Earth’s carbon footprint now threatens satellite operations

In an unexpected shift to the consequences of climate change, researchers at MIT have found that our greenhouse gas emissions are not just about warming the planet, they can dramatically change the environment in near-Earth space, possibly reducing the safety operation capabilities of satellites by more than half by the end of this century.

The study, published on March 10 in Natural Sustainability, reveals how carbon dioxide and other greenhouse gases cause the upper atmosphere to shrink, creating a series of effects that could ultimately render certain orbital areas unable to operate with satellites.

“Over the past 100 years, our behavior of using greenhouse gases on Earth has had an impact on the way we operate satellites over the next 100 years,” explained study author Richard Linares, associate professor in the Department of Aeronautics and Astronautics in MIT.

Although most climate discussions focus on temperature and extreme weather events on Earth, this study highlights how human activity changes the environment hundreds of miles above our heads (in the thermal sphere, the International Space Station and where most current satellite orbits are).

With the explosion of satellite population in recent years, the results of the discovery are at critical moments. “In the past five years, more satellites have been launched in the past five years than in the past sixty years,” said William Parker, head of graduate William Parker at MIT. “One of the key things we are trying to understand is whether our path today is sustainable.”

The problem stems from the unexpected interaction between greenhouse gases and the upper atmosphere. Although these gases capture heat in the lower atmosphere (which leads to the global warming we experience on the Earth’s surface), the effect is the opposite at higher altitudes. In the thermal layer, greenhouse gases actually emit heat, cooling the atmosphere and causing shrinkage.

This shrinkage reduces the atmospheric density at the satellite’s height, thus reducing the resistance in the atmosphere – this natural force pulls aging satellites and space debris to burn in the atmosphere. Less resistance means space garbage stays in orbit longer, increasing the risk of collisions for operating satellites.

“Literally, the sky just falls, just for decades of speed,” Parker said. “We can see this by how we change the drag of the satellite.”

The team’s simulation drew a striking picture. By comparing several options from the intergovernmental group based on climate change forecasts, they found that the continued increase in emissions could reduce the “carrying capacity” of low-Earth orbit by 50 to 66% compared to scenarios that hold at the Year-2000 level.

This “carrying capacity” (a concept borrowed from ecology) describes how many satellites can operate safely in a given area of ​​space without excessive collision risk. If exceeded, some orbital areas may experience what researchers call “out of control instability” – a series of collisions caused so much debris that the satellite could not operate safely there.

Given the rapid deployment of “Megaconstellations” like SpaceX’s Starlink, the time is especially about the timing of the rapid deployment of SpaceX Starlink, which is planned to operate thousands of internet satellites in low-Earth orbit.

“Large structures are a new trend and we show that our orbital capacity will be reduced due to climate change,” Linares said. “In local areas, we are close to the value of our capacity today.”

Satellite services have been woven into the structure of modern life, from the Internet and communications to the basic functions of weather forecasting, navigation and banking. Therefore, a reduction in predicted safety track capacity may have profound implications for technology-dependent societies.

The thermal circle will naturally expand and contract over an 11-year cycle in response to the activity of the sun. Scientists have had theories that greenhouse gases may affect the region since the 1990s, but only in the past decade have they been able to measure changes in satellite drag, confirming that the thermal layer does shrink expectations of natural solar cycles.

In their study, the MIT team, including co-author Matthew Brown of the University of Birmingham, developed sophisticated models that combine atmospheric physics with orbital dynamics to estimate how different climate scenarios affect specific “shells” or altitude range satellites typically operate.

This study highlights our inadequate dependence on natural systems. “We rely on the atmosphere to clean up the debris. If the atmosphere changes, the debris environment will change,” Parker explained. “We show that the long-term prospects for orbital debris depend primarily on curbing our greenhouse gas emissions.”

This adds a new dimension to climate policy discussions, suggesting that sustainable practices on Earth are needed not only to protect the land environment, but also to protect human opportunities to enter near-Earth space, which is an increasingly important boundary for communication, science and security.

As our digital infrastructure becomes increasingly dependent on satellite services, this study shows that addressing climate change is not just about preserving the planet, but about maintaining our ability to use the space around us.