SpaceX tests black satellite to reduce ‘megaconstellation’ threat to astronomy

Re:SpaceX tests black satellite to reduce ‘megaconstellation... by lutorm on Thursday January 16, 2020 @02:51PM (#22068181)

First, satellites are only visible in the optical when they are illuminated by the Sun, which is only for a fairly short window after sunset and before sunrise. The exact size of the window depends on how high they are, but most of the good "dark" time should be unaffected.

Second, astronomers already use image stacking to reject any number of transient artifacts, like satellites, airplanes, cosmic rays, etc.

Third, while these constellations are going to greatly increase the number of satellites in orbit, it's only by about an order of magnitude. Yes, that's worse, but it's not like it's a problem that hasn't existed before.

The type of observations that are likely to be most affected are surveys that actually search for moving near-Earth objects, especially near the Sun (and radio astronomy which apparently can detect terrestrial emissions scattering off of satellites) but I fail to see how this will mean anything like "the end of astronomy" (and I have a Ph.D. in astronomy.)

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Re:SpaceX tests black satellite to reduce ‘megaconstellation... by exrook on Thursday January 16, 2020 @06:11PM (#22070091)

Just to add to this, the satellites can still cause problems during the night after sunset, as they can occlude other objects being observed as they pass overhead.

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Re:SpaceX tests black satellite to reduce ‘megaconstellation... by lutorm on Thursday January 16, 2020 @06:36PM (#22070272)

This is extremely unlikely, and if it were to happen it is for an extremely small time. I have never heard of this being a practical concern.

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Re:SpaceX tests black satellite to reduce ‘megaconstellation... by Dylan16807 on Thursday January 16, 2020 @06:34PM (#22070262)

Half a millisecond of occlusion is enough to cause problems?

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Re:SpaceX tests black satellite to reduce ‘megaconstellation... by xkjkls on Thursday January 16, 2020 @07:26PM (#22070609)

Depends on the telescope, but yes.

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Re:SpaceX tests black satellite to reduce ‘megaconstellation... by taneq on Thursday January 16, 2020 @09:10PM (#22071227)

I thought most 'real' telescope exposures were over minutes to hours?

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Re:SpaceX tests black satellite to reduce ‘megaconstellation... by brians on Thursday January 16, 2020 @08:30PM (#22071014)

What happens from birds, soot, bugs, airplanes, frisbees, and clouds?

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Re:SpaceX tests black satellite to reduce ‘megaconstellation... by xkjkls on Thursday January 16, 2020 @08:33PM (#22071033)

They don't emit giant amounts of EMR.

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Re:SpaceX tests black satellite to reduce ‘megaconstellation... by xkjkls on Thursday January 16, 2020 @08:34PM (#22071038)

Also, almost all of those serious observatory telescopes don't have to worry about. Which is what we are talking about.

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Re:SpaceX tests black satellite to reduce ‘megaconstellation... by gibolt on Thursday January 16, 2020 @08:50PM (#22071129)

I'd love to read an article on how Frisbees are the biggest threat to observing the universe :D

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Re:SpaceX tests black satellite to reduce ‘megaconstellation... by pbreit on Thursday January 16, 2020 @09:25PM (#22071301)

Could describe what such a problem would be in layman's terms?

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Re:SpaceX tests black satellite to reduce ‘megaconstellation... by xkjkls on Monday January 20, 2020 @07:34PM (#22103272)

Terrestrial telescopes, which we've invested a bunch of money in terms of observatories in, receive interference from Starlink satellites. Telescopes in space, like the Hubble, don't have the same problem, but they're on the magnitude of 100x more expensive and its difficult to have the same missions.

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Re:SpaceX tests black satellite to reduce ‘megaconstellation... by manicdee on Tuesday January 21, 2020 @06:51PM (#22113096)

Noting that the orders of magnitude increase in cost are directly caused by infrequent launches by launch systems with tight mass and volume constraints, and the need to build a space telescope on the ground, have the equipment survive launch, and then survive with no intervention for a decade or two in space.

As new launch systems like Falcon 9, Starship, New Glenn and New Armstrong eliminate these constraints it will eventually be cheaper to build telescopes in space than on the ground.

Other “pusher” motivations include worsening access to real estate, reduced control over light pollution, recognition of indigenous rights, etc.

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Re:SpaceX tests black satellite to reduce ‘megaconstellation... by prpl on Thursday January 16, 2020 @06:45PM (#22070339)

correct - I didn't think I meant Starlink would kill astronomy (I thought I was addressing some of the hyperbole rather than extending it) - but probably even at the level to be deployed in the near future we would see severely degraded quality of observations for solar system objects. Furthermore - I do think SpaceX is the "good citizen" here.

I don't think the next 5-10 companies launching constellation satellites will be quite as considerate, so one order of magnitude could creep on to two over 15 years.

I think image stacking has been simulated to work somewhere from okay to unusable even for 15s exposures - I think the trails are actually pretty bad due both due to quantity, velocity in the sky, and brighter-fatter.

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Re:SpaceX tests black satellite to reduce ‘megaconstellation... by xkjkls on Thursday January 16, 2020 @07:25PM (#22070605)

It's an area that is plainly in the need for global regulation that currently has none.

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Re:SpaceX tests black satellite to reduce ‘megaconstellation... by throwawaybbb on Thursday January 16, 2020 @11:11PM (#22071784)

Earth shine is a thing.

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Re:SpaceX tests black satellite to reduce ‘megaconstellation... by lutorm on Friday January 17, 2020 @02:33PM (#22078292)

Not during the night. When the satellite is out of direct sunlight, it also does not see any illuminated part of the Earth.

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Re:SpaceX tests black satellite to reduce ‘megaconstellation... by greglindahl on Thursday January 16, 2020 @06:27PM (#22070206)

Thanks for showing up to be dismissive of concerns that you understand! Nuance is a thing.

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