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Adeldor t1_jafswvk wrote

Instead of blatant click-bait magazine articles, here are the opinions on the subject directly from major professional observatories (a variation of a comment I made a while ago):

Below are four links to professional observatory opinions, with salient quotes. There will be effects, but they are in general minor, or there are mitigating actions being taken now, from satellite design modification to filtering software and timing.

  • "The study finds that large telescopes like ESO's Very Large Telescope (VLT) and ESO's upcoming Extremely Large Telescope (ELT) will be "moderately affected" by the constellations under development. The effect is more pronounced for long exposures (of about 1000 s), up to 3% of which could be ruined during twilight, the time between dawn and sunrise and between sunset and dusk. Shorter exposures would be less impacted, with fewer than 0.5% of observations of this type affected. Observations conducted at other times during the night would also be less affected, as the satellites would be in the shadow of the Earth and therefore not illuminated." [1]

  • "Yet despite the increase in image streaks, the new report notes that ZTF science operations have not been strongly affected. Study co-author Tom Prince, the Ira S. Bowen Professor of Physics, Emeritus, at Caltech, says the paper shows a single streak affects less than one-tenth of a percent of the pixels in a ZTF image ... Prince says that software can be developed to help mitigate potential problems; for example, software could predict the locations of the Starlink satellites and thus help astronomers avoid scheduling an observation when one might be in the field of view. Software can also assess whether a passing satellite may have affected an astronomical observation, which would allow astronomers to mask or otherwise reduce the negative effects of the streaks." [2]

  • "Most recently, the NRAO and GBO have been working directly with SpaceX to jointly analyze and minimize any potential impacts from their proposed Starlink system. These discussions have been fruitful and are providing valuable guidelines that could be considered by other such systems as well ... Among the many proposals under consideration are defining exclusions zones and other mitigations around the National Science Foundation’s current radio astronomy facilities and the planned future antenna locations for the Next Generation Very Large Array." [3]

  • More recently, the National Science Foundation has published an astronomy coordination agreement, detailing procedures and designs aimed at minimizing interference and interaction between observatories and Starlink (both ways, as observatories use sky-pointed lasers to create artificial stars for focussing and the like). [4]

Meanwhile, professional and amateur astronomers both have tools now to deal with the existing satellites and (far worse) night flying aircraft.

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Sealingni t1_jah74yd wrote

Thanks for this rational reply. Please continue posting, we need more reasonable information when faced with sensationalist articles.

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Goregue t1_jai81dk wrote

You are cherry picking data to seem like there is no problem. From the same article 1 you link, it says:

"The study also finds that the greatest impact could be on wide-field surveys, in particular those done with large telescopes. For example, up to 30% to 50% of exposures with the US National Science Foundation's Vera C. Rubin Observatory (not an ESO facility) would be "severely affected”, depending on the time of year, the time of night, and the simplifying assumptions of the study. Mitigation techniques that could be applied on ESO telescopes would not work for this observatory although other strategies are being actively explored."

"The ESO study uses simplifications and assumptions to obtain conservative estimates of the effects, which may be smaller in reality than calculated in the paper."

"Many of the parameters characterising satellite constellations, including the total number of satellites, are changing on a frequent basis. The study assumes 26,000 constellation satellites in total will be orbiting the Earth, but this number could be higher. "

From article 2 you link:

"In the future, the scientists expect that nearly all of the ZTF images taken during twilight will contain at least one streak, especially after the Starlink constellation reaches 10,000 satellites, a goal SpaceX hopes to reach by 2027.

"We don't expect Starlink satellites to affect non-twilight images, but if the satellite constellation of other companies goes into higher orbits, this could cause problems for non-twilight observations," Mróz says. "

"The study authors also note their study is specific to ZTF. Like ZTF, the upcoming Vera C. Rubin Observatory, under construction in Chile, will also survey the sky nightly, but due to its more sensitive imager, astronomers predict that it may be more negatively affected by satellite streaks than ZTF."

Articles 3 and 4 describe mitigation strategies that SpaceX is looking into. But crucially, it ignores that in the future dozens of companies, from all over the world, will want to launch satellites constellations. It's useless if SpaceX follows all mitigation procedures to avoid contaminating astronomical observations, but a random company from China decides that this is not important and launches the satellites anyway. The number of satellites is growing at an exponential rate, and in 10-20 years we will have possibly ten or a hundred times more satellites than SpaceX is currently planing.

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Adeldor t1_jai9c1w wrote

Yes, the Rubin telescope is more sensitive. Nevertheless, in general, the numbers I extracted apply. Meanwhile, regarding that telescope, they go on to say:

> ... depending on the time of year, the time of night, and the simplifying assumptions of the study. Mitigation techniques that could be applied on ESO telescopes would not work for this observatory although other strategies are being actively explored." [Emphasis added]

Regarding other constellations, yes, their higher orbits will be more of an issue. One of the good side effects of Starlink's low orbits is the short period of twilight illumination.

But again, astronomy is in no way experiencing an "existential threat." It's a ridiculous exaggeration. There will be effects. There are and will be workarounds and mitigations. And the sky will be shared.

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Goregue t1_jaibtby wrote

Why are you so keen to downplay the effects of these satellites constellations? Astronomers are trying so hard to warm the public but people simply choose to ignore them and choose to believe that it's not really a problem and that we will easily mitigate the satellites. It reminds me of the climate change debate, where scientists tried for decades to warm the public of this danger, but people simply ignored them, and now that it is becoming mainstream to accept climate change it is too late. Of course satellites constellations are not at the same level of threat as climate change, but the same logic applies. In fact, I suspect there is a great care of astronomy institutions and the writers of these articles you linked to seem "moderate" on this issue, otherwise people would immediately think they are crazy and would promptly ignore the issue. Exactly like what happens with climate change. So stop choosing to believe that everything is okay when it isn't. Satellites constellations are a huge deal and anyone that cares about science should be alarmed by them.

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dern_the_hermit t1_jaj4e2t wrote

> Why are you so keen to downplay the effects of these satellites constellations

Why are YOU so keen on exaggerating the effects? An "existential threat" means astronomy cannot happen, not "every third ultra-wide image loses a few pixels to a satellite".

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Adeldor t1_jaifbtv wrote

Don't conflate my comments with political denial. The point of my responses:

  • the sky is not falling (if you'll pardon the pun). Astronomers - professional and amateur (I count myself among the latter) - continue to operate successfully, what with the tools that are available now to ameliorate the effects of yet higher flying satellites (illuminated for longer periods) and aircraft (illuminated at all hours of the night).

  • Truly global high speed, low latency internet has huge benefits on society, from providing access to remote communities, to assisting those defending their lands. Even without considering the impossibility of global mobile operation otherwise, there's no other kind of system capable of such ubiquitous coverage.

  • a longer term/fuzzier point - beyond terrestrial mitigations, space based observatories are and will be supplementing ground-based telescopes. The technologies that make constellations cost effective will no doubt feed into making more space-borne instruments feasible.

I've seen it written that Elon Musk, Jeff Bezos, etc don't own the sky, and this is certainly true. However, neither do astronomers. Constellations are beyond the point of proving their dramatic worth, so they're here regardless of opinion. Observatories and constellation operators will work together and cooperate because there's no alternative.

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versedaworst t1_jano9bp wrote

> Articles 3 and 4 describe mitigation strategies that SpaceX is looking into. But crucially, it ignores that in the future dozens of companies, from all over the world, will want to launch satellites constellations. It's useless if SpaceX follows all mitigation procedures to avoid contaminating astronomical observations, but a random company from China decides that this is not important and launches the satellites anyway. The number of satellites is growing at an exponential rate, and in 10-20 years we will have possibly ten or a hundred times more satellites than SpaceX is currently planing.

This is really the crucial thing here. People can argue all they want about Starlink’s potential impact and mitigation strategies etc. But Starlink is going to be one of potentially dozens of similar services in the next few decades. There are already many being worked on. Really strict standards need to be set.

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FlingingGoronGonads t1_jahp0sh wrote

This is borderline Misinformation. You are attempting to create an impression that there is no problem, and that everything has been or will be mitigated. Some choice quotes, with sources:

From that totally disreputable, clickbait publication, Science.org:

> The Rubin Observatory, with an 8.4-meter mirror that will take pictures of the sky the size of 40 full Moons in 30-second exposures, "is the perfect machine for running into these satellites," Tyson says.

> He and his team conducted simulations that suggested the track of a satellite image across their camera would saturate each camera pixel as it passes, and cause leakage into neighboring ones. The resulting artifacts "cannot be removed in software. We have failed in doing that," Tyson says. The team looked at altering schedules to avoid satellite trails, but with such a wide field of view, avoiding thousands of satellites would end up as "a wild goose chase," he says.

Speaking of the Rubin Observatory:

> Simulations of the LSST observing cadence and the full 42,000 SpaceX satellite constellation show that as many as 30% of all LSST images would contain at least one satellite streak. With constellations of 400,000 LEOsats, most images will have very bright streaks.

> Due to its rapid cadence, LSST cannot usefully avoid tens of thousands of LEOsats.

> Darkening satellites to 7th magnitude would simplify removal of some artifacts in LSST images, but there is no guarantee most of the satellites will be limited in brightness to fainter than 7th magnitude.

> The bright main satellite trail would still be present, potentially creating bogus alerts and systematics at low surface brightness. This is a challenge for science data analysis, adding significant effort and potentially limiting discovery of the unexpected.

> However there is a larger challenge: because of the unprecedented large samples, LSST science will be limited by systematics rather than sample variance (area incompleteness). Of concern are various systematic effects that do not simply scale with the number of lost pixels—in other words, the residuals from these mitigation strategies on the science cases for which LSST was designed. For example, the LSST ability to detect asteroids approaching from directions interior to the Earth's orbit may be severely impacted because those directions are visible only during twilight when LEO satellites are brightest—nearly every LSST image taken at this time would be affected by at least one satellite trail. [My emphasis added]

TLDR: I could provide further quotes, especially about the harm to radio astronomy, but the point here is that software can't remove the streak when the CCD has been saturated - that would be like dumping thousands of identical lemons into a bin that initially contains only one or two, shaking the bin vigorously, and then trying to identify the original occupants. This isn't about amateur astrophotography - this is about trying to identify transient phenomena that are captured in single exposures. No software in the world can undo the harm if hardware and physics don't allow for it.

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Adeldor t1_jahsf9s wrote

You speak of misinformation, then misrepresent what I wrote with this:

> You are attempting to create an impression that there is no problem, and that everything has been or will be mitigated. [emphasis added]

In fact I wrote:

> There will be effects, but they are in general minor, or there are mitigating actions being taken now ... [emphasis added]

I neither wrote nor implied "no problem" and "everything has been or will be mitigated." Those are your words. Further, I provide the links for everyone to read the full releases in context, in an explicit attempt to avoid the very sin you seem to imply I'm committing.

Regardless, constellations are here now. Their worth has been proven, Starlink at least and professional observatories are working together to share the sky, and astronomy is not facing an existential threat, per that click-bait headline.

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FlingingGoronGonads t1_jahtzyv wrote

I'll leave it to the alert reader to actually read the quotes we both provided. The only thing I will say to you about your "in general minor" harms that have no potential for mitigation (and I have provided a source for that statement already):

If observatories are literally unable to carry out part or all the mission objectives for which they are designed (like searching for Atira-type asteroids, which must be searched for at twilight because they orbit the Sun closer than Earth does), you have an interesting definition of the word "minor".

EDITED TO ADD: This comment has been up for hours and stands at a mere minus-2. I'm disappointed in you Musk worshippers, you're off your game here. I suppose I could keep fielding clueless anti-science comments like dern_the_hermit's below all day, but I'm done with this thread. For people that actually want to understand science and the problems that satellite swarms present, please remember that observatories and photometers are not just taking one-off snapshots - they're often taking data over a certain period of time to build up a light curve (a graph of change in brightness versus time), to give just one example. Tearing out gaps in a curve means loss of data that can be irretrievable, especially when an object is doing something unexpected. You can't mathematically reconstruct something that is non-repeatable!

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dern_the_hermit t1_jaj4p4r wrote

It's just bonkers to suggest observatories can't observe because a portion of some pictures is lost.

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FlingingGoronGonads t1_jaj6mwh wrote

What happens when the actual object you're trying to observe is blotted out with an adjacent satellite streak? Vera Rubin will be taking short exposures - lots of them. Wide-field surveys need the sky to be open because, you know, they're looking for unknown sources, or need to see if known sources are doing unexpected things. Why is that difficult to understand?

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dern_the_hermit t1_jaj8btq wrote

> What happens when the actual object you're trying to observe is blotted out with an adjacent satellite streak

Take another picture. Pictures are cheap.

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FlingingGoronGonads t1_jaj8v7t wrote

Sure, chuckles, loss of data is no big deal. Especially when you know ahead of time that the transient object/behaviour you're looking for means that the light source has no guarantee of being at the same brightness or position next exposure.

Musk fanatics are forever betraying their ignorance of science. Bye-bye, troll.

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dern_the_hermit t1_jaj9367 wrote

Insults are completely inappropriate.

> loss of data is no big deal

It's not necessarily an existential threat, is the point. Let's stayed focused and on-topic here.

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Dismal-Philosopher-4 t1_jafxfte wrote

> blatant click-bait magazine article

This magazine is quite respected and has published articles by more than 150 Nobel Prize-winning scientists. It's as good as it gets.

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Adeldor t1_jagvvp1 wrote

That was then. The current Scientific American doesn't hold a candle to its former self. IMO the decline started when they ceased publishing substantial scientific projects and experiments such as these in their Amateur Scientist column. So no, it isn't now "as good as it gets."

Regardless, the direct statements from professional observatories carry more weight, and that SciAm title is unquestionably click-bait.

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ferrel_hadley t1_jah4wbx wrote

Its swirling around an IFLScience style drain.

It really is past its best.

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