Why Astronomers hate Starlink

[astrnmrtom]

I thought I'd write an informational post to demonstrate why you read on the news that professional astronomers are against the launch of 30,000 Starlink satellites.

I'm an amateur astronomer and recently started dabbling in photographing faint objects in the night sky. On my second night out, I was doing some exposures that captured satellite trails running through the image. This serves as a good proxy for the problem professionals face. and I thought I'd demonstrate how satellite effect the gathering of astronomical data.

It's important to keep a few things in mind when looking at my examples.

1. These images were taken with modest equipment - a 4" telescope and a consumer digital camera. The telescopes used professionally are 1,000,000 times more sensitive to light.

2. My images consist of 30 - 30second exposures, combined to make a single images equaling a single 15 minute exposure. Professional images usually consist of many hours of imaging. Sometime for the real faint stuff, it's days or weeks of accumulated data.

3. I'm limited by convenience, the moon, and weather. Professionals have the same limits but in addition to these, there are only a handful of major observatories around the world and thousands of scientists competing for "telescope time." Some wait years for a few hours of access to the scopes. This time is VERY expensive!

Ok, to keep it simple the professionals are capturing data. In my images the data is the light from a faint galaxy. There's noise mixed with any data, and the less noise, and the more signal the better. If the noise is too high the signal must be tossed out. You throw the baby out with the bath water so to speak. When you've waited years to gather data you you have a limited time to gather, the less you throw away the better.

What is important to this specific example is a satellite passing through the frame is noise. In my example, the satellites passed through a single frame of my run of 30. In the cleaned up example, I threw away one frame and stacked 29. Often professional images are made up of a single exposure of several hours in length.

Now take my example and extrapolate it out in time to when there's now 30,000 more satellite in low Earth orbit. Then realize Elon Musk isn't the only person on Earth planning to offer satellite based broadband. Just throw in a few more big players, i.e. China and Europe, and it won't be long before there's well over 100,000 more satellites zooming overhead. Remember for the most part space is completely unregulated, pretty much anyone that's capable can toss stuff up there.

Also note that simply painting a satellite black isn't much of a solution. Telescope collect data in a wide range of the electromagnetic spectrum. Black paint only works in the visible and reduces not eliminates reflected light. Add to that radio telescopes gathering faint data having to deal with satellite passing through the field screaming social media and streaming movies in the radio spectrum as they pass by.

Some of this will be countered with sophisticated filtering software, but remember, the more noise compared to the signal, the harder it is to separate. Imagine waiting years for limited telescope time only to have to throw away a growing chunk of that data because of noise from 100,000+ orbiting satellites.

The photos:

First is a single frame out of 30. Note how little signal - the galaxy - there is compared to the noise. The galaxy is so faint I circled it's position.

Second is the processed version of the single frame. Processing the image to enhance the galaxy does nothing to help the satellite streaks.

Third, is the all frames stacked and processed. The 29 good frames enhances the signal - the galaxy, and reduced the noise including the satellite streaks but it doesn't eliminate them.

Fourth is the image after tossing out the bad frame. Tossing out this frame didn't cost me anything but 30 seconds of my imaging time, but if I was paying big bucks for telescope time, that's time and data lost.

I hope this offers some insight into the bigger picture of the Starlink issue. While it is a boon to the internet world, it, like so many other things in life, there is always a down side.

If anyone is curious, this is an image of the Galaxy M101, located next to the handle of the Big Dipper. It is visible as a faint glow in dark skies with binoculars. It was taken through a 94mm diameter f/7 refractor on a tracking mount, using a Sony a6000 and an intervalometer, from a few miles outside the town of Moscow Idaho. Around 2am, May 21 2022.

It's also important to note these are probably not Starlink satellites because these are too far north, but they do work as an example.

[astrnmrtom]

Here's another one of my images from last year. This one DOES contain a grouping of satellites that is probably a constellation of StarLink satellite not long after launch. It's a single image of the Great Nebula in Orion - M42. Note the grouping of streaks just above the main nebula.

[SeeTheUSA]

Seems MANY will benefit from Starlink and similar systems. It’s unfortunate astronomers will be adversely affected.

Good info, thanks.

[puttin]

Very interesting post. As a layman I wonder how many more deep space telescopes we can deploy to bring the viewing costs down and get more availability to scientists and other astronomers? Thanks for the information!

[Old-Biscuit]

And yet Millions gotta have them smart phones, internet, high tech gadgets

[TandW]

Astronomers are always searching for the one that got away, with no idea where.
Or, the End has already happened but none of us will ever know it.

[Dutch Star Don]

Maybe Elon can paint big numbers on the sides of the satellites and the astronomers can have fun by identifying the satellites and collecting the numbers until they get all of them.

[Old-Biscuit]

I'll start.....

1

[astrnmrtom]

Originally Posted by Dutch Star Don

Maybe Elon can paint big numbers on the sides of the satellites and the astronomers can have fun by identifying the satellites and collecting the numbers until they get all of them.

Satellite Bingo!

Or paint letters on the side and it could be Satellite Scrabble.

[DerekF]

Need more space telescopes. Don’t forget all the ambient light causes them grief too

[astrnmrtom]

Was just processing another photo from that same night. Guess what? More streaks but fainter ones this time. Galaxies M81 and 82.

Couldn't make out any numbers or letters though.

[ponytl]

what few are speaking about is this is the spaceX bread and butter... and it brings fear to the world that would censor speech and content... soon anyone with a small pizza pan size dish will be able to access unfiltered, uncensored information... good bad or ugly everyone will have access to it... to date there is not a way for countries to block or filter anything... I find this far more interesting than there being far more space trash in orbit...

[dizcom]

Originally Posted by astrnmrtom

Was just processing another photo from that same night. Guess what? More streaks but fainter ones this time. Galaxies M81 and 82.

Couldn't make out any numbers or letters though.

Then how did you know it was 81 and 82??

[FL420]

Originally Posted by astrnmrtom

I thought I'd write an informational post to demonstrate why you read on the news that professional astronomers are against the launch of 30,000 Starlink satellites.

Thank you very much for bringing these concerns to our attention. When I first learned about Musk's plan to plaster thousands of satellites in low earth orbit I immediately thought of what the unintended(or ignored as acceptable collateral damage) might be.
IMHO, the effect most likely will be to increase the amount of space junk that orbits the earth presently which requires satellite operators to monitor and often change the orbits of their satellites if they are able to avoid collisions with space junk. The cost to do so is and will become moreso astronomical(pun was accidental.)
Building a metal junkyard over our heads at the cost of trillions of dollars to further enrich billionaires who make it easier for people to become online gamers, online gamblers and social media addicts while avoiding personal contact with nature and with people is self-destructive.
From the air and from the decks of ships in several oceans I have seen acres and acres of human junk(mostly plastics)floating like islands. Documentarians have shown us videos of human junk littering ocean floors and surrounding waters almost bereft of aquatic life. I have observed strings of barges within sight of the shoreline of New York City. They were loaded with many stacks of compressed garbage shorter and taller than ocean shipping containers but about the same volume that were being dumped into the Atlantic.
I have seen many tranquil valleys between scenic ridgelines filled in with human garbage, much of it very suitable for recycling turning them into man-made mesas with large PVC pipes sticking up out of the dirt to vent methane into the atmosphere. Meanwhile, we blame the effect of methane on global warming on those nasty cows and their farts and patties. Really??
I've gone on too long so I won't get into fracking, throwaway plastic water bottles and other plastic packaging, lack of recycling bins in campgrounds, global warming, wildfires, etc. BTW, I talked to my old high school buddy on the phone last week. He and his DW bought a second home in the San Juan mountains in Rociada, NM two years ago. It was destroyed by the biggest wildfire in NM history. Quite a coincidence that 2 of the houses we lived in were almost destroyed in two different Boulder County wildfires in the same month. The first one destroyed more than 1000 houses and 100 businesses causing the highest financial loss in Colorado history.
Drought and freakishly high sustained and gusting winds causing or coupled with relative humidities in the single digits and teens for the past several years have made much of the West a tinderbox. We get more Red Flag Fire Warnings, High Wind Warnings, Severe Weather Alerts, etc. covering much of the state in a week than I remember seeing in months over the past 30 years. Climate change, oh yeah! Global warming, oh hell yeah! I'm a believer now.
I have been quite guilty in the past but less so in the present of benefitting from some of the things our increasing efforts and capabilities of destroying the planet we live on. I am trying to be better at practicing what I preach but it's difficult. I just hope we all can think more about the big picture and what we can do or not do to keep our environment liveable and sustainable.
Carry on.
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