SATCON1 Report on Impact of Satellite Constellations on Astronomy(noirlab.edu)
noirlab.edu
SATCON1 Report on Impact of Satellite Constellations on Astronomy
https://noirlab.edu/public/products/techdocs/techdoc003/
12 comments
To me, this is the same as building a city. Does it destroy the previous view? Yes. Does looking at a city's skyline inspire awe? Yes. For me replacing one type of awe for another is net neutral.
I grew up in Vancouver, BC, Canada. From downtown Vancouver you can see many mountains. When looking at the city skyline it is back-dropped with these mountain ranges. The combination impresses me even more than either the city or the mountain range.
Similarly, I look forward to seeing satellite constellations and behind them the stars. I would love for my kids to look up and be comforted knowing they can easily contact any other person on the planet. I want them to see the satellite constellations as a monument to human creation (10th wonder of the world), and be inspired to join that technological journey. I also want to point out the stars behind the satellites and have them be humbled by the magnitude that is space and bring with it hope and wonder.
While these satellites should try to be the least intrusive as possible, I'm not sure we need to think of it as a zero-sum game.
I grew up in Vancouver, BC, Canada. From downtown Vancouver you can see many mountains. When looking at the city skyline it is back-dropped with these mountain ranges. The combination impresses me even more than either the city or the mountain range.
Similarly, I look forward to seeing satellite constellations and behind them the stars. I would love for my kids to look up and be comforted knowing they can easily contact any other person on the planet. I want them to see the satellite constellations as a monument to human creation (10th wonder of the world), and be inspired to join that technological journey. I also want to point out the stars behind the satellites and have them be humbled by the magnitude that is space and bring with it hope and wonder.
While these satellites should try to be the least intrusive as possible, I'm not sure we need to think of it as a zero-sum game.
You can always choose to leave a city. You can't avoid polar orbits. A city warps the view in one place, while brightly lit polar orbiting satellites warp the view everywhere. That said, the Starlink sats are supposed to become invisible to the eye in their final orbits.
And thanks to LEO broadband, you can choose to leave the city and still have the high-speed internet that has proved to be necessary in this time of mandated shutdowns.
You can already see planes and the occasional satellite with the naked eye in even very isolated places. Personally, I find satellites to be more aesthetically pleasing because they don't blink like planes. As the number of visible sats increases, I think a bunch of silent criss-crossing points of light will actually be very beautiful, like a constant meteor shower. It's a matter of taste, of course, but it seems very different to me than near-city light pollution and noise pollution.
It has had a minimal impact on our dark skies in Colorado, but an impact nonetheless. In the past it was fun to spot satellites, and we'd usually go 10-15 minutes between seeing them, depending on the time. Now its rare to look up and not see something in motion.
Around the fire at our last camping trip a couple months back, we had a contest to see who could spot the most satellites concurrently, and the record got up to 3. They still aren't very bright (many stars are brighter), but with more Starlink launches, that count will surely increase.
Around the fire at our last camping trip a couple months back, we had a contest to see who could spot the most satellites concurrently, and the record got up to 3. They still aren't very bright (many stars are brighter), but with more Starlink launches, that count will surely increase.
Just by sheer, random, unplanned chance, we counted a string of 10 in a line while hiking in Utah, though only ~3 were visible concurrently. I'm really glad Starlink sats don't stay visible once they reach their final orbits, because part of the allure of the stars is that they are largely motionless.
Most of the time, they won't be visible. Satellites at general commercial orbits fly low enough they hang out in Earth's shadow when they're flying past. It's evening and early morning when they can be seen reflecting sunlight around the curve of the Earth.
Honestly, I think the idea of a sky alive with dozens of fireflies criss-crossing the twilight is kind of cool.
Honestly, I think the idea of a sky alive with dozens of fireflies criss-crossing the twilight is kind of cool.
> I've sat here for a few minutes thinking selfishly about never being able to experience Alaska wilderness on a clear night. Or late night stroll on a beach looking up, etc, etc forever about all kinds of personal moments that will never be the same.
You can't see them on a clear night. They're not a problem for human observation, only telescopes.
You can't see them on a clear night. They're not a problem for human observation, only telescopes.
But that's not true. I've watched the Starlink satellites go by at night with my own eyes. No telescope, just standing in my backyard, there's even websites which tell you the time and direction to look.
There’s a limited time (like a couple weeks) while they are boosting into their designated orbit where this is possible. And significantly less so for the latest generation with the new sunshade.
For the vast majority of the satellites in the constellation they are in fact not visible to the naked eye.
For the vast majority of the satellites in the constellation they are in fact not visible to the naked eye.
How long ago was that? I've not seen anyone saying they've seen them in several months. This is not a fixed situation and SpaceX has mitigated most issues with them. https://www.spacex.com/updates/starlink-update-04-28-2020/
Follow on comment, what are indigenous tribes who aren't part of our connected world going to interpret this change as? I'm thinking about groups of people like the Sentinelese.
People appear to be downvoting my other comment so much that I can't even edit it so reposting again. Indigenous tribes won't have an issue with it as they don't have superhuman eyes to see 7th magnitude objects in the night sky. The satellites are not generally visible to the naked eye after changes SpaceX has made to the operations of the satellites and physical modifications to the satellites themselves.
https://www.spacex.com/updates/starlink-update-04-28-2020/
https://www.spacex.com/updates/starlink-update-04-28-2020/
The indigenous tribes won't be able to see them so it has zero effect on them.
I'm generally a technologist however I am completely appalled at a private company getting the right to significantly impact humanity's view of the night sky, the original source of wonder.
I agree, but we already conceded humanity's view of the daylit earth to private companies, so this is just another depressing step in the exact same direction.
Yes, this is a kind of Wild West situation. We should figure out the best way out, ideally with all interested parties getting something good.
except you as an individual could opt out of the original Wild West; this one, not so much.
perhaps it's exactly like the Wild West from the viewpoint of Native Americans: we're taking your skys.
perhaps it's exactly like the Wild West from the viewpoint of Native Americans: we're taking your skys.
Yes, that's very unfortunate.
I hesitate, however, concluding that we should ban satellite constellations on these grounds. Do you think that would be a good approach?
I hesitate, however, concluding that we should ban satellite constellations on these grounds. Do you think that would be a good approach?
Yes, unless they are invisible in the sky. Put a barrier in place to force innovation.
Anything in the sky is something which at least obstructs the view. If we have too many even black body satellites - which have zero reflection or emission in interesting spectral parts - we're still can't see through them. If we have too many of them, we still have a problem. So - theoretically - it's a choice between space flights and astronomy.
Maybe there can be a more optimal solution than what we have today.
Maybe there can be a more optimal solution than what we have today.
"The original source of wonder" has already been ruined by the light pollution of any nearby city to be fair.
I see bigger benefit in being able to ship new space telescopes and more ubiquitous internet access.
I see bigger benefit in being able to ship new space telescopes and more ubiquitous internet access.
>I see bigger benefit in being able to ship new space telescopes and more ubiquitous internet access.
but parent post brings up a good point -- it's not your sky, it's not my sky, it's our sky.
Opinion without supporting arguments and consensus is inherently unfair when we're talking about an un-ownable concept being changed for all people.
but parent post brings up a good point -- it's not your sky, it's not my sky, it's our sky.
Opinion without supporting arguments and consensus is inherently unfair when we're talking about an un-ownable concept being changed for all people.
> Opinion without supporting arguments and consensus is inherently unfair when we're talking about an un-ownable concept being changed for all people.
I'd say it goes both ways. What makes it "ours" in the first place, I don't think it gets an ownership at all.
I'd say it goes both ways. What makes it "ours" in the first place, I don't think it gets an ownership at all.
It doesn't affect humanity's view of the night sky. It affects the ability of telescopes, especially wide-field telescopes, to be able to see the sky. These satellites aren't naked eye visible.
I am not sure what sort of light pollution you're experiencing for this not to visible in 'your' skies. I can assure you, I've been camping in a few different locations the past few weeks, the Starlink satellites are consistently visible without magnification.
I was often star gazing and looking for shooting stars and I ended up confirming with a satelite tracker app, that most of the satellites I was spotting were Starlink trajectories.
They are planning to deploy 12k satellites, just let that sink in.
I was often star gazing and looking for shooting stars and I ended up confirming with a satelite tracker app, that most of the satellites I was spotting were Starlink trajectories.
They are planning to deploy 12k satellites, just let that sink in.
The satellites deployed now and in future aren't reflective nearly as much. Only the early launches were.
Fair point but you will still have 500+ Starlink satellites, without those mitigations, orbiting for the next 5 years or so until they fall from orbit.
Equally important is what kind of assurance will we have that Amazon, baidu, facebook, or however follows next, will implement these counter measures?
Equally important is what kind of assurance will we have that Amazon, baidu, facebook, or however follows next, will implement these counter measures?
I was just out watching the meteor shower myself and it was quite dark skies (milky way visible) and didn't experience anything like that.
This NIMOP ("Not In My Orbital Plane") movement is very concerning and I feel the need to speak out against the dangers of this "luddite movement" type thinking.
First, of course its good for companies to reduce the negative externalities of things in space (paint, shades, etc). I think there is near universal agreement here, including from SpaceX.
However, there is no way to become a space faring civilization without putting lots of things in space, period. I want to see 1,000,000x more objects in space, including much larger ones.
If we truly become space faring, we have the matter and resources to have a quadrillion humans living in comfort (likely in large rotating space habitats like"O Neil Cylinders"). This is the kind of dream we could have, imagine over 100,000x the humans, artists, friendship, science, and love. We can simultaneously make earth an ecological paradise, with most of the planet reserved for nature.
This "anti-satellite" movement seems to generally have 4 kinds of attacks against the satellites: 1) The satellites "impede my rights to view the sky". The implication is that anyone who attempts to build in their "view to infinity" violates their rights. This seems like an extremely presumptuous statement, like they own trillions of miles. This also doesn't match the current legal framework of any country (nobody needs your permission to fly over your house in aircraft or space). 2) The usecase of these satellites is bad because they are "like cell towers". Getting low cost internet access for the planet is IMO an extremely good thing, one of the best things for the poor. 3) The satellites will kill astronomy. This is absurd, we will have much better astronomy if we are a space fairing species with cheap space access and many things/expertise in space and giant telescopes outside our atmosphere. It may kill amateur astronomy from earth eventually, but I just don't think that as society a relatively fringe hobby should stop the progress of humanity. Many hobbies have been killed over time. I personally think this will inspire more people to look to space, and have the opposite effect. 4) We should not put things into space, and we should look to reduce our impact on the universe. This also manifests itself in those that want to see population reduction on Earth. I believe consciousness is better than lifeless rock. I say this as a human and a parent who has brought consciousness into the world.
Lets upgrade our dreams, take to the stars, and make the universe a more interesting place.
First, of course its good for companies to reduce the negative externalities of things in space (paint, shades, etc). I think there is near universal agreement here, including from SpaceX.
However, there is no way to become a space faring civilization without putting lots of things in space, period. I want to see 1,000,000x more objects in space, including much larger ones.
If we truly become space faring, we have the matter and resources to have a quadrillion humans living in comfort (likely in large rotating space habitats like"O Neil Cylinders"). This is the kind of dream we could have, imagine over 100,000x the humans, artists, friendship, science, and love. We can simultaneously make earth an ecological paradise, with most of the planet reserved for nature.
This "anti-satellite" movement seems to generally have 4 kinds of attacks against the satellites: 1) The satellites "impede my rights to view the sky". The implication is that anyone who attempts to build in their "view to infinity" violates their rights. This seems like an extremely presumptuous statement, like they own trillions of miles. This also doesn't match the current legal framework of any country (nobody needs your permission to fly over your house in aircraft or space). 2) The usecase of these satellites is bad because they are "like cell towers". Getting low cost internet access for the planet is IMO an extremely good thing, one of the best things for the poor. 3) The satellites will kill astronomy. This is absurd, we will have much better astronomy if we are a space fairing species with cheap space access and many things/expertise in space and giant telescopes outside our atmosphere. It may kill amateur astronomy from earth eventually, but I just don't think that as society a relatively fringe hobby should stop the progress of humanity. Many hobbies have been killed over time. I personally think this will inspire more people to look to space, and have the opposite effect. 4) We should not put things into space, and we should look to reduce our impact on the universe. This also manifests itself in those that want to see population reduction on Earth. I believe consciousness is better than lifeless rock. I say this as a human and a parent who has brought consciousness into the world.
Lets upgrade our dreams, take to the stars, and make the universe a more interesting place.
Right. The problem is not that it is 'in my orbital plane', the problem is that it is in everybody's orbital plane whether or not they - or their government - has a say in the matter. You can't escape it. There is no backyard where this isn't an issue.
This is now presented as a fact we will have to live with and if you are against 10's of thousands of orbital satellites you are now - according to you - immediately against progress. This obviously isn't the case.
So, let's stop the clock for a bit until we have a much better idea of what the impact of all this littering will be and whether or not there is something that can be done about it before we end up with a situation that is out of control. SpaceX is not the world, LEO is not US property and whether or not low cost satellite access is such a good thing that we should give up easy access to visible light astronomy is not a given.
This has nothing to do with 'taking to the stars', 'making the universe a more interesting place' or 'upgrading our dreams'. It is a simple commercial proposition.
This is now presented as a fact we will have to live with and if you are against 10's of thousands of orbital satellites you are now - according to you - immediately against progress. This obviously isn't the case.
So, let's stop the clock for a bit until we have a much better idea of what the impact of all this littering will be and whether or not there is something that can be done about it before we end up with a situation that is out of control. SpaceX is not the world, LEO is not US property and whether or not low cost satellite access is such a good thing that we should give up easy access to visible light astronomy is not a given.
This has nothing to do with 'taking to the stars', 'making the universe a more interesting place' or 'upgrading our dreams'. It is a simple commercial proposition.
That simple commercial proposition makes it a bit hard to stop for now, unless SpaceX changes course.
We of course should weight benefits and drawbacks. At least low-orbit Earth satellites aren't too long lived.
We of course should weight benefits and drawbacks. At least low-orbit Earth satellites aren't too long lived.
> This has nothing to do with 'taking to the stars'
Actually it does, because Starlink is intended to fund Starship development and Mars colonization.
Actually it does, because Starlink is intended to fund Starship development and Mars colonization.
Sorry, but Mars colonization is nonsense. It isn't going to happen in the foreseeable future and the people that believe this stuff are no less stupid than the ones following the next messiah. I wrote about it here:
https://news.ycombinator.com/item?id=24058911
Just to put this into perspective a bit: every little bit of civilization in Iceland, every nail, every staple, every fruit, every tool has to be flown in or brought in by boat. Everything. And Iceland is a place that compared to Mars is paradise. The only things they have plenty of are energy, fish and sheep. And on Mars you wouldn't even have that.
It's just too silly to take serious.
Musk and Hughes have a lot in common. They are both genius, wealthy, capable and at times a bit batty. I'm fine with Elon being a bit batty, if that give us electric cars, reusable rockets and more. But I'm not buying into the cult. Starlink is borderline for me. I can see the utility. But the idea that space can be commercialized with such total disregard for what effectively is our largest commons is simply wrong to me.
https://news.ycombinator.com/item?id=24058911
Just to put this into perspective a bit: every little bit of civilization in Iceland, every nail, every staple, every fruit, every tool has to be flown in or brought in by boat. Everything. And Iceland is a place that compared to Mars is paradise. The only things they have plenty of are energy, fish and sheep. And on Mars you wouldn't even have that.
It's just too silly to take serious.
Musk and Hughes have a lot in common. They are both genius, wealthy, capable and at times a bit batty. I'm fine with Elon being a bit batty, if that give us electric cars, reusable rockets and more. But I'm not buying into the cult. Starlink is borderline for me. I can see the utility. But the idea that space can be commercialized with such total disregard for what effectively is our largest commons is simply wrong to me.
> There is no backyard where this isn't an issue.
These aren't visible to human naked eye. Just try and go see them. They already cover the sky in a grid with one of them above the horizon everywhere at all times but just with low density at the moment. I've tried several times and they are not visible.
> So, let's stop the clock for a bit until we have a much better idea of what the impact of all this littering will be
This isn't littering. These are controlled satellites that can be de-orbited at will at any time (and several have been already that had some technical problems with them).
These aren't visible to human naked eye. Just try and go see them. They already cover the sky in a grid with one of them above the horizon everywhere at all times but just with low density at the moment. I've tried several times and they are not visible.
> So, let's stop the clock for a bit until we have a much better idea of what the impact of all this littering will be
This isn't littering. These are controlled satellites that can be de-orbited at will at any time (and several have been already that had some technical problems with them).
I agree with many points here. But :) .
> However, there is no way to become a space faring civilization without putting lots of things in space, period. I want to see 1,000,000x more objects in space, including much larger ones.
But you can have many of those things - majority, if you want - not in an orbit around the Earth. Even farther than GSO, for example.
> imagine over 100,000x the humans, artists, friendship, science, and love.
Humanity isn't only love and friendship. Not to mention that currently we're on a trajectory for the peak population in this century - not quadrillions currently, not even 10 billions. Maybe when we at least colonize Solar system better...
> I just don't think that as society a relatively fringe hobby should stop the progress of humanity.
Astronomy is arguably the first science - that is, brought humanity to asking and thinking about world at large. It's important.
> However, there is no way to become a space faring civilization without putting lots of things in space, period. I want to see 1,000,000x more objects in space, including much larger ones.
But you can have many of those things - majority, if you want - not in an orbit around the Earth. Even farther than GSO, for example.
> imagine over 100,000x the humans, artists, friendship, science, and love.
Humanity isn't only love and friendship. Not to mention that currently we're on a trajectory for the peak population in this century - not quadrillions currently, not even 10 billions. Maybe when we at least colonize Solar system better...
> I just don't think that as society a relatively fringe hobby should stop the progress of humanity.
Astronomy is arguably the first science - that is, brought humanity to asking and thinking about world at large. It's important.
Why would SpaceX care about shading the satellite if there wasn't a movement raising its voice?
Plus, I don't quite get how thousands of tiny satellites used for communication on the planet will make advance us a space faring race.
> Why would SpaceX care about shading the satellite if there wasn't a movement raising its voice?
Because the idea that companies care about NOTHING other than money is generally false with exceptions of a few companies that think like that. (Notably they're not pubicly held, they don't have public quarterly revenue targets and they're not required to make profit for investors.)
SpaceX wasn't aware that they would cause an impact. SpaceX started working on solutions as soon as they heard issues. Companies are not omnipotent. Hanlon's razor, "Never attribute to malice that which is adequately explained by stupidity".
Because the idea that companies care about NOTHING other than money is generally false with exceptions of a few companies that think like that. (Notably they're not pubicly held, they don't have public quarterly revenue targets and they're not required to make profit for investors.)
SpaceX wasn't aware that they would cause an impact. SpaceX started working on solutions as soon as they heard issues. Companies are not omnipotent. Hanlon's razor, "Never attribute to malice that which is adequately explained by stupidity".
I'm not attributing malice at all. The moral obligation of corporation is value for share holders. Shading the satellites doesn't add value. Thus no reason to even think about it, unless there's a public outcry which might damage the value.
I extremely dislike this moral code and Milton Friedman and its second order effects on our society. But that's the frame of mind most people who go through US MBA are indoctrined with.
Regarding Musk, he has proven to have this Randian Hero mentality. He might care about astronomy, and he might just think, who gives a f*CK we're going to Mars.
That's why democracy is important, it reduces the variance of impact these bigger than life type personalities can induce.
I think it's crazy a single person can decide for.all of us how the future will look like.
I extremely dislike this moral code and Milton Friedman and its second order effects on our society. But that's the frame of mind most people who go through US MBA are indoctrined with.
Regarding Musk, he has proven to have this Randian Hero mentality. He might care about astronomy, and he might just think, who gives a f*CK we're going to Mars.
That's why democracy is important, it reduces the variance of impact these bigger than life type personalities can induce.
I think it's crazy a single person can decide for.all of us how the future will look like.
> I'm not attributing malice at all. The moral obligation of corporation is value for share holders. Shading the satellites doesn't add value. Thus no reason to even think about it, unless there's a public outcry which might damage the value.
It's not a moral obligation at all. Corporations don't have morals because they're not alive. The people running them certainly do however. It turns out that people who work in the space industry happen to like space and don't want to ruin the view of it. Elon Musk allegedly specifically tells investors that invest that if they're expecting to get a return on their investment anytime soon to not invest.
> I extremely dislike this moral code and Milton Friedman and its second order effects on our society. But that's the frame of mind most people who go through US MBA are indoctrined with.
What are you even talking about. SpaceX isn't run by MBAs. It's run by engineers.
My personal opinion is that industries self-regulate well as long as they are not given obscene incentives for narrow near-term profit at the expense of the long term. Luckily SpaceX is not a public company so they have no need to worry about the near term.
It's not a moral obligation at all. Corporations don't have morals because they're not alive. The people running them certainly do however. It turns out that people who work in the space industry happen to like space and don't want to ruin the view of it. Elon Musk allegedly specifically tells investors that invest that if they're expecting to get a return on their investment anytime soon to not invest.
> I extremely dislike this moral code and Milton Friedman and its second order effects on our society. But that's the frame of mind most people who go through US MBA are indoctrined with.
What are you even talking about. SpaceX isn't run by MBAs. It's run by engineers.
My personal opinion is that industries self-regulate well as long as they are not given obscene incentives for narrow near-term profit at the expense of the long term. Luckily SpaceX is not a public company so they have no need to worry about the near term.
Whether you agree or disagree with huge sat constrellations, I think that a matter that clearly impacts the entire world should not be decided by a handful of people from a single country.
Nor a single billionaire.
If China or Russia was the one building starlink the reception in the US would be a lot different.
If China or Russia was the one building starlink the reception in the US would be a lot different.
People, let's get real for a minute.
Why are we allowing a private company to ruin the night sky for everybody, and by everybody, I mean literally everybody on this planet?
This should be discussed in a democratic and international way. It’s nor going to be easy, but it is necessary.
I can't believe future generations won't see a pristine night sky anymore...
Why are we allowing a private company to ruin the night sky for everybody, and by everybody, I mean literally everybody on this planet?
This should be discussed in a democratic and international way. It’s nor going to be easy, but it is necessary.
I can't believe future generations won't see a pristine night sky anymore...
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> Why are we allowing a private company to ruin the night sky for everybody, and by everybody, I mean literally everybody on this planet?
They're not being ruined for everybody. There's so many misinformed comments in this thread. These satellites aren't visible to the human eye generally.
They're not being ruined for everybody. There's so many misinformed comments in this thread. These satellites aren't visible to the human eye generally.
"generally" is the key: not long ago in northern Italy everybody was freaking out because of this:
https://cdn.dmove.it/images/18547/StarMain.jpg
Those are the ones by Starlinks. That's not acceptable.
They are so invisible to the naked eye, that the weather website gives you the exact time and date of their passage in the sky: http://www.meteoweb.eu/2020/05/passaggio-satelliti-starlink-... (in Italian)
https://cdn.dmove.it/images/18547/StarMain.jpg
Those are the ones by Starlinks. That's not acceptable.
They are so invisible to the naked eye, that the weather website gives you the exact time and date of their passage in the sky: http://www.meteoweb.eu/2020/05/passaggio-satelliti-starlink-... (in Italian)
1. That is only in the roughly week following launch, which doesn't harm anyone.
2. They changed operations immediately after launch and so you generally can't see this anymore.
They are indeed invisible after launch. Your article is from March, before changes were made. Try to find anyone taking pictures of them in that chain of pearls form in the last few months.
2. They changed operations immediately after launch and so you generally can't see this anymore.
They are indeed invisible after launch. Your article is from March, before changes were made. Try to find anyone taking pictures of them in that chain of pearls form in the last few months.
The document has an executive summary and clear images denoting the impact of these satellites on humanity's view of the stars.
It does a great job of highlighting the collision between high-sensitivity wide-field imaging of both deep fields and transients with the nascent satellite constellations.
Direct link to the PDF: https://noirlab.edu/public/media/archives/techdocs/pdf/techd...
Astronomers have been working for decades toward the Vera Rudin Observatory (nee LSST). It has been the big thing on the horizon for my entire career as a professional scientist. It sees first light in 2021. Images like that seen on page 7 of the PDF will be what they see.
https://en.wikipedia.org/wiki/Vera_C._Rubin_Observatory
It does a great job of highlighting the collision between high-sensitivity wide-field imaging of both deep fields and transients with the nascent satellite constellations.
Direct link to the PDF: https://noirlab.edu/public/media/archives/techdocs/pdf/techd...
Astronomers have been working for decades toward the Vera Rudin Observatory (nee LSST). It has been the big thing on the horizon for my entire career as a professional scientist. It sees first light in 2021. Images like that seen on page 7 of the PDF will be what they see.
https://en.wikipedia.org/wiki/Vera_C._Rubin_Observatory
LSST/Vera is probably the project most impacted by these satellites. Per my contacts, smaller scopes like LBT/Keck/MMT aren't as drastically affected yet. But if we start approaching 100k+ satellites, even they will be having some major issues to deal with.
The real tragedy, from a scientific standpoint in the optical, is that we're entering a new world of wide-field and sensitive time-domain astronomy due to huge improvements in computing power and sensors at the same time that humanity is about to generate thousands of bright transients.
The only practical approach I can think of for combating the constellations is distributed arrays of wide-field transient-hunters. As long as the transient is common-mode across telescopes, then it is real. If there are three LSSTs, and not too many constellation-satellites, that might work.
I just noted, in passing, that the term for the satellite arrays appears to be "constellation"; that is a bummer in this context.
The only practical approach I can think of for combating the constellations is distributed arrays of wide-field transient-hunters. As long as the transient is common-mode across telescopes, then it is real. If there are three LSSTs, and not too many constellation-satellites, that might work.
I just noted, in passing, that the term for the satellite arrays appears to be "constellation"; that is a bummer in this context.
This is an area of very active work by the Rubin/LSST team.
Some documents that might be of interest, pretty hot off the press:
- "Mitigation of LEO Satellite Brightness and Trail Effects on the Rubin Observatory LSST" https://arxiv.org/abs/2006.12417
- "Mitigation of Satellite Tracks in LSST Data Processing" - https://aas.org/sites/default/files/2020-07/MitigationWG_Pre...
There are some good techniques available, and the very smartest experts on image processing are working on this task, so I think we'll manage.
Some documents that might be of interest, pretty hot off the press:
- "Mitigation of LEO Satellite Brightness and Trail Effects on the Rubin Observatory LSST" https://arxiv.org/abs/2006.12417
- "Mitigation of Satellite Tracks in LSST Data Processing" - https://aas.org/sites/default/files/2020-07/MitigationWG_Pre...
There are some good techniques available, and the very smartest experts on image processing are working on this task, so I think we'll manage.
correction to above (can't edit anymore): I meant smaller scopes, as in "smaller field of view" or immediate area of concern, not smaller in aperture
I thought this was going to be about collisions between satellites from two constellations.
As someone loudly lamented a long time ago: please stop using the word “impact” as a substitute for figuring out effect/affect.
As someone loudly lamented a long time ago: please stop using the word “impact” as a substitute for figuring out effect/affect.
As someone loudly lamented a long time ago: please stop using the word “impact” as a substitute for figuring out effect/affect.
"A long time ago" might be the 1700's, because it's been in use that way for several hundred years. So don't hold your breath.
"A long time ago" might be the 1700's, because it's been in use that way for several hundred years. So don't hold your breath.
I’m this case it was within this century, which is quickly becoming a time before some participants here had learned to read. The older you get, the more the line between “long enough” and “a long time ago” begins to blur.
The title of the article is unambiguously not talking about collisions between satellites: "Impact of Satellite Constellations on Optical Astronomy[...]".
Many words have multiple definitions which require you to use context clues to figure out which definition applies.
Many words have multiple definitions which require you to use context clues to figure out which definition applies.
Except our title is
SATCON1 Report on Impact of Satellite Constellations on Astronomy
and orbital debris does have serious consequences for astronomy.
So I'm still going to say: Phrasing!
SATCON1 Report on Impact of Satellite Constellations on Astronomy
and orbital debris does have serious consequences for astronomy.
So I'm still going to say: Phrasing!
The technical report is quite large (105MB). Here is a compressed version (6MB): https://www.dvaun.com/files/satcon1-compressed.pdf
I'm a bit confused by why they included such high-res images in the PDF in the first place.
Edit: After taking a look at the original I see that they embedded some of the files they created with Photoshop and After Effects directly into the document. They forgot to resize the images, hence the huge object streams in the file.
I'm a bit confused by why they included such high-res images in the PDF in the first place.
Edit: After taking a look at the original I see that they embedded some of the files they created with Photoshop and After Effects directly into the document. They forgot to resize the images, hence the huge object streams in the file.
Agreed that they could have downsampled it for expedience, though the point is that systems spanning the gamut from the human eyeball to cryogenically-cooled 3.2 gigapixel imaging sensors are impacted by these constellations.
Those sensors are 3.2 gigapixels at 16-bit depth, so each image alone is 6.4 gigabytes. 108 MB seems small by comparison; that is only one telescope out of all the sky-imaging (optical and radio) systems on the planet.
Those sensors are 3.2 gigapixels at 16-bit depth, so each image alone is 6.4 gigabytes. 108 MB seems small by comparison; that is only one telescope out of all the sky-imaging (optical and radio) systems on the planet.
Human eyeball is not impacted. These satellites are below the limits of human observation generally, even in dark skies.
I appreciate the sense of scale that your explanation brings. I understand that.
The size of the PDF is not a symbol for the work being done here, though. Reducing it makes it cheaper to distribute and easier for viewers to read their findings. That is my reasoning for putting up another version.
The size of the PDF is not a symbol for the work being done here, though. Reducing it makes it cheaper to distribute and easier for viewers to read their findings. That is my reasoning for putting up another version.
Dense satellite groups are a real game-changer in how we observe the sky from the surface of Earth.
We're at the choosing point right now, what's better for us - a good uniform global communications or the pristine sky. The sky was always the norm; but it ceases to be so.
In order to have some compensation to astronomical society - that is, the whole population of Earth, as even looking to bight sky is getting be different - it would be good for SpaceX to create a program of high-orbit astronomical observatories. Working together with Earth astronomers, the company can participate in changes to observation possibilities in a way which has some upside as well, in addition to anticipated degradation. Hubble space telescope was launched some 30 years ago; an observatory of similar class or better can be significantly more affordable today, there can be several - or many - of them and that could be a worthy trade-off to the degradation of Earth-visible sky. I'm sure astronomical society would be very interested in participating and helping with building such a group of space observatories.
We're at the choosing point right now, what's better for us - a good uniform global communications or the pristine sky. The sky was always the norm; but it ceases to be so.
In order to have some compensation to astronomical society - that is, the whole population of Earth, as even looking to bight sky is getting be different - it would be good for SpaceX to create a program of high-orbit astronomical observatories. Working together with Earth astronomers, the company can participate in changes to observation possibilities in a way which has some upside as well, in addition to anticipated degradation. Hubble space telescope was launched some 30 years ago; an observatory of similar class or better can be significantly more affordable today, there can be several - or many - of them and that could be a worthy trade-off to the degradation of Earth-visible sky. I'm sure astronomical society would be very interested in participating and helping with building such a group of space observatories.
I don't think SpaceX can lift LSST-class instruments to orbit (and transport the students/maintenance staff to visit/upgrade monthly), move radio telescopes like VLA/SKA/GreenBank to orbit, transport kids to dark-sky locations for the cost of a school-bus ride, make it possible to watch unfettered nebulae through a pair of 10x50s, or make it possible to photograph the Milky Way rising over a national park without streaks in the sky.
I don't have a solution to the constellation problem -- I just want to point out that, while launching JWST-class instruments would help to mitigate the impact for some professional astronomers, such a strategy cannot the broad impact of artificial stars in the sky.
Constellations can do undeniable good for the ground, but I think it is really a choice between dark skies and global satellite internet.
I don't have a solution to the constellation problem -- I just want to point out that, while launching JWST-class instruments would help to mitigate the impact for some professional astronomers, such a strategy cannot the broad impact of artificial stars in the sky.
Constellations can do undeniable good for the ground, but I think it is really a choice between dark skies and global satellite internet.
SpaceX's next-gen rocket, Starship, will have a 9 meter fairing and aims to be able to launch 100 tons into orbit for ~$10-100/kg. They also plan to support 3 launches per day. LSST has a primary mirror that's 8.4 meters wide, so something like it could potentially fit. Enormous radio telescopes can be constructed from a large array of smaller satellites via radio interferometry.
> Constellations can do undeniable good for the ground, but I think it is really a choice between dark skies and global satellite internet.
It's a good summary of the situation, yes.
> I don't think SpaceX can lift LSST-class instruments to orbit...
Literally - not soon, but the launch industry is at a point of fast evolution, so it might make sense to use it and device different kinds of astronomy tools - not multibillion gems, one-of-a-kinds, practically irreplaceable in case of launch failure, but numerous, with fast turnaround, sensors enjoying short design loops from conception to using and benefiting from decreasing prices of kilogram on orbit.
Frankly, some LSST-class instruments can only be based in space, and SpaceX can well be a good helper in getting them there.
> or make it possible to photograph the Milky Way rising over a national park without streaks in the sky.
With today's photographic equipment, yes. With naked eyes, unfortunately, yes. But there could be a non-insignificant replacement.
It's a good summary of the situation, yes.
> I don't think SpaceX can lift LSST-class instruments to orbit...
Literally - not soon, but the launch industry is at a point of fast evolution, so it might make sense to use it and device different kinds of astronomy tools - not multibillion gems, one-of-a-kinds, practically irreplaceable in case of launch failure, but numerous, with fast turnaround, sensors enjoying short design loops from conception to using and benefiting from decreasing prices of kilogram on orbit.
Frankly, some LSST-class instruments can only be based in space, and SpaceX can well be a good helper in getting them there.
> or make it possible to photograph the Milky Way rising over a national park without streaks in the sky.
With today's photographic equipment, yes. With naked eyes, unfortunately, yes. But there could be a non-insignificant replacement.
Two more ideas here. First, it would help if each satellite can have an astronomical payload; this is likely hard to achieve due to quite conflicting requirements between these two different goals.
Here is the second one. Earth observatories demonstrate streaks of satellites across astronomical images taken over comparatively long time. We know that at each moment satellite is in just one place in the sky; more, those constellations tend to have rather predictable orbits. Image sensing devices can use knowledge of satellite orbits to suppress reading a particular pixel at particular time if a satellite is expected to shine towards that pixel.
It's quite delicate task, I understand, but I also know that practical astronomy is known for inventing solutions to very diverse problems. This approach won't completely restore the abilities to observe the sky, but can significantly diminish the impact, discussed in the article. Especially if Earth-based devices would be constructed with such "shielding" (remember star shielding invention when working on exoplanetary discoveries?) in mind.
Here is the second one. Earth observatories demonstrate streaks of satellites across astronomical images taken over comparatively long time. We know that at each moment satellite is in just one place in the sky; more, those constellations tend to have rather predictable orbits. Image sensing devices can use knowledge of satellite orbits to suppress reading a particular pixel at particular time if a satellite is expected to shine towards that pixel.
It's quite delicate task, I understand, but I also know that practical astronomy is known for inventing solutions to very diverse problems. This approach won't completely restore the abilities to observe the sky, but can significantly diminish the impact, discussed in the article. Especially if Earth-based devices would be constructed with such "shielding" (remember star shielding invention when working on exoplanetary discoveries?) in mind.
Satellites are not new, so many techniques have been used and tested. https://aas.org/sites/default/files/2020-07/MitigationWG_Pre... is a relatively nontechnical survey of some of the techniques that Rubin plans to employ.
Suppressing pixel readings is not plausible with the current CCD designs, as far as I'm aware. These devices are so sensitive that any wiring needs to be done _extremely_ carefully to minimize crosstalk and keep temperatures extremely low (think under -100C).
Masking in data processing is the more likely technique.
Suppressing pixel readings is not plausible with the current CCD designs, as far as I'm aware. These devices are so sensitive that any wiring needs to be done _extremely_ carefully to minimize crosstalk and keep temperatures extremely low (think under -100C).
Masking in data processing is the more likely technique.
> Suppressing pixel readings is not plausible with the current CCD designs
Better than suppressing pixel reading would be suppressing pixel changes. The first process lets pixel to change as a result of incoming photons, the second one maintains the "unread" state.
Yes, current CCD devices can't do that. Advantage of this change is also in reducing crosstalk - if we need, say, to remove accumulated charge and for that we need to draw the current, the current may influence our reading of neighboring pixels. I'm tempted to look towards "smart mirrors" - MEMS systems, even for mirrors of 1 sq. micron - but purely electrical solutions might be possible.
Better than suppressing pixel reading would be suppressing pixel changes. The first process lets pixel to change as a result of incoming photons, the second one maintains the "unread" state.
Yes, current CCD devices can't do that. Advantage of this change is also in reducing crosstalk - if we need, say, to remove accumulated charge and for that we need to draw the current, the current may influence our reading of neighboring pixels. I'm tempted to look towards "smart mirrors" - MEMS systems, even for mirrors of 1 sq. micron - but purely electrical solutions might be possible.
> Image sensing devices can use knowledge of satellite orbits to suppress reading a particular pixel at particular time if a satellite is expected to shine towards that pixel
This is functionally the same, but a less flexible technique, as reading the pixel values anyway, and then discarding or covering up the values during data analysis/preparation. IRAF already contains these tools.
Getting shorter exposure times is actually helpful to mitigating satellite contamination. In the last 5 years, we're down to 1-2 electron noise per read, which is a full order of magnitude improvement.
This is functionally the same, but a less flexible technique, as reading the pixel values anyway, and then discarding or covering up the values during data analysis/preparation. IRAF already contains these tools.
Getting shorter exposure times is actually helpful to mitigating satellite contamination. In the last 5 years, we're down to 1-2 electron noise per read, which is a full order of magnitude improvement.
They're already doing that.
The streaky images in the press releases aren't meant to communicate "we don't know how to clean data," they're meant to communicate the severity of the interfering signal which must now be removed. Imperfectly, with imperfections in proportion to the severity of the interfering signal. Which is large.
The streaky images in the press releases aren't meant to communicate "we don't know how to clean data," they're meant to communicate the severity of the interfering signal which must now be removed. Imperfectly, with imperfections in proportion to the severity of the interfering signal. Which is large.
Of course astronomical societies would be interested in someone gifting them some wildly expensive equipment.
To get better - much better sometimes - view of the sky, yes. And not only gifting - working together with world-class practical space engineers on building space observatories with potential benefits not expected before this issue becoming significant.
I'm serious here - seeing Elon Musk traditions, it would be not ridiculous to test such an approach.
I'm serious here - seeing Elon Musk traditions, it would be not ridiculous to test such an approach.
I think the key part here is "how we observe the sky from the surface of Earth."
The same economics that is putting cheap satellites in orbit should be usable to put cheap telescopes in orbit. What is needed to do that? Because I'm imagining an array telescope with the diameter of an Earth orbit.
The same economics that is putting cheap satellites in orbit should be usable to put cheap telescopes in orbit. What is needed to do that? Because I'm imagining an array telescope with the diameter of an Earth orbit.
We've been covering this issue frequently in Orbital Index (https://orbitalindex.com). With around 10,000 stars visible with the naked eye, there will be significantly more satellites than stars, even from a single constellation like Starlink or Project Kuiper. Granted, most of those satellites won't be visible at any given time, but I do worry about the ability of LSST and other wide-field observatories to do their (very expensive & important) jobs—one of those jobs is spotting near Earth asteroids with a collision potential.
Here's a recording of the recent 'Impacts of Satellite Constellations on Optical Astronomy' webinar that discussed this and had someone from SpaceX: https://www.youtube.com/watch?v=LaR6v0p6pB4
Here's a recording of the recent 'Impacts of Satellite Constellations on Optical Astronomy' webinar that discussed this and had someone from SpaceX: https://www.youtube.com/watch?v=LaR6v0p6pB4
Just wanted to chime in and say I love Orbital Index and read it every week.
I understand this is a bit of a selfish request and entirely a matter of personal preference given my job, but I do wish you guys would talk a little bit more about up and coming companies in the Space industry so I'd know who to keep my eyes on. Not sure if the rest of readership would care but thought I'd throw the idea out there on the off chance others would also be interested.
I don't see any other newsletters / research articles out there that are anywhere near as knowledgeable and I expect more and more people to turn their attention to startups in this space (no pun intended..)
Anyway, thanks again for the incredibly high quality content!
I understand this is a bit of a selfish request and entirely a matter of personal preference given my job, but I do wish you guys would talk a little bit more about up and coming companies in the Space industry so I'd know who to keep my eyes on. Not sure if the rest of readership would care but thought I'd throw the idea out there on the off chance others would also be interested.
I don't see any other newsletters / research articles out there that are anywhere near as knowledgeable and I expect more and more people to turn their attention to startups in this space (no pun intended..)
Anyway, thanks again for the incredibly high quality content!
This is super feedback. Glad you like the newsletter. I feel like we often find it hard get a view into when startups hit what they consider important milestones—those seem to get lost in the noise of flying grain silos and such. Some attempt at aggregation of space startup press releases or similar might be place to start… I'll have to give this a bit more thought. -Ben (co-editor of OI)
As a side note, let me say that Orbital Index is a fantastic service. It's the only newsletter that I read every week without fail.
I'm so glad you're enjoying it!
+1, I look forward to it every week
Do the satellites impact more than a single pixel at a time for a brief moment? Can't the normal image stacking and pixel masking resolve this?
Seems like a bigger threat to astronomy is clouds.
Seems like a bigger threat to astronomy is clouds.
Depends on exactly what type of observation you're doing and how big your telescope is. A lot of telescopes use CCD sensors which are more sensitive but have a bad side effect in that once a pixel saturates it starts to bleed into adjacent pixels causing massive horizontally or vertically oriented blooms that white out a bunch of pixels.
What is the latest news on starlink? A friend of mine had a perfect observation chance for the last launch and said he couldn't see a thing, did they "fix" them?
They did two things for two phases of the satellites' lifetimes. In the first phase the satellites are raising their orbits to their final position over a period of a month or two, and SpaceX started rotating the solar panels to reflect less light toward the Earth. But they can still be visible sometimes, until they reach the operational phase when they are in their final, higher orbit.
For the operational phase SpaceX added a sunshade which reflects light away from the Earth. This plus the higher orbit makes the satellites dim enough that they cannot be seen with the naked eye. This sunshade was designed with feedback from astronomers at the often mentioned LSST, which is the single telescope most affected by large satellite constellations. It will prevent artifacts from the imaging sensor's pixels becoming saturated, which is the main concern. The satellites will be visible to the telescope but can be filtered out with standard techniques already in use to filter out the thousands of other satellites already in orbit. See https://www.spacex.com/updates/starlink-update-04-28-2020/
For the operational phase SpaceX added a sunshade which reflects light away from the Earth. This plus the higher orbit makes the satellites dim enough that they cannot be seen with the naked eye. This sunshade was designed with feedback from astronomers at the often mentioned LSST, which is the single telescope most affected by large satellite constellations. It will prevent artifacts from the imaging sensor's pixels becoming saturated, which is the main concern. The satellites will be visible to the telescope but can be filtered out with standard techniques already in use to filter out the thousands of other satellites already in orbit. See https://www.spacex.com/updates/starlink-update-04-28-2020/
The satellites were only human eye visible because SpaceX let them tumble for a while right after launch. They changed operations and now they're no longer visible to the human eye (generally).
See here: https://www.spacex.com/updates/starlink-update-04-28-2020/
See here: https://www.spacex.com/updates/starlink-update-04-28-2020/
> one of those jobs is spotting near Earth asteroids with a collision potential
What actually happens if they spot an asteroid with collision potential? Is there anything we can do about it?
What actually happens if they spot an asteroid with collision potential? Is there anything we can do about it?
With sufficient time there are plenty of realistic options, ranging from evacuating the impact zone, to nudging it off-course with a "gravitational" space tug (surprisingly feasible), all the way to deflection with nuclear weapons. (Pushing the asteroid enough to nudge it off-course is always a lot easier than blowing it up, Armageddon-style.)
Or build 11,000 city scale engines on one side of the earth!
If it's a week away and massive? Not much.
If it's years or decades away, we could try.
If it's years or decades away, we could try.
If only there were some way to lift a bunch of cheap kill vehicles into orbit that could be used for both detection and interdiction of incoming rocks with little notice...
(I know, it's not exactly that simple. But still.... ;) )
(I know, it's not exactly that simple. But still.... ;) )
Let me do that and I will ready it to drop on your head whenever I want and then I'll hold that threat over you constantly.
I mean, I already live under the constant threat of nuclear armageddon from "conventional" ICBMs. So if you're going to suspend kill vehicles over my head that can also save the world from an asteroid... There's gonna be a lot of international politics to work out, but I'm not gonna be the one stopping you. ;)
I've got to be honest. I'm not going to bother with the asteroid part. I'm just going to tell you that what they're for. After all, you can't check.
There's lots of things I can't check. I delegate.
I would assume the "working out the international politics" part includes "a multinational effort among nuclear-armed countries that spot-checks the kill vehicles can actually do the thing claimed to do."
I would assume the "working out the international politics" part includes "a multinational effort among nuclear-armed countries that spot-checks the kill vehicles can actually do the thing claimed to do."
Any rock you can tackle on little notice is a rock that wouldn't have done much anyways. Anything with the size to have significant impact on Earth is gonna require years of lead time to tackle; you'd need to start changing its orbit well in advance.
No disagreement that less delta-V is needed for big rocks far out in their orbit, so early detection is cheaper.
... but in terms of whether stopping is possible, I believe that depends on the amount of kinetic energy you can apply to it. I'd have to sit down and do some real math to determine the practical stopping power of a kill fleet, but to give a thumbnail comparison: each Starlink sat is about 500 lbs, which is about the weight of one B57 nuclear bomb, with a yield of 5-20kt. There are about 660 Starlinks in orbit now... A constellation of kill vehicles of the same size could have the ability to deliver an upper-bound of 13.2 megatons of explosive energy. According to one source (https://www.space.com/39971-asteroid-destruction-nuclear-bom...), 3 megatons should be sufficient (though the parameters for individual delivery of smaller payloads vs. one big nuke would of course be different).
This is, of course, all a terrible idea; nobody's gonna be comfortable with a mega-constellation of nukes in orbit.
... but in terms of whether stopping is possible, I believe that depends on the amount of kinetic energy you can apply to it. I'd have to sit down and do some real math to determine the practical stopping power of a kill fleet, but to give a thumbnail comparison: each Starlink sat is about 500 lbs, which is about the weight of one B57 nuclear bomb, with a yield of 5-20kt. There are about 660 Starlinks in orbit now... A constellation of kill vehicles of the same size could have the ability to deliver an upper-bound of 13.2 megatons of explosive energy. According to one source (https://www.space.com/39971-asteroid-destruction-nuclear-bom...), 3 megatons should be sufficient (though the parameters for individual delivery of smaller payloads vs. one big nuke would of course be different).
This is, of course, all a terrible idea; nobody's gonna be comfortable with a mega-constellation of nukes in orbit.
I'm pretty skeptical of this experimental approach scaling up:
> The scientists found that a 500-joule-per-gram laser blast was required to break apart a model space rock 0.3 inches to 0.4 inches in diameter (8 to 10 millimeters), if that blast were directed at a premade cavity in the "asteroid." Without the cavity, the necessary energy was about 650 joules per gram.
> The scientists found that a 500-joule-per-gram laser blast was required to break apart a model space rock 0.3 inches to 0.4 inches in diameter (8 to 10 millimeters), if that blast were directed at a premade cavity in the "asteroid." Without the cavity, the necessary energy was about 650 joules per gram.
Really cheap heavy-lift launch capability would be a big help. Developing that capability is exactly what Starlink is intended to fund.
Cheap rockets will make space telescopes way more accessible. Ground survey telescopes have serious limitations. So for science this could be a positive thing.
I am more worried about monopolies and accessibility of this new internet. If it ruins sky for everyone, but only a few can afford it, that would be a terrible deal.
I am more worried about monopolies and accessibility of this new internet. If it ruins sky for everyone, but only a few can afford it, that would be a terrible deal.
>Cheap rockets will make space telescopes way more accessible.
I'm not convinced that's true. If you look at past space telescopes, launch costs are not a large part of the budget. Even if SpaceX gave everyone free launches as a goodwill measure, you'd only make space telescopes maybe 2-5% cheaper. There's very real challenges that space based telescopes have that Earth based ones don't (how do you make a cryocooler that doesn't vibrate your optics? How do you make a machine that can run for years without maintenance? How do you get precise enough positioning to interferometry?). My understanding is that due to adaptive optics, being ground based isn't much of a problem for visual telescopes. And for large radio telescope arrays, I don't see how it's possible at all to move to space
I'm not convinced that's true. If you look at past space telescopes, launch costs are not a large part of the budget. Even if SpaceX gave everyone free launches as a goodwill measure, you'd only make space telescopes maybe 2-5% cheaper. There's very real challenges that space based telescopes have that Earth based ones don't (how do you make a cryocooler that doesn't vibrate your optics? How do you make a machine that can run for years without maintenance? How do you get precise enough positioning to interferometry?). My understanding is that due to adaptive optics, being ground based isn't much of a problem for visual telescopes. And for large radio telescope arrays, I don't see how it's possible at all to move to space
Major cost is reliability. Also design for deployment is complicated. Spitzer telecope was expensive for foldable mirror.
Cheap rockets with fast deployment would be game changer.
Cheap rockets with fast deployment would be game changer.
> If you look at past space telescopes, launch costs are not a large part of the budget.
Satellites are built to narrow margin to reduce weight because of the weight restrictions on satellites. Right now we have reusable rockets but the rockets aren't any bigger so while the cost of launch has come down the volume/mass that can be launched in one go has not gone up. If laser interferometry gets better then large telescopes can be launched as constellations. Larger reusable rockets are also being worked on. When that happens they can care less about mass margin and make cheaper lower margin telescopes.
Telescopes are also generally built as a one-off which also increases cost. I hope the technology for telescope constellations will improve.
Satellites are built to narrow margin to reduce weight because of the weight restrictions on satellites. Right now we have reusable rockets but the rockets aren't any bigger so while the cost of launch has come down the volume/mass that can be launched in one go has not gone up. If laser interferometry gets better then large telescopes can be launched as constellations. Larger reusable rockets are also being worked on. When that happens they can care less about mass margin and make cheaper lower margin telescopes.
Telescopes are also generally built as a one-off which also increases cost. I hope the technology for telescope constellations will improve.
Even if there's room for additional weight, that doesn't help with the other aspects of SWAP.
Size: There's still a finite fairing size. Even the biggest upcoming rockets can't fit a 30m mirror in one piece.
Weight: say you want to put something like ALMA in space, which weighs over ten million pounds. Even with platforms like starship,you're not going to be able to do that in one go. Maybe one launch for each of the 66 antennas,but even that is iffy.
Power: Hubble's power consumption is around 2Kw. Using ALMA as an example again, each individual antenna uses about 10x more electricity than that on average. More electricity means you need RTGs or nuclear reactors (not politically popular, complicates thermal regulation, potential for spreading radioactive waste across orbit and earth a la RORSAT), or massive arrays of solar panels. Massive solar panels means even more weight and space required
For interferometry, knowing your location to the nanometer is just the first of many challenges. You have to station keep across the constellation (tricky to do continuously while you're in orbit!), it becomes even more important to minimize vibrations, etc
Size: There's still a finite fairing size. Even the biggest upcoming rockets can't fit a 30m mirror in one piece.
Weight: say you want to put something like ALMA in space, which weighs over ten million pounds. Even with platforms like starship,you're not going to be able to do that in one go. Maybe one launch for each of the 66 antennas,but even that is iffy.
Power: Hubble's power consumption is around 2Kw. Using ALMA as an example again, each individual antenna uses about 10x more electricity than that on average. More electricity means you need RTGs or nuclear reactors (not politically popular, complicates thermal regulation, potential for spreading radioactive waste across orbit and earth a la RORSAT), or massive arrays of solar panels. Massive solar panels means even more weight and space required
For interferometry, knowing your location to the nanometer is just the first of many challenges. You have to station keep across the constellation (tricky to do continuously while you're in orbit!), it becomes even more important to minimize vibrations, etc
Is ALMA even affected by satellites? I would imagine parallax would make satellites disappear and satellites would just slightly increase the noise floor. So I'm not sure why you're using that as an example.
> For interferometry, knowing your location to the nanometer is just the first of many challenges. You have to station keep across the constellation (tricky to do continuously while you're in orbit!), it becomes even more important to minimize vibrations, etc
I didn't say it wasn't an engineering problem, but the major reason it hasn't been used yet is there was no real benefit to doing that over launching a single large telescope in terms of launch cost. I hope to see these problems solved soon in the future.
> For interferometry, knowing your location to the nanometer is just the first of many challenges. You have to station keep across the constellation (tricky to do continuously while you're in orbit!), it becomes even more important to minimize vibrations, etc
I didn't say it wasn't an engineering problem, but the major reason it hasn't been used yet is there was no real benefit to doing that over launching a single large telescope in terms of launch cost. I hope to see these problems solved soon in the future.
At least from what other radio telescopes, the issue isn't actually the physical satellites. It's the spectrum they're using
>no real benefit to doing that over launching a single large telescope in terms of launch cost
It would be hugely beneficial to do it in space. When you do interferometry on the ground, your maximum aperture size is the diameter of the Earth (if you had two observatories at opposite points on the Earth). When you do it in space, the size of your synthetic aperture is practically limitless.
>no real benefit to doing that over launching a single large telescope in terms of launch cost
It would be hugely beneficial to do it in space. When you do interferometry on the ground, your maximum aperture size is the diameter of the Earth (if you had two observatories at opposite points on the Earth). When you do it in space, the size of your synthetic aperture is practically limitless.
I've sat here for a few minutes thinking selfishly about never being able to experience Alaska wilderness on a clear night. Or late night stroll on a beach looking up, etc, etc forever about all kinds of personal moments that will never be the same.
However there's billions of people who have no idea what Starlink or Kuiper are that are going to find out the hard way when they no longer have that same night sky either.
I hadn't really thought about it much before because it was always framed as an astronomy problem, but it's really a whole Earth's peoples problem.