Impacts of Large Satellite Constellations on Astronomy

[deltaV]

If the claim that terrestrial astronomy is irrevocably broken with the advent of megaconstellations is going to be pursued, then a commitment to a permanent tax by FCC equivalents on spacecraft with substantial terrestrial impact (read any megaconstellation, SAR operators, large area spacecraft) to fund national space based astronomy projects, and permanently abandon any terrestrial project not in active use or under construction has to be made (under the assumption that they will be retired in exchange for replacement space based assets).

You can't say terrestrial astronomy is screwed and still try to ask for terrestrial astronomy handouts. Give up and go orbital.

IMO the astronomy community is in the best position to decide how to use the money raised from a bright satellite tax and should have the choice of how to spend it. Potential uses include better software to identify bad pixels and frames, more terrestrial telescopes so they can get the desired observations done despite losing twilight hours, space telescopes that avoid the problem by being above the mega-constellations, something totally unrelated such as a space X-ray telescope, or just use the money to increase the NSF and/or NASA astronomy budgets. I would actually encourage them to spend the money on things that seem unrelated - we want astronomers to focus on doing the best astronomy they can, not focus on paperwork and how much of a victim they are.

[Lee Jay]

If the claim that terrestrial astronomy is irrevocably broken with the advent of megaconstellations is going to be pursued, then a commitment to a permanent tax by FCC equivalents on spacecraft with substantial terrestrial impact (read any megaconstellation, SAR operators, large area spacecraft) to fund national space based astronomy projects, and permanently abandon any terrestrial project not in active use or under construction has to be made (under the assumption that they will be retired in exchange for replacement space based assets).

How much would it cost to launch a 25-30m multi-hundred ton telescope like the GMT or ELT?  How much extra would it cost to build one for space instead of terrestrial deployment?

[Zed_Noir]

If the claim that terrestrial astronomy is irrevocably broken with the advent of megaconstellations is going to be pursued, then a commitment to a permanent tax by FCC equivalents on spacecraft with substantial terrestrial impact (read any megaconstellation, SAR operators, large area spacecraft) to fund national space based astronomy projects, and permanently abandon any terrestrial project not in active use or under construction has to be made (under the assumption that they will be retired in exchange for replacement space based assets).

How much would it cost to launch a 25-30m multi-hundred ton telescope like the GMT or ELT?  How much extra would it cost to build one for space instead of terrestrial deployment?

Might be better to fund a dozen or so roughly Hubble size space telescopes with adequate datalink bandwidth. Since that will generated observation time slots for more users.

[DigitalMan]

If the claim that terrestrial astronomy is irrevocably broken with the advent of megaconstellations is going to be pursued, then a commitment to a permanent tax by FCC equivalents on spacecraft with substantial terrestrial impact (read any megaconstellation, SAR operators, large area spacecraft) to fund national space based astronomy projects, and permanently abandon any terrestrial project not in active use or under construction has to be made (under the assumption that they will be retired in exchange for replacement space based assets).

How much would it cost to launch a 25-30m multi-hundred ton telescope like the GMT or ELT?  How much extra would it cost to build one for space instead of terrestrial deployment?

Might be better to fund a dozen or so roughly Hubble size space telescopes with adequate datalink bandwidth. Since that will generated observation time slots for more users.

I'd love to see a project to build several Hubble-sized telescopes. If you could attempt using them in array mode that would be something to look forward to.

I think it was Deep Space 3 that was intended to test out something like that on a small scale. I was upset when they cancelled it.

[eeergo]

This also only looks at visible light observations. Radio is a bigger problem. Starlink and other constellations will blast the ground with soo many colors of radio light. All the mitigations spaceX is trying to do for starlink only extends to visible light. The only way to not blind radio telescopes is to turn off over certain regions.

Indeed: https://twitter.com/jvierine/status/1707498050288336996

Wow. Who decides what is "useful data". You? 

You know, painstaking lengths have to be covered to justify the indispensability of astronomical, and in general, scientific observations, including questioning data quality and usefulness. Yet the necessity of a retail commercial communication service is never put in question - a service which is largely advertised as useful for "gaming", general internet browsing (of which a very small amount is either indispensable or indeed useful), derivative finance fantasy-money-crunching, and leisure connections with joyrides. Unironically, the application that gets nearest to incontrovertible usefulness is actually: war and remote weapon control. Plus there ARE currently immediate alternatives to the most useful of those, while the alternative for science is -even technically- prospective at some indeterminate point in the future.

You can't say terrestrial astronomy is screwed and still try to ask for terrestrial astronomy handouts. Give up and go orbital.

Or give up megaconstellations in LEO, of which Starlink is the prime and only example for now, apart from being a prime precedent-setter... and go ground-based! You can even project small-scale space backup options for niche cases where ground-based is unfeasible! Vastly higher capacities, much cheaper (in principle, if we do away with inflated prices in certain markets) durable and easily-upgreadable passive infrastructure, providing more people with a living, much smaller environmental footprint, both on Earth and in LEO itself, negligible future risks coming from the system in case of bankrupcies or other failures, potentially more data privacy and options to diversify providers, fostering competition for small-scale companies and free trade... and zero impacts to astronomy, by the way.

[woods170]

However, we haven't discussed IR either, cause starlink blazes in those colors too. Yet not only is nothing being done about that, making them darker to visible light actually makes the IR problem vastly worse.

I don't see your problem. Given that our atmosphere is opaque to the vast majority of the IR part of the spectrum, it makes sense to do world-class IR astronomy from orbit, not from the surface. Why do you think IRAS, ISO, Spitzer, Hershel, WISE, Akari, Hubble and JWST exist(ed). Not because Starlink got in the way, but because IR astronomy can't be properly done from the surface. Even observatories at mountain tops are severely limited in what they can observe in the IR part of the spectrum. Same for balloon-based one-shot observatories. And guess which flying IR observatory was just retired, mostly over a lack of value-for-money...

[woods170]

If the claim that terrestrial astronomy is irrevocably broken with the advent of megaconstellations is going to be pursued, then a commitment to a permanent tax by FCC equivalents on spacecraft with substantial terrestrial impact (read any megaconstellation, SAR operators, large area spacecraft) to fund national space based astronomy projects, and permanently abandon any terrestrial project not in active use or under construction has to be made (under the assumption that they will be retired in exchange for replacement space based assets).

Climate change, to which pretty much every human on the planet is contributing, has substantially increased the levels of clear-air turbulence, thus impeding the  ability of visible light astronomers to make useful observations. It is one of the reasons why adaptive optics have become a major thing in astronomy. But adaptive optics has its limitations.

So, are we going to tax every human on the planet because surface-based astronomy is currently in a tight spot? I don't think so.

[edzieba]

Has anyone made a quantitative estimate of how much reflections from large constellations will cost astronomy in lost productivity and in mitigations? From the little I know it seems astronomers should be able to work around the satellite reflections with measures such as taking many short exposures and discarding the bad pixels in each frame, not using telescopes near dawn and dusk when they may see sun-lit satellites, or using more space-based telescopes. These mitigations could be expensive (especially if they have to use space telescopes) but probably not expensive enough to justify making internet significantly more expensive for millions of people.

As of today, its more than 10% of all observations are heavily impacted or thrown away. That number will only increase. I don't mean theres a streak in the corner. That 10% is of quite significant impact.

That depends on the proportion of observations that would otherwise make scientific contributions vs. those that are for other purposes or are rejected for other issues (e.g. aircraft overflights, streaks from other local objects, etc). For Starlink in particular (does not apply to Oneweb and other higher orbits) the illumination peak is during twilight, where astronomical observations are more opportunistic. If 10% of observations are impacted but those 10% impacted would have had a 90% rejection rate without satellite streaks due to background light, that's a big difference to impacting 10% of observations at midnight which would have a much higher baseline acceptance rate.

Huh? How do I unpack this. All the observations all the big telescopes make ARE for science. They are so over subscribed its not like they are just randomly pointing for fun half the time.

All* observations are intended for science. Not all will produce useful data. Clouds unfortunately still exist, sometimes atmospheric distortion is unacceptable, non-Starlink orbiting bodies can intrude in the frame, background illumination levels can be too high to observe your target, etc. Every* frame has a purpose, but not every one can satisfy that purpose.

However, we haven't discussed IR either, cause starlink blazes in those colors too. Yet not only is nothing being done about that, making them darker to visible light actually makes the IR problem vastly worse.

The dichroic coatings developed for Starlink are also effective in nIR and mid-IR, not just the visual spectrum. Even in thermal IR, emission is dependant on insolation just as with visual-range emission, so they glow in the same twilight conditions as in the visual range (where sky temperature makes IR observation even more difficult than normal). Observations of and calculations of Starlink impacts are also including IR effects, such as the ZTF studies.
 

I would ask instead why you are so keen to dismiss the concerns of the entire professional astronomy community. Its their job to know this stuff. Why not take what they say at face value? I would posit that if starlink was owned by bezos, no one would be ignoring and second guessing every single scientist on the planet involved in astronomy.

Rather than 'dismiss the concerns of the entire professional astronomy community', I instead listen to the IAU and similar bodies and the outcomes of the SATCON workshops and similar as to the impacts of constellations and their the effectiveness of mitigations. If you're even bothering to care about system ownership, then you're in the realm of crappy tabloid rags rather than actual publications. Finding other sources is recommended.


*Most. There will be some observations for engineering purposes too.

Wow. Who decides what is "useful data". You? 

The people making the requests for observations.
A frame with an overbright streak obscuring your target of interest is as useless as a frame with a cloud obscuring your target of interest, or a frame opportunistically taken early in the night that happened to have too much skyglow to observe your target of interest. Those Dasterdly Satellites are not the only thing that can render a ground-based frame useless for its intended purpose.

[deadman1204]

Sooo..... why don't we address the elephant in the room.
The entire astronomy community is very clear about the problems starlink is causing them. They are the professionals about this. We have 41 pages and counting of people ignoring or disagreeing with scientists about their field of study. Reasons for the disagreement are financial/economic. They don't want anything that will hurt a company they support.

If we swap the subject of astronomy with climate change, it becomes more clear. ITs the exact same pattern.
We have 41 pages of people denying science and scientists. There are names for that, a group that includes flat earthers and anti vaxxers. Anyone who denies what scientists say for their own agenda.

[Hyperborealis]

What, astronomers don't have an agenda? Per the US Bureau of Labor Statistics,  the mean salary for an astronomer in the US in 2022 was $127,246. Of course they have a selfish motive, and a considerable one at that.

Astronomy as a science is well and good. But draping this elite upper-class profession with pieties about climate change burns me up almost as much as astronomers placing their professional security above actually poor people in remote areas who stand to gain the benefits of international communications.

[D_Dom]

Let's not pollute this thread with "junk science" aspersions. Conspiracy theories are not going to be tolerated. Cite evidence supporting your on topic point or risk losing your post.

[daedalus1]

Climate change is a threat to humanity, restricting a percentage of earthly astronomical observation is a threat to no one.

[edzieba]

Sooo..... why don't we address the elephant in the room.
The entire astronomy community is very clear about the problems starlink is causing them.

They have been very clear about the problem multiple constellations launched without any brightness mitigations would cause. They have also been clear what mitigations are required, and have been clear that Starlink have been by far the most responsive in both communicating with the astronomy community and actively implementing mitigations prior to any sort of legislative requirement as soon as issues were highlighted (this includes both optical and RF). Starlink have also been pushing for legislative requirements in line with those proposed by the astronomy community to be imposed on all FCC spectrum requests for constellations.

There are been members of the press who have taken papers on the impact of everyone-launches-their-biggest-proposed-constellation-with-no-mitigations (the worst case scenario) and papers documenting the behaviour of Starlink satellites currently in orbit, and then conflating one with the other because it gets clicks. Listen to the IAU and read the SATCON workshop minutes, rather than clickbait.

What, astronomers don't have an agenda? Per the US Bureau of Labor Statistics,  the mean salary for an astronomer in the US in 2022 was $127,246. Of course they have a selfish motive, and a considerable one at that.

Astronomy as a science is well and good. But draping this elite upper-class profession with pieties about climate change burns me up almost as much as astronomers placing their professional security above actually poor people in remote areas who stand to gain the benefits of international communications.

Climate change is a threat to humanity, restricting a percentage of earthly astronomical observation is a threat to no one.

These are terrible takes. Impacting astronomical observations serves nobody.

[haywoodfloyd]

Has anyone made a quantitative estimate of how much reflections from large constellations will cost astronomy in lost productivity and in mitigations? From the little I know it seems astronomers should be able to work around the satellite reflections with measures such as taking many short exposures and discarding the bad pixels in each frame, not using telescopes near dawn and dusk when they may see sun-lit satellites, or using more space-based telescopes. These mitigations could be expensive (especially if they have to use space telescopes) but probably not expensive enough to justify making internet significantly more expensive for millions of people.

As of today, its more than 10% of all observations are heavily impacted or thrown away. That number will only increase. I don't mean theres a streak in the corner. That 10% is of quite significant impact.

That depends on the proportion of observations that would otherwise make scientific contributions vs. those that are for other purposes or are rejected for other issues (e.g. aircraft overflights, streaks from other local objects, etc). For Starlink in particular (does not apply to Oneweb and other higher orbits) the illumination peak is during twilight, where astronomical observations are more opportunistic. If 10% of observations are impacted but those 10% impacted would have had a 90% rejection rate without satellite streaks due to background light, that's a big difference to impacting 10% of observations at midnight which would have a much higher baseline acceptance rate.

Huh? How do I unpack this. All the observations all the big telescopes make ARE for science. They are so over subscribed its not like they are just randomly pointing for fun half the time.

All* observations are intended for science. Not all will produce useful data. Clouds unfortunately still exist, sometimes atmospheric distortion is unacceptable, non-Starlink orbiting bodies can intrude in the frame, background illumination levels can be too high to observe your target, etc. Every* frame has a purpose, but not every one can satisfy that purpose.

However, we haven't discussed IR either, cause starlink blazes in those colors too. Yet not only is nothing being done about that, making them darker to visible light actually makes the IR problem vastly worse.

The dichroic coatings developed for Starlink are also effective in nIR and mid-IR, not just the visual spectrum. Even in thermal IR, emission is dependant on insolation just as with visual-range emission, so they glow in the same twilight conditions as in the visual range (where sky temperature makes IR observation even more difficult than normal). Observations of and calculations of Starlink impacts are also including IR effects, such as the ZTF studies.
 

I would ask instead why you are so keen to dismiss the concerns of the entire professional astronomy community. Its their job to know this stuff. Why not take what they say at face value? I would posit that if starlink was owned by bezos, no one would be ignoring and second guessing every single scientist on the planet involved in astronomy.

Rather than 'dismiss the concerns of the entire professional astronomy community', I instead listen to the IAU and similar bodies and the outcomes of the SATCON workshops and similar as to the impacts of constellations and their the effectiveness of mitigations. If you're even bothering to care about system ownership, then you're in the realm of crappy tabloid rags rather than actual publications. Finding other sources is recommended.


*Most. There will be some observations for engineering purposes too.

Wow. Who decides what is "useful data". You? 

The people making the requests for observations.
A frame with an overbright streak obscuring your target of interest is as useless as a frame with a cloud obscuring your target of interest, or a frame opportunistically taken early in the night that happened to have too much skyglow to observe your target of interest. Those Dasterdly Satellites are not the only thing that can render a ground-based frame useless for its intended purpose.

Airplanes with navigation lights have ruined more frames for me than satellites.

[RedLineTrain]

If the claim that terrestrial astronomy is irrevocably broken with the advent of megaconstellations is going to be pursued, then a commitment to a permanent tax by FCC equivalents on spacecraft with substantial terrestrial impact (read any megaconstellation, SAR operators, large area spacecraft) to fund national space based astronomy projects, and permanently abandon any terrestrial project not in active use or under construction has to be made (under the assumption that they will be retired in exchange for replacement space based assets).

How much would it cost to launch a 25-30m multi-hundred ton telescope like the GMT or ELT?  How much extra would it cost to build one for space instead of terrestrial deployment?

Within a couple orders of magnitude, that depends entirely on how you build and launch it, including the management of the whole process.

If you want a Christmas tree project costing many billions of dollars, you could certainly conceive of such a project.  If you constrain blue sky wishes, then you could do some amazing things with hardware that is becoming ready-at-hand.

[edzieba]

If the claim that terrestrial astronomy is irrevocably broken with the advent of megaconstellations is going to be pursued, then a commitment to a permanent tax by FCC equivalents on spacecraft with substantial terrestrial impact (read any megaconstellation, SAR operators, large area spacecraft) to fund national space based astronomy projects, and permanently abandon any terrestrial project not in active use or under construction has to be made (under the assumption that they will be retired in exchange for replacement space based assets).

How much would it cost to launch a 25-30m multi-hundred ton telescope like the GMT or ELT?  How much extra would it cost to build one for space instead of terrestrial deployment?

Within a couple orders of magnitude, that depends entirely on how you build and launch it, including the management of the whole process.

If you want a Christmas tree project costing many billions of dollars, you could certainly conceive of such a project.  If you constrain blue sky wishes, then you could do some amazing things with hardware that is becoming ready-at-hand.

The big problem is a lot of ground-based astronomy is doing things that can't be done with small (or even large) space-based telescopes just by dint of having a volume of Hubbles or JWSTs available. Short-baseline interferometry, extreme mirror sizes (e.g. ELT), regular instrument updates and so on do not become easier or cheaper in orbit even if launch were completely free. Same as the LHC could not be replaced by a bunch of mass produced LEPs.

Having a bunch of moderate-capability-low-cost-high-availability orbiting telescopes would be nice, but that an "and" mitigating the impacts of satellites on ground-based astronomy, not an "or".

[deadman1204]

Let's not pollute this thread with "junk science" aspersions. Conspiracy theories are not going to be tolerated. Cite evidence supporting your on topic point or risk losing your post.

Hit a nerve did that? I hope so, because I want people to realize what is happening. Scientists are unequivical about how starlink is damaging astronomy. 41 pages later, people are still denying the science.

Thats the key here: denying science

[haywoodfloyd]

Let's not pollute this thread with "junk science" aspersions. Conspiracy theories are not going to be tolerated. Cite evidence supporting your on topic point or risk losing your post.

So personal opinions or beliefs are not welcome here?
I would appreciate a clarification on that please.
I agree with you on conspiracy theories.

[ulm_atms]

Sooo..... why don't we address the elephant in the room.
The entire astronomy community is very clear about the problems starlink is causing them. They are the professionals about this. We have 41 pages and counting of people ignoring or disagreeing with scientists about their field of study. Reasons for the disagreement are financial/economic. They don't want anything that will hurt a company they support.

If we swap the subject of astronomy with climate change, it becomes more clear. ITs the exact same pattern.
We have 41 pages of people denying science and scientists. There are names for that, a group that includes flat earthers and anti vaxxers. Anyone who denies what scientists say for their own agenda.

Except that those professionals only think about their profession.  If something hurts their profession, they will shout from the rooftops.  If it doesn't, they could care less.  I've seen that in many science disciples...not just astronomy.

So the even bigger elephant in the room.  Who should get precedent?

A technology that is finally allowing people to get decent internet anywhere and is a very NET good for humans in general or telling them they can't have that because it makes the astronomer's science harder?  I don't have an answer to that except that well...the whole thing for me boils down to that.

Who ultimately gets to decide all the compromises that MUST happen?

[RedLineTrain]

Short-baseline interferometry, extreme mirror sizes (e.g. ELT), regular instrument updates and so on do not become easier or cheaper in orbit even if launch were completely free. Same as the LHC could not be replaced by a bunch of mass produced LEPs.

Understood, although on the flip side you get 3x or 4x (or whatever) useful observation time by virtue of being in orbit.  In some scenarios looking into the future, that could make it a net positive.