Quote from: armchairfan on 05/27/2019 06:14 pmI get arccos(r/(r+h))*r = 2400 km for r=6371km and h=500km. But that's all the way down to the horizon. Obviously it will be less if want the satellite visible higher in the sky.6400 km is not that far from 10,000, and my point is [something else]
I get arccos(r/(r+h))*r = 2400 km for r=6371km and h=500km. But that's all the way down to the horizon. Obviously it will be less if want the satellite visible higher in the sky.
I thought I did it right. What did you get?
Quote from: meekGee on 05/27/2019 06:45 pmQuote from: armchairfan on 05/27/2019 06:14 pmI get arccos(r/(r+h))*r = 2400 km for r=6371km and h=500km. But that's all the way down to the horizon. Obviously it will be less if want the satellite visible higher in the sky.6400 km is not that far from 10,000, and my point is [something else]Quote from: meekGee on 05/27/2019 05:52 pmI thought I did it right. What did you get?6400 km is the earth's radius, 2400 km is the distance to the horizon. Just correcting the math error that you originally requested.
Abolish air travel too? What else? I thought you wanted millions of people living and working in space... How will they travel between Earth and orbit? What about in-space propulsion as they fly between their O'Neill cylinders?Besides, enough with the hyperbole already. There won't be "thousands of satellites in the sky"... They are in LEO. There will be maybe a dozen within line of sight from any given point on Earth, and they will only be visible during windows around dusk/dawn
Quote from: meekGee on 05/27/2019 08:50 amAbolish air travel too? What else? I thought you wanted millions of people living and working in space... How will they travel between Earth and orbit? What about in-space propulsion as they fly between their O'Neill cylinders?Besides, enough with the hyperbole already. There won't be "thousands of satellites in the sky"... They are in LEO. There will be maybe a dozen within line of sight from any given point on Earth, and they will only be visible during windows around dusk/dawnYour information and logic are both in error.Explaining an aesthetic to someone who doesn't have it is a fruitless exercise. There's a very large body of prose, poetry and art built around the night sky. For those who live in a well-lit city or don't spend time looking at the night sky, that body of work means little or nothing. For them, the loss of the night sky affects them not at all. For others, it's a big deal. If you care enough for an answer, start with an introductory college course on astronomy, and while you're at it do literature, art history and music appreciation. Heck, as long as you're expanding your mind, read some of the material on the SSI website.SpaceX can certainly continue without 14,000 Starlink satellites if they have to; indeed, no one's sure yet whether Starlink benefits anybody, including SpaceX.
Quote from: tater on 05/27/2019 03:53 pmIt seems like mitigating this would simply be good planetary citizenship. Anti-reflective coatings on the Earth-facing plane of the spacecraft, for example. The goal should be to try and get each sat below mag 6.5 (naked eye limit). If this can be achieved with coatings, why would anyone be against this?I am however firmly against a certain person who would rather humanity gives up space travel than having a few more bright stars on the sky, to me that attitude is pure insanity.
It seems like mitigating this would simply be good planetary citizenship. Anti-reflective coatings on the Earth-facing plane of the spacecraft, for example. The goal should be to try and get each sat below mag 6.5 (naked eye limit). If this can be achieved with coatings, why would anyone be against this?
People need to realize more lights up there is a natural consequence of lower launch costs and more space commerce, voluntary mitigation may slow it down but unless you're willing to stop humanity from using LEO altogether, the sky is going to change no matter what, it's just a question of how fast it'll change.
Is there any evidence that the thrusters are being used to raise the orbit, or cause the satellites to separate?
Quote from: meekGee on 05/27/2019 08:50 amBesides, enough with the hyperbole already. There won't be "thousands of satellites in the sky"... They are in LEO. There will be maybe a dozen within line of sight from any given point on Earth, and they will only be visible during windows around dusk/dawnWhen the constellation is finished, about 500 will be overhead any particular person at any given time. Last night one of the space photographers I follow saw the third pass over Chicago, which was after midnight, I think. That's 4 hours after local sunset, and local sunrise there is at 5:20, you you'd expect passes 4 hours before sunrise then as well. That leaves an hour of night (assuming no visible pass is possible in the intervening hour). Of the 64 tracked objects, last night 3 were at least magnitude 2 (at least as bright as the brighter stars in Ursa Major), and they were bright for the whole pass (SW-->NE). Others flickered in and out of naked eye visibility (in a small city, would have been more someplace dark). Let's assume 5% are visible. That means when all 12000 are up, 25-50 will be as bright as the stars commonly visible in a small city for every observer all the time (counting on the same number popping in and out of visibility). That's actually not as bad as I had thought, but in the back country that likely becomes over 100 visible for at least 8 hours of each night given reports of visible passes well after midnight.Astronomers can deal with this, and Elon has tweeted they can put space telescopes up. I'm not concerned with the astronomy at the moment, I'm concerned with quality of life for all of us here on Earth. It seems like mitigating this would simply be good planetary citizenship. Anti-reflective coatings on the Earth-facing plane of the spacecraft, for example. The goal should be to try and get each sat below mag 6.5 (naked eye limit). If this can be achieved with coatings, why would anyone be against this? Pretending it's not an issue at all doesn't provide any incentive to bother fixing the problem. The engineering balance is thermal management and weight vs creating an eyesore. It's not like a quarter wave coating is going to add much weight.I should add that random sat passes are different than a visible pattern. Humans notice patterns, and that nature of these constellations (there will be more) will make them even more obvious. What happens some other nation does the same, but the sats are bigger, or more reflective? Seems like the standard should be set now to intentionally minimize visual impact.
Besides, enough with the hyperbole already. There won't be "thousands of satellites in the sky"... They are in LEO. There will be maybe a dozen within line of sight from any given point on Earth, and they will only be visible during windows around dusk/dawn
Quote from: tater on 05/27/2019 03:53 pmQuote from: meekGee on 05/27/2019 08:50 amBesides, enough with the hyperbole already. There won't be "thousands of satellites in the sky"... They are in LEO. There will be maybe a dozen within line of sight from any given point on Earth, and they will only be visible during windows around dusk/dawnWhen the constellation is finished, about 500 will be overhead any particular person at any given time. Last night one of the space photographers I follow saw the third pass over Chicago, which was after midnight, I think. That's 4 hours after local sunset, and local sunrise there is at 5:20, you you'd expect passes 4 hours before sunrise then as well. That leaves an hour of night (assuming no visible pass is possible in the intervening hour). Of the 64 tracked objects, last night 3 were at least magnitude 2 (at least as bright as the brighter stars in Ursa Major), and they were bright for the whole pass (SW-->NE). Others flickered in and out of naked eye visibility (in a small city, would have been more someplace dark). Let's assume 5% are visible. That means when all 12000 are up, 25-50 will be as bright as the stars commonly visible in a small city for every observer all the time (counting on the same number popping in and out of visibility). That's actually not as bad as I had thought, but in the back country that likely becomes over 100 visible for at least 8 hours of each night given reports of visible passes well after midnight.Astronomers can deal with this, and Elon has tweeted they can put space telescopes up. I'm not concerned with the astronomy at the moment, I'm concerned with quality of life for all of us here on Earth. It seems like mitigating this would simply be good planetary citizenship. Anti-reflective coatings on the Earth-facing plane of the spacecraft, for example. The goal should be to try and get each sat below mag 6.5 (naked eye limit). If this can be achieved with coatings, why would anyone be against this? Pretending it's not an issue at all doesn't provide any incentive to bother fixing the problem. The engineering balance is thermal management and weight vs creating an eyesore. It's not like a quarter wave coating is going to add much weight.I should add that random sat passes are different than a visible pattern. Humans notice patterns, and that nature of these constellations (there will be more) will make them even more obvious. What happens some other nation does the same, but the sats are bigger, or more reflective? Seems like the standard should be set now to intentionally minimize visual impact.This is the most reasonable skeptic take I've seen so far. More of this quality, please.To be honest, I don't think we'll get all the way to invisible (Mag 6.5). But I do think we'll get better. But satellites are SUPER common and visible already basically any time you have a dark enough sky (except late). ISS is a freaking beacon; no one made a big deal of it. Iridium is a pretty large constellation (60 birds?), and had a MAJOR design feature which caused super bright flares, but again, we all survived and I'm not aware of anyone who made a big deal out of it.At the end of the day, if humans are going to be spacefaring, the effects will be visible. They already definitely are.What's not helpful is over-reacting. I agree it'd be good to mitigate albedo when possible.But this is a public good. Wide access to the Internet, increasing competition everywhere. Of all uses of space, this is practically the MOST accessible and widely usable by the most people. You're not going to get a much better case for being in the public interest than this. I mean, do you think a network of space hotels for the rich is going to be received better? If you're not willing to try to defend these kind of constellations and you're a spaceflight enthusiast that wants us to be spacefaring, then we'll probably just never become spacefaring.
Quote from: su27k on 05/27/2019 05:38 pmQuote from: tater on 05/27/2019 03:53 pmIt seems like mitigating this would simply be good planetary citizenship. Anti-reflective coatings on the Earth-facing plane of the spacecraft, for example. The goal should be to try and get each sat below mag 6.5 (naked eye limit). If this can be achieved with coatings, why would anyone be against this?I am however firmly against a certain person who would rather humanity gives up space travel than having a few more bright stars on the sky, to me that attitude is pure insanity. Was there someone proposing that humanity give up space travel?
Tough to see that taking place - I think I saw an article the other day with an estimate of 120 launch startups.
QuotePeople need to realize more lights up there is a natural consequence of lower launch costs and more space commerce, voluntary mitigation may slow it down but unless you're willing to stop humanity from using LEO altogether, the sky is going to change no matter what, it's just a question of how fast it'll change.Popping somewhere on the order of 30,000 satellites into LEO in under a decade is a major change for the night sky, and to many, a dizzying major new form of light pollution. This is a completely new issue, both for astronomers and for people who just like to look at the stars, and it deserves some consideration before it's just undertaken by companies who see an opportunity for revenue.
Was there someone proposing that humanity give up space travel? Tough to see that taking place - I think I saw an article the other day with an estimate of 120 launch startups....Popping somewhere on the order of 30,000 satellites into LEO in under a decade is a major change for the night sky, and to many, a dizzying major new form of light pollution. This is a completely new issue, both for astronomers and for people who just like to look at the stars, and it deserves some consideration before it's just undertaken by companies who see an opportunity for revenue.
Having just looked up to watch the train pass overhead, I'm praying that they start doing whatever they can to make them invisible. I'd rather have SpaceX and every other constellation manufacturer go permanently defunct than look up to see the night sky swarming with thousands of satellites.
The total constellation is 12,000 satellites. Even if they were to stop at 4400, this would mean more than 150 in sight at any given location.<EDIT> about 4% of the sats are above the horizon at any given time assuming 500km altitude.
