A Global Push Fixed the Ozone Hole. Satellites Could Threaten It.

Low-Earth orbit, a layer of superhighway that wraps around Earth’s thermosphere some 200 to 600 miles above our heads, is newly congested.

Yet no one knows how the vast increase in satellites orbiting Earth will affect the atmosphere, and therefore life down below. With the rush to send up more and more satellites, a new study proposes that the hole in the ozone layer, a problem scientists thought they had solved decades ago, could make a comeback.

“Up until a few years ago, this was not a research area at all,” Martin Ross, an atmospheric scientist at Aerospace Corporation, said of the study, which looked at how a potential increase in man-made metal particles could eat away at Earth’s protective layer.

Ever since Sputnik, the first man-made space satellite, was launched in 1957, scientists have thought that when satellites re-enter our atmosphere at the end of their lives, their vaporization has little impact. But new satellites — much more advanced, but also smaller, cheaper and more disposable than previous satellites — have a turnover that resembles fast fashion, said the lead author of the study, José Pedro Ferreira, a doctoral candidate in astronautical engineering at the University of Southern California.

Almost 20 percent of all satellites ever launched have re-entered Earth’s atmosphere in the last half-decade, burning up in superfast, superhot blazes.