Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

How satellite ‘megaconstellations’ will photobomb astronomy images

nature.com

Post reply on HN
Print view View original

121–130 of 395 posts

Re: How satellite ‘megaconstellations’ will photobomb astronomy images

#121

Post by SiempreViernes »

ImaCake wrote: post #116
51Cards wrote: post #114

Earlier quoted context omitted.

As I noted on a similar thread the issue is not removing the streaks, it's what data is lost behind those. If you take a look at this image you'll see that it can be a non-trivial amount of interference in some cases and that data can't just be filled in with "black". https://i.imgur.com/Qdt0N2g.png The interference also causes a "glow" effect on the CCD which corrupts the data well beyond the edges of the main strea…

I guess you could statistically impute that data. But it is the long tail of unlikely readings which are generally interesting, and imputation will not find those.

Imputing makes little sense when you are trying to _measure_ though.

Re: How satellite ‘megaconstellations’ will photobomb astronomy images

#122

Post by jobigoud »

0-_-0 wrote: post #115
verytrivial wrote: post #15

The article covers the mitigations already in place and how they only partially resolve the issue. These satellites are low, bright (at dawn/dusk) and very soon to be incredibly numerous. Yes, it is possible for data workflows to post-process these streaks away, but not all configurations allow this, and whereas previous intrusions were somewhat rare and could be ignored that simply won't be the case due to three com…

Is it a difficult problem to solve though in software? On its face it seems trivial, and something that should be part of an astronomer's job description. The cost of not having internet satellites seems to be many orders of magnitude higher than writing software to get around the problem.

> On its face it seems trivial

To me it seems completely impossible. How exactly do you expect to replace the missing information? Statistically from the neighboring pixels or frames? That works if your goal is to make an image prettier, but if you want to make measurements on the data "inventing" the background is not good enough.

Re: How satellite ‘megaconstellations’ will photobomb astronomy images

#123

Post by acqq »

LatteLazy wrote: post #107
acqq wrote: post #99

Earlier quoted context omitted.

> has to help fund space based telescopes. The telescopes from space can't do what the Earth based can, so the premise is false.

Is that true? What are they missing? I thought Hubble, JWST etc could do basically everything a ground based one could do only better? Excluding radio telescopes which are huge but not effected by satellites anyway.

> Is that true?

Absolutely.

> What are they missing?

Everything. Whatever one can do on Earth which requires big optics and maintenance is many millions times more expensive to do in the orbit. And the many million times higher expenses of all astronomical projects in the world are certainly not going to be covered by the operators of the "cheap and small" satellites.

Optics, for the purposes we talk about, just doesn't work small. One needs big telescopes, big telescopes just can't be simply launched like the "cheap and small" can -- there are no scalable technologies for that.

Imagine it like this: there is a technology to launch "ant" satellites. But on Earth, one has "elephant" observatories everywhere. No rocket can even launch a single one. And the maintenance of an elephant in the orbit is insanely complicated.

So those who dismiss the problem with "ha ha we can send ants for them too" just show that they don't even understand what the problem is. But to uninformed people, it sounds "plausible."

No, not everything we've discovered was made by Hubble, and also won't be made with JWST.

And the demonstrated complexity of JWST should just give you pause, if you read about it. It's still not launched. The direct development of it started in 1996, the current plan is to launch it "just" 25 years later(!) You know all the problems to "get it right" to unfold? Exactly because the limitations of what can be launched and how.

More specifically, at one moment in time it was believed that the atmosphere limits what can be done from Earth. But then these problems were solved: for almost all purposes, Earth based observatories remain millions of time cheaper and better ways to make observations (as in, when something gets expensive enough, it won't even be done at all).

From 2019:

"This Is Why We Can't Just Do All Of Our Astronomy From Space" by Ethan Siegel

https://www.forbes.com/sites/startswithabang/2019/11/27/this...

Moreover, you can also read in other articles that even the approaches that were suggested by the astronomers to mitigate the problems were completely ignored by the satellite operators.

https://www.forbes.com/sites/startswithabang/2019/11/20/this...

https://www.forbes.com/sites/startswithabang/2020/01/30/dang...

Re: How satellite ‘megaconstellations’ will photobomb astronomy images

#124

Post by vanderZwan »

0-_-0 wrote: post #117
51Cards wrote: post #114

Earlier quoted context omitted.

As I noted on a similar thread the issue is not removing the streaks, it's what data is lost behind those. If you take a look at this image you'll see that it can be a non-trivial amount of interference in some cases and that data can't just be filled in with "black". https://i.imgur.com/Qdt0N2g.png The interference also causes a "glow" effect on the CCD which corrupts the data well beyond the edges of the main strea…

It seems to be around 1-2%, which I would say is trivial. This can be further reduced if you use multiple exposures because then only 1 contains the streak. Getting satellite data from SpaceX about satellite positions and turning off the receiver for a few seconds would also mitigate the issue. I don't understand how this is treated as a problem that's worth halting satellite launches over.

> which I would say is trivial

I'm frankly amazed at the arrogance on display here. Do you honestly think you know better then the entire field of astronomy?

Re: How satellite ‘megaconstellations’ will photobomb astronomy images

#125

Post by welterde »

0-_-0 wrote: post #117
51Cards wrote: post #114

Earlier quoted context omitted.

As I noted on a similar thread the issue is not removing the streaks, it's what data is lost behind those. If you take a look at this image you'll see that it can be a non-trivial amount of interference in some cases and that data can't just be filled in with "black". https://i.imgur.com/Qdt0N2g.png The interference also causes a "glow" effect on the CCD which corrupts the data well beyond the edges of the main strea…

It seems to be around 1-2%, which I would say is trivial. This can be further reduced if you use multiple exposures because then only 1 contains the streak. Getting satellite data from SpaceX about satellite positions and turning off the receiver for a few seconds would also mitigate the issue. I don't understand how this is treated as a problem that's worth halting satellite launches over.

CCDs are not really receivers that can be turned off for a couple seconds. A physical shutter moves in front of the detector and covers it (for most instruments as they exist right now).

Re: How satellite ‘megaconstellations’ will photobomb astronomy images

#126

Post by vanderZwan »

reitzensteinm wrote: post #69
q3k wrote: post #52

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. I've had faster Internet than the average Starlink speedtest says, in rural Romania, at the foot of a mountain, wild bears and all: https://twitter.com/q3k/status/1172621386977861632 . Internet access in rural areas is pretty much a solved problem, it just now hing…

I've been there, it's beautiful. Although under ten kilometers from a town of tens of thousands wasn't exactly what I had in mind; I was picturing some of the places I've been in Africa that don't have mobile reception and may well never get it if it means laying fiber. A solar powered base station that relayed mobile internet, even if slow, would make a meaningful difference. The point of my comment isn't to defend…

> I was picturing some of the places I've been in Africa that don't have mobile reception and may well never get it if it means laying fiber.

When was the last time that you were in Africa? And in which country, because it's an entire continent.

EDIT: So I guess HN doesn't like being called out on https://africasacountry.com/ issues? Well sorry not sorry, but as someone born in Ghana I'm more a little tired of the sentiment on display in the cited part of comment I'm reacting to, which is the implication that Africa as an entire continent is inherently and forever will be a place too poor to have proper infrastructure.

Re: How satellite ‘megaconstellations’ will photobomb astronomy images

#127

Post by 51Cards »

0-_-0 wrote: post #117
51Cards wrote: post #114

Earlier quoted context omitted.

As I noted on a similar thread the issue is not removing the streaks, it's what data is lost behind those. If you take a look at this image you'll see that it can be a non-trivial amount of interference in some cases and that data can't just be filled in with "black". https://i.imgur.com/Qdt0N2g.png The interference also causes a "glow" effect on the CCD which corrupts the data well beyond the edges of the main strea…

It seems to be around 1-2%, which I would say is trivial. This can be further reduced if you use multiple exposures because then only 1 contains the streak. Getting satellite data from SpaceX about satellite positions and turning off the receiver for a few seconds would also mitigate the issue. I don't understand how this is treated as a problem that's worth halting satellite launches over.

In this sample image it's not just the white streak but the glow caused by it which extends about 5-8x it's width to either side. More like 20% of this image is unreliable data.

Taking multiple exposures isn't always possible, this may be a continuous multi-hour exposure. Additionally if you're looking for transients, NEOs, or star field mapping then there is definitely lost data that can't just be inferred.

The conversation isn't just about halting launches. It's about recognizing and working to mitigate the issue now before we get too far down this path.... and accepting that it's not a trivial "photoshop" problem.

Re: How satellite ‘megaconstellations’ will photobomb astronomy images

#128

Post by sumedh »

RedShift1 wrote: post #7

This is bad. This is really really bad. The EU has invested billions in telescopes and that's now going to go to waste. Instead advancing human knowledge it's just going to fill rich guy pockets even more.

> Instead advancing human knowledge it's just going to fill rich guy pockets even more.

Isnt Elon helping to advance human knowledge as well?

Re: How satellite ‘megaconstellations’ will photobomb astronomy images

#129

Post by jclos »

welterde wrote: post #96
dr_dshiv wrote: post #74

Earlier quoted context omitted.

This paper suggests otherwise, what are your thoughts? Optical aperture synthesis with electronically connected telescopes https://www.nature.com/articles/ncomms7852

Like I said interferometers exist but they are very limited in their capabilities. For example the VLT interferometer is limited to observing objects that are brighter than 18th magnitude (and that's using multiple 8m telescopes! Using the auxiliary telescopes which are still 2m you are limited to about 10th magnitude). Something that is easily within the reach of a single telescope less than 50cm in diameter (single…

Thank you for the explanation, I was wondering the exact same thing and I know nothing about optics.

Re: How satellite ‘megaconstellations’ will photobomb astronomy images

#130

Post by Turing_Machine »

q3k wrote: post #52
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. I've had faster Internet than the average Starlink speedtest says, in rural Romania, at the foot of a mountain, wild bears and all: https://twitter.com/q3k/status/1172621386977861632 . Internet access in rural areas is pretty much a solved problem, it just now hing…

There isn't anywhere in Europe that's "rural" by the standards of North America.

The North Slope Borough in Alaska is nearly the size of Romania, but has only about 9,000 people living there. The state as a whole is larger than all of Western Europe, but has only about 700,000 people.

Much of Canada is the same, only more so.

Post reply on HN