Impacts of Large Satellite Constellations on Astronomy

[woods170]

Astronomers do not own the heavens. They will have to learn to deal with a new reality.

A perfect example of why astronomers detest a lot of space advocates ... this "suck it up" attitude is hardly helpful.

Astronomers should also realize that without spaceflight and satellites several fields of astronomy would not nearly be as far along as they are today. Particularly visible (Hubble!) infrared, X-ray, ultraviolet.

Which reminds me of a little incident which took place at the University of Groningen (the Netherlands) in 1983. A resident visible light astronomer discovered that one of his long-exposures had a satellite streak going over it from south to north. He discussed his dismay with some of his fellow astronomers at the university. When one of his colleagues discovered that the streak was caused by IRAS (InfraRed Astronomical Satellite) the dismayed astronomer immediately refrained from any further complaints.
You see, some of his fellow astronomers had worked on DAX, one of the two main instruments on IRAS.

Hubble has shown up in ground-based long exposures. So has (in the past) Compton and other astronomy satellites. Why is that I don't hear the astronomers complaining about THAT?
Hypocrisy?

That answer is just willful anumerism - what's the relative impact of each?

As I explained a few replies back and you chose to ignore (boring), the issue here is whose plans call for a massive deterioration of natural heritage, furthermore for private profit reasons and moreover setting jurisprudence for other such actors - not a handful of unique, non-profit scientific instruments.

OK, I'll bite.

Let's play this scenario out a bit further. Given that constellations are a fact (Iridium, Starlink, OrbComm) and given that more are on their way (not just from the US but other countries too) what exactly do you think SHOULD happen to get to a situation where constellations and astronomers can co-exist?

While I'm waiting for your answer I'll tell what I THINK will eventually happen:

Constellations are happening right now and there will be more. SpaceX being the first to orbit lots of sats naturally makes them the prime focal point for astronomers' complaints. The coming OneWeb and Amazon constellations will only serve to worsen the situation for astronomers.
Given that capitalism rules and astronomers have - historically - been quite unsuccessful in battling Earth-based threats to Earth-based observations, we have witnessed a long trend in astronomers relocating to better suited locations.
That is how most of the excellent Earth-based observatories ended up on high mountain tops in really remote locations.
In my opinion the long term future of astronomy lies not on Earth, but on the Moon. Line of reason: humanity is and will be stuck on Earth for centuries more to come. The number of orbital assets will only increase, regardless of there being constellations or not. Therefore the problems for Earth-based astronomy will increase, regardless of constellations being present or not.
There will IMO come a time that the international astronomical community will come to the IMO inevitable conclusion that the work is best continued off-Earth. The backside of the Moon, or even further out will be the ultimate "remote high mountain top".

[jebbo]

Let's play this scenario out a bit further. Given that constellations are a fact (Iridium, Starlink, OrbComm) and given that more are on their way (not just from the US but other countries too) what exactly do you think SHOULD happen to get to a situation where constellations and astronomers can co-exist?

There are plenty of things that can mitigate the impact of constellations:
- low albedo satellites (not just in visible). Can drop brightness by several magnitudes
- active de-orbit at end of life
- debris avoidance and removal
- orbit planning (e.g. plane selection to minimise overflights of, say, Paranal or Mauna Kea)
- communication frequency selection and antenna design

Some of these are already being done, but there is certainly a lot more that could be done.

Given that capitalism rules and astronomers have - historically - been quite unsuccessful in battling Earth-based threats to Earth-based observations, we have witnessed a long trend in astronomers relocating to better suited locations.
That is how most of the excellent Earth-based observatories ended up on high mountain tops in really remote locations.

That misrepresents why large instruments are on mountains. Mostly it is to minimise the atmospheric water column. Light pollution is easier to avoid.

In my opinion the long term future of astronomy lies not on Earth, but on the Moon. Line of reason: humanity is and will be stuck on Earth for centuries more to come. The number of orbital assets will only increase, regardless of there being constellations or not. Therefore the problems for Earth-based astronomy will increase, regardless of constellations being present or not.
There will IMO come a time that the international astronomical community will come to the IMO inevitable conclusion that the work is best continued off-Earth. The backside of the Moon, or even further out will be the ultimate "remote high mountain top".

I have a lot of sympathy for this, but relocation of large observatories to the moon requires a huge sustained human presence there. The moon has some advantages (observable wavelengths, suitable for large scale instruments) but has other significant issues (dust, thermal environment, micrometeorites, etc).

Also, for most wavelengths, the poles and limb are far better than the farside.

[ But this isn't really the right thread to discuss lunar observatories so I'll leave it at that ]

--- Tony

[eeergo]

Let's play this scenario out a bit further. Given that constellations are a fact (Iridium, Starlink, OrbComm) and given that more are on their way (not just from the US but other countries too) what exactly do you think SHOULD happen to get to a situation where constellations and astronomers can co-exist?

Although jebbo has answered just above with a very good post that reflects my views, since the post was directed at me I'll fill in with a couple of extensions to his reply:

- First and foremost, I think the blame lies not only in the companies aiming to deploy large constellations, but also in the competent regulatory bodies. I can appreciate such matters represent a complicated issue to tackle, but it's also true there was little to no discussion as to how to orderly mitigate impacts before dozens of actual satellites started being orbited. On the other hand, this is usually the case with environmental issues: only when trouble is unavoidable or patently harmful do regulations reach an effective stage. I wish an apparently orderly world as the space business could lead in best practices.

- That said, a public "environmental impact assessment" should be compulsory, just as is is for much less visually impactful items such as, say, windmill park installations or highrises in town ordinances. Just how much EM pollution (not just visible) would the proposed constellation cause, to which stakeholders (or to everyone?) and what mitigation is there available for such an architecture, either trivial, cost-effective or otherwise?

- Also, something like an independent audit of benefits-vs-impacts should also be performed, at least as an non-binding informative document. I personally consider that just increased civil data connectivity, in the already ultra-connected world we live in (with lots of ground-based infrastructure alternatives to account for the still infra-connected minorities), is not even remotely worth the cost of radically and permanently altering the -visible and radio- sky, especially considering the impacts to science. When compounding the fact this is all a business model to profit a single country's company (or a handful), quite probably with strong military implications, it gets even less palatable.

- Iridium, GPS or other such constellations are indeed spearheads, but one cannot seriously compare a system based on dozens of satellites with a multi-tens-of-thousands behemoth. Again, the issue here is not with the proverbial "logger" chopping down a few trees for firewood and his town's carpenter, but instead with the proverbial "papermill conglomerate" whose business model calls for hectares of single-use pinetree crops.

- Once up there, in addition to the guidelines jebbo mentioned - what happens if the responsible company implodes, goes bankrupt... or more diresome there's a potentially Kesslerian situation? Contingency funds for safe disposal or, at the very least, impact reduction should certainly be required to ensure the public doesn't end up with an unmanageable hot mess in our collective hands, while a few others sip on their retirement margaritas while gazing at the remarkably more frequent shooting stars.

I don't believe in rush, "trust us", "go fast and break things" when we're quite literally betting the sky.

The number of orbital assets will only increase, regardless of there being constellations or not. Therefore the problems for Earth-based astronomy will increase, regardless of constellations being present or not.

I hope that is the case. I hope the increase is slow enough so that changes are adiabatic and an understanding of their long-term viability can be understood. I hope debris-removal technologies are developed and deployed while this increase is still manageable and no chain-collision happens for a futile short-term-profit motive for little actual gain to humanity.

I hope eventually we'll have JUST a large fleet of thousands of versatile satellites that get swiftly removed as soon as they're not manageable and nothing else around Earth. I hope maturity instead of the Nth gold rush can be shown in this stance.

There will IMO come a time that the international astronomical community will come to the IMO inevitable conclusion that the work is best continued off-Earth. The backside of the Moon, or even further out will be the ultimate "remote high mountain top".

Sure! That time is not now though, since it is materially impossible. Hopefully that move will happen just for scientific reasons, and not because of inevitability due to pollution. So first things first.

[envy887]

Let's play this scenario out a bit further. Given that constellations are a fact (Iridium, Starlink, OrbComm) and given that more are on their way (not just from the US but other countries too) what exactly do you think SHOULD happen to get to a situation where constellations and astronomers can co-exist?

There are plenty of things that can mitigate the impact of constellations:
- low albedo satellites (not just in visible). Can drop brightness by several magnitudes
- active de-orbit at end of life
- debris avoidance and removal
- orbit planning (e.g. plane selection to minimise overflights of, say, Paranal or Mauna Kea)
- communication frequency selection and antenna design

Some of these are already being done, but there is certainly a lot more that could be done.

Also: active removal of existing dead satellites, spent rocket bodies, and debris. There are tens of thousands of large pieces of junk in LEO. These will for quite some time have a much greater impact than Starlink on astronomers, at least in visible and near IR wavelengths.

Megaconstellations will develop low-cost, high-deltav platforms that are well-suited for debris removal buses. The remaining steps are a regulatory and economic framework that makes removing junk viable.

[envy887]

...a public "environmental impact assessment" should be compulsory, just as is is for much less visually impactful items such as, say, windmill park installations or highrises in town ordinances...

You're greatly overstating the general visual impact of even the largest constellation. These satellites are somewhere between 3rd to 6th magnitude in operation. The vast majority of the general public will never even notice they are there. The vast majority of people don't even notice ISS when it flies over at a (relatively) blinding -4 magnitude, or if they do they think it's an airplane.

[jebbo]

Also: active removal of existing dead satellites, spent rocket bodies, and debris.

I'd assumed this as part of the debris removal, but thanks, it's not obvious and I should have been explicit!

--- Tony

[pochimax]

there exist also a problem of radio frequency interference with locations as NASA DSN stations.

Obviously, constellations are talking with NASA about this problem.

But the most importan thing is that currently we are focusing in solving problems with current instalations. The dramatic consequence of this constellations is that they prevents increasing future capabilities, they are limiting severily the future expansion of optical and infrared astronomy, radio astronomy and even future spacecraft communication ground stations.

Problem is not the current damage to LSST observations; problem is preventing the ground installation of future LSST clones around the globe.

This constellations, also, are supposed to be servicing remote locations.... exactly the better locations for expansing future radio stations, radio antenna or observatories.

It is a very bad news for our future observation of the skies. And there will not be a solution for that.

 

clear skies

[pochimax]

You're greatly overstating the general visual impact of even the largest constellation. These satellites are somewhere between 3rd to 6th magnitude in operation. The vast majority of the general public will never even notice they are there. The vast majority of people don't even notice ISS when it flies over at a (relatively) blinding -4 magnitude, or if they do they think it's an airplane.

3th to 6th magnitude in astronomy are very very very bright objects. the appearance of an object so bright in your FOV ruins your observation

[jebbo]

You're greatly overstating the general visual impact of even the largest constellation. These satellites are somewhere between 3rd to 6th magnitude in operation. The vast majority of the general public will never even notice they are there. The vast majority of people don't even notice ISS when it flies over at a (relatively) blinding -4 magnitude, or if they do they think it's an airplane.

3th to 6th magnitude in astronomy are very very very bright objects. the appearance of an object so bright in your FOV ruins your observation

Yup. Most astronomers consider <=12 magnitude to be "bright" (so >200 times fainter than 6 mag).

--- Tony

[envy887]

You're greatly overstating the general visual impact of even the largest constellation. These satellites are somewhere between 3rd to 6th magnitude in operation. The vast majority of the general public will never even notice they are there. The vast majority of people don't even notice ISS when it flies over at a (relatively) blinding -4 magnitude, or if they do they think it's an airplane.

3th to 6th magnitude in astronomy are very very very bright objects. the appearance of an object so bright in your FOV ruins your observation

My point was that something like 99.99% of the people in the world are not astronomers and do not care in the least about a 3rd to 6th magnitude object in the sky. They don't even care about objects 1,000 times brighter. Comparing the visual impact of such an object to a wind turbine or a high-rise building is absurd.

The impact of such objects in any general environmental assessment would that they have "no to negligible impact". Any assessment which would find such objects to have significant impact would be one focusing strictly on optical astronomy.

[envy887]

...The dramatic consequence of this constellations is that they prevents increasing future capabilities, they are limiting severily the future expansion of optical and infrared astronomy, radio astronomy and even future spacecraft communication ground stations... And there will not be a solution for that.

Yep, that's it. Might as well close up shop now, nobody will ever see the night sky again.

 

[high road]

there exist also a problem of radio frequency interference with locations as NASA DSN stations.

Obviously, constellations are talking with NASA about this problem.

But the most importan thing is that currently we are focusing in solving problems with current instalations. The dramatic consequence of this constellations is that they prevents increasing future capabilities, they are limiting severily the future expansion of optical and infrared astronomy, radio astronomy and even future spacecraft communication ground stations.

Problem is not the current damage to LSST observations; problem is preventing the ground installation of future LSST clones around the globe.

This constellations, also, are supposed to be servicing remote locations.... exactly the better locations for expansing future radio stations, radio antenna or observatories.

It is a very bad news for our future observation of the skies. And there will not be a solution for that.

 

clear skies

Sure there is. Put those telescopes in space, where there is no pesky atmosphere, planes, communication etc messing with the observations. It's not like satellites are the most important hindrance by far. With launch costs dropping, launchable sizes about to increase, and cubesat technology becoming ever more potent, space telescopes become ever more feasible.

[RedLineTrain]

- First and foremost, I think the blame lies not only in the companies aiming to deploy large constellations, but also in the competent regulatory bodies. I can appreciate such matters represent a complicated issue to tackle, but it's also true there was little to no discussion as to how to orderly mitigate impacts before dozens of actual satellites started being orbited.

This discussion did take place in front of the FCC.  Perhaps not to your liking, but it did take place.

[jebbo]

Sure there is. Put those telescopes in space, where there is no pesky atmosphere, planes, communication etc messing with the observations. It's not like satellites are the most important hindrance by far. With launch costs dropping, launchable sizes about to increase, and cubesat technology becoming ever more potent, space telescopes become ever more feasible.

Regardless of launch costs, free-flying telescopes are incredibly expensive, with much more expensive instruments, a huge lead time, and a limited lifetime with few (if any) opportunities for repair or upgrade.

Ground based instruments can be repaired, maintained and upgraded relatively easily, which has enormous advantages.

Simplistic "just launch space telescopes" stuff is not helpful.

--- Tony

[freddo411]

Whereas:

* There are a number of astronomy satellites in orbit that sometimes create "light streaks" in ground based astronomical images
* There are many non-astronomy, non-constellation sats that do the same
* Planes sometimes create "light streaks" in ground based astronomical images
* Meteors create "light streaks" in ground based astronomical images

* Image Processing Software can detect and mitigate non-astronomical effects in images
* A great deal of the available dark sky time is not affected by illuminated satellites

* Constellations provide very large economic, health and welfare benefits to a significantly large population

* Illuminated satellites provide an additional, small reason to an already significant body of reasons to site telescopes in space above many forms of interference

Let it be acknowledged that constellations do create a negative externality for ground based astronomy.

Let it be resolved that:
* Constellations can be constructed despite the astronomical negative externalities. 
* LEO is a public resource that shall not be restricted due to optical visibility.
* Constellations operators shall share current orbital data in digestible formats to any person wanting to detect and mitigate overflight effects
* Constellations operators shall fund and/or provide mitigation software for astronomical images.
* Constellations operators shall fund reasonable astronomical mitigation efforts

[guckyfan]

3th to 6th magnitude in astronomy are very very very bright objects. the appearance of an object so bright in your FOV ruins your observation

Maybe they should consider making those observations at night then.

Edit: Radioastronomers did sit down with SpaceX and found solutions satisfactory for both sides.

Astronomers shoud try the same approach. I am sure there can be a lot of mitigation if not completely satisfactory for the Astronomers.

[rsdavis9]

How about if and when starlink becomes hugely financially successful:
1. Spacex builds a standard satellite with lets say somewhere between 2.4m to 8m size.
2. Let astronomers design some common instruments.
3. Launches 100 of them for free.

They will know how to mass produce satellites.
They will know how to launch many per rocket and cheaply.

If they are building 10,000 to 40,000 satellites and how many a year for maintenance? They should be able to do a custom run of a 100.

EDIT: grammar and punc

[envy887]

Sure there is. Put those telescopes in space, where there is no pesky atmosphere, planes, communication etc messing with the observations. It's not like satellites are the most important hindrance by far. With launch costs dropping, launchable sizes about to increase, and cubesat technology becoming ever more potent, space telescopes become ever more feasible.

Regardless of launch costs, free-flying telescopes are incredibly expensive, with much more expensive instruments, a huge lead time, and a limited lifetime with few (if any) opportunities for repair or upgrade.

Ground based instruments can be repaired, maintained and upgraded relatively easily, which has enormous advantages.

Simplistic "just launch space telescopes" stuff is not helpful.

--- Tony

Change that "regardless" to "BECAUSE of launch costs, ...", as it's impossible to disregard launch costs when even a basic launch costs more than many entire ground observatories. Hubble got about $9B worth of STS missions. Even JWST's launch is worth about $400M to NASA, since if Europe weren't supplying an A5 it would have to go on DIVH.

Orbital observatories can be designed for in-situ repair and upgrade (either automated, or manual like Hubble), or for automated retrieval and return to Earth for those upgrades which is probably cheaper with the right launch vehicle.

[Star One]

You're greatly overstating the general visual impact of even the largest constellation. These satellites are somewhere between 3rd to 6th magnitude in operation. The vast majority of the general public will never even notice they are there. The vast majority of people don't even notice ISS when it flies over at a (relatively) blinding -4 magnitude, or if they do they think it's an airplane.

3th to 6th magnitude in astronomy are very very very bright objects. the appearance of an object so bright in your FOV ruins your observation

My point was that something like 99.99% of the people in the world are not astronomers and do not care in the least about a 3rd to 6th magnitude object in the sky. They don't even care about objects 1,000 times brighter. Comparing the visual impact of such an object to a wind turbine or a high-rise building is absurd.

The impact of such objects in any general environmental assessment would that they have "no to negligible impact". Any assessment which would find such objects to have significant impact would be one focusing strictly on optical astronomy.

I could turn that round and say 99.99% of people in the world are not the kind of space advocates you get on here and don’t care about their interests. I bet a high percentage don’t even know or care about Starlink or whether it doesn’t or does exist. Or will ever use it in spite of claims. As the biggest users of this are actually likely to be by far the money markets of the world and the military who both prioritise the high response speeds.

[eeergo]

- First and foremost, I think the blame lies not only in the companies aiming to deploy large constellations, but also in the competent regulatory bodies. I can appreciate such matters represent a complicated issue to tackle, but it's also true there was little to no discussion as to how to orderly mitigate impacts before dozens of actual satellites started being orbited.

This discussion did take place in front of the FCC.  Perhaps not to your liking, but it did take place.

Could you point me to its conclusions, or at least the considerations they took into account? I'm not aware of any such discussion and it isn't being quoted as a roadmap, but we might be missing something. On the other hand, I'm guessing the FCC will deal with issues narrowly focused on impacts to communications, not the larger visibility and scientific impacts, much less orbital dangers.