Goregue t1_jai81dk wrote on March 1, 2023 at 4:58 PM

Reply to comment by Adeldor in Satellite Constellations Are an Existential Threat for Astronomy by ChieftainMcLeland

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.

Adeldor t1_jai9c1w wrote on March 1, 2023 at 5:06 PM

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.

Goregue t1_jaibtby wrote on March 1, 2023 at 5:22 PM

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.

dern_the_hermit t1_jaj4e2t wrote on March 1, 2023 at 8:21 PM

> 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".

Adeldor t1_jaifbtv wrote on March 1, 2023 at 5:44 PM

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.

versedaworst t1_jano9bp wrote on March 2, 2023 at 7:09 PM

> 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.