The curse of Elon Musk

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  • #27
DEvens
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The appropriate requirement is for Elon Musk to provide free transport of astronomers, all the telescopes, a large amount of support equipment and material, and family members, to a base on the far side of the moon.

That's where you want to be to do astronomy anyway.
- No atmosphere to ruin exposures. No weather. No clouds. Nothing to block the parts of the spectrum that don't get through even clear air.
- Light pollution from cities far less important because no atmosphere to reflect it. Even when there are cities.
- Put up a sun shade and very little change in temperature. So your telescope is not going to "krink" as the daily temperature cycles.
- No wildlife to fly into the telescopes.
- Two week exposures with very little effort.
- And it is never "moon bright." Or even "Earth bright" on the far side.

Probably not a bad place for the gravity wave detector folk also.
 
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  • #29
anorlunda
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Here is a system that blocks exposure for places where satellites are - all of them, not just Starlink. It uses tracking information and then just stops recording in the region directly around the satellite. Overall loss of exposure time is tiny.
Thanks @mfb that's an obvious solution that is not obvious until you think about it. So astronomers will be forced to use a system like that, but when they do the problem mostly goes away.

I read that companies other than SpaceX have similar plans for orbiting nets of satellites; on the order of 45K satellites planned so far.

It is hard to dispute that Internet access for all 7 billion people on the planet is a high priority human welfare issue. Maybe all of them will become PF members and post to this thread :rolleyes:
 
  • #30
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It is hard to dispute that Internet access for all 7 billion people on the planet is a high priority human welfare Facebook issue.

OK, I admit it. . . I obviously messed with your quote. . . . 🤦‍♂️

Lol. . . I believe I made it "more truthful". . . . 😣



Maybe all of them will become PF members and post to this thread

Maybe all of them will become PF members, sometime, after they hold a Facebook

account ?

1580446890794.png




Carry on. . . . 😏.😛

.
 
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  • #31
strangerep
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This image from the International Astronomical Union
.
View attachment 256070
Seriously? You haven't figured out that Elon Musk is a leader of the vanguard for an imminent alien colonization of the Earth? Putting up hundreds of satellites is to reduce our ability to spot the approaching armada and maybe jam any nuclear missiles we might send their way.

(Btw, it's easy to tell that EM is an alien, just from that lame face mask he always wears.)
 
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  • #32
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The appropriate requirement is for Elon Musk to provide free transport of astronomers, all the telescopes, a large amount of support equipment and material, and family members, to a base on the far side of the moon.
I'm sure he would be happy to promise that.
 
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Astronomers are not forced to use a system, but it does improve the quality of some observations. It's quite an obvious approach I think.
I read that companies other than SpaceX have similar plans for orbiting nets of satellites; on the order of 45K satellites planned so far.
~12000 for Starlink (SpaceX), 650-2500 for OneWeb, ~3000 for Project Kuiper (Amazon). Telesat (Canada) and China are planning constellations with a few hundred satellites. SpaceX is considering more satellites but that is not a fixed plan yet.
 
  • #34
It seems to me reflected photons are wasted photons as far as energy generation is concerned. Why should solar panels be reflective? Alternatively, use the NASA black to trap photons and generate thermal phonons to operate solid-state thermoelectric generators (Alphabet Energy).
 
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An ideal solar panel wouldn't reflect anything but an ideal solar panel doesn't exist.
Alternatively, use the NASA black to trap photons and generate thermal phonons to operate solid-state thermoelectric generators (Alphabet Energy).
Too inefficient, especially without a cooling source.
 
  • #36
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Too inefficient, especially without a cooling source.
Assuming the same size for collector and radiator I calculated a theoretical maximum of 0.85 % for the efficiency (according to Carnot's theorem). Is that possible? That would be really inefficient.
 
  • #37
russ_watters
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It seems to me reflected photons are wasted photons as far as energy generation is concerned. Why should solar panels be reflective?
An ideal solar panel wouldn't reflect anything but an ideal solar panel doesn't exist.
Most solar panels are black and reflect very little; the issue is the satellites themselves, which are mirrored for thermal management. If you made the satellites themselves black (or covered with solar panels), one side would be really hot and the other really cold.

Now, even at low reflectivity (a few percent), you'd get a lot of light from a flat solar panel, but it would be a rare, localized flare, not a continuous, widespread, even brightness reflection people are seeing.
 
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The brightness during orbit raising comes mainly from the solar panel. It is very large compared to the main satellite. The brightness in the operational orbit comes from the satellite body.
 
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  • #39
russ_watters
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The brightness during orbit raising comes mainly from the solar panel. It is very large compared to the main satellite.
But why would that cause it to reflect light toward Earth? Isn't it pointed directly at the sun?
 
  • #40
anorlunda
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Is this just a variant of Iridium Flares?

@russ_watters , you're an amateur astronomer, haven't you seen satellite flares before.
On my boat in the keys, the whole harbor watched for ISS flyovers and Iridium Flares, use the heavensabove web site as a guide.


https://en.wikipedia.org/wiki/Satellite_flare
Iridium flares[edit]
Double flare - Iridium 6 and its replacement, #51, both flare in a 21-second exposure.
If a first-generation Iridium satellite is still controlled, its flares can be predicted.[1] The Iridium communication satellites have three polished door-sized antennas, 120° apart and at 40° angles with the main bus. The forward antenna faces the direction the satellite is traveling. Occasionally, an antenna reflects sunlight directly down at Earth, creating a predictable and quickly moving illuminated spot on the surface below of about 10 km (6.2 mi) diameter. To an observer this looks like a bright flash, or flare in the sky, with a duration of a few seconds.

Ranging up to −9.5 magnitude, some of the flares are so bright that they can be seen in the daytime. This flashing has caused some annoyance to astronomers, as the flares occasionally disturb observations.[2]
The article also says:
Flares may also occur from solar panels, but they are not as bright (up to −3.5 magnitude).
 
  • #41
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But why would that cause it to reflect light toward Earth? Isn't it pointed directly at the sun?
Not while it is raising the orbit, where it flies in a configuration that reduces drag. See my previous post.
 
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  • #42
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From this CNN article:
https://www.cnn.com/2020/01/29/tech/spacex-starlink-satellite-internet-launch-scn/index.html

"Astronomers have also raised concerns about the multitudes of Starlink satellites disrupting their view of the night sky. SpaceX says it's working with the science community on ways to address those issues."
The mfb have already mentioned dark coating, and the SpaceX have deployed a prototype of low-reflectance satellite. So called "Darksat", or Starlink-1130. Specifically for astronomers. The measured g-band brightness reduction is 55%.
https://arxiv.org/pdf/2003.07251.pdf
 
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  • #43
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7.57 at 976 km is 7.0 at 550 km, below the visibility for the naked eye even under perfect viewing conditions (typically assumed to be 6 to 6.5). This doesn't include geometry corrections, but overall the conclusion is that Darksat-style satellites completely disappear to the naked eye. Good for a prototype. Musk said that future satellites should be even darker, making them easier to remove from pictures for astronomers.

I noted that Starlink-4 (the latest launch) seems to be harder to spot already, but I don't have precise numbers.

The next launch is planned for March 18, 12:21 UTC (in ~25 hours).
 
  • #44
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Even painted black the satellite would block a distant star. Trying to average multiple snaps would interfere with precision measurements needed to determine distance, mass, etc. It's about time to do something about these billionaires that think they do whatever they want.
 
  • #45
Summary:: this guy should be locked up !!

Seriously, this guy has destroyed astronomy for amateur and professional alike
His actions are criminal and this is just the start :oldmad::oldmad::oldmad:
just one recent example ......

View attachment 256047


Maybe he should redirect his satellites in a path that avoids blocking celestial objects that astronomers are interested in?
May I suggest a path directly INTO the sun? If not, how about directly into Elon's back yard? Either would suit me just fine...
All of Musk's satellites are solutions provided by Dr. Sheldon Cooper(when he was a kid) so if there is anyone to blame it is him.
 
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  • #46
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Half a year and 6 launches later and astronomy still exists. Satellites now come with a sunshade that prevents the Sun from falling onto the most reflective surfaces. This is mainly relevant for satellites in their final orbit to avoid saturating astronomical sensors. In addition they change the orientation of the orbit-raising satellites when they are close to the terminator, making them much darker - this change largely affects the naked-eye visibility early on.
Even painted black the satellite would block a distant star.
That probability is utterly negligible, and even then it's for less than a millisecond.
Trying to average multiple snaps would interfere with precision measurements needed to determine distance, mass, etc.
Quite the opposite, you need to do that anyway.
It's about time to do something about these billionaires that think they do whatever they want.
Like regulating satellite launches? Great, because that's already being done.
 
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  • #47
Half a year and 6 launches later and astronomy still exists. Satellites now come with a sunshade that prevents the Sun from falling onto the most reflective surfaces. This is mainly relevant for satellites in their final orbit to avoid saturating astronomical sensors. In addition they change the orientation of the orbit-raising satellites when they are close to the terminator, making them much darker - this change largely affects the naked-eye visibility early on.That probability is utterly negligible, and even then it's for less than a millisecond.Quite the opposite, you need to do that anyway.Like regulating satellite launches? Great, because that's already being done.
Maybe we should create stelites with big gravity(high density) so we could see the stars behind them due to gravitational lensing.
 
  • #48
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Maybe we should create stelites with big gravity(high density) so we could see the stars behind them due to gravitational lensing.
You might want to run some numbers on that. To misquote Chief Brody, you're gonna need a bigger rocket.
 
  • #49
You might want to run some numbers on that. To misquote Chief Brody, you're gonna need a bigger rocket.
We would need a denser rocket not bigger. Probably made of lead and some of its oxides and we could see behind the satellite.

Lead has a density 1k times less than a neutron star so the effects are not neglible.
 
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  • #50
etotheipi
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We would need a denser rocket not bigger. Probably made of lead and some of its oxides and we could see behind the satellite.
But even if you manage to fulfil this requirement, there's still the small issue of getting it off the ground :smile:
 

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