this post was submitted on 17 Jun 2024
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Abstract from the paper in the article:

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2024GL109280

Large constellations of small satellites will significantly increase the number of objects orbiting the Earth. Satellites burn up at the end of service life during reentry, generating aluminum oxides as the main byproduct. These are known catalysts for chlorine activation that depletes ozone in the stratosphere. We present the first atomic-scale molecular dynamics simulation study to resolve the oxidation process of the satellite's aluminum structure during mesospheric reentry, and investigate the ozone depletion potential from aluminum oxides. We find that the demise of a typical 250-kg satellite can generate around 30 kg of aluminum oxide nanoparticles, which may endure for decades in the atmosphere. Aluminum oxide compounds generated by the entire population of satellites reentering the atmosphere in 2022 are estimated at around 17 metric tons. Reentry scenarios involving mega-constellations point to over 360 metric tons of aluminum oxide compounds per year, which can lead to significant ozone depletion.

PS: wooden satellites can help mitigate this https://www.nature.com/articles/d41586-024-01456-z

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[–] Dasus@lemmy.world 1 points 5 months ago (1 children)

Yeah since most people don't live in the parts of the country no-one lives in, when looking at how many people are covered, it gets pretty good. And we didn't take long to get 5g to a lot of people.

Here's a coverage map from Elisa. https://elisa.fi/kuuluvuus/

[–] RunawayFixer@lemmy.world 1 points 5 months ago (1 children)

Tbh, that 4g coverage up north looks pretty damn good for how few people live there. To me it just makes no economic sense to provide that good a service there. So I'm curious and as a Finn you might know: does it make economic sense or was this investment done for other reasons?

[–] Dasus@lemmy.world 2 points 5 months ago* (last edited 5 months ago) (1 children)

I wish I had a good answer, but I don't, really.

Probably a combination of just providing a service and having good technology to do so and companies which want to sell said technology, I guess?

Everyone enjoys the internet. I might be assuming, but the sort of "if you want services, move to a city" sort of rhetoric that might exist somewhere in the US doesn't really exist for us Finns. We understand wanting to live in the middle of the woods while still having access to basic services.

The Northern part is very sparsely populated, yeah (well not compared to some other places in the middle of huge states in the US but) something like two people per square kilometer, but rural living is pretty common throughout the country, so the whole country understands the need for them, perhaps?

Also, I think a lot of the towers are older towers for just 2g, going back from GSM to NMT, those towers always just being updated with newer technology, again perhaps? (I'm too lazy to research this now.) And the need to have just cellular networks to be able to call emergency services if you're lost deep in the woods has always been a pretty high priority, I think?

The only places you maybe can't get cell reception in Finland are some places in the middle of a few national parks in Lapland.

[–] RunawayFixer@lemmy.world 1 points 5 months ago (1 children)

Hey, thanks for taking the time to answer.

Afaik, high internet speed requires higher frequencies and high frequencies reach less far + have less penetration through/around obstacles. That's what makes providing "4g" virtually everywhere easy (good enough for phone calls at least), but if they want to provide actual high speeds everywhere, then it suddenly becomes not so easy (nor cheap).

That the USA and Canada don't provide proper high speed internet access/choice to many of their rural citizens is caused by the rent-seeking mentality of their network companies + the governments that enable this. Most of those rural citizens live in places where there are more than enough people for it to make economic sense to invest, but investing would lower short term profits, so they don't. Instead those customers are stuck with the choice between a single provider who is offering bad service, or no service at all. And as we've seen with the Boobies American, they've got enough of their dumb citizens convinced that they are oh so exceptional that this is the best that they could ever expect.

[–] Dasus@lemmy.world 1 points 5 months ago (1 children)

Afaik, high internet speed requires higher frequencies and high frequencies reach less far + have less penetration through/around obstacles. That's what makes providing "4g" virtually everywhere easy (good enough for phone calls at least), but if they want to provide actual high speeds everywhere, then it suddenly becomes not so easy (nor cheap).

Why are you putting "4g" in quotes? It is 4g. Basic cellular networks cover the entire country, and using 4g speeds has been common for a long time. Hell, back when I was in the army, I had a laptop with a mobile connection. It was 3g back then, but it worked, even from the deepest of woods we were in.

The terrain of Finland probably makes this easier for us, as this is a rather flat country. We have literally no mountains. A few fells (=large hill, essentially) , but no mountains.

[–] RunawayFixer@lemmy.world 1 points 5 months ago

The quotes are there because it's a common misconception that as soon you have any kind of 4g signal, you have access to a fast connection, which is not the case. So in many countries at some point they proclaim that "xx%" of the population now has access to "4g", which will be technically true, but the actual % that has access to fast 4g will be substantially lower.