5 ms·

> Space based telescopes give a much clearer picture than land based ones. Aren't those far more expensive to launch and operate?

Robotbeat 6y 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...).
kbenson 6y 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_reflecting_telescopes https://en.wikipedia.org/wiki/List_of_largest_optical_reflec...
- rumanator 6y ago
  It seems you're basing your assertion on projections based on wishful thinking. It's like saying to a cancer patient that he shouldn't worry about having cancer because in the future you believe there will be wonder drugs that fix everything. Well, perhaps there will be wonder drugs in the future, but what about real life, and real life solutions to real life problems? I already have a ton of money invested in earth telescopes. What good does it do me if you argue that in the future I might gain some capabilities if I scrap everything and buy a whole new infrastructure? Moreover, you only need a guy with a wrench to fix a telescope on the ground. If your telescope is in orbit then the problem is a tad more expensive to fix.
  - kbenson 6y ago
    > It's like saying to a cancer patient that he shouldn't worry about having cancer because in the future you believe there will be wonder drugs that fix everything. Is the field of astronomy facing death because of Starlink? That seems a bit excessive. I would say it's more like a national healthcare system covering only poor quality glasses for vision for a decade while they pump money into research and training for laser corrective surgery to both reduce the downsides and make it much more affordable, in preparation for covering laser reconstructive surgery at the end of that period. > I already have a ton of money invested in earth telescopes. What good does it do me if you argue that in the future I might gain some capabilities if I scrap everything and buy a whole new infrastructure? Again, telescopes aren't scrapping everything, astronomers aren't going to disappear. They're at most some percentage less useful than they thought they would be prior to this. That sucks, but homeowners have complained about other people moving in and obstructing their perfect view for a long time, so it's not entirely new. I don't support Starlink because I think SpaceX has some right over astronomers, but because I think humanity as a whole benefits from more industry in space, and there's a solution for astronomy on the other side of this, and I don't want humanity held back because astronomers feel it infringes on a domain with a problem they've generally not had to worry about (even if they would probably argue that they are doing it for the benefit of humanity by providing knowledge). Bottom line, I think the benefit to humanity from increased space industry is greater than the benefit unhampered astronomy provides in a case where we impede that industry.
    - astrophysician 6y ago
      To be honest, I understand where you are coming from, and share your opinion that many issues are more important than astronomy, including humanitarian issues. I think actually most astronomers would agree with that (the ones that I know, anyway). But the problem here is with the way that this debate is being framed. There is a false dichotomy that has been repeated here which I sum up as basically "Space-X is trying to solve humanitarian problem A, and astronomers are getting in the way! Deal with it astronomers, you are not more important than humanitarian issue A." but that's not at all what's actually happening. This is a monumentally impactful project undertaken by Space-X in secret, with enormous ramifications on science that -- despite the simplistic claims here -- are not something that can be worked around (LSST and other projects cannot be done in space, regardless of the cost of space delivery). Instead of responsibly investigating the impact, consulting with scientific agencies to either mitigate them, or prepare for the impact (as they are doing now after a huge outcry, but there is little that can be done now), they have instead opted to completely blindside entire branches of science, ruining decades of work around the globe and impacting tens or hundreds of billions of dollars in R&D. Even their press releases now say things like they are "learning how astronomical detectors work" -- that is extremely disturbing. That should basically never happen. There are responsible ways to do what Space-X has done, and they have shirked those responsibilities.
astrophysician 6y 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/ 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-is-why-we-cant-just-do-all-of-our-astronomy-from-space/#36db22c12704 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/ 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 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.

Robotbeat 6y 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...).

kbenson 6y 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_reflecting_telescopes https://en.wikipedia.org/wiki/List_of_largest_optical_reflec...

rumanator 6y ago
It seems you're basing your assertion on projections based on wishful thinking. It's like saying to a cancer patient that he shouldn't worry about having cancer because in the future you believe there will be wonder drugs that fix everything. Well, perhaps there will be wonder drugs in the future, but what about real life, and real life solutions to real life problems? I already have a ton of money invested in earth telescopes. What good does it do me if you argue that in the future I might gain some capabilities if I scrap everything and buy a whole new infrastructure? Moreover, you only need a guy with a wrench to fix a telescope on the ground. If your telescope is in orbit then the problem is a tad more expensive to fix.
- kbenson 6y ago
  > It's like saying to a cancer patient that he shouldn't worry about having cancer because in the future you believe there will be wonder drugs that fix everything. Is the field of astronomy facing death because of Starlink? That seems a bit excessive. I would say it's more like a national healthcare system covering only poor quality glasses for vision for a decade while they pump money into research and training for laser corrective surgery to both reduce the downsides and make it much more affordable, in preparation for covering laser reconstructive surgery at the end of that period. > I already have a ton of money invested in earth telescopes. What good does it do me if you argue that in the future I might gain some capabilities if I scrap everything and buy a whole new infrastructure? Again, telescopes aren't scrapping everything, astronomers aren't going to disappear. They're at most some percentage less useful than they thought they would be prior to this. That sucks, but homeowners have complained about other people moving in and obstructing their perfect view for a long time, so it's not entirely new. I don't support Starlink because I think SpaceX has some right over astronomers, but because I think humanity as a whole benefits from more industry in space, and there's a solution for astronomy on the other side of this, and I don't want humanity held back because astronomers feel it infringes on a domain with a problem they've generally not had to worry about (even if they would probably argue that they are doing it for the benefit of humanity by providing knowledge). Bottom line, I think the benefit to humanity from increased space industry is greater than the benefit unhampered astronomy provides in a case where we impede that industry.
  - astrophysician 6y ago
    To be honest, I understand where you are coming from, and share your opinion that many issues are more important than astronomy, including humanitarian issues. I think actually most astronomers would agree with that (the ones that I know, anyway). But the problem here is with the way that this debate is being framed. There is a false dichotomy that has been repeated here which I sum up as basically "Space-X is trying to solve humanitarian problem A, and astronomers are getting in the way! Deal with it astronomers, you are not more important than humanitarian issue A." but that's not at all what's actually happening. This is a monumentally impactful project undertaken by Space-X in secret, with enormous ramifications on science that -- despite the simplistic claims here -- are not something that can be worked around (LSST and other projects cannot be done in space, regardless of the cost of space delivery). Instead of responsibly investigating the impact, consulting with scientific agencies to either mitigate them, or prepare for the impact (as they are doing now after a huge outcry, but there is little that can be done now), they have instead opted to completely blindside entire branches of science, ruining decades of work around the globe and impacting tens or hundreds of billions of dollars in R&D. Even their press releases now say things like they are "learning how astronomical detectors work" -- that is extremely disturbing. That should basically never happen. There are responsible ways to do what Space-X has done, and they have shirked those responsibilities.

astrophysician 6y 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/ 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-is-why-we-cant-just-do-all-of-our-astronomy-from-space/#36db22c12704 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/ 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 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.