A solar storm in May not only caused colorful auroras to light up the night sky around the world, but also chaos in orbit. Thousands of satellites had to maneuver simultaneously to maintain altitude as the upper atmosphere thickened suddenly.

According to the study, objects consisting of satellites and space debris in low Earth orbit (a region of space up to 2,000 kilometers in altitude) fell to Earth at a rate of 180 meters per day during the four-day storm.

To compensate for the loss of altitude, thousands of spacecraft simultaneously fired their engines and climbed upward. This mass maneuver could lead to dangerous situations because collision avoidance systems did not have time to calculate the changing orbits of the satellites.

The solar storm that hit Earth from May 7-10 reached G5 intensity, the highest level on the five-point scale used by the National Oceanic and Atmospheric Administration (NOAA) to rate the strength of solar storms. It was the strongest solar storm to hit Earth since 2003.

But the authors of the paper noted that the environment around the planet has changed a lot since then. If twenty years ago there were only a few hundred satellites in Earth orbit, today there are thousands. The authors estimate the number of active payloads in low Earth orbit at 10,000 objects.

“The geomagnetic storm of May 2024 was the first major storm to occur during the new paradigm in low-Earth orbit satellite operations dominated by commercial small satellites,” write study authors William Parker and Richard Linares of the Massachusetts Institute of Technology.

Solar storms, caused by powerful charged gas emissions from the Sun, disrupt the Earth’s magnetic field. As a result, charged solar particles penetrate deep into the atmosphere and interact with air molecules. These interactions give rise to the northern and southern lights, but also heat and inflate the atmosphere. As a result, the density of diluted residual gases increases at the altitudes where the satellites orbit. Satellites, struggling with a much denser environment, begin to lose altitude.

The paper notes that space weather forecasts prior to the May storm failed to accurately predict the duration and intensity of the event, making prediction of satellite collisions nearly impossible.

“The storm posed a major challenge to existing convergence assessment infrastructure because it created large, unpredictable perturbations to the orbits of low-Earth orbit satellites. The automatic altitude-holding program caused nearly half of all active satellites in low-Earth orbit to maneuver simultaneously in response to the incoming solar storm. “The combination of the number of satellites and their simultaneous maneuvers made it very difficult to identify potential convergences during the storm and in the days following,” the authors write.

On the other hand, the storm helped clear some space debris from Earth’s orbit, as failed satellites and debris spiraled deeper into the atmosphere. The authors estimated that thousands of pieces of space debris were lost at altitudes of several kilometers during the storm.

More powerful solar storms are expected in the coming months as the current 11-year solar cycle is expected to peak in late 2024-early 2025.