Starlink satellites are 'leaking' signals that interfere with radio telescopes | Hacker News Reader

Starlink satellites are 'leaking' signals that interfere with radio telescopes

theconversation.com

109 pointsc42058 comments

For anyone with an interest in the computing centre behind a square kilometre radio telescope array see:

https://pawsey.org.au/supercomputing/

https://pawsey.org.au/systems/data-cloud/

https://pawsey.org.au/visualisation/

Further infomation about the radio quiet zone referenced: https://www.industry.gov.au/science-technology-and-innovatio...

and yes it's also in an area with zero ground sourced light pollution - aside from those shiny LEO satellites which are visible long beyond 15 minutes after sunset. They'll even reflect moonlight.

From the linked piece from Curtin Uni:

    We estimate emissions in radio wavelengths will need to be reduced by a factor of a thousand or more to avoid significant interference with radio astronomy. We hope these improvements can be made, in order to preserve humanity’s future view of the universe, the fundamental discoveries we will make, and the future society-changing technologies (like wifi) that will emerge from those discoveries.

Factor of a thousand = 30dB.

That's one of the two Science Processing Centres behind the SKA, the other will be in Cape Town, serving the SKA-Mid array in South Africa.

https://www.sarao.ac.za/news/south-africa-will-host-one-of-t...

https://bandwidthblog.co.za/2023/05/16/supercomputer-south-a...

https://www.skao.int/en/explore/big-data/361/science-process...

>Now it is commonplace: sit outside for a few minutes after dark, and you can’t miss them.

As always, this is only the case immediately after sunset, when it's dark on the ground but the satellites are still in direct sunlight. Fifteen minutes later they're completely invisible.

The cutoff is nowhere near that soon after sunset. At midnight? Sure, you're not going to see satellites. But against a dark sky, you can see satellites reflecting for at least a couple hours. They may not be in direct sunlight as it gets later, but they are still illuminated by the atmosphere on the sunny side for a while.

Not low earth orbit satellites. As the name implies, those are flying low enough that they’re only briefly visible after sunset.

The human eye might not, but they show up just fine in astrophotography, amateur or professional, all night long.

The school children p1ss in the public swimming pool while the adult lanes are still open ... but only during their 1 hour lesson on Monday afternoon. After that, it's totally fine.

It is fine though? Swimming pools use a complex chemical and physical filtration system.

every space sci-fi in the world presupposes that we'll do the same once our orbital lanes are packed densely.

Adults blame kids for everything. Google it and you'll think twice about swimming in a pool again :-D

Gave it up long ago!

Light pollution doesn't linger and spread over time. Once it stops being emitted, it's gone one second later.

> Fifteen minutes later they're completely invisible.

That part of the article is just intro fluff - not the problem described in the article

https://james.darpinian.com/satellites/

This is a key misconception. Their SOP is to put the newest batch into an ultra-low orbit for testing. Any that fail should passively deorbit in a few months due to the increased atmospheric density. To minimize drag during this process, they deploy the solar panels parallel to the ground. Once testing is over, the panels reorient to hide behind the darkened satellite body, and then the satellites use their internal ion thrusters to boost to their final operational orbit. The dawn and dusk flaring people see are these early satellites with horizontal reflective solar panels.

There are reports of people near the poles seeing flares that are, in theory, caused by the vertically oriented panels reflecting the sun from the other side of the earth.

Scott Manley - https://youtu.be/P1TsOYcvq9A?si=7yuF2KbQFySDgG31&t=1111

Semi unrelated-

I really wonder what uncontacted tribes think of this.

Sounds like there’s some additional EMI shielding that is needed for future iterations of megaconstellations. On the plus side since they have relatively (compared to geosync satellites) short lifespans of only a few years they can probably sort this out by passively fixing the next generation of satellites. Additionally, from what I have seen of the way they pack the Starlink satellites into the fairing, they seem to be volume constrained in the fairing rather than mass constrained, so there may be additional mass budget available for little overhead.

I wonder if there's also potential for software mitigations on existing satellites? They already power down the radios when flying over RF quiet zones, so it might be possible to power down (or reconfigure) other components to reduce EMI leakage.

It's not just leakage, large constellations lower SNR in radio astronomy just by being long trains of metal.

This article is talking about EMI leakage and so was I.

Do you have links where I can read more about this other effect?

After the first couple space wars we'll have such shielding figured out. Until then, fat chance.

It will I'm afraid going to be a difficult battle to win, e.g.,

- modern iPhones can communicate with global satellite constellations (https://support.apple.com/en-us/HT213885). I imagine this will grow substantially

- Even bike lights nowdays have radar built into them (e.g., https://www.garmin.com/en-GB/p/698001). Also room presence sensors are beginning to use radar 22GHz.

We can now build incredibly cheap and lightweight radio devices up to 80 GHz. They will inevitably be used more on the ground, in air and on satellites as the economics makes new types of uses practical.

This sucks. More false positives to pick up when driving around town.

Even the motion-sensing light in my pantry is a radar now.

Right, in principle they are better than just motion sensing since they can also detect breathing (and even heart beating!). And with modules costing 1-2$ people think... why not?

I used to work for Starlink. The one that was good for astronomy.

https://en.wikipedia.org/wiki/Starlink_Project

In contrast to your values work , I wonder what the benefit of all those satellites should be, besides profit ? It might be easy to say for someone living in a city , but I assume all relevant areas today have somehow internet coverage . So adding 10000s of satellites seems like just the next Netflix , shifting business from one company to another . In difference to GPS , and even ignoring all the impact of all those rocket launches , this is not adding a jot to humanity , and therefore a global light or radio pollution of astronomy is unacceptable

I’ve lived in a few areas in the US where internet was and still is horrible if available at all. Visiting my mother to help her out for longer than a few days was a pain since she had traditional satellite internet and terrible cell which were unusable for work video meetings. That’s in the US.

I doubt every small village in South America or Africa has good internet either. Hopefully they can get starlink and share. Hopefully it’ll give folks more opportunities and access to work or education. Even medical exams over a video call, etc.

Honestly it’s incredible that sending 12,000 satellites into space to provide internet coverage to multiple continents across the world is as cheaper than installing ground based infrastructure. The cost per satellite is reportedly $500k, so the star link constellation cost only $6 billion.

For comparison the Australian NBN (country wide internet infrastructure upgrade) cost over $50 billion, and it still relies on satellites to cover rural areas.

Do you think there are benefits to telecommunications such as telephone and video calls with a doctor?

> It might be easy to say for someone living in a city, but I assume all relevant areas today have somehow internet coverage.

I know people in rural areas who can't even get DSL. And even within a city, having Starlink available sometimes makes the difference between someone having one possible ISP (often something horrible like Comcast) and having two.

Also, see other comments here: this is already being addressed, folks are working with SpaceX on better EMI shielding.

I just got back from St. Croix - the largest, remotest, and poorest of the Virgin Islands. I had far better internet there than I do ~35 miles outside of Atlanta.

Infrastructure in this country is ridiculous sometimes. Comcast told us it would cost 75000 dollars for them to run a line to our street, so us and our neighbors just have to make due without. We have to use T-Mobile right now.

The potential scientific upsides are huge:

https://caseyhandmer.wordpress.com/2021/11/17/science-upside...

(there is a section about Starlink later in the article)

Do you have a link to any more detailed papers on those scientific upsides? What is listed there is high level and would seem to require the satellites to be equipped with equipment they don't necessarily have. If the science upsides are really that huge, I'd expect scientists to already be looking into it.

Why not program the satellites to switch of their radio emissions when they orbit over the radio quiet zones?

They already do.

This isn't about intentional radio emissions, this is radio "leakage" from the onboard electronics, essentially EMI. Strangely there are no legal requirements to limit these emissions, and the detected emissions are so tiny you literally need to point a radio telescope right at the satellite to even detect them. The problem is that even tiny emissions are bad in this case because they're in frequency bands used for radio astronomy.

The fix is simple: add more EMI shielding & filtering. The researchers were already working with SpaceX on the problem, and SpaceX had already started making fixes. The researchers pointed this out in the very first paper on the subject, but somehow that detail almost never makes it into the pop-journalism article treatment....

It's good to share these Lessons Learned because SpaceX is doing things nobody has ever done before, and is (rightly) subject to levels of scrutiny nobody has ever seen before.

If instead you want to shoehorn this into Elon Bad / SpaceX Bad clickbait, its a non-story.

That would get in the way of writing a click-generating Rocket Man Bad article.

It's heartening that SpaceX engineers want to be good citizens here. I hope the financial side of the house, and other satellite operators, also will work to lower the noise.

They already have done a lot for the visual part, so they seem to be active on these topics.

> pop-journalism article treatment....

By which you mean this linked article in The Conversation written by Steven Tingay, a John Curtin Distinguished Professor (Radio Astronomy), Curtin University talking about real and current issues faced by the SKA (Square Kilometre Array), Microwave Cosmic Background, and other projects in the Murchison (supposedly) Radio Quiet Zone ?

I hope not as this linked article refers to the ongoing efforts made by Starlink engineers .. while pointing out that:

    We estimate emissions in radio wavelengths will need to be reduced by a factor of a thousand or more to avoid significant interference with radio astronomy.

> > pop-journalism article treatment

> By which you mean this linked article

I do not.

Thank you for asking, instead of just assuming! That's quite rare these days.

Funny, they're also 'leaking' signals that interfere with optical telescopes

Put telescopes in space, where they belong. Need a crew? Attach a space station.

Can't be!

I was assured by everyone that this would never happen.

Time to refactor the telescopes. They should do that anyway, Amazon is going to get into the same business soon.

Refactor how, exactly, are you suggesting?

Put them somewhere away from the low orbit satellites. Maybe GitHub could send a CD with it and do another version of the annoying Arctic Code Vault Contributor badge.

How about preserving humanity’s capabilities to observe the universe untampered by profit

Move Fast and Break Things and Don't You Dare Make Me Pay For Damages

Especially since public research is so well funded they have the cash to spare to 'refactor' while the private profit-(and king-)making industry surely couldn't handle it.

There are physical limits on how much stuff you can break (or pollute) before you can't "refactor" yourself out of the hole you've dug

I dont like starlink + all the other frivolous satellites we are throwing up there. All I can think of is Kessler syndrome. Capitalism is destroying the biosphere and now space.

Satellites provide humanity a ton of good. Would you say the bad outweighs the good overall? What would you propose we do instead?

I think it's like calories. They also provide humanity a ton of good but being careless with them is a whole other story.

Starlink satellites are not in an orbit where Kessler is a problem. Even if they all broke up, the debris would just get dragged down into the atmosphere fast.

> All I can think of is Kessler syndrome.

Maybe you should consider thinking about more then one thing when trying to understand an issue. Just a suggestion.

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