Stacked images of the comet, photobombed by Starlink satellites

https://twitter.com/djulik/status/1286053695956881409

by _Microft • 6 years ago

249 201 6 years ago

todd3834• 6 years ago

What are some of the potential consequences of this? I’m curious if stars getting photobombed is a signal pointing to a greater issue? If they can coat them in a way to not be reflective then will most astronomers be satisfied?

falcolas• 6 years ago

The greater thread has some data on the latter point - the latest satellites are coated, but it's not had much impact yet.

Seems like this is light pollution taken to a completely new level.

elliekelly• 6 years ago

I remember reading Musk had to get permission from some US regulator (the FCC and/or FAA maybe?) in order to launch these satellites but is there any sort of international body that deals with this?

bryanlarsen• 6 years ago

SpaceX has abandoned the coating approach and is going with a shade approach, which works even better. The next set of satellites all have the shade.

pmontra• 6 years ago

We will exchange white lines for black lines. We won't be able to see through the satellites.

Actually maybe a white line is simpler to remove than a black one on a black background.

jacknews• 6 years ago

exactly, paint them green

gpm8• 6 years ago

Presumably exchanging white lines for transparent lines not a color. For larger projects which don't move around this can be augmented further by removing known satellite tracks instead of lines, or even not imaging areas when satellites are going to be there.

sp332• 6 years ago

Black lines are far preferable because they do not contribute to the total amount of light collected. A momentary flash from a bright light can swamp the sensor, but a brief moment of blackness will leave the pixels' state much less disturbed.

zaarn• 6 years ago

Any good astronomy imaging tool will remove temporary satellite flashes without much effort, provided you take a lot of exposures. If you naively stack them you get this of course.

ardy42• 6 years ago

If they can coat them in a way to not be reflective

Less reflective. I don't think there's a way to make them not reflective, and many, many astronomical objects are very dim.

webmaven• 6 years ago

> If they can coat them in a way to not be reflective
Less reflective. I don't think there's a way to make them not reflective, and many, many astronomical objects are very dim.

Vantablack[0] would probably be adequate for the timescales involved, at least for most terrestrial[1] observations:

[0] https://www.sciencealert.com/this-object-has-been-sprayed-wi...

[1] eg. I can easily imagine a similar but more severe problem for a lunar farside observatory if (when?) Starlink is expanded to provide internet coverage for the Moon's surface. Of course, the main reason for a farside observatory would be shielding from Earth's RF emissions, so just people needing and wanting internet access on farside is probably going to be a problem first.

gpm8• 6 years ago

Easily solved in software by removing the small part of each frame that has a satellite in it. Satellite tracks are completely predictable. This is not novel.

JBorrow2• 6 years ago

Perhaps true for amateur astrophotography but not the case for professional astronomy. Please see reporting in e.g. [1] and [2].

Note that simply putting telescopes in space is not a viable solution to these problems.

[1] https://skyandtelescope.org/astronomy-news/starlink-astronom... [2] https://www.theverge.com/2020/3/24/21190273/spacex-starlink-...

gpm8• 6 years ago

A few particularly large and particularly sensitive telescopes will have problems not easily resolvable by software, the vast majority of telescopes will not.

Kye4• 6 years ago

Somehow I get the feeling people who do this professionally understand what's possible and what effect this has better than you.

gpm8• 6 years ago

They undoubtedly do, but this is an opinion formed by talking to people in person in the industry. Random twitter users who manage to get there tweet on HN is not even close to an unbiased sample of professionals in the industry. My sample undoubtedly also has its biases, but is not selected for sensationalist views at least.

tenuousemphasis• 6 years ago

The person who posted this tweet? I don't think so. They also said this gibberish:

Space junk. There HAS to be another way to improve internet communications, does Humanity and planet Earth's livestock need this (5G)? Really?

abduhl• 6 years ago

Yet another physical layer problem conveniently solved by a software solution (coded over the weekend, of course)!

jcun4128• 6 years ago

Did have a thought about a physical device/notification system that lets you know the sky is clear, would be interesting to work on that the tracking/predicting position assuming data is available.

Nikkau• 6 years ago

It's bad faith, a normal stacking would have made them completely disappear, it's one of main reasons to do stacking, remove things which are not on all images, and it's works flawlessly.

You have to actively tweak your settings to create this kind of photo.

vilhelm_s• 6 years ago

I guess the most basic way to stack (just add the images together) would leave them in, but

Almost every modern astronomical post-processing program has a rejection process (sometimes referred to as sigma-reject) to remove unwanted signals, though the exact sequence will depend on which program you use.

https://skyandtelescope.org/astronomy-blogs/imaging-foundati...

woko• 6 years ago

From your link:

The way this process works is that, while averaging all of the pixels in a series of, say, 10 images, the program mathematically calculates which pixels fall far away from the mean value because they're much brighter (or much fainter) compared to the same pixels in other frames. The algorithm then discards those out-of-range pixel values so they don’t affect the final image.

Wouldn't this process remove part of the comet trails as well as the satellite trails?

I mean, I get how it works if all you care about is relatively static like distant stars, but would it work for this specific use case?

ipsum2• 6 years ago

You have to actively tweak your settings to create this kind of photo.

No, the most basic stacking is just to add the images together, resulting in trails. I don't see this as bad faith at all.

trickstra• 6 years ago

If it created trails, then it would also multiply the brightness of the stars and the comet by the number of pictures (17 in this case). Each satellite appears only on one photo, while the stars and comets appear on all 17 in the exact same spot. The only way to stack them to get a normal looking stars and comet is to make an average. And since the satellites only appear on 1 out of 17 they would effectively disappear.

Unless you actually want to have the satellites there, then the stacking would just cut the region with the satellite from each photo and simply glue them together. That's how you can get this image.

I actually just tried it in Hugin. Normal stacking from 2 pictures by default made the objects that appeared only on one of the pictures semi-transparent. If I did this with more pictures, they would be so transparent that I wouldn't see them at all. But I could manually select a mask to cut out the portions that I don't want. If I select and exclude the object (satellite streak) it would disappear completely. But I could also purposefully include the streak and in that case all the satellite streaks would be included in full brightness in the result. That's most likely how this photo was made.

zelon88• 6 years ago

The OP posted this in the ensuing Twitter argument...

Why (on Earth) do you want to become a multi planetary species??

That's just an un-neccesarily foolish question. Why does a dog swim when you place him in a lake?

Have you ever tried to live in Antarctica or in the Atacama desert (I have)? I support science, exploration, tech development but not foolishness. Do you surround your house with roads to explore distant locations?

Isn't that exactly what we've done as a society already?

dx872• 6 years ago

We did that, realized it was a mistake, and have started placing emphasis on working around nature, instead of tearing it down because it's more convenient.

marcus_holmes6• 6 years ago

in the west, yes. In the places where real nature still exists; no, everyone's still happy to tear it down for convenience.

evidence: Brazil's rainforest. Indonesian palm oil. Chinese mines. African, well, everything.

_Microft3• 6 years ago

The OP posted this in the ensuing Twitter argument...

"OP" refers to the OP of the Twitter thread.

I'm just the submitter and do not share their view on being a multi-planetary species at all (I agree that it sucks to have streaks on your astro-photos, as I started taking them recently).

We have to boldly go where no man has gone before.

Edit: changed wording to restore split infinitive.

marcus_holmes6• 6 years ago

or even go boldly

time4hn• 6 years ago

That's just an un-neccesarily foolish question.

On Twitter there seem to be a lot of people on who expect to live in other worlds soon, and not just to explore and study them. He's likely rhetorically responding to that idea. And I think it's worthwhile to confront those ideas critically. IMO as well, living off of Earth sounds hellish, given what we know now.

The person the Twitter poster is talking with is now suggesting that many people will abandon their physical bodies, and those that won't will live in cylindrical space colonies. He's speaking fantasies.

crowbahr• 6 years ago

Twitter OP is also arguing that there will never be human settlements off this Earth, which is bullshit.

Assuming humanity exists long enough, it will expand throughout the solar system. At very least to the moon.

We can argue about how long that might take, but not about it ever happening.

MrZongle2• 6 years ago

On Twitter there seem to be a lot of people on who expect to live in other worlds soon

On Twitter there seem to be a lot of people who currently live on other worlds.

INTPenis• 6 years ago

For a different type of analogy, look at how long we had to sail around in wooden ships before that evolved.

Without actually venturing out there, we might never develop viable star travel.

stinos• 6 years ago

I found that a bit of an odd question, besides the point, but I might be missing something. Is any of the purposes or uses of Starlink actually related to something multi-planetary? From what I read on it they seem to be there solely for communication on earth itself? Or does the commenter consider Starlink as one of the things further enabling technology to go multi-planetary? Which I still don't really get, since other types of communication are already which go way deeper in space and send messages back and forth to earth.

Ankaios• 6 years ago

A major (the major?) motivation behind Starlink is to try to earn SpaceX vast amounts of money that Musk can invest in settling Mars.

See, e.g., this link for comments by Musk: https://www.space.com/spacex-starlink-internet-satellites-ma...

kergonath3• 6 years ago

I wish we would discipline ourselves to avoid ruining that one planet before we get delusions of grandeur and the urge to wreck another one.

All these talks about “multi-planetary species” are bunk in the long term, anyway. We will probably have observation outposts scattered across the solar system, but that’ll be about it for quite a long time. The only realistically reachable planet in the foreseeable future is Mars. We could fix our issues with Earth for a fraction of what it would take to make it inhabitable.

We’ll send our billionaire pioneers to the moon alright. With a scientific base as a side effect. It still won’t improve anything that’s wrong with Homo Sapiens.

kome• 6 years ago

i can't believe people are suggesting to edit this away with photoshop... you are pointing at the moon and they are looking at the finger...

tebruno99• 6 years ago

It was caused by stacking incorrectly in photoshop to begin with.

catalogia5• 6 years ago

That the image tweeted is a product of photoshop in the first place should be obvious to anybody who looks up. Go outside tonight and look up. Does the sky appear as it does in that tweet? Obviously not.

gus_massa• 6 years ago

It's the result of some image processing. For example, there are like a hundred segments in the photo, but if you look carefully, they are quite aligned in ~27 almost parallel lines (probably the 27 satellites in different frames?)and a strange almost parallel segment (probably another unrelated satellite?).

nimih• 6 years ago

And how about that black hole photo from last year? Definitely a hoax--black holes are supposed to be black, dummies!

LeChuck3• 6 years ago

I wonder if these things will have any effect on astronavigation. It would be sad to see such a cool practice become impossible.

valuearb2• 6 years ago

Starlink Satellites are only visible for short periods just after sunset and before sunrise, because most of the night they are in the earths shadow.

LeChuck3• 6 years ago

Yeah. That's the problem. Celestial navigation can only be performed during twilight, as you need to be able to see both the horizon and celestial objects.

https://en.wikipedia.org/wiki/Twilight#Nautical_dawn_and_dus...

catalogia5• 6 years ago

I don't see why they would. The stars typically used for astronavigation are very bright; brighter than starlink satellites. A brief web search leads me to believe typical starlink satellites have a magnitude of around 5 or more, while the stars typically used for astronavigation have magnitudes of less than three (https://en.wikipedia.org/wiki/List_of_stars_for_navigation)

Even if that weren't the case, it's easy for the human eye to distinguish a star from a LEO satellite; the satellite is the one that's moving fast. I see no reason the sailors couldn't simply ignore the satellites.

LeChuck3• 6 years ago

It was the brightness I was worried about, yes. Should've probably just looked it up myself!

I don't think astronavigation is used in any serious capacity anymore, so in that sense it's a moot point. Still, it's a cool practice and it would've been too bad to see that go away.

whoopdedo• 6 years ago

The truth is most people will never notice the Starlink satellites. Because light pollution obscures the night sky so much you can only see the brightest of stars and nearly nothing close to the horizon. How many kids are hearing about this comet in the sky, rush out at sunset, and are then disappointed to only see the haze of city lights?

daveslash• 6 years ago

Truth is, most people never look at the night sky, period. But this isn't about most people; this is specifically about people who look at the sky a lot -- and those people typically seek out darker skies anyway.

catalogia5• 6 years ago

Truth is, most people never look at the night sky, period.

Truth is people never look at the sky period. Ask people when the moon is visible and most will say "during the night." But about half of the time, the moon is actually visible during the day. Wouldn't people realize this if they simply looked up?

ianmcgowan• 6 years ago

Apart from all the comments about this being a bad faith post, I wonder about the utilitarian argument, if you take it at face value. If you could provide decent internet at low cost to large parts of the world that are underserved, at the cost of ruining ground-based telescopes, is that a good trade-off? What if it's just certain kind of telescopes, or certain classes of astronomers (as this seems to be)?

marcus_holmes6• 6 years ago

I think this is useful if we also consider that part of SpaceX's plan is to make launching satellites cheap (in fact, launching anything cheap). So while ground-based astronomy will suffer, space-based astronomy will get cheaper and easier.

Presumably to the point where people who want to can subscribe to a Hubble-like satellite service and get all the space photos their hearts desire.

Also, we made a similar trade-off a long time ago - most people live in heavily light-polluted cities, because we value having street lighting more than being able to see the stars.

justapassenger• 6 years ago

Cost of launch is not really main reason why we don’t see more space based astronomy.

1. Space is a hostile place, and developing telescope that works there is much harder. 2. There are very real limits on size and weight of what can be put there right now, and rocket equation is ruthless. 3. Any type of maintenance or upgrades are basically impossible, compared to earth based. 4. Adaptive optics were such a huge breakthrough, that basically negated need for most of space based telescopes.

simion3143• 6 years ago

But now if we are forced to move all ground telescopes on space SpaceX will make profit so is a win-win for SpaceX and the public will have to pay to replace working satellites on the ground with expensive and smaller ones on space.

We should be fair and acknowledge all the downsides, and if you disagree I would ask to waste a bit of effort and explain why we should ignore this costs on the public(maybe the costs are worth it in the long run but we should not ignore them)

ClumsyPilot3• 6 years ago

SpaceX going going to sign on the dotted line to provide free service to observatories damaged by starlinked? Because unless it signs a contract, this whole argument is a load of hot air.

CydeWeys5• 6 years ago

This exactly. Satellites are incredibly useful and enable trillions of dollars of worldwide economic output that would not be possible otherwise. This is a very meaningful improvement in everyone's lives. We should not stop using them simply because they are visible in the night sky, and make astrophotography a little bit harder (though not much harder -- removing satellite streaks is a default enabled option in astrophotography image stacking software).

ClumsyPilot3• 6 years ago

Its notntrillions, and should be done ina way that does not ruin other people's jobs

irthomasthomas4• 6 years ago

Phased array ground stations cost about $10,000-$100,000.

jeffbee• 6 years ago

That's a lot of money. Considering that the company has reversed course on almost every promise it has ever made about Starlink -- orbit altitude, inter-sat networking, service area, cost -- I think it's a good bet that Starlink will ultimately just look like a capital-intensive Iridium-like network without the ability to service mobile stations. I imagine the US military will end up being the main customer.

gpm8• 6 years ago

If you're willing to take SpaceX at their word you are off by two orders of magnitude. I don't see why you wouldn't be.

mooman2192• 6 years ago

Which is an order of magnitude less than a cell tower.

mantap2• 6 years ago

The premise is false. Musk doesn't need to ruin ground based telescopes in order to make Starlink a reality. This issue could be resolved by going slower, Musk just doesn't want to wait.

CPUstring• 6 years ago

Musk drives his team for speed because every one of his companies still has the "how much runway do we have" mindset. Lots of people can throw stones from their glass towers knowing they work at a company that will exist in 2030 or 2040, but SpaceX can't say that unless they are always moving.

valuearb2• 6 years ago

This is pretty much a cherry picked worst case scenario. The comet is only visible right above the horizon after sunset for a brief period.

Starlink satellites are also only visible low on the horizon, and only for brief periods after sunset and before sunrise, because their low orbits keep them in the Earths shadow the rest of the night.

asdfadsfgfdda• 6 years ago

Yeah its basically optimized to look bad. The satellites are relatively close to each other. In normal operation, there's no reason to have 30 different satellites in view. I suspect these satellites were very recently launched, so they are not in the normal sun-tracking orientation.

Also, the comet is a wide object. A wide image is just more likely to have any satellite in view.

hombre_fatal• 6 years ago

How much sympathy can I really spare for a purely leisurely hobby like backyard astronomy vs. satellites, Starlink, and our space tech?

To me it's like complaining that your photography hobby is harder now that more people can afford to travel and they get in the way of your favorite tourist shots.

I'm sure there are good examples of trade-offs that matter here like the impact on terrestrial research telescopes, but a guy snapping a pic of a comet and ranting about it on Twitter frankly has the opposite effect on me.

dmitriid• 6 years ago

True, because professional astronomers, lucky them, are provided a completely different sky devoid of satellites, debris and other man-made objects.

marcus_holmes6• 6 years ago

If we can make space travel cheap enough to get more Hubble-like telescopes up there, then yes, this.

I believe that's part of the goal of SpaceX

modzu• 6 years ago

it is a tragedy. what we have in the ever shrinking dark night sky is utterly breathtaking if you have ever seen it; light pollution is a bigger problem imo than starlink, but they relate. survey astronomers and astrophysicists and you will find for many it was being able to look up and see stars, be awed by them and wonder about them that got them into their field in the first place. i am scared to lose that..

justin66• 6 years ago

How much sympathy can I really spare for a purely leisurely hobby like backyard astronomy vs. satellites, Starlink, and our space tech?

Your sympathy or lack thereof is your business, but astronomy is one of the rare sciences where amateurs still do a great deal of work and make important discoveries.

I'm sure there are good examples of trade-offs that matter here like the impact on terrestrial research telescopes, but a guy snapping a pic of a comet and ranting about it on Twitter frankly has the opposite effect on me.

It's a shame you would allow your opinion on an important subject to be swayed by a single tweet on an issue you apparently know little or nothing about.

supernova87a• 6 years ago

How about when satellite stray signals or signatures start to pollute not just amateur hobbies, but GPS, weather? It's all related.

giantrobot3• 6 years ago

Satellites have very constrained transceivers. This is not only for regulatory reasons but efficiency. It's a literal waste of power to leak noise into non-target bands. Everything from the transceiver electronics to antennas are tuned for target bands. Satellites broadcasting stray signals is rare enough to not be a thing.

Interference with GPS and other signals overwhelmingly comes from ground based sources.

shadowgovt5• 6 years ago

That looks so cool.

irthomasthomas4• 6 years ago

It's trivial to erase these things from photos. The photographer no doubt knows this, but that isn't the point.

It's perfectly reasonable for scientists to want to capture accurate data on the space surrounding the main subject being imaged. Simply erasing the satellites from photos does not recover the data on the space behind. Any data from behind the satellites is lost forever. This photo keeps the satellites in order to visually demonstrate this problem.

Remember that astronomy today is often done on a single pixel of data. Starlink blocks multiple pixels, and even ruins entire exposures when they flare up. This will make astronomical research, like searching for exoplanets, far harder and more expensive than it is today. Space telescopes are, and will always be, orders of magnitude more expensive than ground telescopes to launch, maintain and operate.

claydavisss• 6 years ago

Starlink will provide an immediate benefit to humanity, the astronomy performed otherwise, won't. Looking for exoplanets isn't a practical concern for humanity any time soon.

ganafagol3• 6 years ago

Odd perspective when defending technology from the same guy that wants to save humankind by literally colonizing other objects in space.

nsilvestri2• 6 years ago

Exposures are generally taken frequently enough that any that would be problematic for data can simply be dropped. The satellites aren't permanently positioned in the sky. Geostationary satellites permanently lose any data behind them (although I haven't heard of a geostationary satellite being positioned precisely problematically).

irthomasthomas4• 6 years ago

Searching for exoplanets moving in front of a star, involves measuring the luminosity of a single pixel for ~1% change. Dropping frames ruined by a satellite train isn't going to work. E.g https://www.sciencealert.com/a-bunch-of-potential-tabby-s-st...

giantrobot3• 6 years ago

For one a Starlink satellite, or any LEO satellite, is moving really fast relative to a ground based telescope. It'll occult any given star for a fraction of a second.

If you're doing a narrow field long exposure with tracking, that will be problematic and you'll loose data. Most scientific observations don't do long exposures, especially measuring highly variable things like exoplanet transits.

It's more effective to stack a large number of short exposures for scientific measurements. It's much easier to eliminate noise because everything that is not noise will be transient for a single frame in the stack. You can also remove frames with things like satellites, clouds, or airplanes without losing much data.

Knowing the ephemeris of satellites also allows observations to time short exposures to avoid occultations. Astronomers have been dealing with satellites, clouds, and airplanes for a long time. Amateur astronomers might have a harder time with Starlink satellites but they will adapt just like they did with the ISS and Iridium.

irthomasthomas4• 6 years ago

"Members of the LSST science team said last month that, assuming the full deployment of SpaceX’s Starlink satellites, nearly every exposure from the observatory within two hours of sunset or sunrise would have a satellite streak. During summer months, when twilight times longer, there could be a 40 percent impact on twilight observing time, according to the Association of Universities for Research in Astronomy, or AURA, which manages the LSST project for the National Science Foundation.

“Because of scattered light in the optics by the bright satellites, the scientific usefulness of an entire exposure can sometimes be negated,” AURA said in a statement last month. “Detection of near-Earth asteroids, normally surveyed for during twilight, would be particularly impacted. Dark energy surveys are also sensitive to the satellites because of streaks caused in the images. Avoiding saturation of streaks is vital.”"

https://spaceflightnow.com/2019/12/09/spacex-to-experiment-w...

spacemark2• 6 years ago

Most scientific observations don't do long exposures

Not quite the whole truth, I think you're speaking a tad beyond your expertise. While you're right that transient science generally does short exposures (TESS is 2 seconds, Kepler was 6.5, LSST will be ~20 iirc), the vast majority of astrophysical science I've been exposed to (mechanical engineer at an astrophysics research institute), 10 or 20 minute exposures are more the norm. Especially when looking at faint objects.

Doesn't take away from your main point - astronomers will adapt. I think they're perturbed by this because Starlink makes their jobs even more complex, and thus more expensive. A cost that SpaceX doesn't bear at all.

mlindner• 6 years ago

This is completely incorrect. The data is not lost, when you stack images the low signal of a single (or multiple) satellites in a single image disappears into the noise.

serf• 6 years ago

The data is not lost

point me to the data behind the occlusion on a single frame.

dzhiurgis• 6 years ago

There’s no sats up north...

kbenson5• 6 years ago

If the images are stacked, doesn't that mean that there's plenty of images with the parts that are occluded in others not occluded?

I understand for any specific image, there's going to be some lost background because of Starlink satellites, but that's not what this is showing, this is showing something that's not possible, right? Shifting all the satellites temporally so they appear together, arbitrarily maximizing the problem beyond what is real isn't an accurate depiction of the problem, IMO.

Put another way, if you erase the Starlink satellites from the images before stacking them, you then get a fairly accurate representation of the sky without any Starlink satellites, and you still have the data behind them (from the other pictures where that portion of the sky was not occluded). You can also probably fix the intensity of anything occluded in a few of the pictures but not others through some math.

cma• 6 years ago

If the images are stacked, doesn't that mean that there's plenty of images with the parts that are occluded in others not occluded?

As he mentioned, flare can cover a broader area of the sensor.

mturmon2• 6 years ago

Not an actual astronomer, but somewhat aware of detector issues for space-based telescopes.

Typically, you want to use one single integration time, if possible. Doing so can limit readout noise, for one thing. (Note that ground-based astrophotographers, with consumer cameras, often take multiple exposures to cool down the detectors. This is not a factor with the actively-cooled detectors in astronomical telescopes.)

For instance, the observations leading to the recent discovery of the two-planet exosystem [1] used roughly 15-minute integration times [2, sec. 2] across an 8 meter (!) aperture. This is a longer integration time than the 17, 30-second integrations that produced OP.

I think the above considerations about stacking vs single exposures are a side issue, though.

The saving grace is that many astronomical observations are narrow-field-of-view, and are done away from the illuminated part of the StarLink constellation. But, surveys or wide-field images could really be affected strongly, at the 30-40% level [3].

[1] https://news.ycombinator.com/item?id=23917559

[2] https://academic.oup.com/mnras/article/492/1/431/5680498

[3] https://www.eso.org/public/archives/releases/sciencepapers/e...

ortusdux• 6 years ago

Each starlink group is inserted at a low orbit, booted up and tested, and then they boost themselves to a higher orbit over a period of a month or so. During this boost, they orient their panels horizontally to minimize drag. Once they reach their final orbit, they rotate their panels vertically, at which point their visibility goes way down (mag 5 (prior to the new coating) down from a mag 0).

I've seen plenty of people saying some variation of "there are only 600 of these now, imagine what it will be like when there are 42k of them..." If I understand correctly, the number of bright satellites will be proportional to the launch rate, not the total quantity in orbit. Going off Wikipedia, they have launched about 1/8th of their 2024 goal, and the majority of the remaining satellites are destined for much higher (and dimmer) orbits.

https://en.wikipedia.org/wiki/Starlink#Constellation_design_...

Rebelgecko• 6 years ago

If I understand correctly, the number of bright satellites will be proportional to the launch rate, not the total quantity in orbit.

Because the constellation needs constant replenishment, the launch rate (and hence the # of brighter satellites) will have to reach a steady state that is directly proportional to the size of the constellation.

We can extrapolate that in the future this rate will actually be significantly higher than it is currently:

They currently have permission to launch around 12,000 sats. They're launching around 250 per year. The current launch rate is only sustainable if each satellite lasts for 50 years.

If you expand that to the proposed 42,000 constellation, 250 new satellites per year is only sustainable with a MTBF of around 150-200 years per satellite, which is nigh impossible in low Earth orbit. Using a lower (but still very generous and optimistic) MTBF of 10 years, Starlink will need to launch 4,200 satellites every year, about ~15x higher their current launch cadence.

the majority of the remaining satellites are destined for much higher (and dimmer) orbit

Just about all of the satellites they've orbited so far are hanging out around 550km. SpaceX initially got permission to go as high as 1300km, but they've since changed their mind. The new plan (still pending FCC approval I believe) is to keep all of the satellites between 300-550km. So the future satellites will be as low or lower than the current ones.

sparker72678• 6 years ago

Anec-data, but in my shots of the comets there were 0 satellites and about 12 airplanes with flashing lights that I had to remove. ¯\_(ツ)_/¯

I get the frustration, and no doubt I'll be pissed when I have a shot that's more affected, but amateur astrophotography seems like the least-important reason to be concerned about Starlink.

But then, the photo is going to get more attention, for sure.

wl• 6 years ago

Anecdotally, I took about 100 exposures of the comet last weekend with shutter speeds ranging from 10-20 seconds. There were satellite streaks in every exposure! I don't ever remember it being this bad.

autokad• 6 years ago

It doesnt matter the impact of amateur astrophotography's work, starlink doesn't have the right to take that from them. I do think we need to evaluate whether these costs are worth it.

I go further.

I myself think we need to take a second look at city light. I'd like us to begin working on making the milky way visible again.

animal_spirits• 6 years ago

I agree. Vast populations of people can't know their place in the universe because they physically can not see it. What can we do to avoid that? In suburbs it seams feasible to stop building / start removing streetlamps in neighborhoods that don't necessarily need them, but I don't know how that would work in bigger cities

TeMPOraL2• 6 years ago

starlink doesn't have the right to take that from them. I do think we need to evaluate whether these costs are worth it.

Yes, but when doing that, let's also take into account the fact that Starlink exists to open up space access. Starlink doesn't exist (just) to provide Internet access, it exists primarily to fund Starship and further reduce costs of space missions. This makes it one of the most important thing happening for astronomy.

beervirus• 6 years ago

... what’s the most important reason to be concerned?

toohotatopic• 6 years ago

Wait till we have the first moon bases and there will never be a new moon again.

f00zz• 6 years ago

Can't wait!

asdfk-12• 6 years ago

Perhaps to remedy the situation, SpaceX would do well to introduce a large fleet of freely-accessible amateur astronomy platforms with some kind of timeshare credit component? I ordered several images through a university terrestrial telescope as part of an astronomy course and it was a great experience to refine the object's orbital parameters based on the observations.

kbenson5• 6 years ago

Flipped on its head, I would say Starlink, or at least the underlying technology that makes it feasible (and it's all related, since it's all SpaceX) may be good for astronomy... eventually.

Space based telescopes give a much clearer picture than land based ones. You can't have ubiquitous and/or (relatively) cheap space based telescopes without a thriving launch industry that reduces costs. You can't have that without innovation and competition in the space launch industry. You are unlikely to innovation or competition in that industry the without a market need. Starlink is the market need right now.

Want lots of space telescopes to give you even better pictures? Don't kill off what's going to take you there before it begins. The astronomy industry needs to work with SpaceX to minimize the problem while also encouraging them (and anyone else working to drop costs to launch something into orbit) to succeed, not killing off or greatly delaying the oncoming age of ubiquitous and easy access to space telescopes because they are short sighted.

rumanator2• 6 years ago

Space based telescopes give a much clearer picture than land based ones.

Aren't those far more expensive to launch and operate?

Robotbeat• 6 years ago

Not necessarily? Starlink represents an order of magnitude improvement in both launch and hardware costs. And that’s with Falcon 9. Starship represents another order of magnitude improvement (or better, over time...).

kbenson5• 6 years ago

Right now? Yes. As I understand it you get much more capability for your size of telescope if in space, because you don't have to look through the atmosphere. If launch costs go down (which they are), and satellite components and labor to build operate become cheaper (because of increased general experience, supply of parts and labor, etc), then space satellites become cheaper. If we get better at assembling things in space (which we're only going to do after demand and experience in doing it), it might even be easier to make a larger telescope in space than on land eventually, and the stresses of gravity on the structure for the mirror are greatly reduced or eliminated. It looks like all the recent large telescopes are with segmented mirrors now anyway.[1]

1: https://en.wikipedia.org/wiki/List_of_largest_optical_reflec...

astrophysician2• 6 years ago

Yep. Lots of very clearly uninformed opinions here. Can confirm there are many advantages and disadvantages of space-based vs ground-based telescopes. Saying "well astronomers should just use space telescopes those are better" is quite ridiculous and reveals a deep ignorance for how astronomy is actually done (as though an entire field of science has not maybe had that thought?).

Extreme expense and complexity of space based telescopes is one large downside (saying "well space x will make that cheaper" um, maybe? but that will not happen for quite some time, and you realize you are parroting a PR department known for being hyperbolic? While ignoring the actual, real impact these satellites are currently having on billions of dollars of astronomy research, which happens on 10-20 year timescales?).

There are numerous benefits conferred by ground based telescopes that cannot be accomplished in space. Ground based telescopes allow you to have much larger collecting area, allow you the option to maintain + upgrade instrumentation (not possible in space, and if someone mentions "hey they replaced the hubble mirror, didn't they?" yes, at the cost of 250 million dollars), not to mention the barrier to entry for building ground based instruments is much lower and allows smaller projects to have a large impact without requiring a ridiculous amount of funding. See, e.g. https://www.astro.princeton.edu/~gbakos/satellites/ <- one astronomer's page detailing the impact these satellites currently have on his work; this is just one example. Lots of links, e.g. https://www.forbes.com/sites/startswithabang/2019/11/27/this... that will confirm the bare basics of what I'm saying here.

People thinking "oh well ML should fix that" may also be completely unaware that: no it cannot, unless you just want a pretty picture, because astrophysics is done on pixel-level brightnesses and once you saturate a pixel, there is no more information there, not to mention that even non-saturated pixels will have an insane amount of noise now, which degrades the SNR of otherwise good observations. Astronomy is done with some of the most sensitive optical/IR/radio equipment that exists (a large motivation to fund astronomy is for the innovation here that is relevant to other applications).

People saying "oh but space x is going to add some anti-reflectivity coating so it'll all be alright, Elon will fix it." Ohhh boy. Yikes. Here's the incredible page addressing this on space-x: https://www.spacex.com/updates/starlink-update-04-28-2020/ <- it's incredible because it flat out admits to an astounding level of ignorance about the impact of this, and makes several promises that may seem nice to a non-astronomer but basically amount to "we'll do something but it will not really change anything at all for any astronomy research, but we totally understand now that someone has finally educated us on the bare basics of operating in space."

For example, earlier this year we launched DarkSat, which is an experimental satellite where we darkened the phased array and parabolic antennas designed to tackle on-station brightness. This reduced the brightness of the satellite by about 55%,

To give you an idea of how completely meaningless this is to astronomy: these satellites currently have an average magnitude of 5.5, brighter than the brightest stars, and virtually all of astronomy tries to be sensitive to > 10th mag (i.e. 1.5% of the brightness of 5.5 mag, so we're looking for > 99% brightness reduction before this even begins to mean anything) + this coating will affect IR measurements because black coatings are black because they absorb light, and things that absorb light get hot and things that are hot emit IR radiation. LSST will have a 5-sigma single exposure sensitivity of at least 22 mag (0.000025% of the current satellite brightness, no that is not a typo, so we would need 99.99997% brightness reduction).

The huge collecting area of a larger telescopes like Vera C. Rubin Observatory leads to a sensitivity that will render even the darkest satellites visible.They are so sensitive that it won't be possible to build a satellite that will not produce streaks, in a typical long integration. There is much that can be done to reduce the impact of satellite streaks, and that starts with an understanding of how astronomical sensors work.

So nice of them to think of that, um, now? The rest of that section is a goldmine, saying basically "here is why we really can't mitigate this for CCD detectors used by all of astronomy because, well, they are looking at dim things and bright things ruin a large portion of the observations" while also concluding with

While it will not be possible to create satellites that are invisible to the most advanced optical equipment on Earth, by reducing the brightness of the satellites, we can make the existing strategies for dealing with similar issues, such as frame-stacking, dramatically more effective.

No, no, no, no, no and no. There is absolutely nothing you can do with 30,000 5-6th mag satellites in the sky at all times. They will be in your images. Frame stacking will help to a point, but not even close to what you would need (not even within a few orders of magnitude). We will lose a large amount of effective sensitivity and a large amount of science will be completely lost.

People still shrugging this off should remember: instruments like LSST cost the taxpayer half a billion dollars and took 20 years of development, countless and priceless time investment from a large fraction of astrophysicists and astronomers (many at the top of their field), and would allow us to do incredibly impactful science, both from a philosophical standpoint (being able to observe 20 billion galaxies + stars allows you to do cosmology and other astrophysics that is otherwise impossible, see the science book: https://arxiv.org/abs/0912.0201), and from a practical standpoint (like NEO's)

So: even if you don't think astronomy is important, you should still care about this. It's a colossal waste of money due to the complete arrogance and ignorance of one rich guy. Absolutely did not have to be this way.

Alupis4• 6 years ago

I find it astounding that just any old for profit company can decide to ruin a world-wide public resource just to turn a few bucks. In 2020.

I'd expect that from something like the East India Company in the 1700's or something. Not a modern company in a modern society.

oh_sigh5• 6 years ago

Do you shake your fist at every airplane that flies overhead too?

Alupis4• 6 years ago

The country agreed to that. One day the country may decide against it. No-Fly Zones can be created.

A US company airplane passing over my house doesn't impact people in India, for example.

Airplanes have proven utility. Airplanes proved their utility before bothering people worldwide.

perl4ever2• 6 years ago

Not me, but I know I read something once lamenting that almost any place in the world, you can be lost in the wilderness but will still see the occasional plane or at least contrail, and thus can't avoid civilization.

guerrilla• 6 years ago

This is how many externalities work, most just aren't so globally distributed.

tinus_hn• 6 years ago

That’s odd, I took a bunch of pictures of that same comet and saw no satellites at all. Did I do something wrong?

dvxvd• 6 years ago

im 100% against that commercial project is destroying my night sky.. its like building highway through my yard.. our already overglobalized world will be even more 'globalized' in the hands of few.. w t f..

aaron695• 6 years ago

How did we get to this cargo cult where sitting on our behinds taking photos of the stars and un-ironically posting on the internet supersedes mastering space.

It's mostly the media, who care's not for science at all pushing this 'we should be outraged', but we eat it up.

Starlink and others helping the world will also create a whole new genre for ground based space photography the super rich can get into, but this drama is so tiring.

mchusma• 6 years ago

If you want humans to become a space faring people, you need to accept the idea that there will be at least 1000x more things in space.

People's comments here are generally insane to me.

Let's go to other planets. Let's build a Dyson swarms of O'Neil cylinders with a quadrillion humans living in luxury. Let's keep the light of consciousness alive.

Some things will change along the way, like amateur photography.

ineedasername• 6 years ago

There's a tension here, and I'm not saying that I know where the appropriate balance is-- but it's a tension between the positive societal impact that inexpensive and ubiquitous broadband may have, vs. the societal impact of scientific knowledge from ground-based observatories.

I'm sure there's other ways of solving the broadband problem. I'm sure there are other ways of getting the astronomical data. I'm also pretty sure that all of them would have their own trade offs. Everything does.

In this case, I think the unilateral approach that Musk is taking has hurt perception of the project as much as the trade offs represented by the project itself.

Stacked images of the comet, photobombed by Starlink satellites

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