WASHINGTON — A pair of main geomagnetic storms this yr led to unprecedented “mass migrations” of 1000’s of satellites in low Earth orbit that create new issues about house site visitors coordination.
The phenomenon was first seen in May throughout a significant photo voltaic occasion referred to as the Gannon storm. That occasion is finest remembered for creating auroral shows within the northern hemisphere at latitudes a lot additional south than regular.
The storm additionally elevated atmospheric density at low Earth orbit altitudes by as much as an order of magnitude, mentioned William Parker of the Massachusetts Institute of Technology throughout a presentation on the annual assembly of the American Geophysical Union right here Dec. 9. That elevated density leads to extra drag, affecting satellite tv for pc orbits.
The first drawback was the low accuracy of forecasts of the timing, magnitude and period of the storm. “As a results of this low talent in our forecasts, SpaceX noticed 20 kilometers of place error of their one-day computations” of the orbits of Starlink satellites, he mentioned. “If we’re unsure in the place our spacecraft are by 20 kilometers, then you’ll be able to throw collision avoidance out the window.”
The drawback was compounded by a lack of awareness of simply how inaccurate the forecasts had been on the time. “We had been fairly assured in these dangerous options,” he mentioned. “Being assured within the incorrect reply essentially modifications the choices that we’re making whether or not or to not maneuver the spacecraft.”
The second subject got here shortly after the height of the storm. The elevated drag triggered satellites’ orbits to decay to the purpose the place they carried out maneuvers, usually automated, to lift their orbits to the altitudes they had been at earlier than the storm. In the final geomagnetic storm of the identical magnitude because the Gannon storm, in 2003, there was a rise by an element of two to a few from the baseline of about 10 satellites a day making orbit-raising maneuvers.
After the Gannon storm there was a far sharper response. In sooner or later after the storm, almost 5,000 satellites, almost all Starlink, carried out orbit-raising maneuvers, far larger than the baseline of about 300 satellites a day. “This is half of all energetic satellites deciding to maneuver at one time,” Parker mentioned. “This makes it the biggest mass migration in historical past.”
That document, he added, was damaged in October after one other geomagnetic storm with a barely larger variety of satellites transferring in sooner or later, the distinction being the addition of a whole lot of Starlink satellites launched within the months between the 2 occasions.
Those mass maneuvers additional complicate collision avoidance efforts already hampered by the place errors from the storm. “Then we don’t know when a collision goes to occur. We lose that functionality for days at a time,” he mentioned.
That wasn’t appreciated on the time by satellite tv for pc operators, he mentioned, due to a lack of information of the place errors and the mass-migration phenomena. “Lots of operators continued to maneuver as if nothing was incorrect, however all of these maneuvers had been pointless as a result of they didn’t signify actuality.”
That underscores the necessity, he concluded, for improved house climate fashions and forecasts. “This is a big impression,” he mentioned. “This is essential infrastructure to all of our house operations transferring ahead, and it’ll solely grow to be extra vital as time goes on.”
