The Sun is in its solar maximum, a period characterized by intense solar flares and bursts of charged particles directed toward the Earth. These flares have a significant impact on our satellites in low Earth orbit, causing them to change position in an alarming way.
This year, the Earth experienced two geomagnetic storms caused by a series of solar eruptions. The solar storms affected the orbits of thousands of satellites, leading to unprecedented mass migration, said William Parker, a researcher at the Massachusetts Institute of Technology, during a presentation at the annual meeting of the American Geophysical Union, SpaceNews reports.
Geomagnetic storms are perturbations in the Earth’s magnetosphere, a large bubble of magnetic field around our planet, caused by the solar wind. Last May, a G5, or extreme, geomagnetic storm hit the Earth as a result of powerful plasma emissions from the Sun’s corona (also known as a coronal mass ejection). The G5 storm, the first in 20 years, caused devastating impacts on the Earth’s electrical grid and spectacular auroras that could be seen across much of the globe.
According to Parker, the storm increased the density of the atmosphere in low Earth orbit by an order of magnitude, which in turn caused atmospheric drag that affected the satellites. The satellite migration was most noticeable in SpaceX’s Starlink constellation, which has more than 6,700 satellites in low Earth orbit.
“SpaceX saw 20 kilometers [12.4 miles] of positioning error in its one-day calculations,” SpaceNews quoted Parker as saying. “If we’re not sure where our spacecraft are 20 kilometers away, then you can throw collision avoidance out the window.” The researcher is referring to the risk of collision between satellites in low Earth orbit, a danger that is usually avoided by precise tracking of spacecraft positions in orbit. A slight shift in orbit increases the risk of collision.
After the peak of the storm, some satellites performed automatic maneuvers to return to their pre-storm altitude, correcting the displacements caused by the event. According to Parker, nearly 5,000 satellites, mostly Starlink, performed orbit-raising maneuvers the day after the storm.
“That’s half of all active satellites that decided to maneuver at the same time,” he said. “This is the largest mass migration in history.” The maneuvers make it even more difficult to predict where satellites will be from each other, increasing the risk of collision.
Scientists are still trying to understand the behavior of the Sun to better predict the occurrence of these geomagnetic storms, which would help satellite operators prepare their equipment for space operations.
