Dangerous satellite air pollution exists in a legal loophole

Air pollution from satellites burning up in Earth's atmosphere could become the world's next big environmental problem — but the tricky form of contamination seems to evade the reach of both international space treaties and Earth-focused environmental laws. So, some researchers are suggesting a solution: Maybe chemicals produced during satellite reentries should be incorporated in the 1987 Montreal Protocol which bans certain substances that can harm our planet's protective ozone layer.

Satellites have been burning in Earth's atmosphere since the beginning of the space age, but for decades, nobody really paid much attention to the issue. That changed when the era of megaconstellations arrived.

In the past, old spacecraft made up barely a drop among the thousands of tons of meteorites falling to Earth every year. However, the rise of megaconstellations, which can comprise hundreds, or even thousands, of satellites, meant the proportion of human made space debris began to rise.

For example, up to two hundred metric tons of dead satellites evaporated in Earth's atmosphere in 2023, according to estimates presented at the workshop on Protecting Earth and Outer Space from the Disposal of Spacecraft and Debris held at the University of Southampton in the U.K. on Sept. 23 and Sept. 24.

In comparison, more than 16,000 metric tons of meteorites burn up in Earth's atmosphere every year. By 2033, the annual amount of incinerated satellite trash could reach 3,600 metric tons — that's more than 20% of the amount of natural space rocks, Andrew Bacon, chief technology officer at in-orbit manufacturing firm Space Forge, said at the workshop.

This expected increase in human-made space debris concerns scientists because, unlike meteorites, satellites are made of alloys containing aluminum and other metals that oxidize into chemical compounds not otherwise present in the atmosphere. The most concerning of those is aluminum oxide, or alumina, a white powder that acts like "sunscreen" in the atmosphere preventing sunlight from penetrating closer to the surface.