MOUNTAIN VIEW, Calif. — Up to 80% of the Starlink satellites launched by SpaceX last week will soon reenter, or have already done so, because a geomagnetic storm kept the spacecraft from raising their orbits.
SpaceX said late Feb. 8 that the 49 satellites it launched Feb. 3 were affected by a geomagnetic storm the next day. Such storms, triggered by solar activity like coronal mass ejections, can increase the density of the upper atmosphere, including at the initial low orbit SpaceX uses to check out Starlink satellite before raising them to their higher operational orbits.
“Onboard GPS suggests the escalation speed and severity of the storm caused atmospheric drag to increase up to 50 percent higher than during previous launches,” the company said. “The Starlink team commanded the satellites into a safe-mode where they would fly edge-on (like a sheet of paper) to minimize drag—to effectively ‘take cover from the storm’—and continued to work closely with the Space Force’s 18th Space Control Squadron and LeoLabs to provide updates on the satellites based on ground radars.”
Exacerbating the problem is the low orbit used by SpaceX for deployment of Starlink satellites, with a perigee of only 210 kilometers. The company says it intentionally uses the low orbit so that any spacecraft that fails initial tests after reaching orbit will quickly deorbit naturally.
That safe mode, though, kept the satellites from raising their orbits using their onboard electric propulsion, and was also not enough to counteract the increased atmospheric drag. “Preliminary analysis shows the increased drag at the low altitudes prevented the satellites from leaving safe-mode to begin orbit raising maneuvers, and up to 40 of the satellites will reenter or already have reentered the Earth’s atmosphere,” SpaceX stated.
The company added that the satellites posed no risk to other spacecraft in orbit and that the spacecraft are designed to burn up completely on reentry.
While SpaceX emphasized the severe nature of the storm, forecasts before the launch, and data collected during it, indicated only a minor storm. NOAA’s Space Weather Prediction Center said Feb. 2 it expected a moderate geomagnetic storm, rated G2 on a scale of G1 to G5, that day, going down to G1 on Feb. 3, the day of the launch. The Space Force’s Space Launch Delta 45 prediced only a low risk from space weather in the last forecast it issued before the launch. Other satellite operators have not reported issues with their spacecraft, but were not in SpaceX’s unique position of having satellites in very low orbits.
The incident could be a precursor for more space weather problems in the future as the sun moves into a more active phase of its 11-year cycle. Solar events have occasionally in the past caused problems for individual satellites, such as damaging or disabling electronics.
This solar cycle, though, will take place amid a boom in the deployment of small satellites in low Earth orbit, many of which do not use customized and expensive radiation-hardened electronics. In a presentation at the SmallSat Symposium here Feb. 8, Carissa Christensen, founder and chief executive of Bryce Space and Technology, said the number of active satellites has grown from about 1,000 five years ago to more than 5,000 today. “That’s a big leap,” she said.
That growth is driven by small satellites, which Bryce defines as those weighing no more than 600 kilograms. In 2016, 126 such satellites were launched, compared to 1,743 in 2021. About three-quarters of the smallsats launched in 2021 belonged to Starlink and another satellite megaconstellation, OneWeb.
