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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

• wnkrshm 7y ago
  Also, asteroid detection may be hampered - there is still a significant contribution of 'amateur' observations to detecting them.
• bryanlarsen 7y ago
  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.
• ogre_codes 7y ago
  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.
  • rtkwe 7y ago
    Most astronomy is long exposure which the eventual mega constellation is particularly harmful too because there's no way currently to deal with the light reflecting off them.
    • deleted 7y ago
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    • CamperBob2 7y ago
      You know they don't use film plates for those exposures anymore, right? They stack images digitally. Removing satellite trails is the easiest part of the post processing flow, or it damned well should be.
      • rtkwe 7y ago
        Digit and film single long exposures are functionally identical and for very dim objects you still need long exposures because the amount of light reaching the sensor is very low. You can't image stack if the object is too dim to appear in the shorter exposure's you're stacking.
        • CamperBob2 7y ago
          Digit and film single long exposures are functionally identical Wow, OK. We're done here.
          • petschge 7y ago
            Astronomical sensors typically are 12 bit. So anything 4000 times brighter will overflow the sensor and can not be subtracted. And of course you have perfect solutions to Poisson noise, bleeding pixels, and increased dead time caused by shorter read out intervals as well, right? We are done here. But not for the reasons you think. You did not win this discussion.
            • lutorm 7y ago
              A simple median filter will take care of it. Have you seen what an unprocessed image from the Hubble Space Telescope looks like? It's riddled with cosmic ray tracks, and they all get filtered out.
  • clmul 7y ago
    The amount of important work in modern astronomy that is satellite based is limited, as pointed out elsewhere on this thread.
    • stcredzero 7y ago
      For now. Do the Elon Musk analysis from first principles. The future of astronomy is clearly outside of Earth's gravity well and atmosphere.
      • 317070 7y ago
        Yes, but the current budgets clearly are not.
        • eecc 7y ago
          He's working on that ;) /s (jeez, your sense of humor folks...)
          • CamperBob2 7y ago
            Well, he is. For the Luddites in these threads, it's enough to cite the JWST as a reason to keep doing things the same old way, over and over, in space and on Earth. Of course, the reason why people who enjoy lecturing others about why something can't be done differently or shouldn't be done differently seem to gravitate to a site called "Hacker News" is one of those universal mysteries that can't be answered with a computer or a telescope.
      • pretendscholar 7y ago
        How is that clear? What principles did you use?
    • CamperBob2 7y ago
      Because access to space is insanely expensive. Don't fight the people who are trying to fix this.
  • Rebelgecko 7y ago
    >It will likely affect some earthbound astronomy significantly, but much (most?) of the most important work in modern astronomy is satellite based. I'm not an astronomer but I'm not convinced that that's the case. The number of space telescopes pales in comparison to the number of terrestrial observatories. Moreover, advances like adaptive optics have done a lot to close the gap between ground and space capabilities (for optical telescopes). Even once you've invested in expensive tech like adaptove optics, a telescope in space still costs an order of magnitude more than one on the ground (thats being really conservative. JWST has already cost ~10x more than the most expensive ground telescope ever, and the thing hasn't even launched yet) There were a few space based radio telescopes in the past, but I don't think there are any now. Imagine building something like the Arecibo Observatory[1] or VLA[2] in space. And speaking of the VLA, some of the techniques for getting high quality results (e.g. interferometry without physically conjoining the receivers) are difficult if not impossible to do in space. [1]: https://en.wikipedia.org/wiki/Arecibo_Observatory https://en.wikipedia.org/wiki/Arecibo_Observatory [2]: 27 of these guys, which are able to move around precisely on rails to generate constructive interference with the different waves they're receiving: https://public.nrao.edu/wp-content/uploads/2016/04/vla_panorama_med-1.jpg https://public.nrao.edu/wp-content/uploads/2016/04/vla_panor...
    • shadowgovt 7y ago
      Can adaptive optics be applied to filter out objects like Starlink satellites?
      • toomuchtodo 7y ago
        You can filter them out computationally without adaptive optics with enough frames captured.
        • HorstG 7y ago
          Modern astronomy works at the edges of whats possible, a single frame might take hours. Needing multiple frames would mean multiple days per observation. It would mean no longer seeing faint and distant objects, limiting us to younger, closer and frankly far more boring objects. It would make observing variability impossible for certain timescales. You need old distant objects for cosmology, observing the structure if the universe, big bang and stuff. You need variability for finding exoplanets, measuring distance and observing transitions such as supernovae. Oh, and then a huge part is taking spectra, which means bouncing the light directly off a grating. Filtering transients is hard to impossible there. You need spectra for relative motion, magnetic fields, composition of matter and radiation and of course temperature. Needing such filters would set astronomy back a few decades
  • SiempreViernes 7y ago
    > but much (most?) of the most important work in modern astronomy is satellite based. You're going to have to point out which source you pulled that out of! As a simple example, more than half of the Nobel prizes awarded for astronomy since 2000 are for discoveries made with ground based detectors. And of those awarded to satellite experiments, none was actually competing with a ground based experiment, so satellites mainly bring different, not better, capabilities.
    • jessaustin 7y ago
      ...ground based detectors... When I encounter this phrase I think of things like the neutrino detector in Antarctica, which of course isn't affected by satellites at all. How much contemporary astronomy relies on visible-light telescopy?
      • petschge 7y ago
        A very large fraction. Optical is still the most important band, probably followed by radio, x-ray, IR and gamma ray in that order. And less then 10% of optical is done using satellites.
  • Ididntdothis 7y ago
    “It will likely affect some earthbound astronomy significantly, but much (most?) of the most important work in modern astronomy is satellite based.” Not true at all. Ground based is much cheaper and easier to maintain and reconfigure with new and different equipment. Just look at the cost of the upcoming >30m telescopes vs the James Webb or Hubble.
    • maccam94 7y ago
      On the plus side, SpaceX is making launches much bigger and cheaper, which will make space-based telescopes much more affordable. Cheaper launches = more, cheaper satellites.
      • Ididntdothis 7y ago
        That's good but I am not sure if the launch cost is where the money goes for telescopes.
        • ecpottinger 7y ago
          You are right, but also wrong. Because the launch cost so much you spend even more move on the space telescope because you want it to work for a very long time to get the best value for your money. And since you are going to spend so much money to launch it, you also add extra hardware to do other type of observations, so the cost of the telescope balloons upward but you are get more bang for the buck. If on the other hand you have cheap launches then you can send up the minimum telescope needed since you can always send up a better one or even a very different one if you later discover the need. Today because of high costs, we need to design the scopes to meet all the possible needs we can think of and afford, result very expensive space scopes.
          • Ididntdothis 7y ago
            I guess we would have to look at the actual costs and trade offs. Personally I am still not convinced that launch cost is the biggest problem but I am sure astronomers are crunching budget numbers right now and will adjust plans if it makes sense.
  • HorstG 7y ago
    It will kill astronomy pretty good. The key point is usable observation time. Our current handful of satellite telescopes provide 24h of time a day. Each terrestrial telescope provides maybe 8h. However, there are a magnitude more telescopes on Hawaii alone than in space. You would need to get a hundred satellite telescopes to begin to replace earthbased observation time. And that doesn't even begin to talk about the possible instruments, mirror sizes, astronomical costs of buulding and running satellites, etc.
    • nwallin 7y ago
      It really won't. Satellites are invisible if they're in the Earth's shadow. By the time useful observation can begin, there's an enormous swath of the sky that will have zero visible satellites in it. Diversify your observation targets. There's more than one interesting thing to science at any given moment. If that means spreading out your observations so you spend two hours a night observing four targets as opposed to four hours a night on two targets, so be it. At the very worst, this means astronomers will need to do more work during the day shift scheduling and prioritizing. This isn't a new problem. I remember reading a back page article in Astronomer magazine sometime in the late 90s with a page of BASIC code. Someone wanted to optimize a computer controlled telescope to make one observation of 100 or so stars every night. You need to roughly minimize the total Manhatten distance between every two observations, while also eliminating observations below the horizon and penalize observations low in the sky. So the author wrote a program to roughly approximate the traveling salesman problem with the additional constraints. In the 90s. In BASIC. In one page. It might be NP complete to get the perfect solution, but good enough is pretty good. Add an additional constraints penalising observations where they might be impacted by satellites. Hire an intern working on their degree who's taken an optimization course and have them do it for you.
    • vsareto 7y ago
      >And that doesn't even begin to talk about the possible instruments, mirror sizes, astronomical costs of buulding and running satellites, etc. We're going to have to start thinking bigger if we want to leave this rock. Might as well start now. The real risk is Elon's companies dissolving and the satellites adding pollution for no real gain. If I could trade observatory time for (working) world-wide internet, I'd take the latter with no hesitation. As much as I sympathize, most of the cosmos aren't really going anywhere. It'll be there after we build hundreds of telescopes.
  • letitgo12345 7y ago
    My impression is that a lot of interesting "leads" are generated by ground based telescopes and only then examined in more detailed by space based telescopes. If you kill off the generating mechanism, then effectiveness of space telescopes could also decline a lot.
• martythemaniak 7y ago
  Could you explain how something that orbits 500km up could be seen at night?
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  • TeMPOraL 7y ago
    Like most other satellites, it can be seen when it reflects the Sun. Satellites tend to be shiny. For an extreme case, check out "Iridium flares" - a brief but bright flares on the sky caused by old Iridium satellites, whose antennas were essentially large, rectangular mirrors.
    • martythemaniak 7y ago
      To reflect sunlight you need the sun. If a satellite is 500km up (and 300km for later revisions), there is no way for sunlight to reach it. There is no way to see Starlink at night. You can potentially see them for a short period around twilight.
      • outworlder 7y ago
        > There is no way to see Starlink at night. You can potentially see them for a short period around twilight. The time window is limited, yes. So it is not the end of the world. It is still a problem.
      • reaperducer 7y ago
        You've really never looked into a night sky and seen a satellite? Unless you live underground or never leave a big city, it's quite easy and there are dozens of apps that will help you understand what you're looking at.
        • outworlder 7y ago
          I guess the point they are trying to make is that 500km (or 300km) is essentially hugging the planet. Which means that, if it is night, they will be in the shadow for the majority of the time. The satellites you can easily see at any time are much higher up.
• shadowgovt 7y ago
  > Bright, fast-moving things are pretty terrible. Why is that? Almost everything astronomy studies isn't fast-moving. Shouldn't it be easy to filter out that noise?
  • hackinthebochs 7y ago
    This is what I'm wondering. It seems pretty trivial to filter out with some basic image processing.
    • Klathmon 7y ago
      I think there are 2 issues here, and it's making the conversation around it difficult. First is the impact to "professional astronomers", and from what I've seen this group won't be impacted nearly as much as the other. This group has the ability to use satellite based telescopes, or has the tech already to be able to filter/post-process the images to remove satellites, planes, meteor showers, and any other stuff that might get in the way. Then you have "amateur astronomers", this groups is likely to be impacted by starlink. This group doesn't have access to the digital filtering stuff that the "big guys" do, from what i've seen, most of the people in this group just use normal long-exposure setups and adding in a processing step would mean a pretty significant change to their process, and probably a lot of additional costs. Even still, the impact to amateur astronomers seems limited to when the sats are in sunlight, which traditionally isn't a super popular time for stargazing (although I may be wildly wrong on this, as I've read that these sats are removing up to 1/3 of the normal viewing time for some astronomers, so don't take this as gospel), and I still think the impacts will be a lot less doom and gloom than some are saying, but I still hope that SpaceX can work with the astronomy community to see if there are solutions or mitigations that can help everyone out.
      • nwallin 7y ago
        We absolutely use short exposures. It's actually more important for us than the pros because the mounts are a lot less stable and polar assignment is far worse. Doing a lot of short exposures is a lot easier than nailing your polar assignment. It also help with bad seeing; you throw away the blurriest quarter of your images and the stack looks a lot better. Filtering is less advanced, but masking outliers (and their neighbors) and replacing them with an average of the others isn't advanced filtering. It's annoying the way getting cut off in traffic is annoying, not the way getting T-boned is annoying.
• deleted 7y ago
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• BurningFrog 7y ago
  I think you're missing OP's point: Once the sun is set in their orbit, they should be invisible both to the eye and telescopes.
  • reaperducer 7y ago
    "Invisible" isn't quite correct. They won't be visible as white spots, they'll be black spots blocking out the things behind them. Not a big deal for human eyes. Quite a big deal for astronomers.
    • lutorm 7y ago
      This is totally false, the solid angle subtended by the satellites is tiny so the effect of their obscuration is totally negligible.
      • reaperducer 7y ago
        If it's flying in front of the sun, you are correct. If it's flying in front of an object 100 light years away, you are incorrect.
        • endorphone 7y ago
          It'd be in front of an object 100 light years away for an absurdly tiny amount of time. The percentage of the sky occluded by these satellites is absolutely minuscule. This is not a rational notion. These are not geosynchronous satellites, but instead are 200-500 miles above the Earth, moving many, many thousands of mph. No, it isn't blocking anything 100 light years away unless your shutter speed is in the single-digit nanoseconds.
        • natch 7y ago
          The relative (apparent) motion differences and the fact that the locations of the satellites are known should take care of that, no? It’s unlikely that the motions are going to track each other exactly in most cases. In fact if, as you believe, these satellites would actually occlude things beyond them, they sound very useful for calibration and education.
• CamperBob2 7y ago
  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.
• TrainedMonkey 7y ago
  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.
• lutorm 7y ago
  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.)
  • exrook 7y ago
    Just to add to this, the satellites can still cause problems during the night after sunset, as they can occlude other objects being observed as they pass overhead.
    • Dylan16807 7y ago
      Half a millisecond of occlusion is enough to cause problems?
      • xkjkls 7y ago
        Depends on the telescope, but yes.
        • brians 7y ago
          What happens from birds, soot, bugs, airplanes, frisbees, and clouds?
          • xkjkls 7y ago
• chrisco255 7y ago
  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.
• optimiz3 7y ago
  Is there any way, perhaps with software, that we could remove a moving object, from an otherwise mostly static set of images?
  • gibybo 7y ago
    Absolutely, in fact it's pretty easy and is routinely done by amateur and professional astronomers alike. We've had satellites, airplanes, and meteors obstructing astronomical images ever since we began taking them. A very simple and common way is to stack all of the static images aligned on top of each other such that you have a set of values for each pixel corresponding to the same region of sky. Then sort the values of each pixel by brightness and keep the median value for that pixel. Or throw out that top and bottom 10% and average the rest, or throw out the top and bottom N, etc. This is a standard feature of essentially all astronomical image processing software and has been for a long time.
    • petschge 7y ago
      Sure. But increasing the number of frames with tracks increased the number of datapoints you need to throw away, reducing the effective time on target and therefore sensitivity of your observations. Astronomers are not idiots. They know how to deal with obstructions. But that is not free of cost. Neither in observational limits nor computer time nor required brain power.
      • gibybo 7y ago
        Sure it's not without cost, but in most cases the cost is not very high. Remember you don't need to throw away the whole frame, only the pixels that were obstructed. One track across a frame will obstruct less than 1% of the data in that frame.
  • jsweojtj 7y ago
    One of the key assumptions that's being made, throughout this thread, is that astronomy is mostly imaging. Taking or stacking images. A ton of astronomy is spectroscopy, which is nothing like a stack of static images with one that has a streak in it.
• kerng 7y ago
  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.
  • krastanov 7y ago
    OP is talking about affecting astronomy the science, not astrophotography the hobby. Land-based survey telescopes are incredibly useful cheap tools that do not have alternatives.
    • discordance 7y ago
      I guess the argument becomes this: Does the proliferation of high speed Internet to every part of the world outweigh the cheapness of current land based astronomy tooling? If not, maybe spacex can compensate by providing some launch load for space bound telescopes.
      • xkjkls 7y ago
        Ok, then Tesla should really prove they can provide that or find ways to compensate those with land based astronomy tooling. They have done neither and have not communicated in any form that they want to.
        • skuthus 7y ago
          tesla?
• pbreit 7y ago
  Could someone explain what the actual tangible negative implications are besides astronomers needing to adjust?