Captured by astronaut Don Pettit aboard the International Space Station (ISS), this long-exposure photograph showcases Earth’s city lights, the upper atmosphere’s airglow, and streaked stars. The bright flashes at the center are reflections of sunlight from SpaceX’s Starlink satellites in low-Earth orbit.
Image credit: NASA
The ongoing human attack on Earth’s atmosphere is resulting in climate change according to a majority of the scientific community. That alteration, in part, involves increasing greenhouse gas emissions.
A new study by researchers report that this change will reduce the atmosphere’s ability to “burn up” space clutter.
MIT aerospace engineers have found that greenhouse gas emissions are changing the environment of near-Earth space in ways that, over time, will reduce the number of satellites that can sustainably operate there.
The new research has been published in Nature Sustainability.
Thermosphere contraction
Carbon dioxide and other greenhouse gases can cause the upper atmosphere to shrink. Of special interest is the thermosphere because when the thermosphere contracts, the decreasing density reduces atmospheric drag.
Image credit: NOAA
That reduction in atmospheric drag affects the force that pulls satellites and other space riff-raff down to altitudes where they encounter air molecules, causing reentry into Earth’s atmosphere.
Less drag therefore means extended lifetimes for space junk, which will litter sought-after regions for decades and increase the potential for collisions in orbit, the research team points out.
Fragile state
“The upper atmosphere is in a fragile state as climate change disrupts the status quo,” explains William Parker, a graduate student in MIT’s Department of Aeronautics and Astronautics (AeroAstro) and lead author of the work.
“At the same time, there’s been a massive increase in the number of satellites launched, especially for delivering broadband internet from space,” Parker adds. “If we don’t manage this activity carefully and work to reduce our emissions, space could become too crowded, leading to more collisions and debris,” he states in a MIT research statement release.
Falcon 9 booster topped with sixty Starlink satellites.
Credit: SpaceX
Enter the megaconstellation
Says study member Richard Linares, associate professor in MIT’s AeroAstro department: “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.”
Enter the megaconstellation, a new trend, Linares notes, “and we’re showing that because of climate change, we’re going to have a reduced capacity in orbit.” Furthermore, in local regions, “we’re close to approaching this capacity value today.”
Observes Parker: “We rely on the atmosphere to clean up our debris. If the atmosphere is changing, then the debris environment will change too.”
Their research work includes co-author Matthew Brown of the University of Birmingham.
“We show the long-term outlook on orbital debris is critically dependent on curbing our greenhouse gas emissions,” says Parker.
In-orbit explosions can be related to the mixing of residual fuel that remain in tanks or fuel lines once a rocket stage or satellite is discarded in Earth orbit. The resulting explosion can destroy the object and spread its mass across numerous fragments with a wide spectrum of masses and imparted speeds.
Credit: ESA
Over-utilized
Considering the recent, rapid expansion in the number of satellites in low Earth orbit, the study team points out that understanding environmental variability and its impact on sustainable operations is necessary to prevent over-exploitation of the region.
“On-orbit satellite failures, explosions and collisions have contributed to a large population of non-maneuverable and often non-trackable debris objects. Meanwhile, decreasing launch costs and maturing satellite technology have created conditions favorable for rapid commercialization across orbital regimes, especially in LEO [Low Earth Orbit],” Parker and his fellow researchers state.
“If no governance action is taken to manage the occupation of Earth’s orbit, the environment will very likely become over-utilized, diminishing the orbital resource and limiting future access,” the study team observes. “Any realistic projection of the orbital debris environment should consider that fragmentation events (collisions, explosions, anti-satellite weapon tests and so on) will occur.”
This research is supported, in part, by the U.S. National Science Foundation, the U.S. Air Force, and the U.K. Natural Environment Research Council.
To read the research paper – “Greenhouse gases reduce the satellite carrying capacity of low Earth orbit” – go to:
https://www.nature.com/articles/s41893-025-01512-0