Satellites orbiting Earth.
Greenhouse gas emissions will decrease the amount of satellites that can safely orbit Earth, according to a new study.
Currently, around 11,900 satellites are orbiting Earth, providing essential services such as internet connection, communication capabilities, weather prediction and navigation technology.
However, researchers in the United States and United Kingdom now say greenhouse gas emissions might drastically reduce the amount of satellites humanity can safely launch into orbit by the end of the century. Their work is detailed in a study published Monday in the journal Nature Sustainability .
Burning coal, oil and gas releases greenhouse gases like carbon dioxide (CO2) into the atmosphere. “As greenhouse gas concentrations rise, they warm the troposphere where we live but cool and contract the upper atmosphere—the stratosphere, mesosphere and thermosphere,” study lead author William Parker, an expert in space sustainability at the Massachusetts Institute of Technology (MIT), tells Gizmodo’s Passant Rabie.
The International Space Station and many low-Earth orbit satellites circle the planet in the thermosphere, an atmospheric layer that “plays a crucial role in creating drag on orbital debris,” Parker adds. Drag is like air friction, and it pulls space junk and old satellites down to lower altitudes where they eventually burn up, removing them from orbit.
“We rely on the atmosphere to clean up our debris. There’s no other way to remove debris,” Parker explains to the Associated Press’ Seth Borenstein. “It’s trash. It’s garbage. And there are millions of pieces of it.”
Simply put, more greenhouse gases leads to a less dense upper atmosphere, which exerts less drag on satellites, extending their lifetimes in orbit. That means less space junk burns up, creating a higher risk of collisions. Given this, Parker and his colleagues wanted to calculate exactly how the process might impact low-Earth orbit’s “satellite carrying capacity.”
Low-Earth orbit includes orbital paths at or below 1,200 miles from the surface. The team examined altitudes in the thermosphere between about 125 and 620 miles above the Earth.
The scientists used computer models to simulate how CO2 would influence the thermosphere and satellite orbital dynamics under different emission scenarios. They ultimately concluded that, depending on future CO2 emissions, the satellite carrying capacity of low-Earth orbit’s busiest regions could decline by roughly 50 to 66 percent by 2100—or as high as 82 percent in a worst-case scenario.
“Our behavior with greenhouse gases here on Earth over the past 100 years is having an effect on how we operate satellites over the next 100 years,” Richard Linares, a co-author of the study and an aerospace engineer at MIT, says in a statement. And at the same time, the number of satellites launched has dramatically increased.
“Without checking this proliferation, we are in danger of entering a ‘Kessler syndrome,’ where a chain reaction of collisions causes space to become unusable,” says Matthew Brown, a co-author of the study and space physicist from the University of Birmingham in England, in another statement.
The researchers say launches should be done with long-term satellite carrying capacity in mind. In fact, satellite operators regularly perform collision-avoidance maneuvers.)—SpaceX conducted 50,000 of them in just six months in 2024.
The recent study is probably the first to measure the changing atmospheric density’s impact on the satellite carrying capacity of low-Earth orbit, Petr Šácha, an atmospheric physicist at Charles University in the Czech Republic who was not involved with the research, tells the Verge’s Justine Calma. Šácha also notes that other factors could cause short-term changes in the thermosphere’s density, particularly due to uncertainties surrounding the behavior of gravity waves in the atmosphere.
“I think the goal behind this paper was to engage the public a little bit … space sustainability impacts them,” Parker tells the Verge. “And to make sure that within the satellite operator community, people are aware that this resource is finite and it’s changing.”
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Margherita Bassi | READ MORE
Margherita Bassi is a freelance journalist and trilingual storyteller. Her work has appeared in publications including BBC Travel, Discover magazine, Live Science, Atlas Obscura and Hidden Compass.
Filed Under: Climate Change, Fossil Fuels, Global Warming, NASA, New Research, Satellites, SpaceX, Technology