“When energy from a solar storm reaches Earth, it causes the atmosphere to expand slightly, meaning that satellites flying in what would normally be a safe, 209 km parking orbit are suddenly encountering a lot of air resistance that can pull them back to the ground. SpaceX was aware of the problem as soon as the 49 satellites reached space and attempted to ride out the storm, positioning the relatively flat-shaped spacecraft edge-forward, to minimize air resistance.”
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“But in this case physics has a bigger vote than SpaceX, and the safe-mode maneuver worked for only nine of the fleet of 49. The others were effectively clawed out of the sky and are already reentering the atmosphere or will begin to do so by the end of the week.”
https://www.yahoo.com/news/solar-storm-knocks-40-spacex-173705826.html