The viewing window is actually pretty small. For most of the night the satellites are not visible because they are in Earth's shadow. There is an impact on astronomy but it is being overstated by journalists hungry for yet another "Big Tech bad" story.
No, it’s not. This hurts survey telescopes and it’s an orders of magnitude issue.
A rule of astronomy is that if you can see it with your eyes near a city than it’s really really fucking bright, if you can see it with your eyes in the wilderness after your eyes have adjusted for 10 minutes, than it’s still extremely bright.
Bright, fast-moving things are pretty terrible.
Even if Starlink doesn’t kill astronomy, the next 4 companies with similar deployment will definitely exclude types of sciences and ruin billions of dollars of investments in new observatories.
First, satellites are only visible in the optical when they are illuminated by the Sun, which is only for a fairly short window after sunset and before sunrise. The exact size of the window depends on how high they are, but most of the good "dark" time should be unaffected.
Second, astronomers already use image stacking to reject any number of transient artifacts, like satellites, airplanes, cosmic rays, etc.
Third, while these constellations are going to greatly increase the number of satellites in orbit, it's only by about an order of magnitude. Yes, that's worse, but it's not like it's a problem that hasn't existed before.
The type of observations that are likely to be most affected are surveys that actually search for moving near-Earth objects, especially near the Sun (and radio astronomy which apparently can detect terrestrial emissions scattering off of satellites) but I fail to see how this will mean anything like "the end of astronomy" (and I have a Ph.D. in astronomy.)
Saying it will "Kill astronomy" is pretty hyperbolic.
It will likely affect some earthbound astronomy significantly, but much (most?) of the most important work in modern astronomy is satellite based.
I'm on the fence on this whole issue. It's not exactly clear what impact it will have on astronomy. Nor what impact it will have on making the internet pricing and availability. Where I used to live, the only options for internet access were expensive and really bad, the positive impact this might have is potentially quite big.
It's hard with a story like this to suss out what the long term effects will be so it's a big grey area.
It's nothing really new and the same dynamics can be observed throughout history. Imagine there was a time one could look over and see the bay without the Golden Gate bridge or high rise buildings. And now, its even an iconic thing!
A generation or two in the future astronomy will probably get redefined quite a bit via remote telescopes and adventure vacations to space and so forth.
Even now there are plenty of enthusiasts who are excited to take pictures of rockets during take off or explore satellites as they pass by. So it actually get more people interested in space and astronomy.
And there will always be people on either side supporting or opposing technological advances - as we have seen thought history. The one thing that is certain in my opinion though is that things will change.
Staring at a night sky in a designated dark sky area is amazing. Given the pace of SpaceX launches amount of time you can do that without sky crawling with LEO constellations is pretty limited. So days of humans experiencing night sky raw are pretty limited (some would argue it is already impossible). However, I think astronomers will find a way to operate even in a noisy environment of mega-constellations. Given that the objects are bright they can be tracked extremely well. Filtering out them out of the datasets does not seem intractable. Am I missing anything here?
Moreover, I think mega-constellations will actually be a boon for astronomy. Think of it as a platform, while initial iterations will be focused on communication systems, what is stopping them from adding sensor packages looking both inwards and outwards? They already have the bandwidth to downlink all of that. Once on the ground those streams could be combined to produce datasets of unprecedented coverage and fidelity.
It's bright because it's in a low orbit and a lot closer to us. Because it's in a low orbit it's in the earth's shadow for most of the night. It's not bright while in shadow.
Personally, I don't want to be limited to observing the stars from planet Earth for too much longer. The development of commercially viable space technology will fund and fuel investment in interplanetary expeditions and help us move to the next stage of human progress.
A shortsighted attitude, IMO. Terrestrial observatories are in a good position to clean up satellite artifacts digitally. They already have to do more image processing than the staff at Playboy. Meanwhile, cheaper access to orbit can only be a good thing for astronomy, given that we've picked most of the low-hanging fruit in terrestrial-bound optical observations.
Depending on source class and telescope location it ruins between 1/3 and 1/2 of the available observing time. Are you willing to pay $1 more in taxes to to fund the extra telescopes we need to make up the short fall? Please write to your representatives and senators if you do.
Tonight. And what about when SpaceX gets all 11,000 satellites up there? And then Amazon's constellation. and then all the other American companies planning to do the same thing. And the European companies. And the Chinese companies and the Indian companies, and on and on and on.
Dropping a piece of plastic in a lake isn't a big deal. Until it's 11,000 pieces of plastic. And then hundreds of other people do it, too.
The viewing window is the same length no matter how many satellites there are at the same altitude, because Earth's shadow is the same for all of them.
Astronomers are already criticizing such ideas, and have already created an international appeal by professional astronomers open for subscription to ask for an intervention from institutions and governments. See: https://astronomersappeal.wordpress.com/
Isn't this exactly the same view as "if we regulate the use of fossil fuels, China will use way more than us and outcompete us economically" and "if we limit the number of nuclear weapons we create, there's going to be a gap between our nuclear firepower and Russia's"?
Creating a livable planet is not easy, but nationalistic thinking makes it a hundred times harder.
Which do you think has more capability to improve and save lives?
1. Cheaper internet available everywhere for anybody willing to pay
2. Better data on the cosmos
You believe there's no use in developing global cooperation to regulate issues like this? Because if so, we have far more to worry about than satellites.
What useful science has been achieved in the last 100 years thanks to astronomy?
Meanwhile, what kind of useful science do you think can be facilitated by globally accessible high-speed internet? The value generated by such a network is clearly orders of magnitude more useful than observing the cosmos, at this juncture of human endeavor. Not too mention that Starlink will allow SpaceX to re-invest more and more money into space launches / space travel. I'd much prefer humans actually visit other celestial bodies rather than just staring at them.
SpaceX could provide a handful of at-cost launches for astronomy projects per year. It wouldn't fix anything for the ground telescopes but could be a bit of an olive branch for the community.
Starlink satellites cost < 500k each, compared to hundreds of millions for traditional sats.
If you mass produced space telescopes they wouldn't cost the ridiculous sums spent on JWST, which is a terrible example of the wasteful cost plus contracts of nasa. They've been planning it since 1996, and costs have risen from 1 billion to 10 billion.
I wonder how much it would cost to get a decent camera on one of those Starlink launch missions just so it would beam down some distortion free, high-resolution pictures to the masses.
Although I doubt that would provide meaningful data to professional astronomer.
One of the targeted markets of VantaBlack was the aerospace industry to paint the inside of baffles on telescopes and optical sensors. It is currently being used in some star trackers on satellites [1].
Overheating is definitely a big concern for painting your satellite back. There is a lot of work that goes in to thermal design of satellites and that surfaces have the proper optical properties for absorption, reflection and emission.
It's possible, although it's kind of tricky to use in practice.
From the Vantablack wikipedia article:
When light strikes Vantablack, instead of bouncing off, it becomes trapped and is continually deflected amongst the tubes, eventually becoming absorbed and dissipating into heat.[7]
Dealing with heat in space isn't easy, since you have no air to dissipate heat into.
Black radiates heat faster than white as well as absorbin it faster, so ostensibly the side in shadow should dump heat quickly if you have something like heatpipes to move it there.
Question: If SpaceX is successful in developing the Starship, couldn't they launch huge space telescopes for a very low cost? I'd imagine that SpaceXs efforts will be a net positive for astronomers in the end. If the satellite problems becomes too big, maybe they should offer discounts for launching space telescopes.
Another question.. if you are building a radio telescope in space, could you just use a thin foil that folds out like origami for the reflector?
> If SpaceX is successful in developing the Starship, couldn't they launch huge space telescopes for a very low cost?
If the BFR (the rocket behind the starship) is successful then yes it could mean the ability to launch very large telescopes in to space. The scientific community would be very exited about this possibility. However, this doesn't necessarily make it very low cost. One launch of the BFR would still likely be much more than an a Falcon Heavy launch.
> if you are building a radio telescope in space, could you just use a thin foil that folds out like origami for the reflector?
Yes! This technology already exists and it is really pretty amazing to see in action. Right now most of them are used on communications satellites or for synthetic aperture radar satellites. See the videos below:
BFR isn't a name that's still in use. Poster you're responding to was correct in calling it Starship: "SpaceX's Starship spacecraft and Super Heavy rocket (collectively referred to as Starship)" (from https://www.spacex.com/starship).
Starship projects to be significantly less expensive than Falcon Heavy _or_ Falcon 9. With total reusability of both stages and a construction built toward little to no refurbish or rehab, the cost per launch is nearly completely dictated (order of magnitude) by fuel costs, and project to be ~$2 million. This is an order of magnitude reduction in $/kg over the Falcon 9.
I know it’s extremely far fetched, but part of me hopes that if Starship is successful and they have they room, they could capture the Hubble and bring it back down to put in a museum.
Launch costs are a relatively small part of the cost of space telescopes. Pretty much always less than 10%, sometimes as low as 2% of the program's cost. The expensive part is building something that can run for years at a time with no maintenance. Things that are relatively easy on the ground (keeping some parts at cryogenic temperatures, having enough electricity) get significantly more complicated (and expensive) in space.
Is there a specific reason we're still doing ground based astronomy? With satellites becoming ever cheaper, sure we at some point should be able to get a significant telescope up there right? Are we waiting for the bigger rockets to accomplish that?
Yeah. Depending on the spectrum, the telescope might need to be really big. Not to mention at the moment a telescope in orbit would hard, if not impossible, to service.
It seems possible to launch multiple small telescopes and operate them as one large scope using aperture synthesis. I don't know if there are any existing designs or plans for this.
Also: somewhat ninja'd, see other replies as well.
> It seems possible to launch multiple small telescopes and operate them as one large scope using aperture synthesis. I don't know if there are any existing designs or plans for this.
We know how to do that in radio (VLBI), have some experience in IR (ALMA), are doing research on how to do that in optical. But in practice that is much harder than you think. The relative distances of the telescopes have to be known and constant to within a few fractions of the wavelength you are using. Hard when you are using centimeter radiowaves, insanely hard with optical light that has 600 nanometers wavelength.
Innumberable reasons. Data transfer, stability, power, heat dissipation, ability to use large area parts, accessibility for fixing and upgrades, and on and on.
It's very expensive to build (especially large) space telescopes (JWST is already costing more than 8 billion at this point), and astronomy is not very well funded.
It's fascinating to me that the telescope costs so much more than the launch.
A high-quality 24" or 1-meter university-grade observatory telescope can be had for well under $1 million. If you multiply that by a factor of 100 to mount it on a satellite, you're still at 'just' $0.1 billion and can buy a whole Ariane-5 launch just like the JWST to put it at your desired orbit for $0.15B, for a total of $0.25B (a Falcon Heavy runs about half the cost for a launch). You could launch 30 of those (hopefully improving your factor-of-100 cost increase to something more manageable) for less than what the JWST will cost.
I get that JWST is a 6.5 meter telescope, not a piddly backyard 24" device, but why do we have to launch the best single scope possible?
Aren't they mainly large so they have less hindrance of earth's atmosphere? Couldn't telescopes that are in space be smaller and have similar performance?
Is there a specific reason we're still doing ground based datacenters? With satellites becoming ever cheaper, sure we at some point should be able to get a significant datacenter up there right? Are we waiting for the bigger rockets to accomplish that?
That thought exercise should give you 90% of the answers to your question. The atmosphere and light pollution from cities are pretty easy to counteract with location and bigger optics.
I have no experience in astronomy or satellites, but here's my naive idea. The article suggested erasing trails from the images using software. If SpaceX made an open API that detailed the precise location of every satellite at every point in time, could the imaging software use this to know that at this location in the image there is definitively a satellite that can be erased? I'm not sure what kind of sensors these telescopes use, and it probably wouldn't solve the issue of the bright spot messing up the exposure, but at least you could get rid of the trails?
SpaceX is publishing the precise location of each satellite continuously. It's really cool actually; most satellite operators don't do this. The raw data is available at Celestrak here: https://celestrak.com/NORAD/elements/supplemental/
This site is awesome! Have you thought about extending it to check for the position of the ISS? I would assume that information is probably readily available, as well.
I've mostly dealt with amateur and semi-pro equipment and I'm not certain what the state-of-the-art is so someone else might be able to answer this better than me.
These telescopes essentially work by capturing photon counts on a sensor. The individual pixels on the sensor have a limit to the number of photons they can count. You could theoretically subtract the satellite pixel-count values from the photon counts to get rid of the trails. The two problems I see are: 1) You don't know the correct counts for the satellites and I'm not sure how you could get them. 2) The trails will probably saturate the pixels anyway (which can also cause bleeding into other pixels), in which case you just don't have the data of what's 'behind' the trails.
Tl;dr: Perfect subtraction is impossible due to physics.
Problem is: With photon count the uncertainty in the number of photons also goes up (the relative error goes down). So even if you know that you should have received 100 photons from the satellite (and have not reached the overflow of 256 in this example yet), Poisson statistics means you will actually get anything between 90 and 110 photons. So if you subtract 100 you have an uncertainty of plus or minus 10 photons left. That is deadly if you astronomical source only gave you 2 photons in that pixel in that time.
Are the sensors recording a timestamp with the photon counts? If so, it should be trivial to filter out bright fast moving objects with zero impact on image fidelity.
Nearly every object in orbit is already tracked and any specific object of interest can be tracked even more precisely, so no need for an additional API. That won't work as they use multiple hour exposures that accumulate the light, you can't "erase" something, as most of the info is already discarded, unless it's a deep stack. You can try recording the video of the same field of view with a smaller auxiliary telescope, accounting for the satellites that crossed the view of the big instrument in the resulting exposure. But that's still artifact-prone, and won't work in many cases (saturated pixels, very faint objects etc). You have to pause the exposure for every satellite that crosses the view, if that's possible at all.
Telescope images are usually long exposures so that won't work. AFAIK there's no method of selectively dumping or damping the pixels only ass the Starlink satellites pass through the frame.
To do it you'd need a screen in front of the sensor that could occlude the pixels that the Starlink sats were passing over..
Going further, put a small space facing camera on each satellite. The images can be stiched together to improve resolution and maintain continuous observation of space at all angles. Image downloads can be limited to save bandwidth.
There is SW already to subtract satellite trails from pictures. And astronomers have stated that it's not a big deal yet. But 42000 extra satellites might be too much. Nobody knows, everybody is worried, lots of talk.
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The viewing window is actually pretty small. For most of the night the satellites are not visible because they are in Earth's shadow. There is an impact on astronomy but it is being overstated by journalists hungry for yet another "Big Tech bad" story.
A rule of astronomy is that if you can see it with your eyes near a city than it’s really really fucking bright, if you can see it with your eyes in the wilderness after your eyes have adjusted for 10 minutes, than it’s still extremely bright.
Bright, fast-moving things are pretty terrible.
Even if Starlink doesn’t kill astronomy, the next 4 companies with similar deployment will definitely exclude types of sciences and ruin billions of dollars of investments in new observatories.
Second, astronomers already use image stacking to reject any number of transient artifacts, like satellites, airplanes, cosmic rays, etc.
Third, while these constellations are going to greatly increase the number of satellites in orbit, it's only by about an order of magnitude. Yes, that's worse, but it's not like it's a problem that hasn't existed before.
The type of observations that are likely to be most affected are surveys that actually search for moving near-Earth objects, especially near the Sun (and radio astronomy which apparently can detect terrestrial emissions scattering off of satellites) but I fail to see how this will mean anything like "the end of astronomy" (and I have a Ph.D. in astronomy.)
It will likely affect some earthbound astronomy significantly, but much (most?) of the most important work in modern astronomy is satellite based.
I'm on the fence on this whole issue. It's not exactly clear what impact it will have on astronomy. Nor what impact it will have on making the internet pricing and availability. Where I used to live, the only options for internet access were expensive and really bad, the positive impact this might have is potentially quite big.
It's hard with a story like this to suss out what the long term effects will be so it's a big grey area.
A generation or two in the future astronomy will probably get redefined quite a bit via remote telescopes and adventure vacations to space and so forth.
Even now there are plenty of enthusiasts who are excited to take pictures of rockets during take off or explore satellites as they pass by. So it actually get more people interested in space and astronomy.
And there will always be people on either side supporting or opposing technological advances - as we have seen thought history. The one thing that is certain in my opinion though is that things will change.
Moreover, I think mega-constellations will actually be a boon for astronomy. Think of it as a platform, while initial iterations will be focused on communication systems, what is stopping them from adding sensor packages looking both inwards and outwards? They already have the bandwidth to downlink all of that. Once on the ground those streams could be combined to produce datasets of unprecedented coverage and fidelity.
Once the sun is set in their orbit, they should be invisible both to the eye and telescopes.
Deleted Comment
Why is that? Almost everything astronomy studies isn't fast-moving. Shouldn't it be easy to filter out that noise?
Tonight. And what about when SpaceX gets all 11,000 satellites up there? And then Amazon's constellation. and then all the other American companies planning to do the same thing. And the European companies. And the Chinese companies and the Indian companies, and on and on and on.
Dropping a piece of plastic in a lake isn't a big deal. Until it's 11,000 pieces of plastic. And then hundreds of other people do it, too.
The satellites are not in sunlight unless the sun is not that far below the horizon.
Indeed, and let's not forget that Elon has upset a lot of applecarts with SpaceX and Tesla.
Creating a livable planet is not easy, but nationalistic thinking makes it a hundred times harder.
I'd go with #1.
You mean..."Science"?
Meanwhile, what kind of useful science do you think can be facilitated by globally accessible high-speed internet? The value generated by such a network is clearly orders of magnitude more useful than observing the cosmos, at this juncture of human endeavor. Not too mention that Starlink will allow SpaceX to re-invest more and more money into space launches / space travel. I'd much prefer humans actually visit other celestial bodies rather than just staring at them.
If you mass produced space telescopes they wouldn't cost the ridiculous sums spent on JWST, which is a terrible example of the wasteful cost plus contracts of nasa. They've been planning it since 1996, and costs have risen from 1 billion to 10 billion.
Although I doubt that would provide meaningful data to professional astronomer.
https://en.wikipedia.org/wiki/Vantablack
https://culturehustle.com/collections/black/products/black-3...
- needs to survive vacuum
- needs to survive atomic oxygen, that does show up at low Earth orbital altitudes
- needs to handle the thermal cycling as the satellite goes in and out of Earths shadow
- needs to survive unfiltered sunlight without any atmospheric convection to normalize temperature
- needs to avoid overheating the part of the satellite it is covering
- should not emit particles, that could collide with other satellites
- needs to keeps doing this for about 5 years (design lifetime of individual Starlink satellites)
- should harmlessly burn up on satellite reantry
If the given material can do all the above, while still keeping it's desirable properties, then it can be used on a Starlink satellite. :)
Overheating is definitely a big concern for painting your satellite back. There is a lot of work that goes in to thermal design of satellites and that surfaces have the proper optical properties for absorption, reflection and emission.
[1] http://www.eurekamagazine.co.uk/design-engineering-news/worl...
From the Vantablack wikipedia article:
When light strikes Vantablack, instead of bouncing off, it becomes trapped and is continually deflected amongst the tubes, eventually becoming absorbed and dissipating into heat.[7]
Dealing with heat in space isn't easy, since you have no air to dissipate heat into.
Oops that's classified. But probably such satellites need a dedicated cooling system.
It's never as easy as, just paint it black and hope for the best.
But odds are they're only going as far as is required, which would be "no brighter than typical satellites" - right?
Another question.. if you are building a radio telescope in space, could you just use a thin foil that folds out like origami for the reflector?
If the BFR (the rocket behind the starship) is successful then yes it could mean the ability to launch very large telescopes in to space. The scientific community would be very exited about this possibility. However, this doesn't necessarily make it very low cost. One launch of the BFR would still likely be much more than an a Falcon Heavy launch.
> if you are building a radio telescope in space, could you just use a thin foil that folds out like origami for the reflector?
Yes! This technology already exists and it is really pretty amazing to see in action. Right now most of them are used on communications satellites or for synthetic aperture radar satellites. See the videos below:
Animation of the radar antenna on SMAP:
https://smap.jpl.nasa.gov/resources/83/smap-antenna-deployme...
Actual video of a large communcations antenna (12m diameter) being deployed. Skip ahead to ~2:15 for the actual unfurling.
https://www.youtube.com/watch?v=_mFnNDzxKFk&feature=emb_titl...
BFR isn't a name that's still in use. Poster you're responding to was correct in calling it Starship: "SpaceX's Starship spacecraft and Super Heavy rocket (collectively referred to as Starship)" (from https://www.spacex.com/starship).
Starship projects to be significantly less expensive than Falcon Heavy _or_ Falcon 9. With total reusability of both stages and a construction built toward little to no refurbish or rehab, the cost per launch is nearly completely dictated (order of magnitude) by fuel costs, and project to be ~$2 million. This is an order of magnitude reduction in $/kg over the Falcon 9.
https://www.space.com/spacex-starship-flight-passenger-cost-...
https://www.thespacereview.com/article/3740/1
What really needs to happen is the ability to build mirrors in LEO so they don't have to be built to survive the launch.
Perhaps a review of telescope design is in order: https://en.wikipedia.org/wiki/Telescopehttps://en.wikipedia.org/wiki/Optical_telescope
Building large telescopes is hard enough. Putting them in orbit just adds to all the costs. Look at the James Webb Telescope (which still hasn't been launched). https://en.wikipedia.org/wiki/James_Webb_Space_Telescope
It seems possible to launch multiple small telescopes and operate them as one large scope using aperture synthesis. I don't know if there are any existing designs or plans for this.
Also: somewhat ninja'd, see other replies as well.
We know how to do that in radio (VLBI), have some experience in IR (ALMA), are doing research on how to do that in optical. But in practice that is much harder than you think. The relative distances of the telescopes have to be known and constant to within a few fractions of the wavelength you are using. Hard when you are using centimeter radiowaves, insanely hard with optical light that has 600 nanometers wavelength.
A high-quality 24" or 1-meter university-grade observatory telescope can be had for well under $1 million. If you multiply that by a factor of 100 to mount it on a satellite, you're still at 'just' $0.1 billion and can buy a whole Ariane-5 launch just like the JWST to put it at your desired orbit for $0.15B, for a total of $0.25B (a Falcon Heavy runs about half the cost for a launch). You could launch 30 of those (hopefully improving your factor-of-100 cost increase to something more manageable) for less than what the JWST will cost.
I get that JWST is a 6.5 meter telescope, not a piddly backyard 24" device, but why do we have to launch the best single scope possible?
There are only 7 visible-light space telescopes listed at https://en.wikipedia.org/wiki/List_of_space_telescopes#Visib.... I wish there were 70 or 700, with live Internet feeds.
That thought exercise should give you 90% of the answers to your question. The atmosphere and light pollution from cities are pretty easy to counteract with location and bigger optics.
I'm using this data to power my site that shows when you can see Starlink yourself: https://james.darpinian.com/satellites/?special=starlink-lat...
These telescopes essentially work by capturing photon counts on a sensor. The individual pixels on the sensor have a limit to the number of photons they can count. You could theoretically subtract the satellite pixel-count values from the photon counts to get rid of the trails. The two problems I see are: 1) You don't know the correct counts for the satellites and I'm not sure how you could get them. 2) The trails will probably saturate the pixels anyway (which can also cause bleeding into other pixels), in which case you just don't have the data of what's 'behind' the trails.
Problem is: With photon count the uncertainty in the number of photons also goes up (the relative error goes down). So even if you know that you should have received 100 photons from the satellite (and have not reached the overflow of 256 in this example yet), Poisson statistics means you will actually get anything between 90 and 110 photons. So if you subtract 100 you have an uncertainty of plus or minus 10 photons left. That is deadly if you astronomical source only gave you 2 photons in that pixel in that time.
To do it you'd need a screen in front of the sensor that could occlude the pixels that the Starlink sats were passing over..