SpaceX working on fix for Starlink satellites so they don’t disrupt astronomy(spacenews.com)
spacenews.com
SpaceX working on fix for Starlink satellites so they don’t disrupt astronomy
https://spacenews.com/spacex-working-on-fix-for-starlink-satellites-so-they-dont-disrupt-astronomy/
275 comments
(I'm not speaking for any of my current or past employers, just for myself, and how I've seen this play out. One employer being a telescope impacted by Starlink, and the other being SpaceX, I want both sides to succeed.)
First, astronomers know that satellites can disrupt observations. They've known for a while, and have had to deal with things like flares from Irridium satellites, which were probably when these problems were first taken seriously. (It was a design defect where shiny panels would reflect the sun in a very efficient way).
Astronomers use all sorts of image processing, because satellites aren't the only noise in the picture. The CCDs have to be kept cryogenically cool, and there's all sorts of electrical noise as well. There's not a lot of photons being collected in the grand scheme of things, so dealing with the noise floor is a real problem. There are all sorts of ways for removing tracks. And don't forget weather!
Now, that being said, even I was confused why this would cause a problem. The satellites are in low earth orbit, so low that they won't be able to reflect the sunlight, since they are in earth's shadow. Only during twilight and dawn will satellites be in the right position to reflect the sunlight back to the ground off of some panel.
Now, these are not prime observing hours for many people, since it is still not as dark as it could be. So most people point into the darkest parts of the sky (up) rather than at parts where there is still twilight (like nearer the horizon).
But for some types of observations, like near earth asteroids, you want to point into the evening sky to look for them, since that is one of the places you want to look, and the sky conditions should be good enough. In these pictures you'll get streaks of light as the satellites pass through.
Even if there is no light reflecting, these satellites could occlude a distant star or galaxy momentarily. You wouldn't see a streak as much as the light would go away and come back. This would affect how bright you see the star, since over the time of the exposure (let's say 30 seconds) you'll collect less light while something is blocking the light. This can also make it a bit more tricky to look at variable stars, where the light gets stronger and dimmer naturally.
I would say that astronomers definitely knew about these problems, since they have to deal with all sorts of similar problems, but the pitch didn't get fevered until people saw the first set of Starlink satellites and just how bright they were. SpaceX moves a lot faster than astronomy.
As for SpaceX not thinking about the astronomical implications of Starlink, I could believe that. I think most of them were more concerned with if it is possible rather than the implications of doing it. As much as I would think the two fields would know more about each other, I find they are very different and run in different circles it seems (launch vehicle industry vs astronomers), so I could easily see not much cross pollination between the two. For example, there were lots of NASA astronauts and air force people visiting SpaceX, but I don't remember one astronomer (not that I met everyone).
First, astronomers know that satellites can disrupt observations. They've known for a while, and have had to deal with things like flares from Irridium satellites, which were probably when these problems were first taken seriously. (It was a design defect where shiny panels would reflect the sun in a very efficient way).
Astronomers use all sorts of image processing, because satellites aren't the only noise in the picture. The CCDs have to be kept cryogenically cool, and there's all sorts of electrical noise as well. There's not a lot of photons being collected in the grand scheme of things, so dealing with the noise floor is a real problem. There are all sorts of ways for removing tracks. And don't forget weather!
Now, that being said, even I was confused why this would cause a problem. The satellites are in low earth orbit, so low that they won't be able to reflect the sunlight, since they are in earth's shadow. Only during twilight and dawn will satellites be in the right position to reflect the sunlight back to the ground off of some panel.
Now, these are not prime observing hours for many people, since it is still not as dark as it could be. So most people point into the darkest parts of the sky (up) rather than at parts where there is still twilight (like nearer the horizon).
But for some types of observations, like near earth asteroids, you want to point into the evening sky to look for them, since that is one of the places you want to look, and the sky conditions should be good enough. In these pictures you'll get streaks of light as the satellites pass through.
Even if there is no light reflecting, these satellites could occlude a distant star or galaxy momentarily. You wouldn't see a streak as much as the light would go away and come back. This would affect how bright you see the star, since over the time of the exposure (let's say 30 seconds) you'll collect less light while something is blocking the light. This can also make it a bit more tricky to look at variable stars, where the light gets stronger and dimmer naturally.
I would say that astronomers definitely knew about these problems, since they have to deal with all sorts of similar problems, but the pitch didn't get fevered until people saw the first set of Starlink satellites and just how bright they were. SpaceX moves a lot faster than astronomy.
As for SpaceX not thinking about the astronomical implications of Starlink, I could believe that. I think most of them were more concerned with if it is possible rather than the implications of doing it. As much as I would think the two fields would know more about each other, I find they are very different and run in different circles it seems (launch vehicle industry vs astronomers), so I could easily see not much cross pollination between the two. For example, there were lots of NASA astronauts and air force people visiting SpaceX, but I don't remember one astronomer (not that I met everyone).
This sounds to me like a new technology and a way of operating has come and we're trying to make it accommodate the old way of doing things.
If we really have a way to launch thousands of satellites easily, can't we replace the terrestrial functionality with that? Let's launch hundreds of satellites observing near earth asteroids.
If a private company can do it, governments definitely can
If we really have a way to launch thousands of satellites easily, can't we replace the terrestrial functionality with that? Let's launch hundreds of satellites observing near earth asteroids.
If a private company can do it, governments definitely can
So while it sounds good that we've fixed the launch industry and can launch everything cheaper, that we should only have space based telescopes, space telescopes are a very different game from ground based telescopes.
First, as others have pointed out, is size. Ground based mirrors are very large, in the 10s of meters, and those mirrors are extremely heavy, like tons. You can't lift one of those mirrors up on one rocket, so you'll have to figure out some kind of in orbit construction. Not impossible, but we haven't assembled a lot of things in space, probably the biggest would be the ISS. But telescopes have tricky tolerances...
Which leads me to the next issue: not only is it heavy, but telescopes are fragile. They have to be very carefully calibrated and put together. Launching something into space tends to be a very bumpy ride, and making something that can withstand that kind of vibration for launch, and then the thermal problems while in space would be certainly not trivial.
But let's say you could build something and get it to work in orbit. Then it's still hard to service. Servicing the hubble to fix the optics was a very hard mission, and the hubble is relatively close to the earth. And that was when we had the shuttle, which we don't now.
Cooling is very tricky for both telescopes and space. Since there's no air to radiate to, you can get big thermal gradients over the length of your craft and you have to be very careful how you point it. Same for the optics and the camera, you want to make sure they have as little thermal gradient as possible.
Unlike a lot of commercial satellites, many scientific probes and telescopes are constantly refitted and reused. Ground based telescopes frequently reuse the same expensive (typically one-off) mirrors and put better cameras on them all the time. This is pretty hard to do in space.
That being said, being in space does have a lot of advantages, the most obvious one being a lack of atmosphere to mess with your observations. But assembling large telescopes in space still isn't exactly easy.
I think over time though, we will be heading to more space based telescopes as the cost comes down. But many slower moving telescope projects (mostly slow due to government funding) were started before Starlink was even announced.
First, as others have pointed out, is size. Ground based mirrors are very large, in the 10s of meters, and those mirrors are extremely heavy, like tons. You can't lift one of those mirrors up on one rocket, so you'll have to figure out some kind of in orbit construction. Not impossible, but we haven't assembled a lot of things in space, probably the biggest would be the ISS. But telescopes have tricky tolerances...
Which leads me to the next issue: not only is it heavy, but telescopes are fragile. They have to be very carefully calibrated and put together. Launching something into space tends to be a very bumpy ride, and making something that can withstand that kind of vibration for launch, and then the thermal problems while in space would be certainly not trivial.
But let's say you could build something and get it to work in orbit. Then it's still hard to service. Servicing the hubble to fix the optics was a very hard mission, and the hubble is relatively close to the earth. And that was when we had the shuttle, which we don't now.
Cooling is very tricky for both telescopes and space. Since there's no air to radiate to, you can get big thermal gradients over the length of your craft and you have to be very careful how you point it. Same for the optics and the camera, you want to make sure they have as little thermal gradient as possible.
Unlike a lot of commercial satellites, many scientific probes and telescopes are constantly refitted and reused. Ground based telescopes frequently reuse the same expensive (typically one-off) mirrors and put better cameras on them all the time. This is pretty hard to do in space.
That being said, being in space does have a lot of advantages, the most obvious one being a lack of atmosphere to mess with your observations. But assembling large telescopes in space still isn't exactly easy.
I think over time though, we will be heading to more space based telescopes as the cost comes down. But many slower moving telescope projects (mostly slow due to government funding) were started before Starlink was even announced.
The large telescope mirrors aren’t single parts even in terrestrial telescopes. We have to assemble and calibrate them on their isolated mountaintops, starting with the giant support structures intended for suspending the mirrors against the pull of gravity with minimum distortion regardless of orientation of the telescope.
We then add active optics to compensate for atmospheric distortion, alter airline routes and city lighting to help improve conditions, and then pray for no clouds on the nights we want to observe.
Constructing telescopes in space will become a reality within the next decade, while terrestrial telescopes currently in planning will be finding it harder and harder to navigate the mixture of light pollution, accessibility and indigenous rights. I expect there are terrestrial telescopes already in planning and even at early stages of construction which will never be finished. Between the ever-growing forest of red tape and the ever shrinking cost of building space telescopes in orbit, there will be an inflexion point where it makes sense to dedicate the remaining budget of a terrestrial telescope project to building its spaceborne replacement.
We then add active optics to compensate for atmospheric distortion, alter airline routes and city lighting to help improve conditions, and then pray for no clouds on the nights we want to observe.
Constructing telescopes in space will become a reality within the next decade, while terrestrial telescopes currently in planning will be finding it harder and harder to navigate the mixture of light pollution, accessibility and indigenous rights. I expect there are terrestrial telescopes already in planning and even at early stages of construction which will never be finished. Between the ever-growing forest of red tape and the ever shrinking cost of building space telescopes in orbit, there will be an inflexion point where it makes sense to dedicate the remaining budget of a terrestrial telescope project to building its spaceborne replacement.
> Ground based mirrors are very large, in the 10s of meters, and those mirrors are extremely heavy, like tons.
Seemingly fantastically - SpaceX is currently constructing a system designed to launch 100 tons to LEO, for as low as $35/kg [1]. Musk says this capability is what the Starlink business is to pay for. It appears lately, more realistic than it has sounded.
[1] https://caseyhandmer.wordpress.com/2019/10/29/the-spacex-sta... ( https://news.ycombinator.com/item?id=21397285 )
Seemingly fantastically - SpaceX is currently constructing a system designed to launch 100 tons to LEO, for as low as $35/kg [1]. Musk says this capability is what the Starlink business is to pay for. It appears lately, more realistic than it has sounded.
[1] https://caseyhandmer.wordpress.com/2019/10/29/the-spacex-sta... ( https://news.ycombinator.com/item?id=21397285 )
One of the things I'm most excited about related to Starship is its landed mass capability for science purposes. Imagine being able to build radio and optical telescopes in the Daedalus crater on the central lunar far side. They'd be shielded from the optical and radio noise of the sun for 2 weeks out of 4, and permanently shielded from Earth. Or imagine infrared telescopes at the bottom of permanently shadowed polar craters, where ambient temperatures are even colder than in interplanetary space. No need to design and deploy a complex sunshield and worry about maintaining spacecraft orientation. The science potential of reusable heavy-lift rockets can't be understated.
So SpaceX creates the problem and sells the solution - brilliant business strategy :P
Terrestrial telescopes are huge. Hubble is comparatively tiny, and launching a telescope the same size as the ones we use down here would be completely out of the question with any near-term launch capability.
Well let's figure out a way to assemble them in space.
Hubble is thirty years old, and is being used now as a reference. I don't understand all this negativity. Had we had this mindset, Hubble would not have been there
Hubble is thirty years old, and is being used now as a reference. I don't understand all this negativity. Had we had this mindset, Hubble would not have been there
Part of the negativity is who benefits from the problem versus who has to pay to fix it. If SpaceX were causing a problem for astronomers while also for free launching radically better space-based tools, it wouldn't be nearly as big a deal. But instead SpaceX hopes to pocket a lot of money, while the harms are falling on other people.
> SpaceX hopes to pocket a lot of money
and SpaceX customers hope to pocket a lot of use for that money. So taking that point literally - tiny astronomer's society is against the whole Earth load of Spacelink customers, and of course those customers' needs on average trump astronomers' ones.
I'm exaggerating, of course.
and SpaceX customers hope to pocket a lot of use for that money. So taking that point literally - tiny astronomer's society is against the whole Earth load of Spacelink customers, and of course those customers' needs on average trump astronomers' ones.
I'm exaggerating, of course.
You're also confusing money with value. If we only go by market price, air pollution should be fine, since lots more people buy electrical power than die from coal plant particulates. But market price only captures a relatively narrow slice of value, and it's heavily biased in favor of people with money.
Hubble's mirror is 8 feet in diameter, and you aren't going to be assembling something as high precision as that in space, at least not from a few components. If we had the manufacturing capability to make it from scratch in space, maybe, but that's a much larger enterprise.
There is a question of whether 100 a foot diameter telescopes can work as well or better than one 8 foot one. Or 500. If it's about photons hitting the lens, do enough lenses in an area and post-processing make up for the fact that they aren't connected?
There is a question of whether 100 a foot diameter telescopes can work as well or better than one 8 foot one. Or 500. If it's about photons hitting the lens, do enough lenses in an area and post-processing make up for the fact that they aren't connected?
There are several large terrestrial telescopes that use assemblies of a number of coordinated smaller mirrors.
This looks like something reasonably doable on Earth orbit with the current launch capabilities.
This looks like something reasonably doable on Earth orbit with the current launch capabilities.
Well let's make the manufacturing capability to do so. It's as if the "manufacturing capability" is some limited rare earth metal. What is the actual limited resource other that ingenuity and engineering?
You can’t manufacture complicated objects in space
We shouldn't have been able to land on the moon using whiteboard engineering and calculator level computers, but we did
That won't magically make it feasible to manufacture such precise objects in space anytime soon.
In fact, in space we can make something which we can't do on Earth - weightlessness being the critical enabling factor.
With capabilities to launch as cheap as Spaceship promises, we can develop space manufacturing rather soon.
With capabilities to launch as cheap as Spaceship promises, we can develop space manufacturing rather soon.
Why shouldn't we have been able to land on the moon?
Because, as you've said, we can't manufacture complex objects in space.
Is the ISS not comparable in size?
That's a good point. SpaceX could be the key to launching a horde of new Hubbles. However that's not so likely in the short run because everything is going towards the JWST.
JWST is a great project and a type of project we should strive for. I'm personally just annoyed why the conversation is so defensive and negative.
I don't know much about astronomy, but from what I understand the Earth's atmosphere is hard to deal with, why aren't we talking more about what can be done with this new tech, and not how it makes current things more difficult
I don't know much about astronomy, but from what I understand the Earth's atmosphere is hard to deal with, why aren't we talking more about what can be done with this new tech, and not how it makes current things more difficult
Earth's atmosphere is annoying, yes, but for huge swathes of observational science it's not a deal-breaker. Not having massive telescopes on the ground where you can fiddle with your instrumentation and take advantage of apertures and construction techniques simply not possible in space _is_ a deal-breaker.
The required precision for construction of telescopes is incredible, and doesn't translate to space well, especially once you start talking about apertures that even folded won't fit into even the largest Starship SpaceX is proposing.
Ground-based astronomy is here to stay and with good reason. SpaceX needs to avoid or minimise the harms to these users of the night sky.
There is another aspect of harm, too - the casual observer. The night sky is a precious resource and shared by all. Introducing huge constellations which in many parts of the world will be visible year-round (and in some quite heavily populated areas like northern Europe, even through the night at some times of year) is like building a huge mobile phone mast outside someone's window and expecting them not to complain, but on a much larger scale.
Light pollution is a huge issue, and satellites can pollute just as well (if not more effectively) than ground based sources - it needs to be an ecological consideration of any launch.
The required precision for construction of telescopes is incredible, and doesn't translate to space well, especially once you start talking about apertures that even folded won't fit into even the largest Starship SpaceX is proposing.
Ground-based astronomy is here to stay and with good reason. SpaceX needs to avoid or minimise the harms to these users of the night sky.
There is another aspect of harm, too - the casual observer. The night sky is a precious resource and shared by all. Introducing huge constellations which in many parts of the world will be visible year-round (and in some quite heavily populated areas like northern Europe, even through the night at some times of year) is like building a huge mobile phone mast outside someone's window and expecting them not to complain, but on a much larger scale.
Light pollution is a huge issue, and satellites can pollute just as well (if not more effectively) than ground based sources - it needs to be an ecological consideration of any launch.
I live in a very large city in Europe. I think the number of stars you can see is less than 20. Ground based pollution is horrible, I don't know how you can compare those two.
Maybe because large telescopes aren't in very large cities.
Here’s an example of a large telescope in a very large city:
https://www.rmg.co.uk/discover/explore/great-equatorial-tele...
https://www.rmg.co.uk/discover/explore/great-equatorial-tele...
100 years ago, lots of them were.
Kind of. Some on mountains near cities, but even then light polution was an issue they had to mitigate.
https://en.wikipedia.org/wiki/List_of_largest_optical_telesc...
In general, I'm fine with scientists needing to accommodate people more than they had to 100 years ago.
https://en.wikipedia.org/wiki/List_of_largest_optical_telesc...
In general, I'm fine with scientists needing to accommodate people more than they had to 100 years ago.
That list of telescopes only goes back to 1932, and I studied astronomy at one of the institutions in question.
As an example, why is this area named Observatory Hill? https://www.google.com/maps/place/Observatory+Hill,+Cambridg...
> In general, I'm fine with scie!tists needing to accommodate people more than they had to 100 years ago.
Indeed, that's the majority opinion.
As an example, why is this area named Observatory Hill? https://www.google.com/maps/place/Observatory+Hill,+Cambridg...
> In general, I'm fine with scie!tists needing to accommodate people more than they had to 100 years ago.
Indeed, that's the majority opinion.
You're right, not quite 100 years.
... it's named Observatory Hill, in the middle of Cambridge Massachusetts, quite near to downtown Boston, because it has an observatory that used to work great before light pollution.
If you go back 100 years, you could see stars great from the middle of your very large city in Europe. Then the lights came, one by one.
This process is just starting with satellites. Can you see the connection now?
This process is just starting with satellites. Can you see the connection now?
> Not having massive telescopes on the ground where you can fiddle with your instrumentation and take advantage of apertures and construction techniques simply not possible in space _is_ a deal-breaker.
Why do you think telescopes in space - where they don't need to fight gravity just to stand - can't soon, with reasonable development, surpass land-based ones in capabilities?
Why do you think telescopes in space - where they don't need to fight gravity just to stand - can't soon, with reasonable development, surpass land-based ones in capabilities?
It's the kind of telescope we should strive for, but definitely not the sort of project we should.
It's more than a decade late and billions over budget.
It's more than a decade late and billions over budget.
I'm personally just annoyed that people are so happy to be annoyed at each other every time this discussion comes up, so there's that.
Astronomers have been talking and acting for decades to take advantage of new technologies like orbital observatories.
Astronomers have been talking and acting for decades to take advantage of new technologies like orbital observatories.
As an expert would you be able to comment on my speculation:
It seems like this whole hullabaloo is because a SpaceX launch happened to coincide with a rare event at an inopportune time:. The alpha monocerotids have a narrow band with a long recurrence time (2h window, with a peak recurrence on the order of 10 years). Moreover, some monocerotid observers are in parts of the world where they will appear near Dawn or dusk, so yes some of the starlinks will flash (as you mentioned). In general, the SpaceX launches will only cluster in that fashion a few days after launch as they haven't disperesed into final formation yet. Any other time this wouldn't be a problem.
It seems like this whole hullabaloo is because a SpaceX launch happened to coincide with a rare event at an inopportune time:. The alpha monocerotids have a narrow band with a long recurrence time (2h window, with a peak recurrence on the order of 10 years). Moreover, some monocerotid observers are in parts of the world where they will appear near Dawn or dusk, so yes some of the starlinks will flash (as you mentioned). In general, the SpaceX launches will only cluster in that fashion a few days after launch as they haven't disperesed into final formation yet. Any other time this wouldn't be a problem.
“No one thought of this,” she said. “We didn’t think of it. The astronomy community didn’t think of it.”
I really have trouble believing that nobody mentioned adding thousands of satellites would go unnoticed. It is damn near impossible to take any image of the night sky without having a satellite streak through the frame. I have plenty of images with multiple satellites visible at the same time. In wide angle timelapse sequences, they are just small dots that move against the natural movement of the stars. In longer lenses/telescopes, they appear as long straight lines totally ruining the image.
The first time I heard about thousands more of lower altitude satellites, my first thought was about this very thing. We had already had the discussions from the giant disco ball that was launched. It was planned to be short lived, but it caused quite the stir. Saying people at SpaceX didn't think about it is one thing, but to claim nobody in the astronomy community didn't is hard to take. Maybe they didn't have any way to voice those thoughts in a way that SpaceX could hear.
I really have trouble believing that nobody mentioned adding thousands of satellites would go unnoticed. It is damn near impossible to take any image of the night sky without having a satellite streak through the frame. I have plenty of images with multiple satellites visible at the same time. In wide angle timelapse sequences, they are just small dots that move against the natural movement of the stars. In longer lenses/telescopes, they appear as long straight lines totally ruining the image.
The first time I heard about thousands more of lower altitude satellites, my first thought was about this very thing. We had already had the discussions from the giant disco ball that was launched. It was planned to be short lived, but it caused quite the stir. Saying people at SpaceX didn't think about it is one thing, but to claim nobody in the astronomy community didn't is hard to take. Maybe they didn't have any way to voice those thoughts in a way that SpaceX could hear.
Yeah even the wikipedia page mentions the astronomers' concerns
https://en.wikipedia.org/wiki/Starlink_(satellite_constellat...
btw the amount of satellites is staggering and this is just a tiny batch: https://www.youtube.com/watch?v=gRz3988El7Q&t=116s (Warning: hilarious commenter)
https://en.wikipedia.org/wiki/Starlink_(satellite_constellat...
btw the amount of satellites is staggering and this is just a tiny batch: https://www.youtube.com/watch?v=gRz3988El7Q&t=116s (Warning: hilarious commenter)
> even the wikipedia page mentions the astronomers' concerns
Note, this section was added June 03 2019.
https://en.wikipedia.org/w/index.php?title=Starlink_(satelli...
Note, this section was added June 03 2019.
https://en.wikipedia.org/w/index.php?title=Starlink_(satelli...
yep. the referenced articles are from this summer. still before the launches
60 satellites were launched on 24 may 2019. It looks like all the articles are after that, in response to people seeing the satellites in the sky.
Here's a 1999 article, well before the announcement of Starlink, talking about the increasing problems of trails spoiling deep sky observations--- https://www.sciencedirect.com/science/article/pii/S027311779...
> From Table 1 it is clear that since 1985 the annual mean number of trails has risen from 2.5 to 2.9 in a 60 minute exposure, an increase of 16%; the number of spacecraft on orbit has increased by 39% in the same period. Since the trail rate data comes from a set of plates not selected for time of night of exposure, the trail rate is averaged over an entire night. Since trailing is most frequent in the two hours after sunset and before sunrise, it would be expected that the trail rate would not increase as rapidly as the spacecraft population. However, the trend is such that it supports the view that plate trailing is caused by spacecraft and large debris and not by debris more generally. The figures suggest that the satellite population is doubling approximately every 14 years at present launch rates. The concern of the astronomical community is that due to the advent of large satellite constellations such as IRIDIUM and, further in the future, a TELEDESIC network, there will be a sudden increase in the numbers of satellites capable of causing trailing. The time available to find a solution is thereby reduced.
It even foresees SpaceX's "solution" that they are trialing:
> The Space Agencies could also assist by reducing satellite albedos.
It's also discussed in similar terms in "Adverse Environmental Effects on Astronomy", D. McNally, 1992.
You can find early 2000's complaints about Iridium-spoiled optical observations.
You can find late 1960's papers analyzing the impact of satellites on optical astronomy... that point to exactly where we are now.
It's hardly a "surprise to the optical astronomy community." If there's any surprise, it's that people are actually willing to listen to their concerns.
> From Table 1 it is clear that since 1985 the annual mean number of trails has risen from 2.5 to 2.9 in a 60 minute exposure, an increase of 16%; the number of spacecraft on orbit has increased by 39% in the same period. Since the trail rate data comes from a set of plates not selected for time of night of exposure, the trail rate is averaged over an entire night. Since trailing is most frequent in the two hours after sunset and before sunrise, it would be expected that the trail rate would not increase as rapidly as the spacecraft population. However, the trend is such that it supports the view that plate trailing is caused by spacecraft and large debris and not by debris more generally. The figures suggest that the satellite population is doubling approximately every 14 years at present launch rates. The concern of the astronomical community is that due to the advent of large satellite constellations such as IRIDIUM and, further in the future, a TELEDESIC network, there will be a sudden increase in the numbers of satellites capable of causing trailing. The time available to find a solution is thereby reduced.
It even foresees SpaceX's "solution" that they are trialing:
> The Space Agencies could also assist by reducing satellite albedos.
It's also discussed in similar terms in "Adverse Environmental Effects on Astronomy", D. McNally, 1992.
You can find early 2000's complaints about Iridium-spoiled optical observations.
You can find late 1960's papers analyzing the impact of satellites on optical astronomy... that point to exactly where we are now.
It's hardly a "surprise to the optical astronomy community." If there's any surprise, it's that people are actually willing to listen to their concerns.
The original assumption, as far as I'm aware, was that Starlink being in such a low orbit wouldn't have these issues that previous satellites had.
That's a bit of a strange assumption. Height doesn't have too great of an impact, other than reaching eclipse from solar illumination a little earlier. Given that Iridium has been a nuisance and they're at 780km, versus Starlink at 550km and 1150km...
A quote from a user above who worked for both SpaceX and the astronomy community:
"Now, that being said, even I was confused why this would cause a problem. The satellites are in low earth orbit, so low that they won't be able to reflect the sunlight, since they are in earth's shadow. Only during twilight and dawn will satellites be in the right position to reflect the sunlight back to the ground off of some panel.
Now, these are not prime observing hours for many people, since it is still not as dark as it could be. So most people point into the darkest parts of the sky (up) rather than at parts where there is still twilight (like nearer the horizon).
But for some types of observations, like near earth asteroids, you want to point into the evening sky to look for them, since that is one of the places you want to look, and the sky conditions should be good enough. In these pictures you'll get streaks of light as the satellites pass through."
"Now, that being said, even I was confused why this would cause a problem. The satellites are in low earth orbit, so low that they won't be able to reflect the sunlight, since they are in earth's shadow. Only during twilight and dawn will satellites be in the right position to reflect the sunlight back to the ground off of some panel.
Now, these are not prime observing hours for many people, since it is still not as dark as it could be. So most people point into the darkest parts of the sky (up) rather than at parts where there is still twilight (like nearer the horizon).
But for some types of observations, like near earth asteroids, you want to point into the evening sky to look for them, since that is one of the places you want to look, and the sky conditions should be good enough. In these pictures you'll get streaks of light as the satellites pass through."
[deleted]
I think the issue is more that no one has previously been launching constellations of literally thousands of satellites.
It's just not a thing that seemed like it would actually happen. I can very much imagine that it didn't get a lot of attention until they actually started going up.
It's just not a thing that seemed like it would actually happen. I can very much imagine that it didn't get a lot of attention until they actually started going up.
Yes, it might be that the astronomer community didn't expect Starlink to actually happen. A lot of people still haven't learned that SpaceX isn't just hyping things up.
Off topic: I mentioned to someone at StarLink the idea of equipping their gear to perform global RF interferometry, will let you know if it turns into something!
That's not a new idea, and it's a lot harder than it looks.
It would be awesome if Starlink would donate bandwidth for the Greenland and South Pole EHT telescopes. Right now there's no "first look" capability for them.
It would be awesome if Starlink would donate bandwidth for the Greenland and South Pole EHT telescopes. Right now there's no "first look" capability for them.
Asking is free. I don’t mind making a hundred asks and looking silly if one turns out to be helpful.
If I have the opportunity, I’ll mention your suggestion.
If I have the opportunity, I’ll mention your suggestion.
That's awesome!
(Also, why do I get a feeling the two of us talked about using satellite constellations and interferometry on HN before?)
(Also, why do I get a feeling the two of us talked about using satellite constellations and interferometry on HN before?)
We did! That’s what caused me to inquire when the opportunity presented itself.
Right! I found it: https://news.ycombinator.com/item?id=19188205.
Thanks for remembering!
Thanks for remembering!
No need to thank me, was your idea!
it remains an experiment; if the network test proves useful, they ll have to mitigate this issue somehow. perhaps also make the satellites smaller
They've now launched 120 satellites (there's been 2 launches of 60 satellites). The test has already proved successful. They're heading on to production now.
Software should be able to account for this. If photoshop can remove people from photos, why can't astronomy software remove satellites? Orbit is already pretty cluttered and we can't remove much that gets stuck up there already.
Software can make a picture look pretty, but it has very limited use when you are fighting against the limits of information theory. You want an actual new measurement, not a guess of what a reasonable measurement would look like based on past measurements.
heavenlyblue(1)
This isn't just about astrophotography, this has to do with real science too. Remember, most science work is already on a tight budget and now they will have to waste some of that budget sorting through the added visual clutter.
Yes, and SpaceX seems to be actively downplaying that fact.
>. “We want to make sure we do the right thing to make sure little kids can look through their telescope,” she said. “Astronomy is one of the few things that gets little kids excited about space.”
>. “We want to make sure we do the right thing to make sure little kids can look through their telescope,” she said. “Astronomy is one of the few things that gets little kids excited about space.”
It's like with nature on earth, tech pollutes things. It's not really anything new.
since starlinks may change positions autonomously it's impossible to predict their positions. and they are so damn many
You don't need a position prediction to remove an anomaly.
Starlink satellites are too small to do much orbital maneuvering. They only carry a small supply of krypton gas for their station keeping thrusters.
They have enough propellant to change their orbital height by quite a lot, more than the typical satellite (other than GTO-to-GEO thrusters.)
OTOH you can just ask SpaceX or the Air Force where they have been in the past, SpaceX uses GPS and the Air Force radar is accurate enough for knowing where they were.
OTOH you can just ask SpaceX or the Air Force where they have been in the past, SpaceX uses GPS and the Air Force radar is accurate enough for knowing where they were.
If the astronomer community requested it, I'm sure spacex would give them a real-time (or even a few minutes ahead of time) feed of satellite positions accurate to less than a pixel on these telescopes.
Yes, I’m an astronomer and I can tell you this SpaceX statement is pure BS. The astronomy community absolutely thought of this before any of these satellites were launched. I’ve personally talked about it at public outreach events (and it was members of the public who brought it up) and topic has definitely come up at professional meetings...but there is just a general feeling of powerlessness, both from the point of how do you fight a company like SpaceX and a charlatan like Musk, and also from the point of many members of the public don’t care.
I also know a lot of people directly involved in SSA and all of them are very concerned with how much these new constellations are going to increase the risk of collisions, and they all think it’s completely irresponsible when the SpaceX cultists just dismiss the concerns with, “space is a big place,” or, “they’ll deorbit in 20 years or so.”
I also know a lot of people directly involved in SSA and all of them are very concerned with how much these new constellations are going to increase the risk of collisions, and they all think it’s completely irresponsible when the SpaceX cultists just dismiss the concerns with, “space is a big place,” or, “they’ll deorbit in 20 years or so.”
> charlatan like Musk
If Musk was a charlatan, we wouldn't have this problem. Musk would have failed to put spacelink satellites in orbit and we wouldn't have this problem.
The reason why we have this problem is precisely because Musk isn't a charlatan.
> I also know a lot of people directly involved in SSA and all of them are very concerned with how much these new constellations are going to increase the risk of collisions
Just because they are concerned doesn't mean they are against SpaceX or Musk. Every venture is open to concern.
> SpaceX cultists
Is NASA and the US government SpaceX cultists? You act like Musk just sent this satellites up there without any warning or government approval. He didn't.
All you've done is toss ad hominems at Musk, SpaceX and those who support this venture.
If Musk was a charlatan, we wouldn't have this problem. Musk would have failed to put spacelink satellites in orbit and we wouldn't have this problem.
The reason why we have this problem is precisely because Musk isn't a charlatan.
> I also know a lot of people directly involved in SSA and all of them are very concerned with how much these new constellations are going to increase the risk of collisions
Just because they are concerned doesn't mean they are against SpaceX or Musk. Every venture is open to concern.
> SpaceX cultists
Is NASA and the US government SpaceX cultists? You act like Musk just sent this satellites up there without any warning or government approval. He didn't.
All you've done is toss ad hominems at Musk, SpaceX and those who support this venture.
I call Musk a charlatan because he tries to pass himself off as something he isn't. His physics and engineering knowledge is nowhere near the level he boasts about, and he often states things that an SME would find laughable were they not eaten up without question by so many ill-informed cultists. It's dangerous, and unfortunately it's probably going to result in even more harm to people before he's reigned in.
And to clarify, the SSA folks I was referring to are against these types of constellations particularly in the context of the speed and lack of oversight (and no, FCC/ITU spectrum approval has nothing to do with oversight and regulation of the physical objects in orbit) of these ventures.
And to clarify, the SSA folks I was referring to are against these types of constellations particularly in the context of the speed and lack of oversight (and no, FCC/ITU spectrum approval has nothing to do with oversight and regulation of the physical objects in orbit) of these ventures.
It's very unlikely that SpaceX, who has to be concerned about space debris every time they launch, didn't think about the collision risk while they were designing their satellite system.
In fact they petitioned the FCC(?) to lower the constellation's altitude for the very reason that, in the case of a malfunction, the satellite's would orbit would degrade more quickly. A carefully tracked constellation of satellites would be much easier to avoid than the random chunks of shrapnel left behind by other mishaps.
EDIT: a few typos
In fact they petitioned the FCC(?) to lower the constellation's altitude for the very reason that, in the case of a malfunction, the satellite's would orbit would degrade more quickly. A carefully tracked constellation of satellites would be much easier to avoid than the random chunks of shrapnel left behind by other mishaps.
EDIT: a few typos
I think they lowered the orbit because Starlink latency was/is not competitive.
Lowering orbit doesn't substantially reduce latency, building more satellites does.
Building more satellites doesn't reduce latency. Are you referring to the ISL?
Adding more ground stations and building more satellites does reduce latency, because there will be a satellite closer to "halfway between" you and a ground station, which defines the shortest possible path.
If there is just one (non-stationary) satellite in your sky, the geometry is probably pretty crummy, so light-speed delay is greater. Also, link budget is worse, so probably data rate is lower too.
Yes, once you have a ton of satellites, adding more doesn't improve latency much.
If there is just one (non-stationary) satellite in your sky, the geometry is probably pretty crummy, so light-speed delay is greater. Also, link budget is worse, so probably data rate is lower too.
Yes, once you have a ton of satellites, adding more doesn't improve latency much.
Having more satellites lets you communicate in a straighter line. Lower altitude lets you hug the Earth more closely. Higher altitude lets you see more neighbors. I'd wager the low altitude satellites are for last mile communication moreso than global linkage. I mean, otherwise they'd have no use for the higher altitude ones? An optimal low latency link around the planet would mostly alternate low-high-low-high-low in sequence, if there aren't enough low altitude nodes to use them exclusively. But maybe you could crush this argument by doing the actual math in this case.
You are referring to the ISL in these satellites, that are not in the first batch, nor are there any plans to change that soon from what I've seen. So without the ISL, their latency is certainly not lower by adding more satellites. The difference in latency from different altitudes LEO is negligible.
compared to geostationary sats, starlinks are 1/30 of the distance, and thus 1/30 of the latency
They didn't lower it from geostationary, so this is--while correct--irrelevant.
It makes a difference there, sure, but SpaceX lowered orbits from 1,150 to 550km. Half the latency, but only by about as much as traffic between LA to SF incurs.
I was a bit wrong in my initial estimate. More satellites can't improve latency by much once they get dense enough, and it looks like Starlink has enough such that the altitude would be on the same scale as distance. Still doesn't matter for the typical home user. Like, I get 21 ms ping to servers in my local city.
> Still doesn't matter for the typical home user.
One very important market they're going after is global arbitrageurs.
One very important market they're going after is global arbitrageurs.
Do you have any evidence of this? I work in algorithmic trading/finance and I'm relatively certain that this isn't true.
> Do you have any evidence of this?
My only evidence is a very basic evaluation of their publicly stated capabilities.
> I work in algorithmic trading/finance and I'm relatively certain that this isn't true.
It sounds like you have a much better informed opinion than I do.
With my limited knowledge, I see no reason why SpaceX wouldn't aggressively go after that market, but like I said, my knowledge is limited.
My only evidence is a very basic evaluation of their publicly stated capabilities.
> I work in algorithmic trading/finance and I'm relatively certain that this isn't true.
It sounds like you have a much better informed opinion than I do.
With my limited knowledge, I see no reason why SpaceX wouldn't aggressively go after that market, but like I said, my knowledge is limited.
The funny part is that by providing low latency service to them, they are (hopefully) going to be able to fund SpaceX longer to build rockets to get human colonies off-planet.
It’s almost like a Gibson or Stephenson novel.
It’s almost like a Gibson or Stephenson novel.
> Still doesn't matter for the typical home user.
550km vs 1,150km might not matter, but it matters a ton vs 40,000km. Even without the bandwidth limits, I wouldn't be able to use geostationary internet for my normal usage.
550km vs 1,150km might not matter, but it matters a ton vs 40,000km. Even without the bandwidth limits, I wouldn't be able to use geostationary internet for my normal usage.
Starlink has been LEO since it was first announced, so how bad geostationary internet may be is not relevant to the discussion about why SpaceX lowered the altitude.
[deleted]
right i didn’t know that
I was under the impression that Starlink latency is actually very competitive with terrestrial fiber. Why do you say it wasn't or isn't? Everything I find suggest Starlink will have low latency.
For most usages yes. For gaming though it's right on the edge: theoretical minimum at 350km orbit is 40ms roundtrip, which would work for most games. But many complications, including position of the satellite, latencies within the networking components, packet loss etc, can easily slow this to 100ms+, which is unsuitable for many online games.
No, the round trip for electromagnetic waves at 350km it’s about 2 ms not 40.
The lowest orbit of the satellites though would be 550km and not 350km, but it would still be less than 4ms.
From where did you get the 40ms figure that it’s wrong by an order of magnitude?
I don't know where they got that figure from, but it is unrealistic to not also expect a decent amount of latency to be introduced by the transmission hardware, particularly under load. I have no idea how much, but this has generally been the case with most systems of this sort.
Electromagnetic waves travel at essentially the speed of light. The speed of light is roughly 300km per millisecond. So if they are 550km up, that’s roughly 4ms round trip. Even with horrible inefficiency, it won’t likely increase that by 10x.
It can’t be both?
>charlatan like Musk
I'm not a fanboy by any means but the guy built two companies and launched a car from his factory into space from a rocket his other business built. He's personally spearheading the early stages of commercial space exploration. I don't know that I'd describe him as a charlatan.
I'm not a fanboy by any means but the guy built two companies and launched a car from his factory into space from a rocket his other business built. He's personally spearheading the early stages of commercial space exploration. I don't know that I'd describe him as a charlatan.
Starting companies, even successful, relatively technical companies, does not preclude a person from being a charlatan. The charlatan part comes when he publicly dismissed the concerns of experts and claimed there wouldn't be a problem, but of course there was a problem.
> charlatan: a person falsely claiming to have a special knowledge or skill
"publicly dismissed the concerns of experts" i.e falsely claiming to have special knowledge
[deleted]
Musk did not found Tesla, but would like you to believe that he did: https://www.quora.com/Did-Elon-Musk-found-Tesla-1
Maybe 'charlatan' is unfair, but he's certainly more of a sales-and-hype man than a real engineering type. I don't understand why so many technical people are snowed by his razzle dazzle.
Maybe 'charlatan' is unfair, but he's certainly more of a sales-and-hype man than a real engineering type. I don't understand why so many technical people are snowed by his razzle dazzle.
What I have observed over the years is that Musk routinely burrows into engineering considerations, for better or for worse, most especially at SpaceX but also with regards to manufacturing, specifically, at Tesla. He is an engineering enthusiast with a well documented skillset.
Regardless of how we characterize Musk, however, reducing the issue at hand to a pro/anti Musk ad hominem argument is a distraction and a waste of time. It is suddenly relatively cheap to put a huge number of small satellites in low earth orbit. This creates a conflict with astronomical interests. What remains is a policy debate worth having.
SpaceX's statement may be ignorant, erroneous, or even deceitful. I have no doubt that the astronomy community identified the problem immediately and has been trying to bring it to public attention. However, as with light pollution at both optical and radio frequencies, they are relatively powerless compared to the interests with which they are in conflict. If the FCC is the arbiter of how many satellites a company can launch into LEO, they have already lost. This was a regulatory and legislative battle that they needed to be fighting, and probably were fighting, and basically had very little chance of winning unless they were somehow able to mobilize public support for earth-based astronomy against the telecommunications industry.
Regardless of how we characterize Musk, however, reducing the issue at hand to a pro/anti Musk ad hominem argument is a distraction and a waste of time. It is suddenly relatively cheap to put a huge number of small satellites in low earth orbit. This creates a conflict with astronomical interests. What remains is a policy debate worth having.
SpaceX's statement may be ignorant, erroneous, or even deceitful. I have no doubt that the astronomy community identified the problem immediately and has been trying to bring it to public attention. However, as with light pollution at both optical and radio frequencies, they are relatively powerless compared to the interests with which they are in conflict. If the FCC is the arbiter of how many satellites a company can launch into LEO, they have already lost. This was a regulatory and legislative battle that they needed to be fighting, and probably were fighting, and basically had very little chance of winning unless they were somehow able to mobilize public support for earth-based astronomy against the telecommunications industry.
And so what? founding a company is the easiest step (a little bit of money and paperwork). executing to make it the world leader in electric mobility is what really matters. So your point is really irrelevant.
While true, the company was founded in July 2003 and Musk joined in February 2004. The first Roadster prototypes were revealed in 2006.
Acting like he hitched his flag to an already successful company is disingenuous.
Acting like he hitched his flag to an already successful company is disingenuous.
And then there was paypal.
It's not clear to me how active Elon was with PayPal, I really think it was much more Peter Thiel that made it successful (although I am not claiming expertise). Elon founded x.com which merged with what become PayPal, but as PayPal started to become successful it was Peter Thiel at the helm. That doesn't mean Elon wasn't instrumental to its success, only that I cannot find much evidence that he was instrumental to its success.
https://en.wikipedia.org/wiki/PayPal#Early_history
> In October of that year, Musk made the decision that X.com would terminate its other Internet banking operations and focus on the PayPal money service.[25] In the same month, Elon Musk was replaced by Peter Thiel as CEO of X.com. The X.com company was then renamed PayPal in 2001,[26] and expanded rapidly throughout the year until company executives decided to take PayPal public in 2002.
https://en.wikipedia.org/wiki/PayPal#Early_history
> In October of that year, Musk made the decision that X.com would terminate its other Internet banking operations and focus on the PayPal money service.[25] In the same month, Elon Musk was replaced by Peter Thiel as CEO of X.com. The X.com company was then renamed PayPal in 2001,[26] and expanded rapidly throughout the year until company executives decided to take PayPal public in 2002.
No, he wasn't a first-day founder. But he joined not to long after and it was his private money and him as a CEO which built Tesla.
"Founder" is a label decided by the company, not by outsiders. Many Silicon Valley companies have "founders" who were not there on Day 1.
Founder is a word that has meaning, we shouldn't let companies dictate our use of language.
It's fun to watch people up and downvote me for just relaying what Silicon Valley founders have actually been doing for decades. I totally agree that it's a surprise to most people how it works, but I don't think "they" are going to change. It just is.
I find the "did Musk found Tesla thing" petty and unnecessary. Without Musk it would have been a footnote in history.
But I dislike your assertion that just because SV companies feel free to rewrite their history, we should consider that canonical.
It's totally valid to point out that Musk wasn't a founder, though using it as some kind of slight is juvenile.
eBay is free to claim it was invented to sell Pez dispensers and we're free to point out that's PR spin. Neither side is in the wrong.
But I dislike your assertion that just because SV companies feel free to rewrite their history, we should consider that canonical.
It's totally valid to point out that Musk wasn't a founder, though using it as some kind of slight is juvenile.
eBay is free to claim it was invented to sell Pez dispensers and we're free to point out that's PR spin. Neither side is in the wrong.
I didn't assert that, nor did I say it was invalid to not understand the inside-Silicon-Valley use of "founder".
I was just explaining how to not embarrass yourself.
I was just explaining how to not embarrass yourself.
With all respect, I can't read your previous posts without taking the meaning I did, but the fault may be mine.
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> Yes, I’m an astronomer and I can tell you this SpaceX statement is pure BS. The astronomy community absolutely thought of this before any of these satellites were launched. I’ve personally talked about it at public outreach events (and it was members of the public who brought it up) and topic has definitely come up at professional meetings...but there is just a general feeling of powerlessness, both from the point of how do you fight a company like SpaceX and a charlatan like Musk, and also from the point of many members of the public don’t care.
Why aren't you talking about any of the other constellations that are being built? They're all planning huge numbers of satellites, many of which are larger or in higher orbits than SpaceX's satellites. You can't single out Elon Musk's companies just because of a personal vendetta if you're actually trying to be fair and attack this from a technical perspective.
Why aren't you talking about any of the other constellations that are being built? They're all planning huge numbers of satellites, many of which are larger or in higher orbits than SpaceX's satellites. You can't single out Elon Musk's companies just because of a personal vendetta if you're actually trying to be fair and attack this from a technical perspective.
Many of the other constellations look unlikely to be completed.
[deleted]
I agree. I remember hearing/reading about similar problems from previous satellite constellations. Nobody thought of this means that SpaceX spoke with nobody who could tell them about this issue.
> “No one thought of this,” she said.
> “We didn’t think of it.
> The astronomy community didn’t think of it.”
Oh Really?
In 1979, NASA founded the Orbital Debris Program to adopt mitigation measures for space debris in earth orbit.
Apparently heaven forbids a web search on Astronomy & space junk. Or checking with astroimagery software to detect & mask frames contaminated with existing satellites streaks
Oh Really?
In 1979, NASA founded the Orbital Debris Program to adopt mitigation measures for space debris in earth orbit.
Apparently heaven forbids a web search on Astronomy & space junk. Or checking with astroimagery software to detect & mask frames contaminated with existing satellites streaks
That program's purpose is entirely different, though. It's focused on crashes between satellites, not avoiding impacts on astronomy.
SpaceX's constellation is already specifically set at a low orbit to prevent buildup of space debris. That impact was absolutely considered and mitigated from the start.
SpaceX's constellation is already specifically set at a low orbit to prevent buildup of space debris. That impact was absolutely considered and mitigated from the start.
>“No one thought of this,” she said. “We didn’t think of it. The astronomy community didn’t think of it.”
That is absolutely ridiculous. The Iridium satellites were decommissioned recently and it was a big deal because, for the longest time, you had to check for "iridium flares" if you were using any type of sensitive equipment. Basically, the entire class of iridium satellites was highly reflective and they tended to create shooting star type phenomena, sometimes really really bright, bright enough to be seen during the daytime!
Maybe she didn't think of it, but to say the astronomy comunity didn't think of it is just blatantly absurd on its face.
On another note, I miss spotting iridium flares and I'm looking forward to a new class of satellites being added into my weekly observations.
That is absolutely ridiculous. The Iridium satellites were decommissioned recently and it was a big deal because, for the longest time, you had to check for "iridium flares" if you were using any type of sensitive equipment. Basically, the entire class of iridium satellites was highly reflective and they tended to create shooting star type phenomena, sometimes really really bright, bright enough to be seen during the daytime!
Maybe she didn't think of it, but to say the astronomy comunity didn't think of it is just blatantly absurd on its face.
On another note, I miss spotting iridium flares and I'm looking forward to a new class of satellites being added into my weekly observations.
They announced their plans years ago. The astronomy community could have raised concerns then. The fact that they didn't would indicate nobody connected the dots.
> The fact that they didn't would indicate nobody connected the dots.
Or that nobody knew who/where to contact someone to raise their concerns. A lot of people will think that if I just had this thought, then it must be pretty obvious so that others will have the same thought as well. No need for further action. Others will just not feel the need to spend their time/effort trying to look up the complaints department. Others might not even feel like it is their place to say anything.
Or that nobody knew who/where to contact someone to raise their concerns. A lot of people will think that if I just had this thought, then it must be pretty obvious so that others will have the same thought as well. No need for further action. Others will just not feel the need to spend their time/effort trying to look up the complaints department. Others might not even feel like it is their place to say anything.
> nobody knew who/where to contact someone to raise their concerns
SpaceX had to get approval from the FCC to launch these satellites. There was a comment period intended to provide an opportunity to voice these concerns. I looked into this the last time it was in the news (late May?), and could not find any petitions that raised concerns about reflecting light. There were several from other satellite companies requesting that the FCC deny the application based on concerns about increased risks of collision and/or radiointerference with their licensed bands.
SpaceX had to get approval from the FCC to launch these satellites. There was a comment period intended to provide an opportunity to voice these concerns. I looked into this the last time it was in the news (late May?), and could not find any petitions that raised concerns about reflecting light. There were several from other satellite companies requesting that the FCC deny the application based on concerns about increased risks of collision and/or radiointerference with their licensed bands.
FCC isn't going to reject a radio license based on reflection of unregulated frequencies (light).
But IAU publicly decried satellite constellations in January, months before May-- and this public statement followed literally years of IAU discussions and discussions with SpaceX, etc.
Despite that, years later, SpaceX is only just getting around to taking small mitigation measures now, after two launches.
But IAU publicly decried satellite constellations in January, months before May-- and this public statement followed literally years of IAU discussions and discussions with SpaceX, etc.
Despite that, years later, SpaceX is only just getting around to taking small mitigation measures now, after two launches.
It wasn't a "radio license." It was an authorization to "construct, deploy, and operate a proposed non-geostationary orbit (NGSO) satellite system comprising 4,425 satellites for the provision of fixed-satellite service (FSS) around the world."
I don't see why the FCC wouldn't consider impact to visual astronomy, when they did consider increased collision risk (also unrelated to any regulated frequencies).
> IAU publicly decried satellite constellations in January, months before May
Can you link to information about this public statement from January? When I google "IAU satellite constellations," I find only https://www.iau.org/news/announcements/detail/ann19035/ from June.
I don't see why the FCC wouldn't consider impact to visual astronomy, when they did consider increased collision risk (also unrelated to any regulated frequencies).
> IAU publicly decried satellite constellations in January, months before May
Can you link to information about this public statement from January? When I google "IAU satellite constellations," I find only https://www.iau.org/news/announcements/detail/ann19035/ from June.
> It wasn't a "radio license."
It's fundamentally a radio license:
https://www.law.cornell.edu/cfr/text/47/25.114
> when they did consider increased collision risk
Yup, they are supposed to evaluate orbital debris and collision risk, too, 47 CFR 25.114(d)(14). That, and equitable service (for some services) to Alaska/Hawaii are the only non-radio concerns they are permitted by regulation to consider.
It's fundamentally a radio license:
https://www.law.cornell.edu/cfr/text/47/25.114
> when they did consider increased collision risk
Yup, they are supposed to evaluate orbital debris and collision risk, too, 47 CFR 25.114(d)(14). That, and equitable service (for some services) to Alaska/Hawaii are the only non-radio concerns they are permitted by regulation to consider.
> they are permitted by regulation
Where is the restriction to only those concerns? 47 CFR § 25.156 has some pretty vague language about "the public interest, convenience and necessity."
Thanks for pointing out that the FCC is required to evaluate orbital debris and collision risk, but I don't think the FCC is prohibited from considering other concerns (and i might be wrong on that).
Where is the restriction to only those concerns? 47 CFR § 25.156 has some pretty vague language about "the public interest, convenience and necessity."
Thanks for pointing out that the FCC is required to evaluate orbital debris and collision risk, but I don't think the FCC is prohibited from considering other concerns (and i might be wrong on that).
OK, OK, insert "explicitly" in front of "permitted by regulation."
The public comments relate to the adequacy of the application, which is required to address those points.
Yes, users of radio frequency spectrum do have public interest obligations. Thus far, for spacecraft this has been entirely confined to coverage requirements (aka, helping out Alaska when it's not infeasible).
It would be highly unusual-- and likely to be overturned in judicial review-- if the FCC were to decline to issue a radio license because of secondary impacts of the business. (Outside the specific areas where the FCC has been granted oversight-- environmental impacts of radio towers, space debris mitigation, safe operation of radio facilities, etc).
The public comments relate to the adequacy of the application, which is required to address those points.
Yes, users of radio frequency spectrum do have public interest obligations. Thus far, for spacecraft this has been entirely confined to coverage requirements (aka, helping out Alaska when it's not infeasible).
It would be highly unusual-- and likely to be overturned in judicial review-- if the FCC were to decline to issue a radio license because of secondary impacts of the business. (Outside the specific areas where the FCC has been granted oversight-- environmental impacts of radio towers, space debris mitigation, safe operation of radio facilities, etc).
It’s not that hard to get in contact.
If you cared you could LinkedIn message a SpaceX employee. Tweet at Elon Musk. Connected with nyt or other media who’d love to run such a story.
...etc
If you cared you could LinkedIn message a SpaceX employee. Tweet at Elon Musk. Connected with nyt or other media who’d love to run such a story.
...etc
They also list contact info on their webpage.
https://www.spacex.com/about
https://www.spacex.com/about
I would expect this to work as well as contacting Google when you have a problem with their service.
I'm really dubious of how well that approach is going to work.
Yes very simple. Anyone can be a multi-millionaire working 4hrs a day or less.
Or they were ignored
Your theory is that corporate responsibility ends when you make the first press release? That if specialists everywhere aren't paying attention to the business news, we've arrived at "who could have known"?
[deleted]
Last time this was in the news, there was another discussion on HN: https://news.ycombinator.com/item?id=20095462.
User 'twtw asked the following, with no responses:
> Why didn't the IAU petition the FCC during the comment period for SpaceX's application? Seems sorta weird to wait for the first launch to express concerns when the application was submitted to the FCC many months ago (and I think I recall an earlier version years ago).
I think this is an interesting question. There are a number of commenters criticizing SpaceX's claim that "no one thought of this." I'd be interested in their response to this question. If so many people knew it was going to be a problem, why not raise those concerns to the organization tasked with regulating this stuff?
User 'twtw asked the following, with no responses:
> Why didn't the IAU petition the FCC during the comment period for SpaceX's application? Seems sorta weird to wait for the first launch to express concerns when the application was submitted to the FCC many months ago (and I think I recall an earlier version years ago).
I think this is an interesting question. There are a number of commenters criticizing SpaceX's claim that "no one thought of this." I'd be interested in their response to this question. If so many people knew it was going to be a problem, why not raise those concerns to the organization tasked with regulating this stuff?
As an astronomer once upon a time I follow a number of my former colleagues on Twitter and pretty regularly see them posting images that have been ruined by Starlink. Here is one from just 12 hours ago:
https://twitter.com/MassiveStarGuy/status/120358895831320576...
This is going to have a bigger impact on the more expensive observations that require long-duration exposures.
https://twitter.com/MassiveStarGuy/status/120358895831320576...
This is going to have a bigger impact on the more expensive observations that require long-duration exposures.
This definitely wasn't ruined (it's amateur video) but if anyone wants to see Starlink photobombing an astronomer, this amateur video of a recent meteor shower is an example:
https://www.youtube.com/watch?v=uHI8Z5qpd6I
(an astronomer friend thought I'd be able to identify the satellite amongst all the meteors, which was sweet... I think it's a bit after the 2 minute mark)
https://www.youtube.com/watch?v=uHI8Z5qpd6I
(an astronomer friend thought I'd be able to identify the satellite amongst all the meteors, which was sweet... I think it's a bit after the 2 minute mark)
Aside note: I didn't imagine one could see / film that much meteors during the night in some city. If I remember correctly, I saw 2 or 3 my whole life, and was driving at some road.
I know you can see the Leonids in San Francisco, at least if you're not standing directly under a streetlight. Some years are brighter than others. A lot of it is making note of when to go outside and look.
Is it the one making a line starting from the bottom left corner, or the thing that makes a very short bright streak at 2:08?
I assume it's the brightest one, yeah.
Also do not forget that SpaceX is not the only company that wants to launch low orbit satelites. I do not think it is possible to find any other real solution other then to move telescopes to space.
With James Web having an decently sized mirror on a space telescope that's not as ridiculous as it once was. Still we should search for cheaper solutions first.
https://www.eso.org/public/usa/images/eso1617z/?lang
https://www.eso.org/public/usa/images/eso1617z/?lang
JWST still hasnt launched after all these years. Building space based telescopes that will last years without maintenance is hard.
For some added context, JWST costs about 10x more than the most expensive terrestrial telescope ever built.
sprash(2)
Sure there is another solution: we ban them, or at least highly regulate them.
The idea that private companies can just do whatever, and there's nothing we can do is just so cliché HN.
The idea that private companies can just do whatever, and there's nothing we can do is just so cliché HN.
You broke the site guidelines badly with this flamebait and generic tangent, which predictably started a wretched flamewar. Then you perpetuated it.
You do a lot of good for HN with your interesting submissions, but you've also been vandalizing HN with destructive comments for years. We've asked you not to do this many times.
https://news.ycombinator.com/item?id=20356880
https://news.ycombinator.com/item?id=18887148
https://news.ycombinator.com/item?id=17952388
https://news.ycombinator.com/item?id=17441941
https://news.ycombinator.com/item?id=17432633
https://news.ycombinator.com/item?id=17113849
https://news.ycombinator.com/item?id=17111984
https://news.ycombinator.com/item?id=14693327
https://news.ycombinator.com/item?id=11705439
Eventually the cost outweighs the benefit. I definitely do not want to ban you, so would you please review https://news.ycombinator.com/newsguidelines.html and fix this? All users here need to have self-control, and experienced contributors more so.
You do a lot of good for HN with your interesting submissions, but you've also been vandalizing HN with destructive comments for years. We've asked you not to do this many times.
https://news.ycombinator.com/item?id=20356880
https://news.ycombinator.com/item?id=18887148
https://news.ycombinator.com/item?id=17952388
https://news.ycombinator.com/item?id=17441941
https://news.ycombinator.com/item?id=17432633
https://news.ycombinator.com/item?id=17113849
https://news.ycombinator.com/item?id=17111984
https://news.ycombinator.com/item?id=14693327
https://news.ycombinator.com/item?id=11705439
Eventually the cost outweighs the benefit. I definitely do not want to ban you, so would you please review https://news.ycombinator.com/newsguidelines.html and fix this? All users here need to have self-control, and experienced contributors more so.
How is this comment flamebait? First time that I have really thought you missed the boat.
Please don't censor people just because they criticize HN or the community.
Please don't censor people just because they criticize HN or the community.
I was also surprised but then I read up on the rest of The comments from that account in this thread as well and think that it something like that might be justified.
I also read the rest of the comments linked as examples and some of them where obvious to me and some were not.
I'm not a native speaker though and I realize dang has a huge advantage there as well as access to see detailed voting statistics to see what riles people up.
I also read the rest of the comments linked as examples and some of them where obvious to me and some were not.
I'm not a native speaker though and I realize dang has a huge advantage there as well as access to see detailed voting statistics to see what riles people up.
"The idea that private companies can just do whatever" distorted the other comment into something ideologically inflammatory (which the site guidelines explicitly ask not to do), and took the thread on a generic ideological tangent. Those routinely turn into flamewars. Posting something that predictably induces a flamewar is flamebait.
I am a big fan of astronomy, but satellites are doing a lot more for humanity than ground-based astronomy.
What does an Internet access satellite network do for science? Those scientific uses SpaceX talks about are speculative and clearly secondary (or tertiary behind military use).
By contrast, earth-based telescopes are doing lots and lots of science right now.
By contrast, earth-based telescopes are doing lots and lots of science right now.
> What does an Internet access satellite network do for science?
One example: https://www.usap.gov/technology/1935/
> Amundsen-Scott South Pole Station uses communications satellites that serve as relay stations, receiving radio signals from one location and transmitting them to another. The United States Antarctic Program utilizes the satellites for the transfer of South Pole science, operational, and weather data, as well as Internet, telephone, and email services.
One example: https://www.usap.gov/technology/1935/
> Amundsen-Scott South Pole Station uses communications satellites that serve as relay stations, receiving radio signals from one location and transmitting them to another. The United States Antarctic Program utilizes the satellites for the transfer of South Pole science, operational, and weather data, as well as Internet, telephone, and email services.
Nobody has jurisdiction over space. We can try to create an international agency and get all space fairing nations to submit to its regulations and rulings, but even if that was politically viable it would take years. Meanwhile Starlink will be deployed mid 2020 if no major delays happen
Great, so any of the hundred-something countries on earth are free to destroy those satellites? ;-)
I was thinking about what would be the easiest way to destroy those satellites. A highly collimated microwave beam could do the trick. Or may be a really high powered Argon Ion Laser which are rather easy to build. Maybe somebody can come up with a neat DIY solution.
Generally destroying other people's property isn't looked kindly upon, even if done in international waters or in space.
quantdev(1)
Not a valid solution but I thought maybe SpaceX could launch a bunch of telescope satellites that could be used by hobbyists.
SpaceX directly profits from space enthusiasm, and having their in-house satellite team design such satellites (during downtime, as practice or testbed, etc) and launch them using unused capacity on existing launches would be way cheaper than anything NASA could do. It's not as absurd as it seems at first glance. Not a good replacement for a proper solution, but a nice idea for something they could do in any case.
Could you imagine the enthusiasm from amateur astronomers, kids in school, etc where they could schedule time on a space based telescope? Sure, they won't be anywhere close to Hubble, but even a 6"-12" mirror in ~0% atmosphere would be very cool. And if it were a true constellation, you could schedule time on a satellite in the night time part of the sky during normal daytime class room time rather than trying to take a class field trip to a typical astronomy facility. You would also eliminate the most frustrating thing about astronomy: cloudy skies. And you'd also be able to see parts of the sky that you wouldn't normally based on location, ie Northern/Southern hemisphere.
Yeah there’s a ton of other engineering skills you could teach in parallel. It really isn’t that crazy of an idea. If SpaceX is putting them in orbit on excess capacity from scheduled flights I’d hope they’d give away the time for free. Or they could invent their own market here for scheduling time.
Why is it not a valid solution? It is actually a much better solution than using small low quality telescopes. If starlink is successful in a few years launching satellites will become cheap enough to allow us to launch multiple telescopes better than hubble, and we'll have equivalent of google earth with high quality images of night sky. Combined with VR why would anyone even want to use telescopes? (Maybe people who have personal memories linked to telescopes, like watching night sky with parents, but then even their children would prefer to use the VR version instead).
Because there is a difference between things that could maybe happen, and things that are almost certainly going to happen. Especially when the "maybe" is relying on the largesse of somebody else to fix the problem they created.
History is full of disasters and situations where that absolutely does not work out.
Pinning the near-entire future of astronomical observation on Musk's good will is ridiculous.
History is full of disasters and situations where that absolutely does not work out.
Pinning the near-entire future of astronomical observation on Musk's good will is ridiculous.
First it doesn't depend on Musk's good will at all. It depends on companies making profit by selling space launches. Second "the near-entire future of astronomical observation" is a gross exaggeration, the satellites only add a bit of inconvenience, which is a much smaller issue, than existing issues like light pollution from the cities. The benefits of starlink, and the slight inconvenience for astronomers are simply not comparable.
There are a tiny handful of space based satellites, its far more than only a "bit" of inconvenience.
I mean it is a small inconvenience for telescopes on earth, and not that "it is a small inconvenience in general because there are space telescopes".
Genuine question: is your opinion about these satellites based on working in some related field, or simply on dislike of greedy capitalists? I have a phd in physics and have friends who work as astronomers, with whom i've talked about this. Of course there is always a chance that we misunderstand everything, but i have never seen any plausible arguments for why are some people considering starlink to be the end of world for astronomy, and i don't understand why are there so many people on hn defending "poor astronomers" from "The Evil Corporation".
Genuine question: is your opinion about these satellites based on working in some related field, or simply on dislike of greedy capitalists? I have a phd in physics and have friends who work as astronomers, with whom i've talked about this. Of course there is always a chance that we misunderstand everything, but i have never seen any plausible arguments for why are some people considering starlink to be the end of world for astronomy, and i don't understand why are there so many people on hn defending "poor astronomers" from "The Evil Corporation".
I have worked on high-end telescope controls and imaging systems.
For some types of astronomy --- especially larger fields -- heavily increased use of LEO may reduce the effective hours of observation by 4 hours a night by spoiling most exposures, while creating some impact at other hours. This is more than a 33% reduction in throughput.
Even with a smaller satellite population, there's been losses of valuable data. Two images in an early sequence of SN1987A had a (amazing improbable) perfect satellite streak right down the middle.
Or there's this past APOD https://apod.nasa.gov/apod/image/1910/M31Before_Scherer_4298... where we see the effect of the current satellite population (and a few planes with the ~10 parallel lines from upper right to lower left) on a big stack of images of Andromeda. Zooming in makes it obvious there are many more trails than leap out -- including a few neat tumbling objects's with periodic brightness changes (not the plane strobes).
What's tripling the number of satellites going to do?
I am concerned about increasing satellite counts for a few reasons (including the potential debris problems) I don't think it should preclude progress, but existing and future stakeholders (astronomers, people who enjoy dark skies, current/future users of LEO) should be considered.
For some types of astronomy --- especially larger fields -- heavily increased use of LEO may reduce the effective hours of observation by 4 hours a night by spoiling most exposures, while creating some impact at other hours. This is more than a 33% reduction in throughput.
Even with a smaller satellite population, there's been losses of valuable data. Two images in an early sequence of SN1987A had a (amazing improbable) perfect satellite streak right down the middle.
Or there's this past APOD https://apod.nasa.gov/apod/image/1910/M31Before_Scherer_4298... where we see the effect of the current satellite population (and a few planes with the ~10 parallel lines from upper right to lower left) on a big stack of images of Andromeda. Zooming in makes it obvious there are many more trails than leap out -- including a few neat tumbling objects's with periodic brightness changes (not the plane strobes).
What's tripling the number of satellites going to do?
I am concerned about increasing satellite counts for a few reasons (including the potential debris problems) I don't think it should preclude progress, but existing and future stakeholders (astronomers, people who enjoy dark skies, current/future users of LEO) should be considered.
[deleted]
> “No one thought of this,” she said. “We didn’t think of it. The astronomy community didn’t think of it.”
This implies the community was asked or involved in such a discussion and no objections were raised, which is unlikely.
Whenever some "armchair specialist" commented about Musk's plans to put people on Mars and the challenges with the radiation, the magnetic field, the etc. the answer was always "Do you think a room full of scientists haven't thought about that?". Well there you have it, straight from the source: sometimes they (claim they) do not think about "that". Question everything, worst case someone already thought of that.
This implies the community was asked or involved in such a discussion and no objections were raised, which is unlikely.
Whenever some "armchair specialist" commented about Musk's plans to put people on Mars and the challenges with the radiation, the magnetic field, the etc. the answer was always "Do you think a room full of scientists haven't thought about that?". Well there you have it, straight from the source: sometimes they (claim they) do not think about "that". Question everything, worst case someone already thought of that.
Yeah, that's why Musk always asks people to come to him if they have a better idea. Even in large groups, or maybe especially in large groups, things can be overlooked.
He recently said in a video that if anyone can convince him an aerospike is better than their solution, he wants to know.
He recently said in a video that if anyone can convince him an aerospike is better than their solution, he wants to know.
There is a cultural risk involved though - we don't know how comfortable SpaceX employees feel raising objections given how aggressive Musk has been against concerns in the past (see the somewhat credible reports that Musk angrily rejected yellow safety markings on equipment based on personal taste: http://nymag.com/intelligencer/2018/04/tesla-workers-getting...)
I've heard similar reports from former Tesla employees. They found it stressful working with him in many cases (his brilliance/openness to feedback aside) which could impact this a lot.
I've heard similar reports from former Tesla employees. They found it stressful working with him in many cases (his brilliance/openness to feedback aside) which could impact this a lot.
The reports about the yellow markings are not credible. Just look at photos taken at the freemont car plant: https://laughingsquid.com/wp-content/uploads/2018/04/tesla-t...
Plenty of yellow lines in those.
Plenty of yellow lines in those.
He also has a history of calling people pedophiles for disagreeing with his designs. Even when they are domain experts and he is not.
I think that’s more just PR and he’s not honestly seeking feedback.
I think that’s more just PR and he’s not honestly seeking feedback.
CEO's "open door policies" tend to be a way to quickly get fired.
Just to be clear, because I'm aware objecting what your (potential egomaniacal) CEO says is as career-limiting as it gets, I suggested that everyone else should publicly question everything. Having the objections out there makes plausible deniability claims a lot harder.
[deleted]
Hoping i can get an answer here from somebody who actually knows, and not just a spacex fanboy or hater: what's the actual scope of the problem here?
Shotwell's response and other comments i've seen seem to imply starlink satellites are primarily impacting amateur astronomy ("kids looking through telescopes") and that scientific research is performing post-processing to the recorded images which can mostly eliminate the effects of the starlink satellites. Is that accurate, or is this also impeding telescopes at the big observatories?
Shotwell's response and other comments i've seen seem to imply starlink satellites are primarily impacting amateur astronomy ("kids looking through telescopes") and that scientific research is performing post-processing to the recorded images which can mostly eliminate the effects of the starlink satellites. Is that accurate, or is this also impeding telescopes at the big observatories?
Shotwell's comment is extremely patronising under the circumstances. This doesn't affect kids looking through telescopes at all. If it's bright enough to see through an amateur telescope, it's bright enough to ruin a precision observation from a real instrument. A large part of the outcry is lack of tact from Spacex.
Satellites in images is not new and has caused astronomers problems for a while. It's not common, but most people in the field know someone it's happened to.So now the issue is there will be an order of magnitude objects in space.
Any kind of time series where you observe brightness over time would be affected by a satellite impinging the field. Spectroscopic measurements would also be affected. Astronomers use incredibly sensitive instruments looking for very faint objects - if a bright object is in the field of view, it can saturate the detector and ruin the image.
For context some measurements, like imaging exoplanets, are so precise that you have to block the light from the (already faint) target star to see what's around it.
In reality it's amateurs that can compensate with post processing. Professional astronomers are likely to just trash the data and try again.
Then there are upcoming survey instruments like the LSST which take very wide angle images (I expect they already have some mitigation strategy becuase of other spacecraft). That said, the smaller your field of view, the lower the chance of a satellite impinging.
One solution could be a mechanical shutter which could be activated when a satellite is about to impinge the field, or triggered by a database of satellite ephemirides.
Satellites in images is not new and has caused astronomers problems for a while. It's not common, but most people in the field know someone it's happened to.So now the issue is there will be an order of magnitude objects in space.
Any kind of time series where you observe brightness over time would be affected by a satellite impinging the field. Spectroscopic measurements would also be affected. Astronomers use incredibly sensitive instruments looking for very faint objects - if a bright object is in the field of view, it can saturate the detector and ruin the image.
For context some measurements, like imaging exoplanets, are so precise that you have to block the light from the (already faint) target star to see what's around it.
In reality it's amateurs that can compensate with post processing. Professional astronomers are likely to just trash the data and try again.
Then there are upcoming survey instruments like the LSST which take very wide angle images (I expect they already have some mitigation strategy becuase of other spacecraft). That said, the smaller your field of view, the lower the chance of a satellite impinging.
One solution could be a mechanical shutter which could be activated when a satellite is about to impinge the field, or triggered by a database of satellite ephemirides.
Isn't it obvious that this will happen? It's like taking a picture of nature and having airplane evidence in it, or take a picture of a city or even countryside and there are cars in it.
I'm sure the same was said about cars and planes. It will be weird and things will drastically change - but so have things the last 2000+ years.
I'm sure the same was said about cars and planes. It will be weird and things will drastically change - but so have things the last 2000+ years.
You can easily get yourself between cars and whatever natural thing you're trying to observe on the rare cases that what you're trying to study is anywhere near cars. The only way to do the same for Starlink is to launch multi-million dollar+ space telescope.
But in that case you have to travel to a remote location (most likely using a car or plane ironically).
Hence, is it so far fetched that if you want to explore space in future you will do it from a different vantage point? Like via a satellite, or maybe in 50 years you go to a space station or the moon directly to do so.
With tech it has always been this way- it's nothing new.
Hence, is it so far fetched that if you want to explore space in future you will do it from a different vantage point? Like via a satellite, or maybe in 50 years you go to a space station or the moon directly to do so.
With tech it has always been this way- it's nothing new.
Good that is is being fixed!
Regarding "The astronomy community didn’t think of it"
I think just because we have public spaces does not mean one can do whatever one wants with them.
1) There has been disturbances in the past of radio astronomy spectrum from communication equipment, this limits our ability to learn and observe space. 2) There will be visual disturbances if we launch of satellite constellation for visual astronomy 3) There will be space junk when these satellites run out of service.
Regarding "The astronomy community didn’t think of it"
I think just because we have public spaces does not mean one can do whatever one wants with them.
1) There has been disturbances in the past of radio astronomy spectrum from communication equipment, this limits our ability to learn and observe space. 2) There will be visual disturbances if we launch of satellite constellation for visual astronomy 3) There will be space junk when these satellites run out of service.
It will be interesting how they solve it without causing thermal issues. Just absorbing all light won't work, the energy has to go somewhere and the only viable way to loose it is through radiation (not much air around even in these low orbits). Maybe the satellites will be black on the earth-facing side and radiate heat on the other side?
My impression from the article is that they launch one coated satellite just to see if the coating helps at all, and how bad the thermal issues get, so SpaceX is still in the early stages of solving this. But if they keep up with launching 60 satellites every 2-3 weeks for the next months they have to make progress fast.
My impression from the article is that they launch one coated satellite just to see if the coating helps at all, and how bad the thermal issues get, so SpaceX is still in the early stages of solving this. But if they keep up with launching 60 satellites every 2-3 weeks for the next months they have to make progress fast.
Diffuse reflection might help as well. A sphere and a cube have very different maximum reflection values.
> “No one thought of this,” she said. “We didn’t think of it. The astronomy community didn’t think of it.”
It seems probable that this is one of the things that can be ruled out. I find it inconceivable that none of the thousands of brilliant heads in SpaceX never thought of this.
- They spoke, but were not heard
- They never felt like speaking
It seems probable that this is one of the things that can be ruled out. I find it inconceivable that none of the thousands of brilliant heads in SpaceX never thought of this.
- They spoke, but were not heard
- They never felt like speaking
I'm not an expert, so take this with a grain of salt, but isn't this fixable with mirrors and angles?
For a satellite in LEO most of the light is coming from the sun and a much smaller amount is coming from earthshine and perhaps the moon. If your solar panels are on an articulated arm it should be possible to place them so they reflect the light upwards and the satellite's body is in the shadow of the panels. Now the only light on the satellite (and the back of the panels) will be the earthshine, and you can perhaps combat that by painting the satellite black. If it's always in the shadow of the solar panels then heating shouldn't be a problem, right?
As I say I'm not an expert and there are probably multiple reasons this won't work.
For a satellite in LEO most of the light is coming from the sun and a much smaller amount is coming from earthshine and perhaps the moon. If your solar panels are on an articulated arm it should be possible to place them so they reflect the light upwards and the satellite's body is in the shadow of the panels. Now the only light on the satellite (and the back of the panels) will be the earthshine, and you can perhaps combat that by painting the satellite black. If it's always in the shadow of the solar panels then heating shouldn't be a problem, right?
As I say I'm not an expert and there are probably multiple reasons this won't work.
My first thought was that they should paint them with Vantablack, but then I wondered if that might be too dark?
Do they need to aim for a specific reflectivity or just aim for the lowest possible value?
Do they need to aim for a specific reflectivity or just aim for the lowest possible value?
I think the lowest possible reflectivity is desirable. Space isn't perfectly black but very close to it. Any reflectivity means you sometimes reflect something very bright like the sun and sometimes nothing, so you have the wrong brightness no matter what you do. Black dots are at least fairly unambiguous.
That is often considered, but the light is absorbed and turns into heat. Where does that heat go? It would fry the electronics with no way to get rid of it.
You could use some mechanisms to convert and dissipate the heat, though that doesn't come for free. Though the atmospheric pressure at that altitude is pretty low, you might be able to rig up some sort of peltier cooler setup to dissipate heat. Alternately if you can convert enough of the heat to electricity some other way, you could convert the heat back to light using LEDs or something and only turn on the ones facing away from earth, perhaps?
Plenty of other orbital devices have to deal with heat so I'm sure this is something that has existing solutions.
Plenty of other orbital devices have to deal with heat so I'm sure this is something that has existing solutions.
> Alternately if you can convert enough of the heat to electricity some other way
Thermodynamics says "lolnope", I'm afraid. You need a temperature differential to convert heat to power.
Thermodynamics says "lolnope", I'm afraid. You need a temperature differential to convert heat to power.
Peltier coolers won't do anything but draw power and create more heat you have to dissipate, they're not magic you have to remove the heat from the hot side too which means you need radiators for them too plus more than you'd need originally because peltier coolers are quite inefficient.
Same thing with the LED idea converting that heat into electricity requires some heat differential which requires... a radiator.
Same thing with the LED idea converting that heat into electricity requires some heat differential which requires... a radiator.
I was thinking about this also but wonder if it would collect too much heat while in direct sun light.
reflectivity/aborbtion is more than a percentage value. it's also a hemispherical distribution. if you glued retroreflectors to the surface most of the light would go back in the direction of the sun and thus never hit the surface. Those are probably too costly or bulk for satellites. If specular reflections are the problem they might just apply a more diffuse coating.
Since there are folks here in the field, does anyone know what the feasibility of building something similar to the VLA, but with thousands of smaller satellites? If doable, seems potentially possible to cover a lot more sky at once with less terrestrial interference. No idea if this is practical or not.
There's a number of problems w/ doing interferometry in space, which vary a bit depending on the frequencies you're working with—
Thermal: Parts of the detectors need to be very cold. Depending on what you're doing you may have to cool parts of the satellite down to 5 kelvin (-450°F) or even lower. You need to use a cryocooler than won't vibrate too much and impact your measurements.
Power: Each VLA antenna uses about 18kW just for cooling. That's a lot of juice— back of the envelope math says you need a lot of solar panels for that. An area smaller than a football field but bigger than a tennis court. It's manageable if you're only building a few of these, but less practical if you want to build 64 or even thousands.
Positioning: Most proposals for space based interferometry didn't actually consist of individual satellites. They're typically one big satellite with telescopes sticking out on different arms. If they're free-flying, it gets a lot harder to know the precise relative positions of the different receivers.
Thermal: Parts of the detectors need to be very cold. Depending on what you're doing you may have to cool parts of the satellite down to 5 kelvin (-450°F) or even lower. You need to use a cryocooler than won't vibrate too much and impact your measurements.
Power: Each VLA antenna uses about 18kW just for cooling. That's a lot of juice— back of the envelope math says you need a lot of solar panels for that. An area smaller than a football field but bigger than a tennis court. It's manageable if you're only building a few of these, but less practical if you want to build 64 or even thousands.
Positioning: Most proposals for space based interferometry didn't actually consist of individual satellites. They're typically one big satellite with telescopes sticking out on different arms. If they're free-flying, it gets a lot harder to know the precise relative positions of the different receivers.
> Each VLA antenna uses about 18kW just for cooling.
That’s likely at minimum partially proportional to the size of each VLA antenna, no? Each VLA antenna is larger than any antenna ever put in space I believe.
> If they're free-flying, it gets a lot harder to know the precise relative positions of the different receivers.
That’s exactly what I thought would be one of the biggest challenges, but wasn’t sure if we’d solved that problem or not yet.
That’s likely at minimum partially proportional to the size of each VLA antenna, no? Each VLA antenna is larger than any antenna ever put in space I believe.
> If they're free-flying, it gets a lot harder to know the precise relative positions of the different receivers.
That’s exactly what I thought would be one of the biggest challenges, but wasn’t sure if we’d solved that problem or not yet.
True that 18kW isn't a totally fair comparison. On one hand it's easier to cool because you don't have to worry about the air warming you up. OTOH it's harder because sunlight is way stronger once you get out of the atmosphere.
I don't understand why SpaceX is allowed to make this decision nearly unilaterally. This is so similar to how the modern tech companies treat data extraction: they find something unregulated and push until they get pushback.
This should have a been a worldwide consultation.
This should have a been a worldwide consultation.
On the plus side, Starship will be able to launch more and bigger space telescopes for lower prices, to places beyond the Starlink constellation. That doesnt help ground based observations though.
On the other hand we could use all this reflectivity ( and a ton more! Adding space sails on each of those) to cool the earth
LEO just got a lot cheaper. Get ready for humans to fill this space with shit since it's economical.
SpaceX sabotaging earth based astronomy sounds like yet another business trying to create a market/demand for itself.
Herefore I bet my ass they'll do just too little to fix things and just enough in order to not be prosecuted.
We want to make sure we do the right thing to make sure little kids can look through their telescope
Before the end of next year, there is going to be 12,000 of these units above our Earth. One must certainly hope.
Before the end of next year, there is going to be 12,000 of these units above our Earth. One must certainly hope.
I would bet that there will be no more than 1,200 (if they raise the money needed to launch and manufacture that many).
And I would also bet that even in an 8 year time-horizon, they will not launch 12,000 satellites for Starlink because simply, there will be no market for so much capacity. In my opinion, we are heading towards an Iridium, Teledesic, Globalstar 2.0 scenario.
And I would also bet that even in an 8 year time-horizon, they will not launch 12,000 satellites for Starlink because simply, there will be no market for so much capacity. In my opinion, we are heading towards an Iridium, Teledesic, Globalstar 2.0 scenario.
https://news.ycombinator.com/newsguidelines.html