SpaceX's Starlink may be keeping the ozone from healing, research finds

> Ozone layer recovery is on track, helping avoid global warming by 0.5°C

https://www.unep.org/news-and-stories/press-release/ozone-la...

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2024GL10... is a much better link.

“We consider a generic satellite reentering the mesosphere from LEO. The satellite structure is taken to be entirely aluminum, and the relevant ambient gas is molecular oxygen (COESA, 1976; Plane et al., 2021). In this study, we first carry out an atomic-scale MD simulation—a first-principle informed method for modeling physical and chemical interactions between atomic particles (Rahman, 1964)—to simulate the bond breakage between aluminum atoms (Al-Al bonds) due to the impact of oxygen molecules (O-O bonds) and the formation of aluminum oxides (Al-O bonds) during the ablation stage of reentry.”

The study itself was discussed here five days ago:

https://news.ycombinator.com/item?id=40667786

One point of discussion was making satellites out of other materials that won't deplete the ozone.

I feel the article does a poor job at explaining the researcher's base assumptions:

* What is the relationship between aluminum oxides and ozone depletion? * How long is the useful life of a satellite (when will this be a problem)? * What's the margin of error in the predictions (how confident are the scientist)?

This feels like sensationalism. On the other hand, the paper itself might be underestimating the number of launches as it relies on another paper expecting "triple the count of tracked objects in low-Earth orbit (LEO) over the next century". This feels low given how much the cost of launching has been decreasing.

> "The environmental impacts from the reentry of satellites are currently poorly understood," the researchers note in their paper. "As reentry rates increase, it is crucial to further explore the concerns highlighted in this study."

In other words, they have no idea what effect, if any, some extra aluminium oxide is having on the ozone layer.

Fun to play follow-the-citation though:

> Dominant drivers in re-entry destruction are NO (nitrogen oxides) and chlorine emissions. Other re-entry elements play a negligible role.

https://indico.esa.int/event/321/contributions/6403/attachme...

> The results of the present study lead to the conclusion that deorbiting space debris has very little impact on stratospheric ozone

https://apps.dtic.mil/sti/pdfs/ADA414310.pdf

A couple good pull quotes from the simulation study itself:

> The chlorine activation reaction is catalyzed on the surface of aluminum oxide particles, with a reaction probability of 2% that boosts ozone depletion

> Concerning the future mega-constellations scenario, the worst-case estimation of Organski et al. (2020) is taken

The upshot here is that aluminum oxide, where present, negligibly but measurably increases the breakdown of ozone by catalyzing chlorine, where present.

Keeping chlorine levels in the atmosphere low is an imperative, and one of the overall success stories of international environmental cooperation. A bit of alum is not going to move the needle, it's entirely inert to ozone chemistry on its own, and a poor catalyst of breakdown in the presence of chlorine.

If enough satellites broke up in the atmosphere to provide an atom of aluminium oxide for each chlorine atom, which won't happen, that would lead to a maximum of 102% ozone damage from a baseline of 100%, if every one of those atoms collided with a chlorine molecule, which is also very much not how gas phase chemistry works.

So yeah, great study. Seems the satellites are worth the nonexistent risk to ozone that they don't pose. Glad someone checked!

it's almost like any important new technology presents a constellation of tradeoffs

Nothing better than research am I right?

I research stuff all the time.

I love research.

I was going to make a flippant remark asking the lines of “why is it never good news?” but realized it’s a good question and the obvious answer is that everything is in perfect balance after millennia of the planet’s existence. All of this is an aberration from the norm and it’s all going to be bad.