Climate change is ‘shrinking’ space as satellites jostle for orbital real estate

Satellites could collide in space due to climate change shrinking part of the atmosphere, scientists have warned.

Space junk could get stuck in orbit due to humans damaging a layer called the thermosphere, according to MIT engineers. That would leave less room for new satellites that provide internet, navigation and weather forecasting to our planet.

Overcrowding in orbit could lead to “runaway instability” in which a cascade of collisions leaves so much debris that satellites can no longer venture to that part of space, researchers say. They predict that satellite capacity will be 50 to 66 per cent lower than without climate change.

“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,” said William Parker, the lead author of the new findings from MIT's AeroAstro department.

“More satellites have been launched in the last five years than in the preceding 60 years combined,” he said. “One of key things we’re trying to understand is whether the path we’re on today is sustainable.”

About 10,000 satellites are drifting in low-Earth orbit today, occasionally given a push to avoid collisions. The International Space Station is among the satellites drifting in the layer known as the thermosphere.

Once left to their fate, satellites are dragged down over time to an altitude where they burn up in the Earth's lower atmosphere. However, the new study reports that carbon dioxide and other greenhouse gases cause the thermosphere to shrink, which in turn reduces the “drag” effect.

'Sky is falling'

“The sky is quite literally falling – just at a rate that’s on the scale of decades,” Mr Parker said. “We rely on the atmosphere to clean up our debris. And if the atmosphere is changing, then the debris environment will change too.”

The thermosphere naturally contracts and expands every 11 years in response to solar activity, say scientists who worked on the US Air Force-funded research. However, it is believed that climate change is tampering with this natural cycle.

The predictions of a 50 to 66 per cent cut in capacity are for the year 2100, but the scientists say “megaconstellations” are already forming. One of these is the fleet of Starlink internet satellites run by Elon Musk's SpaceX.

“Our behaviour 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,” an MIT associate professor. “The megaconstellation is a new trend, and we’re showing, because of climate change, we’re going to have a reduced capacity in orbit.”

The study, Greenhouse gases reduce the satellite carrying capacity of low Earth orbit, is published today in the journal Nature Sustainability.