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>Do a search for "atmospheric drag" or anything about orbital lifetimes, gabbard diagrams [0] or the like >nothing, instead it equates all constellations and s

by xoa 3y ago

>Do a search for "atmospheric drag" or anything about orbital lifetimes, gabbard diagrams [0] or the like >nothing, instead it equates all constellations and satellites together as the same thing Yet another click bait crummy article, with the obligatory "concerned astronomers" emotional tug on top but no serious engagement. And "big numbers!!" but no sort of context on if or why it's a problem. It's so tiresome how this gets trotted out over and over again. SpaceX's approach isn't bad for debris risks, it's good! The absolute best possible fail safe solution for sats is to have them low enough that they will passively deorbit very quickly without continuous boosts, or even better VLEO orbits where they must maintain aerodynamic orientation as well. Which in turn requires lots of sats that are actively replaced regularly, which in turn helps ensure updates can also be made rapidly based on real experience and they can become extremely refined. Sloppily throwing it all into some vague fear panic of "Kessler Syndrome" is not just wrong it's actively bad for that very reason vs clear differentiation between stuff at 300-550km vs 700+. Also the implication that the utility function for earth-based astronomers is unlimited and they have some special right on top, ignoring the potential future paths for improvement and approaches that would ensure that (a small tax that would go directly towards a fund for space based telescopes say). And so on and so forth. There are real important discussions to be had which makes it all the more disappointing it's so very, very shallow. Edit: Also to be clear it's not like orbital lifetimes are a new thing to think about. [1] is a classic old school webpage excerpting info from the 1987 "Satellite Orbits in an Atmosphere - Theory and Applications". It gives both very rough initial guidelines for thinking but then dives a bit more into how m/A and solar flux affect that a lot. Keep in mind when looking at the "LOW CIRCULAR ORBITS" section and graph what the m/A of diffuse debris looks like vs an original intact satellite (not that Starlink sats are big compact high weight spheres anyway). ---- 0: https://www.youtube.com/watch?v=mQT5aMa_7iI https://www.youtube.com/watch?v=mQT5aMa_7iI 1: https://www.spaceacademy.net.au/watch/debris/orblife.htm https://www.spaceacademy.net.au/watch/debris/orblife.htm

adolph 3y ago
> the utility function for earth-based astronomers Nobody likes change. As time goes by the opportunities for astronomy will grow larger than what is lost. I'd be surprised if there isn't a backdoor plan within SpaceX to use the backside of their fleet as a giant outward facing array.
- xoa 3y ago
  >As time goes by the opportunities for astronomy will grow larger than what is lost I want to be fair to both sides here, as I sort of side mentioned at the end of my post I think it'd be perfectly reasonable not to take this as a given which will happen by itself. A lot of places have long had mechanisms like universal service funds, or other ways to effectively recognize that sometimes even extreme broad societal goods might create concentrated losers and that when the good is high it's also reasonable to help ameliorate that a bit. SpaceX making access to space enormously cheaper, higher mass, and higher cadence will absolutely open up incredible new opportunities for astronomy, but that doesn't mean said opportunities will be easy to take advantage of, astronomers have had to lobby and work hard for their existing installations and funding over the decades. And some of it even is also legacy from Cold War or boom times and they could very understandably fear that losing value in existing instruments will not necessarily then get an automatic replacement with new better ones in the current environment right? But the answer there isn't to lobby to hobble Starlink (or other constellations) somehow which is likely not happening at this point anyway, but rather to quantify what's needed, form solid plans, and figure out a reasonable all around way to pay for it. Maybe governments start taking that into account directly as part of local licensing. Maybe a 0.5% (or reasonable) "replacement space instruments" fee could be added to megaconstellation services to go into a dedicated fund that will get to work planning and building Starship class instruments. Maybe SpaceX agrees to some number of launches for astronomy per year at-cost. Maybe some combo or things I'm not thinking of at all, I won't pretend to have given this massive thought. Working to reduce albedo, emissions and so on are all good anyway, but I do think existing terrestrial instruments (some more than others) will face a degraded environment. I also think that's extremely worth it, but that's no reason to be dismissive. But I think the broad public conversation I've seen so far hasn't done a great job of engaging with this which risks the worst of both worlds, where existing interests do manage to slow things up without really helping themselves much in the end and simultaneously poison the water so that everyone is left worse off than might have happened.
  - adolph 3y ago
    > the worst of both worlds, where existing interests do manage to slow things up without really helping themselves much in the end and simultaneously poison the water so that everyone is left worse off than might have happened. That is a really great way to put it. > "replacement space instruments" fee I realize you hadn't given this much thought but a downside to that approach is exactly how cell phone bills get padded. Regulatory capture fees ought to be rated as a backdoor tax like inflation.

by xoa 3y ago

adolph 3y ago

> the utility function for earth-based astronomers Nobody likes change. As time goes by the opportunities for astronomy will grow larger than what is lost. I'd be surprised if there isn't a backdoor plan within SpaceX to use the backside of their fleet as a giant outward facing array.

xoa 3y ago
>As time goes by the opportunities for astronomy will grow larger than what is lost I want to be fair to both sides here, as I sort of side mentioned at the end of my post I think it'd be perfectly reasonable not to take this as a given which will happen by itself. A lot of places have long had mechanisms like universal service funds, or other ways to effectively recognize that sometimes even extreme broad societal goods might create concentrated losers and that when the good is high it's also reasonable to help ameliorate that a bit. SpaceX making access to space enormously cheaper, higher mass, and higher cadence will absolutely open up incredible new opportunities for astronomy, but that doesn't mean said opportunities will be easy to take advantage of, astronomers have had to lobby and work hard for their existing installations and funding over the decades. And some of it even is also legacy from Cold War or boom times and they could very understandably fear that losing value in existing instruments will not necessarily then get an automatic replacement with new better ones in the current environment right? But the answer there isn't to lobby to hobble Starlink (or other constellations) somehow which is likely not happening at this point anyway, but rather to quantify what's needed, form solid plans, and figure out a reasonable all around way to pay for it. Maybe governments start taking that into account directly as part of local licensing. Maybe a 0.5% (or reasonable) "replacement space instruments" fee could be added to megaconstellation services to go into a dedicated fund that will get to work planning and building Starship class instruments. Maybe SpaceX agrees to some number of launches for astronomy per year at-cost. Maybe some combo or things I'm not thinking of at all, I won't pretend to have given this massive thought. Working to reduce albedo, emissions and so on are all good anyway, but I do think existing terrestrial instruments (some more than others) will face a degraded environment. I also think that's extremely worth it, but that's no reason to be dismissive. But I think the broad public conversation I've seen so far hasn't done a great job of engaging with this which risks the worst of both worlds, where existing interests do manage to slow things up without really helping themselves much in the end and simultaneously poison the water so that everyone is left worse off than might have happened.
- adolph 3y ago
  > the worst of both worlds, where existing interests do manage to slow things up without really helping themselves much in the end and simultaneously poison the water so that everyone is left worse off than might have happened. That is a really great way to put it. > "replacement space instruments" fee I realize you hadn't given this much thought but a downside to that approach is exactly how cell phone bills get padded. Regulatory capture fees ought to be rated as a backdoor tax like inflation.