From an article from NOAA in 2023.

"Scientists found aluminum and exotic metals embedded in about 10 percent of sulfuric acid particles, which comprise the large majority of particles in the stratosphere. They were also able to match the ratio of rare elements they measured to special alloys used in rockets and satellites, confirming their source as metal vaporized from spacecraft reentering Earth's atmosphere."

https://csl.noaa.gov/news/2023/388_1016.html
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