Satellites face new challenges from solar storms

Rising levels of carbon dioxide in our atmosphere aren’t just affecting climate on Earth — they could also make weather in space more dramatic, says new research.

A team led by scientists from the National Center for Atmospheric Research (NCAR) in Boulder, Colorado, reports that the Earth’s upper atmosphere is changing how it responds to energy dumped from space during geomagnetic storms. Their findings, published June 14, 2025, in the journal Geophysical Research Letters, reveal that higher levels of carbon dioxide will make the upper atmosphere less dense overall — but more prone to dramatic increases in density during solar storms.

These atmospheric fluctuations can increase drag on satellites in orbit, which could have significant implications for technology like GPS, satellite internet, and spacecraft like the International Space Station.

Earth’s protective blanket

To understand this discovery, it’s essential to first understand our planet’s atmosphere. It isn’t a single, uniform entity but more resembles a multi-layered cake, with each layer defined by distinct temperature characteristics. We live and breathe in the troposphere, the lowest layer, where weather occurs. Above that lies the stratosphere, home to the ozone layer that protects us from the Sun’s harmful ultraviolet radiation. Next is the mesosphere, where most meteors burn up.

The focus of this new research is on the thermosphere, which extends from about 50 to 440 miles (80 to 700 kilometers) above the Earth’s surface. This is the realm of the aurora borealis and the International Space Station (ISS). The air here is incredibly thin, but it plays a crucial role as the first line of defense against solar radiation. The thermosphere absorbs extreme ultraviolet (EUV) and X-ray radiation from the Sun, which heats this layer and causes its temperature to increase with altitude. Despite the high temperatures, the density is so low that it would feel frigid. This region is where the drama of space weather unfolds.

Solar storms: When the Sun erupts

Our Sun is an active star that constantly sends a stream of charged particles, known as the solar wind, out into space. Sometimes, it releases massive eruptions of plasma with magnetic fields called coronal mass ejections (CMEs). When these solar outbursts are directed at Earth, they can trigger a geomagnetic storm — a major disturbance of our planet’s magnetosphere, the magnetic bubble that surrounds and protects Earth.

These storms are powerful events. They can induce intense electrical currents in the magnetosphere and ionosphere, create spectacular auroral displays far from the poles, and pose risks to our technology. 

Geomagnetic storms can disrupt GPS navigation, damage transformers on power grids, and, crucially for this study, heat and expand the upper atmosphere. This expansion increases the density of the thermosphere. 

For satellites in low-Earth orbit, this is like flying into a stronger headwind. Atmospheric drag is friction caused by a satellite colliding with the sparse molecules of gas in the upper atmosphere. When the density increases, there are more of these molecules in the satellite’s path. Each collision, though tiny, slows the satellite down. The cumulative effect of hitting millions of these extra particles creates significant drag. This drag can alter a satellite’s speed and altitude and shorten its operational lifespan; for instance, a storm in February 2022 created enough atmospheric drag to cause the loss of 38 Starlink satellites, while the intense storm of May 2024 also contributed to the premature reentry of several others.

A new atmospheric recipe

The composition of our atmosphere is changing, and not just near the surface. While carbon dioxide (CO₂) is well-known for its warming effect in the lower atmosphere — the greenhouse effect that traps heat and makes our planet habitable — it behaves differently at high altitudes. In the thin environment of the thermosphere, CO₂ molecules are more effective at radiating heat back out into space. This means that as CO₂ concentrations increase globally, the upper atmosphere is cooling and contracting, leading to a lower baseline density over time.

This fundamental shift in the thermosphere’s normal condition is what prompted the new research. Scientists wanted to know: How will an upper atmosphere that is cooler and less dense respond when hit by the energy of a powerful geomagnetic storm?

To find the answer, the research team used an advanced computer model that connects the layers of the atmosphere, allowing them to see how changes near the surface can influence regions hundreds of miles above. They simulated the powerful geomagnetic superstorm of May 10–11, 2024, using atmospheric conditions from a baseline year, 2016, which was chosen because it occurred during the minimum of the 11-year solar cycle.

With this baseline established, they ran the simulation again, keeping the storm’s intensity the same but changing the atmospheric conditions to reflect future projections based on standard climate model simulations. They modeled how the same storm would behave in three future solar minimum years: 2040, 2061, and 2084. This selection allowed for a direct comparison, isolating the effect of atmospheric changes from the Sun’s natural variability.

The results were striking. Because the atmosphere’s baseline density will be lower to begin with, the researchers found that the peak density during a future storm would also be lower, 20 to 50 percent less dense than what we would see today.

However, the most significant finding was the relative change from the pre-storm condition. While a strong storm today might cause the thermosphere’s density to double, the simulations showed that in the future, a similar storm would cause the density to nearly triple from its much lower starting point. Although the study used a high-emissions scenario to clearly illustrate this effect, Nicolas Pedatella, the study’s lead author, tells Astronomy, “The results of our study indicate that even more moderate increases in greenhouse gases would also still impact the upper atmosphere response to a geomagnetic storm.”

While these predictions are a major step forward, the scientists note that there are still complexities to explore. For instance, rising surface temperatures, caused by the greenhouse effect in the lower atmosphere, could cause the lower atmosphere to expand. This expansion could potentially offset some of the cooling and contracting effects in the thermosphere.

A changing world for satellites

This shift could have profound consequences. While a lower peak density might sound like good news, the greater variability is the real challenge for satellite operators. According to Pedatella, the larger relative change in density means that geomagnetic storm impacts will become “more severe.” This creates a more volatile environment where atmospheric drag can change rapidly and dramatically. 

For instance, during the May 2024 geomagnetic superstorm — the strongest such storm in 20 years — the increase in atmospheric density caused nearly half of all satellites in low Earth orbit to automatically fire their thrusters in an attempt to stay spaceborne, a study found. Such “mass migrations” make it harder to predict satellite orbits, as space-tracking systems can’t keep up with the changes. This increases the risk of collisions with other satellites or space debris.

As Pedatella explained in an August 2025 press release, “For the satellite industry, this is an especially important question because of the need to design satellites for specific atmospheric conditions.”More research is needed to fully grasp how different types of storms and the Sun’s 11-year cycle will interact with our changing atmosphere. But this study makes one thing clear: As increasing levels of CO₂ continue to alter the composition of our atmosphere, we are also changing its relationship with the Sun and the very nature of space weather.