WASHINGTON -- A pair of significant geomagnetic storms this year resulted in unprecedented "mass migrations" of thousands of satellites in low Earth orbit, raising new concerns about space traffic coordination.
The phenomenon first emerged in May during a major solar event known as the Gannon storm, which was notable for creating auroral displays at unusually low latitudes in the northern hemisphere.
William Parker from the Massachusetts Institute of Technology, speaking at the annual meeting of the American Geophysical Union on December 9, explained that the storm increased atmospheric density at low Earth orbit altitudes by as much as an order of magnitude. This heightened density leads to increased drag on satellites, impacting their orbits.
One major issue was the poor accuracy of forecasts regarding the storm's timing, magnitude, and duration. Parker noted, "As a result of this low skill in our forecasts, SpaceX saw 20 kilometers of position error in their one-day computations" of Starlink satellite orbits. He emphasized that such uncertainties undermine collision avoidance efforts.
The situation worsened due to a lack of understanding regarding the extent of forecast inaccuracies. Parker stated, "We were pretty confident in those bad solutions. Being confident in the wrong answer fundamentally changes the decisions we're making about maneuvering spacecraft."
Following the storm's peak, increased drag caused satellites to decay in their orbits, prompting many to perform automated maneuvers to regain their previous altitudes. In 2003, during a similar geomagnetic storm, about 10 satellites a day executed orbit-raising maneuvers. However, after the Gannon storm, nearly 5,000 satellites, primarily Starlink, performed such maneuvers in one day, marking the largest mass migration in history.
This record was surpassed in October after another geomagnetic storm, which saw an even higher number of satellites moving in a single day, largely due to the addition of hundreds of newly launched Starlink satellites.
The mass maneuvers complicate collision avoidance efforts, already hindered by position errors from the storm. Parker highlighted that operators struggled to gauge collision risks due to a lack of awareness about the position errors and the mass migration phenomenon. Many continued to maneuver as if conditions were normal, rendering their efforts ineffective.
He concluded by stressing the importance of improved space weather models and forecasts, stating, "This is a significant impact. This is critical infrastructure to all of our space operations moving forward, and it will only become more important as time goes on."