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Comment by jl6 | Hacker News Reader

I couldn’t see a quantitative estimate of how much ozone would be depleted in a typical year as a result of the extra catalyst being present. If it’s only ~hundreds of tons, that seems both immaterial (there are about 3 billion tons of ozone in the atmosphere currently) and potentially easy to replace (fly up there and dump some fresh ozone).

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If starlink thinks it may have 40,000 satellites at full capacity[1] .. and we expect at least 1 if not 2 competitors..

With a 5-year lifespan for an LEO sat, that's potentially 120,000 deorbits every 5 years...

That will add up quickly... I don't know the science of aluminum oxide increase to ozone depletion.. but this can certainly warrants more research and consideration

1: https://starwalk.space/en/news/spacex-starlink-satellites-ni...

https://www.antipope.org/charlie/blog-static/2024/05/on-mist...

Can't they spray some ozone as they deorbit?

No, but I imagine they could include some other solid mass that has a counter effect.

Chemtrails!

The satellites are typically much smaller than historic satellites. I think ~50-60 are launched in a fairing that would house 1 or two older-style satellite.

Does the mass make a difference?

All of those starlinks are designed to burn up though. And there will be many thousands more of them then there ever was of those older larger satellites.

Starlink satellites have gotten big. The V2 Mini they are launching now is 1600 lb, and they fit only 20 some on Falcon 9. The V2 for Starship will be 2700 lbs.

Why would the number of satellites be pertinent here? It’s a mass problem, and starlink satellites are tiny compared to most of the satellites that are up there.

Many little number make big number. Mhmmm.

And SpaceX boasts to have launched more mass than the rest of the world combined...

Im guessing it would make sense to release more pro ozone catalyst. It may even be an option to release more it from the ground, as an inverse to CFCs.

NOx is also has a global cooling effect, taking the edge off climate change.

NOx and VOCs from power plants and diesel vehicles produce ozone.

Catalysts don't get consumed by the reactions they facilitate, so the weight of the catalyst compared to the ozone doesn't say much about the effect.

For example, consider that a car exhaust catalyst contains ~5 grams of platinum, and AFAIK, that doesn't really "wear out".

I think it says its a catalyst, for some chlorine reaction. So its not out of the question 300 tons (per year) could effect ozone concentrations.

There's absolutely no estimation of the impact. Your 300 tons of activated chlorine per year idea is as baseless as the GP's 300 tons of ozone, but the GP is aware that his number is a complete invention.

Any exercise in making numbers out of nothing is completely useless.

(Besides, is chlorine activation really a bottleneck in ozone depletion? AFAIK it gets activated by UV light quite quickly.)

GP never implied the amount of ozone just the amount of aluminum oxide. All I know is catalysts can speed up reactions by orders of magnitude. CFCs actually created a hole in the ozone layer so its not like human activities haven't accidentally created problems before. Probably something that at least needs to be ruled out.

Correct. That's the same way I read that comment.

More fundamentally, chemical catalysts by definition are not consumed by the reactions they catalyze.

Think: a cheese grater. It doesn't react with the cheese, so a few ounces of grater could make hundreds of pounds of grilled cheese.

A hypothetical 300 tons of catalyst is not limited stoichiometrically to how much substrate it would affect.

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