Low Earth orbit, the superhighway layer that wraps around Earth’s thermosphere some 200 to 600 miles above our heads, is newly congested.
Still, no one knows how the huge increase in satellites orbiting Earth will affect the atmosphere, and therefore life below. With the rush to launch more and more satellites, a new study suggests that the hole in the ozone layer, a problem scientists thought they solved decades ago, may be back.
“Until a few years ago, this was not a research area at all,” Martin Ross, an atmospheric scientist at the Aerospace Corporation, said of a study that looked at how the potential increase in artificial metal particles could destroy the 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 evaporation has little impact. But the new satellites — much more advanced but also smaller, cheaper and more disposable than previous satellites — are taking a turn that resembles fast fashion, said study lead author José Pedro Ferreira, a doctoral student in astronautical engineering at the University of Southern California.
Nearly 20 percent of all satellites ever launched have re-entered Earth’s atmosphere in the past half decade and burned up in super-fast, super-hot flames.
Mr Ferreira calculated that upon re-entry, much of the spent satellite could become aluminum oxide, a pollutant that could disrupt the chemistry of stratospheric ozone. Each satellite can generate less than 70 pounds of alumina nanoparticles.
The study, which relied on laboratory measurements and computer models, hypothesized that if the number of satellites launched led to megaconstellations of hundreds or thousands, they could create an excess of aluminum 640 percent above natural levels, potentially leading to a significant increase in ozone. exhaustion.
“We’re still at the very beginning of a major research effort, so it’s too early to be sure that it’s having a negative impact, but we’re clearly starting to see evidence,” said Mr Ferreira, whose research, published in Geophysical Research Letters, was funded by NASA and the National Science Foundation.
Mr Ferreira said studies like his were not anti-satellite but added to the growing body of research on sustainable space development.
Daniel Cziczo, a professor of earth, atmospheric and planetary sciences at Purdue University, flies high-altitude aircraft to look at particles left in the atmosphere from meteoroids. Last year, he published a study showing that these particles collide with artificial metals from satellites.
He said Mr Ferreira’s study had jumped to conclusions not supported by his own research by applying the wrong size, composition and chemistry to particles that exist in the atmosphere.
Increasing the number of launches and discarding more satellites, which will largely burn up, means there will be more material in the atmosphere, said Dr. Czicza. “The question is what the impact will be, and we don’t know that yet.” He said there was a need to study ozone depletion and the climate effects of satellites, but he didn’t think the paper approached those issues properly.
Mr Ferreira said “models are only as good as the data you have to validate them against, so we should be cautious and careful about the level of certainty we have about environmental impacts.”
Regulators are slow to acknowledge the unanswered questions that come with growing space hardware. In 2019, the UN Committee on the Peaceful Uses of Outer Space published long-term sustainability guidelines that recommended regulating the environmental effects of space activities on the planet. In 2022, the Federal Communications Commission, which licenses most satellites, approved 7,500 of SpaceX’s requested batch of nearly 30,000 satellites.
The Montreal Protocol, an international agreement that regulated ozone-depleting substances in 1987, was, according to Dr. Rosse of Aerospace Corporation written to cover gases, not particles. But the regulatory body could intervene in the coming years.
“This is something the world should take really seriously, and the Montreal Protocol is aware of it and will address it,” said David Fahey, co-chair of the Montreal Protocol’s Scientific Review Panel and director of the Chemical Sciences Laboratory at the National Oceanic and Atmospheric Administration.
The protocol, he said, will address the issue for their next assessment, which will be completed in 2026.