- cross-posted to:
- furry_scientists@pawb.social
- cross-posted to:
- furry_scientists@pawb.social
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
Finland is not a small country compared to its population density and distribution.
Finland has 18 inhabitants per km².
USA have 35 inhabitants per km².
That’s not a good measurement as populations are not spread evenly. You could have 10 000 people per km^2 in the US then have 0.001 people per km^2 in another
You are absolutely correct that distribution matters. However, Finland has an even more uneven population distribution than the US. 75% of the population lives in the costal cities, with 30% of the entire population living in the capital region( density of 193 persons/km²). The entire rest of the country is not empty dessert ( which would require no services), but very sparsely populated rural woodlands, down to 2 people per km².
Density still is an overall useful quantifier given that extra knowledge, as providing services for a small population of only 5.6mio inhabitants is not easy either. Sure, providing coverage for the 75% in the cities is fairly easy. But that still leaves 1.5mio rural residents, which require huge investments in cable to supply with broadband. And due to the vast distances, you definitely cannot cover them with wireless alone, if you were thinking that.
Compare the diameter of the two countries
If you only look at one line between LA and NYC, that is a lot more cable being laid. Now add something remote like the middle of Alaska vs the middle of Finland. We can assume for this example that they both service 100 people but the cost to do so for the US is a lot higher
That’s why using density makes no sense
Laying even 10 times the cable should not be more difficult when you have 60 times the total population (335mio in US vs 5.6mio in Finland) and hence more resources.
And sure, Alaska definitely it’s expensive and inefficient to service, having a pop density of about 0.5 inhabitants per km². But unlike Northern Finland, most of Northern Alaska is in fact entirely void of human life and more akin to a desert. There really mostly are a handful of oil industry clusters and native communities. And still, the extremely low pop density means it’s only 730 000 people living in Alaska. That is 0.2% of the entire population of the USA. If you were to completely ignore and not service Alaska, you should have a an even easier time providing service to the vast majority of the US population in all the main states. I think it’s pretty clear this is a political failure and not a matter of financial resources or natural obstacles.
Huh. TIL.
But these are sort of not that good indicators, because the US has huge population centers on the coasts, and nothing in the vast center.