Solar Storms Are Pushing Elon Musk's Satellites Back to Earth

Gizmodo

2 days ago

New research suggests that heightened solar activity shortens the lifespans of SpaceX's Starlink satellites, and may send them careening back to Earth at greater velocities. Perhaps unintuitively, this could increase the risk of satellite debris making landfall.
This preprint study, which has yet to undergo peer review, adds to a wealth of evidence showing that solar storms wreak havoc on Elon Musk's Starlinks. Over the last several years, the frequency and intensity of these storms have increased as the Sun approaches solar maximum—the peak in its 11-year cycle. At the same time, the number of satellites orbiting Earth has skyrocketed, largely due to the rise of private megaconstellations like Starlink.
A team of researchers led by Denny Oliveira from NASA's Goddard Space Flight Center tracked reentries of Starlink satellites between 2020 and 2024. This period coincided with the rising phase of the current solar cycle, when solar activity ramps up ahead of the solar maximum, which occurred in October 2024.
Over the course of those five years, 523 Starlink satellites reentered Earth's atmosphere. Oliveira and his colleagues analyzed the orbits of these satellites using a statistical technique that identifies patterns in how their rates of orbital decay and reentry change during periods of high solar activity.
The researchers found that geomagnetic activity—disturbances in the upper atmosphere triggered by solar eruptions—causes Starlinks to reenter Earth's atmosphere sooner than expected. These satellites are designed to remain in orbit for roughly five years. But during bouts of severe geomagnetic storms, their lifespans may be reduced by 10 to 12 days, Oliveira told Gizmodo.
He and his colleagues believe this happens because geomagnetic activity heats the atmosphere and causes it to expand. This increases drag on satellites, shortening their lifespans and causing them to lose altitude more quickly as they interact with the upper atmosphere. What's more, atmospheric drag may increase the chances of satellite-on-satellite collisions, as the orbital models that guide collision avoidance measures don't fully account for the effects of geomagnetic activity. The team's findings are currently available on the preprint server arXiv.
A difference of 10 to 12 days may not sound like a big deal, but it could make it nearly impossible for SpaceX to ensure that Starlink satellites return to Earth via controlled reentry, Oliveira explained. What's more, his analysis shows that increased drag causes satellites to reenter at higher velocities, which he believes could raise the chances of debris reaching the ground.
This may seem counterintuitive, since increasing the velocity of an object during reentry generally increases the likelihood of total disintegration. But Oliveira posits that Starlinks falling at greater speeds may have a better chance of surviving reentry due to reduced atmospheric interaction. Further research will need to confirm this hypothesis, as the study did not directly assess debris risks.
Starlinks are designed to fully burn up during reentry, but that doesn't always happen. In 2024, a 5.5-pound (2.5-kilogram) chunk of Starlink debris made landfall on a farm in Saskatchewan, New Scientist reported. In February of this year, SpaceX said it is possible for Starlink debris fragments to fall back to Earth, but claimed that this poses 'no risk to humans on the ground, at sea, or in the air.'
There are now more than 7,500 Starlinks in orbit, according to Harvard University astronomer Jonathan McDowell, who tracks the constellation. Eventually, SpaceX hopes to quintuple the size of this fleet, with a goal of launching 42,000 Starlinks in total, according to Space.com. This is in addition to the thousands of other satellites currently orbiting Earth.
'[This is] the first time ever in history that we have so many satellites in orbit at the same time,' Oliveira said. 'So, now, we have satellites reentering pretty much every week. And possibly, in the next months or years, every day.' Understanding how changes in solar activity impact their lifespans and their reentries will be critical as Earth's orbit becomes increasingly crowded.