Solar Storms From Raging Sun Are Set to Make Satellites Fall From Sky

Satellites are being pushed out of their orbits by the sun as space weather is set to get even more intense over the next few years.

Back in February, Elon Musk's rocket company SpaceX announced that as many as 40 of its internet-beaming Starlink satellites had been destroyed after a burst of solar activity caused them to fall out of orbit.

The solar activity caused Earth's atmosphere to heat up, increasing the amount of drag that the Starlink satellites experienced in their relatively low orbits. The satellites, which had just been launched, entered a "safe-mode" and flew edge-on to try and minimize this drag—but dozens of them were unable to correct their altitudes and ultimately plummeted back to Earth where they likely vanished in balls of flame.

Solar flare
An image of a solar flare erupting from the side of the sun seen in January, 2015, by NASA's Solar Dynamics Observatory. Flares are examples of solar activity that may increase during the sun's solar cycle. NASA/SDO

The incident will have been an expensive but minor setback for SpaceX, which had already launched over 1,500 Starlink satellites into orbit by that point. For other space operators, losing multiple satellites could be a more significant issue.

The European Space Agency (ESA) has noticed that a number of its Swarm satellites, which are built to study Earth's magnetic field, have been sinking fast. A couple of weeks ago, Anja Stromme, Swarm mission manager, told Space.com that, between December and April, the satellites had sunk at a rate of 12 miles per year—roughly 10 times faster than in the past several years.

The Swarm satellites operate at an altitude of around 300 miles high—a similar altitude to Starlink satellites. The difference is that while SpaceX currently has over 2,000 Starlink satellites in orbit, the number of Swarm satellites is: three. In short, the ESA can't afford to lose any without disruption to the mission.

"But since December last year, they have been virtually diving," Stromme told Space.com. "It's almost like running with the wind against you. It's harder, it's drag—so it slows the satellites down, and when they slow down, they sink."

This increased drag is probably due to solar wind—streams of energetic particles released from the sun—and other solar eruptions like solar flares and coronal mass ejections. When this solar material interacts with our atmosphere, denser air moves higher.

The reason the drag is increasing now is because the sun is becoming more and more active as part of its current, roughly 11-year solar cycle. Each solar cycle sees the sun move from a quiet period to a very active one, and it's currently building up to peak activity.

Scientists are not unprepared for this. Satellites in low Earth orbit face a small amount of drag all the time due to tiny amounts of atmosphere present, so they're often built with on-board thrusters that can be used to boost their altitude every so often.

The International Space Station, for example, regularly has altitude boosts to prevent it from sinking too low.

Still, satellite operators will have to be increasingly vigilant to offset the power of the sun over the coming years.