"Satellight Pollution" of the Night Sky by SpaceX

[profdant139]

Those of us who boondock in search of dark skies will be dismayed to hear that the new satellite internet system will scatter a lot more junk across the field of view. (I am claiming the coinage of the term "satellight pollution.") Here is an article:

Article

On the other hand, all of those spacecraft should provide us with great internet coverage as we sit in remote locations, grumbling about all of those spacecraft.

[vermilye]

One method used for low light & IR images is to cool the sensor with liquid nitrogen (-321°F). While this reduces noise, and is practical for telescope sensors, in might just be a bit of a problem for a DSLR!

[DrewE]

profdant139 wrote:

Based on absolutely no factual information, my guess is that the military folks have high ISO cameras that take flawless snapshots at night, but they are not releasing those tools for public use.

They would have to have large (diameter) lenses to do so, to collect more light. Current commercial camera sensors are, if my vague memory serves, somewhere in the rough neighborhood of 50% quantum efficiency; which means they could get at most about a stop better before hitting a hard limit of noise performance: that imposed by light being composed of discrete photons, and not actually being a continuous phenomenon.

As I understand it, a fair few modern digital cameras adjust the ISO purely in software, basically bumping the brightness on high ISO shots, without altering the sensitivity at the sensor level or in the readout circuitry.

[profdant139]

Just a follow-up on how a time exposure can reveal things we can't see -- if you look carefully at the upper left corner, you should be able to see two meteor tracks. We could not see them at the time -- there was a bright moon. We did not even know they were there until we viewed the shot on the computer. This was about a 20 second exposure -- it was taken in the Boulder Mountains of Idaho, north of Ketchum and south of Stanley:


Click For Full-Size Image.

[profdant139]

phil, the problem with very fast cameras is the phenomenon of "noise." If I set my ISO to 3200, a good Milky Way exposure will take 20 to 30 seconds, but the image will be pretty clean. If I set it to 12,800 (I think that is the number), it takes an equally-bright image in about 8 seconds. But the higher ISO is infected with a lot of electronic noise that is very hard to edit out.

Having said all of that, your question is about approximating what the eye sees. I think that a 3200 shot at five seconds might do that much. But the joy of the digital SLR is the ability to take shots that are better than the eye can see. That feature has added so much to our enjoyment of boondocking.

Based on absolutely no factual information, my guess is that the military folks have high ISO cameras that take flawless snapshots at night, but they are not releasing those tools for public use.

[pnichols]

profdant139 wrote:
avoid, you'd be amazed at how many of my time exposures of the night sky have been ruined by satellight pollution. (I want credit for that phrase if it catches on!!) So as the sats increase in number, there will be more ruined photos. The sats show up like a long line in a 30 second exposure.

No big deal for me -- I am just an amateur. It might be a problem for the pros, though.

Dan ... an interesting discussion thread!

I have a couple of comments, the first one being a serious one:

1. What kind of camera and lens combination would it take to be able to view/capture the night sky like the human eye/brain combination can do it? i.e. Instantaneously - with long time exposures to capture light from images not required? Is image capture technology capable yet of duplicating the human eye in this respect? :h

2. A lot of satellites up there just might help with Global Warming ... doesn't each one keep a bit ot the sun's energy from reaching the earth? :B

[profdant139]

avoid, you'd be amazed at how many of my time exposures of the night sky have been ruined by satellight pollution. (I want credit for that phrase if it catches on!!) So as the sats increase in number, there will be more ruined photos. The sats show up like a long line in a 30 second exposure.

No big deal for me -- I am just an amateur. It might be a problem for the pros, though.

[avoidcrowds]

Hmmm. When I am boondocking, I seem to see way more than 2,000 stars in the sky. Maybe 2,000 when viewing the sky in a city.

I am not too concerned about it. Even if there are 12,000 birds put up there by SpaceX, it is going to take much longer than I will be around to get them all up there. If they can launch 10 at a time, and do a launch each month, that will be 100 years to put them all up. If they can launch more each time, then they will be pretty small, and may not be visible to the naked eye.

I like trying to spot satellites when I am stargazing.

If someone is looking through binoculars or a telescope, the chances of a SpaceX satellite entering your field of view will be, in my opinion, very slim.

Yes, there is legitimate concern of additional hazards flying around, and I will grant that is valid. But, as for seeing a swarm of them in the small portion of sky we can see while stargazing, I think that is being overblown.

[profdant139]

Maybe it won't be as bad as we feared. The orbits are getting steadily higher, dimming the light pollution. This is an update from another article:

"The satellites' visibility in the sky — a source of consternation for some astronomers, both professional and amateur — will decrease considerably as they rise, SpaceX representatives said. The satellites' solar arrays will also move behind the craft as they point their antennas toward Earth, contributing to this fadeout, SpaceX representatives added."

[CFerguson]

Unpolluted air, normal human vision, good dark observing site = about 2000 stars visible. Just a number I rem from astronomy class.


https://phys.org/news/2019-05-spacex-starlink-satellites-harder.html

[MNGeeks61]

It's odd for me. I haven't used my telescope in months. But sitting outside back in March on the warm night (40's) around a campfire, we did see more than a few satellites and the ISS.

When looking at semi-deep sky objects, it's been semi rare for me to catch a satellite. And I don't do much astrophotography so it's even more rare. but I sure would hate to be outside at night and wonder if that was a plane, a satellite, or an asteroid very close to the earth...

[SidecarFlip]

Maybe Putin will get pizzed and shoot them down....

[timmac]

HadEnough wrote:
Not a fan.

One astronomer mentioned that if they put all 12,000 satellites up that they plan to use, there will be more satellites than there are stars right now visible to the naked eye.

But the good side is fast strong internet world wide..

:W

[HadEnough]

Not a fan.

One astronomer mentioned that if they put all 12,000 satellites up that they plan to use, there will be more satellites than there are stars right now visible to the naked eye.