DSHR's Blog: Chatbots vs. Ozone

Tuesday, June 16, 2026

Chatbots vs. Ozone

Source<br>Back in February I posted The Kessler Syndrome, which also included a brief section mentioning the impacts of the proposed megaconstellations on the environment, specifically global warming from CO2 and black carbon, and depletion of the ozone layer. Three months earlier Anton Petrov had examined the last of these in Risk of Ozone Layer Destruction from Internet Satellite Swarms and Rocket Fuel. He has now followed up with SpaceX Is Conducting a Giant Chemical Experiment on Our Atmosphere Without Realizing. Below the fold I survey the papers Petrov cited and a few others.

The papers involved are, in date order, as follows together with extracts from their abstracts:

Impact of Rocket Launch and Space Debris Air Pollutant Emissions on Stratospheric Ozone and Global Climate by Robert Ryan et al (9th June 2022):

Rockets, unlike other anthropogenic pollution sources, emit gaseous and solid chemicals directly into the upper atmosphere. We compile inventories of these chemicals from rocket launches in 2019 and projections of future growth and speculative space tourism activity. We incorporate these in a 3D atmospheric chemistry model to simulate the impact on climate and the protective stratospheric ozone layer. We find that loss of ozone due to current rockets is small, but that routine space tourism launches may undermine progress made by the Montreal Protocol in reversing ozone depletion in the Arctic springtime upper stratosphere. The BC (or soot) particles from rockets are also of great concern, as these are almost five hundred times more efficient at warming the atmosphere than all other sources of soot combined.

Note that even four years ago it was already clear that the space industry was both depleting ozone and aggravating global warming. But this was before the scale of the proposed mega constellations was evident.

Metals from spacecraft reentry in stratospheric aerosol particles by Daniel Murphy et al (7th September 2023):

So far, models of spacecraft reentry have focused on understanding the hazard presented by objects that survive to the surface rather than on the fate of the metals that vaporize. Here, we show that metals that vaporized during spacecraft reentries can be clearly measured in stratospheric sulfuric acid particles. Over 20 elements from reentry were detected and were present in ratios consistent with alloys used in spacecraft. The mass of lithium, aluminum, copper, and lead from the reentry of spacecraft was found to exceed the cosmic dust influx of those metals. About 10% of stratospheric sulfuric acid particles larger than 120 nm in diameter contain aluminum and other elements from spacecraft reentry. Planned increases in the number of low earth orbit satellites within the next few decades could cause up to half of stratospheric sulfuric acid particles to contain metals from reentry.

Much of the reentry burn happens above the stratosphere, and it takes time for the aluminum nanoparticles to drift down to the levels where they were collected. So the 10% number represents pollution from an earlier period with fewer reentries that the 2020s. Murphy notes that:

Most of the meteoric mass is deposited at altitudes between 75 and 110 km by a very large number of sub-millimeter meteoroids. Reentering spacecraft, which are larger and moving more slowly, ablate between 40 and 70 km over a ~300 km long footprint

His samples were collected at 19km altitude.

Potential Ozone Depletion From Satellite Demise During Atmospheric Reentry in the Era of Mega-Constellations by José P. Ferreira et al (11th June 2024):

This paper investigates the oxidation process of the satellite's aluminum content during atmospheric reentry utilizing atomic-scale molecular dynamics simulations. We find that the population of reentering satellites in 2022 caused a 29.5% increase of aluminum in the atmosphere above the natural level, resulting in around 17 metric tons of aluminum oxides injected into the mesosphere. The byproducts generated by the reentry of satellites in a future scenario where mega-constellations come to fruition can reach over 360 metric tons per year. As aluminum oxide nanoparticles may remain in the atmosphere for decades, they can cause significant ozone depletion.

Ferreira et al confirm the potentially long delay between reentry and the nanoparticles reaching the ozone layer and depleting it:

we find that these reentry byproducts may take up to 30 years to settle from the top of the mesosphere into the stratospheric ozone layer. Upon reaching an altitude of about 40 km, aluminum oxides catalyze chlorine activation which promotes ozone depletion. This suggests that concentrations of aluminum oxide compounds may start increasing in the mesosphere well before reaching the stratospheric ozone layer. This would introduce a noticeable delay between the beginning of the injection process when orbiting bodies...