Author Topic: The ultimate light pollution?  (Read 696 times)

cesconali

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Re: The ultimate light pollution?
« Reply #15 on: January 14, 2018, 05:58:18 AM »
Considering that they don't know what they're doing, I doubt it will fly.

Gregory Station

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Re: The ultimate light pollution?
« Reply #16 on: January 15, 2018, 08:51:39 PM »
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Considering that they don't know what they're doing, I doubt it will fly.


All they have to do is launch to 300 km. Their satellite willoperate precisely the same, they'll have the illumination they wish, and they'll be ableto show off their 'ability'. The satellite will de-orbit in a timely manner.

But a launch to 600 km suggests they wish a greater degree of worldwide 'permanence' for their project.

How bright will this be? How long in orbit? Unknowns. The Mayak team is not specific on these issues.

Write the Mayak team with your concerns at http://cosmomayak.com/. Write the IAU at http://www.iau.org/a...on/secretariat/.

compjiggrehols

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Re: The ultimate light pollution?
« Reply #17 on: January 20, 2018, 09:14:48 PM »
I'm more grateful for 600km vs. 300km in that, all things being equal, it'll be 1.5-magnitudes fainter. Yes, 300 km would mean quicker orbital decay. I would guess a lower orbit would limit the satellite's ability to interfere during peak observing hours, too. Would Mayak's orbit place it directly above the earth's terminator?

How is a satellite's brightness calculated?

My absolute worst-case scenario I come up, assuming 100% reflectivity, is -11.3 mag. I get this because 16 m^2 @ 600-km is a little more than 1.5-million times smaller in apparent area as the sun, which is Mv = -26.74. But I haven't factored in phase angles, the actual % reflectivity; etc. Plus, I'd have to think peak brightness would be for a VERY fleeting amount of time.
But again, I don't know that much about satellites, or quite frankly, if my math's correct. Any satellite experts here have their own calculations / guesstimates of its peak brightness?

Clear Skies,
Phil

Nick Ellis

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Re: The ultimate light pollution?
« Reply #18 on: January 20, 2018, 11:18:32 PM »
The bigger problem with this proposal than the "mirror" satellite proposal is what further entrepreneurial ideas for brightly visible satellites this may inspire - for example, variants of digital billboards. Although the feasible illuminated size of such "billboard" satellites my be much too small to include any legible written message - it might be feasible to create tiny but legible simplified company logos (e.g. Nike Swoosh). Or, use refraction to create a changing stream of different reflective colors, and the commercial value will be the widespread recognition that e.g. Nike sponsored the spectacle. The bottom-line point is that the specific proposal at hand here may inspire someone to build on the idea in even more night-sky intrusive ways, knowing that most people like a light show.

Roger Dixon

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Re: The ultimate light pollution?
« Reply #19 on: January 21, 2018, 02:45:19 AM »
The way I look at it, such a satellite is only going to be seen by those that look at the sky at night, and maybe even images it. The only ones that could really see such a satellite would be the ones that have the optics to capture it. I find it hard to create a business model that would have you upsetting the only ones that could see your venture. I might be wrong, but just saying ......

vieproltesro

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Re: The ultimate light pollution?
« Reply #20 on: January 23, 2018, 01:54:26 PM »
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I'm more grateful for 600km vs. 300km in that, all things being equal, it'll be 1.5-magnitudes fainter. Yes, 300 km would mean quicker orbital decay. I would guess a lower orbit would limit the satellite's ability to interfere during peak observing hours, too. Would Mayak's orbit place it directly above the earth's terminator?

If it's obscenely bright, we want that thing de-orbiting ASAP. NASA states objects at 600 km take years to come down.

In reply to my e-mail, the Mayak team leader told me it will come down in "25 days" and will be similar to an Iridium satellite. He said also his 'team' did not consult the International Astronomical Union.

I replied with NASA's data for 600 km orbits and some questions about how their satellite will be decommissioned but got no further response.

Write your concerns to http://cosmomayak.com/ and to the IAU. There seems to be little popular support for this project.

plurcontitear

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Re: The ultimate light pollution?
« Reply #21 on: January 23, 2018, 02:34:02 PM »
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But again, I don't know that much about satellites, or quite frankly, if my math's correct. Any satellite experts here have their own calculations / guesstimates of its peak brightness?

Clear Skies,
Phil


Hi Phil,

Update--I found an online calculator that predicts satellite orbital decay times using mass, surface area, altitude, and solar-geomagnetic flux. It suggests about 150 days for the Mayak satellite.

I tried 25 kg and 100 m^2 at 600 km. However, the calculator also yielded about 800 days for Skylab's mass and surface area at 400 km. Skylab was shut down in early 1974 and re-entered some 5.5 years later, or 2,008 days, which is a different by a factor of 2.51 compared to the calculator's results. So, using that factor, the Mayak satellite could be in orbit as long as 377 days.

The Mayak team leader told me the satellite's orbit will last only 25 days. This stated number differs by a calculated factor of 6 and, by practical example, a factor of 15.

I then halved my original mass and surface area values for Mayak and got 157 days which, when employing that (possibly) corrective factor, still works out to over a year in orbit.

So, maybe the good news is that Mayak won't be up there for years, but, going by this calculator, it seems the satellite's design team notably underestimates its orbital lifetime.

laucongsnagal

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Re: The ultimate light pollution?
« Reply #22 on: January 23, 2018, 04:15:03 PM »
It's good to know it won't last that long, but still, if it's really bright, having it up there for a year could be a real issue.

What about the brightness? Any good calculators for determining peak brightness for this satellite?

Clear Skies,
Phil

unamprodce

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Re: The ultimate light pollution?
« Reply #23 on: January 23, 2018, 07:40:13 PM »
The lowest estimate I've read is -3.6, but the team claims it will be the brightest night-sky object after the moon. A quarter moon washes the sky with about visual mag -7.5. The entire summer Milky Way is about the same number.

Your calculation suggested -11, so that's a reasonable upper number.

I found a technical paper if anyone wishes to delve deeper: http://www.amostech....NROC/HEJDUK.pdf

Venus at -4.6 can cast ground shadows, so every -1 past that number is another 2.512 times as bright.

The orbit will be about 96 minutes--assuming this 'team' gets their thing to work.

rennlispuring

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Re: The ultimate light pollution?
« Reply #24 on: January 26, 2018, 01:40:26 AM »
Heralding the demise of night for amateur astronomers because of this purposed satellite? Give me a break! This has got to be one of the silliest gloom and doom threads I've ever run across on this forum. Did any poster even give a moments serious thought to the circumstances governing this satellite potential impact?

First off, at 170 square feet in surface area this satellite really isn't very large at all. It's reflective surfaces are flat like a common mirror's. The article, what ever its true degree of accuracy, suggests that at least one of its triangular reflective surfaces will be aligned so as to permanently reflect sunlight in the direction of the Earth's surface. It will be orbiting the Earth at a rough distance of 600 kilometers every 96 minutes, or so.

The consequences of these facts, considering that the satellite presents only a flat surface of reflection, means that it will likely only direct a very narrow beam of sunlight onto the Earth's surface. Given the relatively small reflective surface area, combined with the distance from the Earth's surface, will dramatically limit the size of the full illuminate spot projecting on the Earth's surface. With the satellite orbiting the Earth once every hour and a half this solar reflection spot will sweep rapidly across the Earth's surface. I suspect that even were the beam to intercept the observer's location exactly the flash of maximum brightness off the satellite would last no more than a few seconds anywhere along the path's center-line. Peak brightness would be preceded by a progressive brightening phase and followed by a similar decline, the entire event lasting a total of perhaps a minute or two.

My guess would be that even just at a few dozen miles off the path's center-line the observer would see an event no different from those we see now almost any night with the passage of various Iridium satellites which we have been viewing without harm to our skies for years now. Some Iridium passages supposedly peak in brightness at -8 right on their path's center-line. This would also be as bright as a quarter moon, yet I haven't heard of them ruining our skies. I would advise folks to think over any replies regarding the heralding of night's doom from any single satellite before posting and to worrying more about their own ever growing local terrestrial light pollution sources. These are what will bring about the end of night for us all.

BrooksObs

Jason Bryant

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Re: The ultimate light pollution?
« Reply #25 on: January 30, 2018, 05:46:54 AM »
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Quote

Ever feel that the future shown in Wall-E is coming to fruition?


This is a clear violation of the Outer Space Treaty of 1967. Are we going to let this happen?

Even if it is a violation, and that is not at all obvious, if the US or any treaty nation believes that the project might violate the treaty it can ask Russia for a consultation. That's it. We can ask them to talk. Given Putin's concern for international opinion is there much hope that anything, except lack of money, will stop this project.

Sooner or later some company or country, perhaps one that hasn't signed the treaty will want to do this in a really big way, either for "green" lighting or advertising. Russian law allows advertising in space, so far limited to product placement. The idea is hardly new, The Man Who Sold the Moon by Robert Heinlein and later some serious proposals to place ads in orbit.

artufanchess

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Re: The ultimate light pollution?
« Reply #26 on: January 30, 2018, 11:41:06 PM »
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I would advise folks to think over any replies regarding the heralding of night's doom from any single satellite before posting and to worrying more about their own ever growing local terrestrial light pollution sources. These are what will bring about the end of night for us all.
I agree; no single satellite is a serious problem. But the satellite fleet as a whole is already a major nuisance for stargazing -- and much more so for astrophotography. Satellites are immensely useful, so I accept their light pollution as a necessary evil. But I hate to see a satellite launched for the sole purpose of creating light pollution.
If the much-ballyhooed tenfold or hundredfold reduction in cost to lauch to low Earth orbit ever happens, then this and other environmental evils of satellites will become very serious concerns indeed. However, I'm not holding my breath. People have been forecasting cheap orbital launches almost as long as they've been forecasting controlled nuclear fusion as a power source.

wellbanstubars

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Re: The ultimate light pollution?
« Reply #27 on: January 30, 2018, 11:53:45 PM »
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I would advise folks to think over any replies regarding the heralding of night's doom from any single satellite before posting and to worrying more about their own ever growing local terrestrial light pollution sources. These are what will bring about the end of night for us all.


Do we really needorbital Mylar balloon pyramids designed simply to reflect sunlight as much sunlight as possible back to the night side of Earth?

You may have overlooked the factthe satellite is cleverly three-dimensional, not a flat panel: it can aim two faces at once towards the relevant portion of Earth's nighttime hemisphere below.

Also:
the Mayak team claims their satellite will de-orbit in 25 days but actual satellite data suggests their number isdownplayed by a factor of 6 to 15;
the team states their satellite is designed for 'research' into the upper atmosphere but there already is considerable established data on that;
the team states their satellite is to 'inspire' Russian youth for Russian benefit;
the team states their satellite will demonstrate 'you don't need to be Elon Musk or a world power to put something in Earth orbit';
the team's original statements were that the satellite, by being as bright as possible in orbit,was designed simply to remind the world of Russia'spre-eminence in space.
You mightlook at the larger international, geopoliticalquestions involved in such a nationalistic space stunt--and the deliberate sketchiness of the Mayak team's press releases and intentions--and re-assess what you "advise."

But you're right: nobody thought about light pollution from Earth orbit. It's advisable everyone think about it. I'd rather drive for two hours out to a dark location thanbe forced by another country to live withwith some useless artificial full moon in orbit. How about you?

Ivan Deane

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Re: The ultimate light pollution?
« Reply #28 on: January 31, 2018, 12:14:32 AM »
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Even if it is a violation, and that is not at all obvious, if the US or any treaty nation believes that the project might violate the treaty it can ask Russia for a consultation. That's it. We can ask them to talk. Given Putin's concern for international opinion is there much hope that anything, except lack of money, will stop this project.


Maybe the IAU should be watching press releases more about suchorbitalstunts instead of worrying about the Moon's 'real name'.

Ryan Hernandez

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Re: The ultimate light pollution?
« Reply #29 on: January 31, 2018, 01:42:27 AM »
What a bunch of morons. Hopefully this fails....I would think other countries would have something to say about an obnoxious bright object cruising over their country over and over.