As Earth’s surface continues to buckle from the burdens of climate change, its upper atmosphere faces different troubles altogether as greenhouse gases threaten space sustainability. A new study warns that the future could bring a sharp increase in space debris as satellites start to get stuck in Earth’s orbit because of climate change.
The study, recently published in Nature Sustainability, cautions that greenhouse gases are causing the upper atmosphere to cool and shrink, leaving satellites unable to sink to lower altitudes where they should burn up. Instead, they are stuck orbiting in a less dense atmosphere, and they could now begin to collide more often. Projections from the study envision a dangerously crowded upper atmosphere in the years to come.
A Crisis In the Upper Atmosphere
Greenhouse gases like C02, trapped in the lower atmosphere, pull heat down from the upper atmosphere. The cooling effect on the upper atmosphere decreases density and, in turn, reduces atmospheric drag on satellites, which would normally pull them back down to Earth. As a result, the lifetime of satellites in low Earth orbit may be extended.
The upper atmosphere can only carry so many satellites before things start to get dangerous. In the new study, researchers aimed to evaluate the “satellite carrying capacity” of certain altitudes of interest, or “shells”, in low Earth orbit by creating simulations of carbon emissions scenarios.
Increased emissions over the next century, the researchers found, will likely contribute to reduced carrying capacity in low Earth orbit. Based on this scenario, they estimate that the carrying capacity — or the amount of satellites that can safely exist within the altitudes of 200 and 1,000 kilometers — could be reduced by 50 to 66 percent by the end of this century.
Read More: What Is Space Junk And Why Is It A Problem?
A Surge of Satellite Launches
Exceeding the carrying capacity would create unstable regions where collisions would create too much debris for satellites to safely operate there. The researchers say that some regions are already in danger of overcrowding due to waves of satellite launches over the past few years.
“More satellites have been launched in the last five years than in the preceding 60 years combined,” said lead author William Parker, a graduate student at MIT’s AeroAstro department, in a statement. “One of [the] key things we’re trying to understand is whether the path we’re on today is sustainable.”
Currently, there are over 10,000 satellites occupying low-Earth orbit, and this number is expected to skyrocket in the coming years. Mega-constellations, which are networks of hundreds or thousands of communication satellites being launched into space, could start to destabilize already congested areas in the upper atmosphere. Starlink, one such constellation headed by SpaceX, is looking to launch up to 42,000 satellites.
Cleaning Up Space
While missions aren’t being thwarted by space debris just yet, the risk of damage is still present. According to the European Space Agency, collisions with debris larger than 1 cm would disable a spacecraft, and collisions with millimeter-size debris could still cause local damage.
The ESA plans to partner up with Swiss aerospace company ClearSpace to launch the first ever space debris removal project in 2025, sending a “chaser” spacecraft to retrieve a space debris target with its four robotic arms. However, the cost and potential for atmospheric pollution related to these types of projects have raised concerns.
The new study offers another solution here on Earth: slashing greenhouse gas emissions. Doing so may help restore order to the upper atmosphere.
“We rely on the atmosphere to clean up our debris. And if the atmosphere is changing, then the debris environment will change too,” Parker added in the statement. “We show the long-term outlook on orbital debris is critically dependent on curbing our greenhouse gas emissions.”
Read More: Space Junk Is Falling in Airplane Flight Paths, but Chances of Impact Is Low
Article Sources
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Jack Knudson is an assistant editor at Discover with a strong interest in environmental science and history. Before joining Discover in 2023, he studied journalism at the Scripps College of Communication at Ohio University and previously interned at Recycling Today magazine.
