The Sun is in its solar maximum, a period marked by intense solar eruptions and bursts of charged particles directed toward Earth. These flare-ups are having a significant influence on our satellites in low Earth orbit, causing them to shift positions in a concerning way.
This year, Earth experienced two geomagnetic storms caused by a series of solar eruptions. The solar storms affected the orbits of thousands of satellites, resulting in an unprecedented mass migration, according to William Parker, a researcher at the Massachusetts Institute of Technology, during a presentation at the annual meeting of the American Geophysical Union, SpaceNews reported.
Geomagnetic storms are disturbances in Earth’s magnetosphere—a large bubble of magnetic field around our planet—caused by solar wind. This past May, a G5, or extreme, geomagnetic storm hit Earth as a result of large expulsions of plasma from the Sun’s corona (also known as coronal mass ejections). The G5 storm, the first to hit Earth in more than 20 years, caused some deleterious effects on Earth’s power grid and some spectacular auroras seen across much of the globe.
The storm increased atmospheric density in low Earth orbit by up to an order of magnitude, which in turn caused atmospheric drag that affected satellites, according to Parker. The resulting migration of satellites was most noticeable on SpaceX’s Starlink constellation, which includes more than 6,700 satellites in low Earth orbit.
“SpaceX saw 20 kilometers [12.4 miles] of position error in their one-day computations,” Parker is quoted in SpaceNews as saying. “If we’re uncertain in where our spacecraft are by 20 kilometers, then you can throw collision avoidance out the window.” The researcher is referring to the risk of having satellites crash into each other in low Earth orbit, a danger that’s typically avoided by precisely tracking the positions of orbiting spacecraft. A satellite’s slight shift in orbits puts it at a greater risk of collision.
Following the peak of the storm, some satellites performed automated maneuvers to return to their pre-storm altitudes, correcting the shifts caused by the event. One day after the storm, nearly 5,000 satellites, mostly Starlink, performed orbit-raising maneuvers, according to Parker.
“This is half of all active satellites deciding to maneuver at one time,” he said. “This makes it the largest mass migration in history.” The maneuvers make it even harder to predict where the satellites will be from one another, increasing the risk of collision.
Scientists are still trying to understand the behavior of the Sun in order to better predict the occurrence of these geomagnetic storms, which would help satellite operators prepare their hardware in space.
