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Saying it will "Kill astronomy" is pretty hyperbolic. It will likely affect some earthbound astronomy significantly, but much (most?) of the most important wor
by 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 agoMost 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[deleted]
- CamperBob2 7y agoYou 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 agoDigit 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 agoDigit and film single long exposures are functionally identical Wow, OK. We're done here.
- petschge 7y agoAstronomical 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 agoA 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.
- CamperBob2 7y agoThere are any number of ways to correct observations for satellite trails, not the least because their appearance and duration are both transient and 100% predictable in any given field of view, and can be gated out of the exposure series. Cosmic rays don't even give us the latter break. (To be fair, the rabbit hole does go deeper than the usual places where a median filter alone will save you, but the general problem is far from intractable.) But never mind, we've been told that digital imaging is "functionally identical to film," and we're "losing the discussion."
- clmul 7y agoThe amount of important work in modern astronomy that is satellite based is limited, as pointed out elsewhere on this thread.
- stcredzero 7y agoFor 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 agoYes, but the current budgets clearly are not.
- eecc 7y agoHe's working on that ;) /s (jeez, your sense of humor folks...)
- CamperBob2 7y agoWell, 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 agoHow is that clear? What principles did you use?
- CamperBob2 7y agoBecause 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 agoCan adaptive optics be applied to filter out objects like Starlink satellites?
- toomuchtodo 7y agoYou can filter them out computationally without adaptive optics with enough frames captured.
- HorstG 7y agoModern 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 agoA 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 agoOn 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 agoThat's good but I am not sure if the launch cost is where the money goes for telescopes.
- ecpottinger 7y agoYou 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 agoI 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 agoIt 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 agoIt 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 agoMy 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.