A giant solar storm in May that lit up night skies around the world with colorful displays of aurora borealis caused chaos in orbit, with thousands of satellites forced to maneuver simultaneously to maintain altitude amid the sudden swelling of the upper atmosphere.
Satellites and other space debris in low Earth orbit — the region of space that reaches an altitude of 1,200 miles (2,000 kilometers) — were sinking toward the planet at a speed of 590 feet (180 meters) per day during the four-day storm, according to a preprint paper posted to the online repository arXiv on June 12.
To compensate for the loss of altitude, thousands of spacecraft began firing their engines at the same time to climb back up. The authors of the study suggest that this collective movement may have led to dangerous situations because collision avoidance systems did not have enough time to calculate the satellites’ changing paths.
The solar storm that struck Earth from May 7 to 10, 2015, reached a G5 intensity, the highest level on a 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.
However, the paper’s authors point out that the environment around the planet has changed dramatically since then. Whereas just a few hundred satellites orbited Earth twenty years ago, today there are thousands. The paper’s authors estimate the number of “active payloads” at about 1.5 billion satellites. [low Earth orbit]”At 10,000.”
“The May 2024 geomagnetic storm was the first major storm to occur during a new paradigm in low-Earth orbit satellite operations dominated by small commercial satellites,” wrote the study’s authors, William Parker and Richard Linares of MIT.
Solar storms, caused by massive eruptions of charged gas from the Sun, disrupt the Earth’s magnetic field. As a result, charged solar particles penetrate deep into the Earth’s atmosphere, where they interact with air molecules. These interactions produce the spectacular northern and southern lights, but they also heat the atmosphere and cause it to swell. As a result, the density of the remaining gases scattered at the altitudes at which satellites orbit increases. The satellites, suddenly struggling against a thicker medium, begin to lose altitude.
The new study suggests that space weather forecasts ahead of the May storm failed to accurately predict the duration and intensity of the event, making satellite collision predictions nearly impossible.
“The storm posed a serious challenge to the existing conjugation assessment infrastructure by causing significant and unpredictable disruptions to the trajectories of low-Earth orbit satellites,” the authors wrote. “Automated station-keeping operations, particularly from the Starlink constellation, caused nearly half of all active low-Earth orbit satellites to ground.” [low Earth orbit] “It was very difficult or impossible to identify possible conjunctions during the storm and in the days following it.”
On the other hand, the storm helped clear some debris from Earth after dead satellites and other debris slid deep into the atmosphere. The report’s authors estimate that thousands of space objects lost several kilometers of altitude during the storm.
More powerful solar storms are expected in the coming months, with the peak of the current solar cycle — an 11-year ebb and flow of sunspots and solar flares — expected in late 2024 and early 2025.
the paper Accepted for publication in the journal Spacecraft and Rockets.
