Impacts of Large Satellite Constellations on Astronomy

[su27k]

The real question is: Can astronomers adapt? If so, adapt and stop complaining as noone is going to ban megaconstellations, they are just so much useful.

For many so much useful things, like you know, hazardous asterioid detection, no they cannot.

There's zero data to show Starlink has or will have strong impact on hazardous asteroid detection. In fact the ZTF study specifically said the effect is small and they can adapt:

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.

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.

"There is a small chance that we would miss an asteroid or another event hidden behind a satellite streak, but compared to the impact of weather, such as a cloudy sky, these are rather small effects for ZTF."

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.

[daedalus1]

To be fair Lee Jay the writing was on the wall for uninterrupted visible light telescope viewing since aeroplanes became a thing and sputnik 1 was launched. Good luck with telling China that they can't do what Russia and the west have been doing for 70 years with increased numbers of orbital objects. LEO is becoming a cheap place to place a satellite even poor countries are having them built. Ground based astronomy will have to learn to live with it.

"Good luck telling Brazil it cant chop down and burn the Amazon, so those ivory tower biologists and botanists might as well learn to live with savage deforestation anywhere else on the planet. Cannot deny people worldwide wood to heat up their homes".

"Good luck telling Japan not to kill whales or release tritiated water from Fukushima into the Pacific, so those pesky oceanographers might as well learn to live with industrial drag fishing worldwide and radioactive barrel dumping in the high seas, 50s-style. Can't deny people of healthy food, for Pete's sake are you a monster? Plus the economy needs cheap nuclear, are you a luddite?"

Yes I see you are in agreement with me. In a world of increasing population and ever increasing wealth for that population . then the resources will be consumed at an ever growing rate regardless of what the UN legislate.

[eeergo]

I appreciate your experience but the poster made it clear the image was a stack of 90 mins centered around 3 am, not an entire night.


On the other hand, she uses much stronger language than I do on this thread to describe megaconstellations, and she also appears to have 'some' experience with these observations.

I don't see a reference anywhere to it being a stack of 90 mins- the original tweet references "Overnight on 2nd3rd April 2022", and the curves called out as star trails in the image are unambiguously longer than 90 minutes worth of exposure. 

There's a video showing the separate frames that were later stacked in her profile, right after the other one - as I mentioned regarding the context of her tweet:

https://mobile.twitter.com/Spicey_Spiney/status/1510952233873158149

[eeergo]

To be fair Lee Jay the writing was on the wall for uninterrupted visible light telescope viewing since aeroplanes became a thing and sputnik 1 was launched. Good luck with telling China that they can't do what Russia and the west have been doing for 70 years with increased numbers of orbital objects. LEO is becoming a cheap place to place a satellite even poor countries are having them built. Ground based astronomy will have to learn to live with it.

"Good luck telling Brazil it cant chop down and burn the Amazon, so those ivory tower biologists and botanists might as well learn to live with savage deforestation anywhere else on the planet. Cannot deny people worldwide wood to heat up their homes".

"Good luck telling Japan not to kill whales or release tritiated water from Fukushima into the Pacific, so those pesky oceanographers might as well learn to live with industrial drag fishing worldwide and radioactive barrel dumping in the high seas, 50s-style. Can't deny people of healthy food, for Pete's sake are you a monster? Plus the economy needs cheap nuclear, are you a luddite?"

Yes I see you are in agreement with me. In a world of increasing population and ever increasing wealth for that population . then the resources will be consumed at an ever growing rate regardless of what the UN legislate.

Sure, I guess, especially if by wealth you're proposing material wealth. I'm just proposing the radical thought that that is not sustainable, nor in our best interest as a species.

In any case, this utilization (rather, land grab) of LEO and the night sky as seen from the ground with it, is not conmesurate to the growth you postulate.

Also, it's needless to say regulation, UN or otherwise, has avoided mindless overconsumption of resources many times.

[eeergo]

The real question is: Can astronomers adapt? If so, adapt and stop complaining as noone is going to ban megaconstellations, they are just so much useful.

For many so much useful things, like you know, hazardous asterioid detection, no they cannot.

There's zero data to show Starlink has or will have strong impact on hazardous asteroid detection. In fact the ZTF study specifically said the effect is small and they can adapt:

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.

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.

LOL, sure: [SATCON-1] "LEOsats already cause loss of data to Pan-STARRS, the Catalina Sky Survey, and other NEO surveys, effectively wiping out a long trail in the focal plane. Trails also generate spurious artifacts that can confuse automated pipelines. Just after evening twilight and just before morning twilight are the only usable parts of the night for detecting NEOs at low solar elongation, a particularly rich area for NEO searches thanks to the line of sight along the orbit of Earth [...] either the Starlink Generation 2 or the OneWeb scenario (of order 40,000 satellites) will significantly degrade twilight near-Sun observations".

We already know your modus operandi and I'm again not interested in your bad faith nitpicking on special cases or decontextualized details to change a clear, uncontroversial conclusion.

Your quote is based on CURRENT impacts to ONE FACILITY, by the way, which are necessarily minor since megaconstellation systems amount to about 1-2% of the immediate, already-proposed systems. It would be egregious if huge impacts were already proven. Note they also only talk about a 10k Starlink v1.

[woods170]

The real question is: Can astronomers adapt? If so, adapt and stop complaining as noone is going to ban megaconstellations, they are just so much useful.

For many so much useful things, like you know, hazardous asterioid detection, no they cannot.

No offense, but I call BS.

Hazardous asteroid detection is actually better done in infrared. Same for comets. The likes of IRAS, Akari and Spitzer have proven this. And guess what: Infrared observatories need to be in space anyway, due to our atmosphere absorbing most of the infrared radiation.

Further supported by:
https://www.nasa.gov/sites/default/files/atoms/files/nasem_report_finding_hazardous_asteroids.pdf

From that report, page S-3:

After hearing from representatives of different organizations, including persons who had sought to
develop alternative proposals for both ground- and space-based NEO detection systems, the committee
concluded that a space-based thermal-infrared telescope designed for discovering NEOs is the most
effective option for meeting the George E. Brown Act completeness and size requirements in a timely
fashion (i.e., approximately 10 years) (see Figure S.2). The most important justification for a shorter
timespan is that mitigation by deflection requires early detection.
A thermal-infrared discovery survey will provide an immediate measure of asteroid diameters—and
hence a mass estimate—even without a measurement of the asteroids’ optical brightness. An optical
discovery survey is not able to provide this diameter measurement/mass estimate with the same accuracy
within a similar timeframe, as it depends upon thermal-infrared follow-up observations. Furthermore, the
availability of an observation asset capable of obtaining this thermal-infrared follow-up is not guaranteed
(ground-based observations are strongly limited in wavelength range and sensitivity, while future spacebased infrared observatories like the James Webb Space Telescope are not able to perform quickturnaround observations of nearby NEOs). Hence, only a space-based thermal-infrared survey is capable
of meeting the requirement of obtaining a diameter/mass estimation. A major advantage of an infrared
space-based system is its ability to provide the diameter shortly after detection, as soon as orbital
parameters are available. Visible light and near-infrared measurements are severely compromised for size
determination, whereas even relatively simple analyses of mid-infrared measurements can return accurate
sizes for NEOs. Visible, ground-based surveys are also compromised by the day-night cycle and weather,
as compared to space-based surveys. As a result, a space-based infrared survey is better able to detect and
characterize the NEO population to meet the requirements of the George E. Brown Act goal.

So, if you wish to argue that mega constellations should adapt to astronomers, instead of the other way around, than you better come up with a better argument. Because the "hazardous asteroids/NEO" argument does not fly.

[daedalus1]

To be fair Lee Jay the writing was on the wall for uninterrupted visible light telescope viewing since aeroplanes became a thing and sputnik 1 was launched. Good luck with telling China that they can't do what Russia and the west have been doing for 70 years with increased numbers of orbital objects. LEO is becoming a cheap place to place a satellite even poor countries are having them built. Ground based astronomy will have to learn to live with it.

"Good luck telling Brazil it cant chop down and burn the Amazon, so those ivory tower biologists and botanists might as well learn to live with savage deforestation anywhere else on the planet. Cannot deny people worldwide wood to heat up their homes".

"Good luck telling Japan not to kill whales or release tritiated water from Fukushima into the Pacific, so those pesky oceanographers might as well learn to live with industrial drag fishing worldwide and radioactive barrel dumping in the high seas, 50s-style. Can't deny people of healthy food, for Pete's sake are you a monster? Plus the economy needs cheap nuclear, are you a luddite?"

Yes I see you are in agreement with me. In a world of increasing population and ever increasing wealth for that population . then the resources will be consumed at an ever growing rate regardless of what the UN legislate.

Sure, I guess, especially if by wealth you're proposing material wealth. I'm just proposing the radical thought that that is not sustainable, nor in our best interest as a species.

In any case, this utilization (rather, land grab) of LEO and the night sky as seen from the ground with it, is not conmesurate to the growth you postulate.

Also, it's needless to say regulation, UN or otherwise, has avoided mindless overconsumption of resources many times.

https://spacenews.com/new-chinese-small-sat-manufacturing-capacity-could-have-international-ramifications/
Just a taste of what I am talking about. Like I said this is inevitable and will only get more.

[Robotbeat]

This seems like a very productive use of LEO that helps a lot of people? Why would this be characterized as “land grab”?

[Robotbeat]

I’m gonna summarize.

Starlink: in operation, almost complete invisibility to the naked eye. Only briefly visible near sunrise or sunset. Has some impact to astronomy, but the pixels are not as saturated due to going fairly fast. Sun shields help a lot. The earlier Starlinks would’ve been much more visible.

OneWeb: completely invisible to the naked eye due to altitude. However, impact on astronomy is similar (maybe higher in some cases?) since the apparent motion is slower, which can cause pixels to saturate more. Also, illuminated much longer past sunset and before sunrise.

Kuiper: similar to Starlink, but at slightly higher altitudes. The satellites are also about twice the mass (size?). Unknown if it has a sun shield. Without a sun shield, impact both visibly and on astronomy likely to be greater.

In all cases, the impacts are primarily to survey telescopes with minimal to no impact to anything else (including naked eye). Impact on radio telescopes is, IMHO, a completely separate thing and in some ways easier to solve. Can just null out transmissions toward radio telescopes.

Importantly, these impacts are not new. The sky after dusk is already filled with satellites. Satellites appearing in astronomical observations has been commonplace for decades, and techniques exist to address them. As far as visible satellites go, megaconstellation satellites are much, much dimmer. ISS is a massive, bright object approximately equal in brightness to the entire Starlink constellation combined. It completely saturates image frames.

[Robotbeat]

It would be good to add some (reasonable!) international regulations to codify some of the stuff these companies are already doing voluntarily.

[su27k]

The real question is: Can astronomers adapt? If so, adapt and stop complaining as noone is going to ban megaconstellations, they are just so much useful.

For many so much useful things, like you know, hazardous asterioid detection, no they cannot.

There's zero data to show Starlink has or will have strong impact on hazardous asteroid detection. In fact the ZTF study specifically said the effect is small and they can adapt:

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.

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.

LOL, sure: [SATCON-1] "LEOsats already cause loss of data to Pan-STARRS, the Catalina Sky Survey, and other NEO surveys, effectively wiping out a long trail in the focal plane. Trails also generate spurious artifacts that can confuse automated pipelines. Just after evening twilight and just before morning twilight are the only usable parts of the night for detecting NEOs at low solar elongation, a particularly rich area for NEO searches thanks to the line of sight along the orbit of Earth [...] either the Starlink Generation 2 or the OneWeb scenario (of order 40,000 satellites) will significantly degrade twilight near-Sun observations".

You conveniently deleted multiple sentences from the paragraphs you're quoting which completely refuted your claim:

1. "For the Catalina Sky Survey, one way of characterizing the impact is the fractional loss of pixel area from satellite trails; a rough estimate is that a satellite trail in every image will cost a few tenths of a percent in detection efficiency. This can be qualified as “negligible,” but bright trails from satellites not yet on-station or that are brightly illuminated without mitigations may have more impact.", so it's exactly the same conclusion as the one I quoted.

2. "either the Starlink Generation 2 or the OneWeb scenario (of order 40,000 satellites) will significantly degrade twilight near-Sun observations" is followed by "especially for the LSST, as implied by several presentations at the SATCON1 workshop.", which shows this is referring to the problem of LSST detector being saturated, which they're working with SpaceX to solve, and it's a unique problem for big survey telescopes like LSST, doesn't apply to every asteroid detection telescope.

3. Also this claim that "Either the Starlink2 or the OneWeb scenario will significantly degrade twilight near-sun observations" is just from one guy (Rob Seaman, Catalina Sky Survey), if you actually read the accompany tech report, another guy from Catalina Sky Survey (Eric Christensen) made the opposite claim: "Satellite mega-constellations [probably do not] represent an existential threat to NEO surveys, at least for programs like CSS that have a single goal of moving object detection and operate in a truly NEO-optimized way"

We already know your modus operandi and I'm again not interested in your bad faith nitpicking on special cases or decontextualized details to change a clear, uncontroversial conclusion.

As I showed above, it is you who are nitpicking on special cases (i.e. LSST) or decontextualized details (i.e. deleting sentences that doesn't fit your narrative)

Your quote is based on CURRENT impacts to ONE FACILITY, by the way, which are necessarily minor since megaconstellation systems amount to about 1-2% of the immediate, already-proposed systems. It would be egregious if huge impacts were already proven. Note they also only talk about a 10k Starlink v1.

Well if you actually read the paper you'd know they didn't just talk about CURRENT impacts nor did they limit analysis to 10k Starlink v1: "To estimate the fraction of pixels that are lost for the expected constellation of 42,000 Starlink satellites, and knowing that currently about 18% of all images taken during twilight are affected with about 1600 satellites deployed, we use a simple scaling 0.04% × 0.18 × 42,000/1600 = 0.2%. For images taken when the solar elevation is greater than −30°, this fraction is 0.1%. Taking into account that about 36% of all ZTF observations are taken when the solar elevation is greater than −30° (and almost no trails are visible if the solar elevation is lower), approximately 4 × 10⁻⁴ of all pixels would be lost over the course of a year."

And your counter-quote above is also from ONE FACILITY, not only that, it's from a single person in this facility and the claim is contradicted by one of his colleagues, so I don't see how your claim is more authoritative than mine, in fact it's less so given: a. The claim is contradicted by his colleague; b. He made the claim in response to a questionnaire instead of making the claim in a peer reviewed paper.

[Robotbeat]

I think there might be a lot of room to improve the speed with which the satellites reach station. More on-board propellant (allowing lower Isp, chemical thrusters), higher launch altitude, lower operational altitude, etc.

[Tev]

[...] megaconstellation systems amount to about 1-2% of the immediate, already-proposed systems. [...]

I would like to hear more about those 1-2% . . . I might have missed something (just a casual observer), but regarding megaconstellations-possibly-affecting-astronomy that are actually funded I noticed only Starlink (12k approved, up to 42k sats proposed), Kuiper (3k approved; maybe up to 10k proposed?) and OneWeb (1k). Starlink seems to be the outlier.

In orbit there are currently ~2k Starlink satellites, and over 10k other satellites (wiki number, I have no idea about what fraction of those actually affects astronomy).

Impliying there will be 50-100 times as many satellites in megaconstellations assumes hundreds of thousands of satellites . . . can you link list of such (serious) attempts? And I mean serious, not just some-guy-would-like-his-own-constellation. We are not talking about astronomy impact of "millions of people living and working in space" after all.

[Robotbeat]

There was that one Rwandan proposal; Greg Wyler is involved I think.

[Tev]

I remembered that, and I was not sure whether combination of Greg Wyler, Rwanda and astonishingly huge satellite numbers is something to treat as a real thing. Seems to me on the same level as the mentioned "millions of people living and working in space".

EDIT: oh shit he got 50M$ already - https://spacenews.com/wyler-raises-50-million-for-sustainable-megaconstellation/
No idea how big those birds will be but ok, maybe hundreds of thousands of satellites might actually happen.

[eeergo]

[...] megaconstellation systems amount to about 1-2% of the immediate, already-proposed systems. [...]

I would like to hear more about those 1-2% . . . I might have missed something (just a casual observer), but regarding megaconstellations-possibly-affecting-astronomy that are actually funded I noticed only Starlink (12k approved, up to 42k sats proposed), Kuiper (3k approved; maybe up to 10k proposed?) and OneWeb (1k). Starlink seems to be the outlier.

In orbit there are currently ~2k Starlink satellites, and over 10k other satellites (wiki number, I have no idea about what fraction of those actually affects astronomy).

Impliying there will be 50-100 times as many satellites in megaconstellations assumes hundreds of thousands of satellites . . . can you link list of such (serious) attempts? And I mean serious, not just some-guy-would-like-his-own-constellation. We are not talking about astronomy impact of "millions of people living and working in space" after all.

You might have not been paying attention, but the reason I'm calling this phenomenon a land grab is not out of capriciousness. Also, the fact parts of the systems are not approved yet means zilch - the whole megaconstellation push has been growing out of FOMO from different actors rather than a definite capability gap only this solution can fulfill, as well as a lurch to acquire as many spectrum and orbital slots as practicable. So if the already-approved systems grow to their full approved size, I have no doubt they will be approved further if there's no pushback from other parts of society. In short:

- Starlink 42k
- Kuiper 3.2k
- OneWeb 6.3k
- Guowang 13k
- Lightspeed 1.6k
- Dozens of other companies with more modest constellation sizes (in the hundreds or low thousands) but even more doubtful corporate governance and business models (I must add I'm not the only "radical" who is doubtful the business model subsists: https://spacenews.com/industry-skeptical-about-the-business-case-for-megaconstellations/), yet are frenzied to launch, which are not always based on telecommunications but rather EO, SIGINT, defense... - would add up to a few thousands more.

This racks up to around 70k openly projected *operational* satellites within the next 10-15 years, supposing China feels Guowang is enough (hint: many "private" Chinese space companies are also discussing their own constellations), Russia doesn't have the oomph to develop their proposed Sfera beyond the currently proposed few-hundred satellites (although we know about Russia's approach to LEO sustainability), and Europe/EU/EC continues to put forward half-assed minimalistic trade studies that are probably going to end up in the file cabinet rather than orbit. However, if the previously-listed projects materialize, it's reasonable to expect at least some of these other state actors to act too.

This estimate counts a few of the (in my view) less realistic projects and tallies 94k: http://www.parabolicarc.com/2021/11/08/planned-comsat-constellations-now-exceed-94000-satellites/

This is evidently before counting in, or out, Wyler's (shameful) "sustainable" Rwandan megaconstellation of hundreds of thousands... even if he deploys 10% of that it already competes with the largest projects out there. And before the market saturates (or the bubble is allowed to burst) there's no doubt other entrepreneurs will be willing to join the fun.

[JayWee]

eeergo, so your solution is to ban satellites? What gives the astronomers the right to claim sole ownership of LEO?

[eeergo]

eeergo, so your solution is to ban satellites? What gives the astronomers the right to claim sole ownership of LEO?

I wouldn't be in this website in the first place (probably in a cave heating myself with sticks, actually).

Reduction to absurdity is just a fallacy. Is anyone's solution to ocean pollution to ban any ship, and give kayakers the sole ownership of marine waters? Is anyone's solution to deforestation to ban any tree felling, and give monkeys the sole ownership of forests? Is anyone's solution to smog to ban any fire, and give birds the sole ownership of the sky?

The ideological biases, which are turning into complete, wilfull blindness to every facet of an issue except through a very narrow viewing glass, in these boards are becoming haunting.

[Lee Jay]

Is anyone's solution to smog to ban any fire, and give birds the sole ownership of the sky?

That one is coming closer.  With a few changes I've been able to reduce my personal use of fire (natural gas and gasoline) by over 95% over the last few years.  We don't yet have the technology to get all the way to zero for every industry (intercontinental aircraft is the hardest to solve) but we can reduce it by well over 90% globally right now if we want to.

[eeergo]

Is anyone's solution to smog to ban any fire, and give birds the sole ownership of the sky?

That one is coming closer.  With a few changes I've been able to reduce my personal use of fire (natural gas and gasoline) by over 95% over the last few years.  We don't yet have the technology to get all the way to zero for every industry (intercontinental aircraft is the hardest to solve) but we can reduce it by well over 90% globally right now if we want to.

Yeah, where I live, open fires are illegal except for wood-fired ovens in restaurants or a few other special circumstances, even in the countryside, because of the microclimate in the (flat, surrounded by high mountains) region, which favors smog and fine particulate accumulation to -very- unhealthy levels. With "fire" I was evoking any kind of combustion, also internal, but it was a metaphor anyway