Greenhouse Gases Are Reshaping Space

Greenhouse gas emissions are not only warming Earth but also altering near-Earth space. As emissions cool and contract the thermosphere, satellites experience less drag, allowing more space debris to accumulate.

With thousands of new satellites launching yearly, congestion in low-Earth orbit is rising, increasing the risk of catastrophic collisions. If emissions remain unchecked, experts predict that by 2100, space could become too crowded for sustainable missions.

Figure 1. Space Junk.

Shrinking Atmosphere, Growing Risks

MIT aerospace engineers, in a Nature Sustainability study, found that greenhouse gases are shrinking the upper atmosphere, particularly the thermosphere, where most satellites orbit. This contraction reduces atmospheric drag, which typically helps clear space debris by pulling it into lower altitudes to burn up. Figure 1 shows Space Junk.

Simulations indicate that by 2100, low-Earth orbit’s “satellite carrying capacity” could decrease by 50–66% due to these changes.

Climate Change and Space Sustainability

“Our emissions today are shaping satellite operations for the next century,” says MIT’s Richard Linares. Lead author William Parker warns that, alongside the surge in satellite launches, unregulated growth and rising emissions could make space overcrowded and prone to collisions.

Human Impact on the Thermosphere

The thermosphere naturally expands and contracts with the Sun’s 11-year cycle, but scientists have observed its ongoing shrinkage beyond this cycle. Greenhouse gases, while trapping heat in the lower atmosphere, radiate it away at higher altitudes, causing cooling and contraction, which disrupts satellite drag and debris clearance.Recent satellite drags measurements confirm that the thermosphere is contracting due to more than just solar activity, highlighting the urgent need for emissions control and space traffic management.

The Sky Is Falling—Gradually

“The sky is quite literally falling—just over decades,” says Parker. “We see this in the changing drag on satellites.”

MIT researchers examined how atmospheric shifts impact satellite operations in low-Earth orbit (LEO), where over 10,000 satellites provide crucial services like communication and navigation. The growing satellite population increases the risk of collisions, creating debris that lingers for decades.

Simulating Space Congestion

The team modeled greenhouse gas emission scenarios to predict their effects on atmospheric density and satellite collisions. Using the concept of "carrying capacity," they estimated how many satellites LEO can safely sustain. Their findings suggest rising emissions will drastically reduce this capacity.

The Risk of Collisions Escalates

By 2100, satellite capacity in LEO (200–1,000 km) could shrink by 50–66% if emissions continue rising. Overcrowding may trigger a “runaway instability,” where collisions generate debris, making orbits unusable. Some regions, especially those with megaconstellations like Starlink, are already nearing critical congestion.

The Atmosphere’s Role in Debris Cleanup

“The atmosphere naturally clears space debris,” Parker explains. “But as it changes, so does our ability to manage it. Long-term orbital sustainability depends on reducing greenhouse gas emissions.”

Reference:

1. https://scitechdaily.com/the-sky-is-falling-and-its-leaving-space-junk-stuck-in-orbit/
2. https://www.nationalgeographic.com/science/article/space-junk

Cite this article:

Keerthana S (2025),The Sky Is Falling – Leaving Space Junk Trapped in Orbit, AnaTechmaz,pp.255