of course the seeing - how much the atmosphere distorts the image) so nothing is as straightforward as one might hope for.

In space that approach would work quite well indeed, but then you wouldn't need it in the first place..

Edit: Even if one still has to mask the streak in the data in the end, it might still be useful to do, since it will protect the rest of the image from any excess blooming.

Re: How satellite ‘megaconstellations’ will photobomb astronomy images

#166

Post by DoingIsLearning »

tom-khagai wrote: post #136
DoingIsLearning wrote: post #36

Earlier quoted context omitted.

> there is so much more demand for global, low-latency wireless internet than for astronomical observations. This is very much not true and a remarkably narrow utilitarian view. I understand US folks are poorly served in terms of ISP infrastructure and competition but please don't try to project those issues as a 'global' problem. Internet service is a solved problem, you have transoceanic cables and distribution net…

The demand is not limited to americans, most third-world countries will benefit from having high speed internet unconstrained by local infrastructure and lack of investment. Having stayed in South East Asia I know the locals would very much appreciate having more than one option: pay-as-you-go mobile data bundles. Even in rural parts of Scandinavia where I spent my vacation, 4G signal was too weak and ISP's refuse to…

The demand that exists is tackled by an increase and expansion of the existing ISP and public infrastructure.

A satellite based internet provider is inneficiently duplicating the existing fiber/copper/cellular infrastructure but more importantly cannot scale to serve the billions of people you mention in your comment.

Do the maths you cannot keep up this alleged 50Mbps link if you add more than a few million users, there is a finite amount of satellites they can add in contiguous trajectories.

The capacity issue means this will never be affordable but to a few select few or state/defense actors.

I agree with your problem statement but this unfortunately is just not the solution.

Re: How satellite ‘megaconstellations’ will photobomb astronomy images

#167

Post by sreevisakh »

0-_-0 wrote: post #145
vanderZwan wrote: post #120

Earlier quoted context omitted.

First of all, as GP pointed out: whose cost? Second of all: I highly doubt that this is "trivial", given that observatories are built in the most remote areas of the planet because light pollution was already an enormous problem before these satellites appeared, despite the extra costs that adds to any such project.

Light pollution is global, while a satellite streak is localised to a part of an image. These are not the same problem.

It's the other way around. It's possible to escape light pollution by moving away from electrified areas, whereas satellite streak ruins observations in every part of the world. Besides, the streaks are not really localized in the image. Its glow reportedly extends up to 15 arc seconds. That's a very large area for a carefully exposed array.

Re: How satellite ‘megaconstellations’ will photobomb astronomy images

#168

Post by cheph »

jsiepkes wrote: post #46
cheph wrote: post #6

Earlier quoted context omitted.

> We need to do something about millionaires. Urgently. Can you elaborate what premise this conclusion follows from? And what do you want to do about them? And going out on a limb, I would assume you have a problem with the satellites, but Amazon, SpaceX and OneWeb are companies, not a Millionaires. So maybe you meant to say we should do something about companies?

> I would assume you have a problem with the satellites, but Amazon, SpaceX and OneWeb are companies, not a Millionaires. Elon Musk is CEO of SpaceX and owns > 50% of the shares. As for Blue Origin (aka Bezos / Amazon); Bezos is the owner of the company. That means these people can make decisions on their own without consulting anyone else. They appoint the board, they appoint the CEO, etc. And sure, there are outsid…

So are you positing that it would be impossible for a company to make such decisions if no individual shareholder owned >50% of the shares? If so the problem is still not with millionaires.

And I'm not sure by what mechanism this will function. What will prevent a company where no individual shareholder owns >50% of shares from making a similar choice?

Re: How satellite ‘megaconstellations’ will photobomb astronomy images

#169

Post by sreevisakh »

sumedh wrote: post #153
ashtonbaker wrote: post #150

Earlier quoted context omitted.

Not really?

Making space flight cheaper and more reliable certainly helps advance human knowledge in my opinion.

Spaceflight wouldn't be there in the first place if astronomical observations didn't help generations of scientists (including Kepler, Newton and Oberth) evolve the concepts of astrodynamics. Astronomy is far from having given up all its secrets - many of which will surely be applied in everyday life some time in the future. Besides, nobody would be complaining if this was about making spaceflight cheaper. This is about commercial exploitation of space by destroying a scientific resource. As others mentioned, there are easier ways to bring internet to rural areas - if only there was social resolve. This is more about worldwide internet controlled by a few big corporations.

Re: How satellite ‘megaconstellations’ will photobomb astronomy images

#170

Post by m4rtink »

fock wrote: post #72
netram88 wrote: post #10

What I'm concerned about is how much the launching of tens of thousands (maybe hundreds of thousands) of satellites will affect our ability to launch things out of orbit. Launch windows are already very precisely calculated, and the more junk we put in orbit the harder that will become.

that's actually a fascinating idea. think about how humanity solves the environment problems and fusion works out, bringing global peace and prosperity for once. Now a smallish rock comes from space. We don't see it, because of "we go to mars, bro"-elon making ground based astronomoy infeasible and debris from crashes from his great internet satellites making 9/10 new launches fail. so, even if we saw it, we couldn't…

Space based observation of objects on potential collision course with Earth is far superior to earth observatio. For example you can't really observe anything coming from the direction of the sun. Look up NEOCam project that aims to have a near Earth asteroid telescope in solar orbit.
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