Starlink satellite tracks seen from space
Don Pettit/NASA
The number of satellites in orbit is growing at a tremendous rate, but we don't yet have a clear understanding of how susceptible they are to solar storms – and this problem will only get worse.
Since May 2019, SpaceX has launched more than 10,000 satellites into its Starlink space internet megaconstellation, although about 1,000 of them have already been launched. re-entered the Earth's atmosphere at the current price one or two per day. The satellites are deployed in a gigantic network around the planet, covering almost the entire globe. This means that a solar storm and accompanying geomagnetic storm, where our planet's magnetic field fluctuates in response to charged particles and the sun's magnetic fields, will likely affect at least some satellites, no matter when it happens.
To investigate the impact of such storms on Starlink, Eunju Kang from the University of California, Irvine, and her colleagues examined publicly available satellite tracking data from the May 2024 solar storm.
They found that at the height of the storm, Starlink satellites on the sun-facing side of Earth experienced an altitude drop of up to half a kilometer—a small drop in their 550-kilometer orbits, but still significant as the atmosphere was exposed to incoming solar radiation, creating drag on the spacecraft.
Satellites in other regions were also severely affected, such as satellites near the Earth's poles, where our planet's magnetic field directs more charged particles from the Sun, and satellites located over a region of South America called South Atlantic Anomaly where, for unknown reasons, the planet's magnetic field is weaker and therefore the atmosphere is more susceptible to solar activity.
According to the data the team had, this created an unusual effect in the constellation, Kang says. “If one satellite loses altitude, a nearby satellite will also have to compensate,” she says, using its onboard ion thrusters to automatically match with the affected satellite as the satellites communicate with each other using line-of-sight lasers to maintain the network, creating a ripple effect as other satellites in the chain follow suit. “It looks like waves,” says a team member. Sangeeta Abdu Jyotialso at the University of California, Irvine.
This could create problems for other satellites trying to navigate the Starlink constellation to avoid collision. “When we have less predictability in trajectories, it can increase the risk of collisions,” says Abdu Jyoti.
Other publicly available data also sheds light on the impact of solar storms. Some Starlink customers use an online service called MATURE Satin to share your connection status. Using this data, Kang and her team found that during a solar storm in May 2024, network outages were reported as satellites were disrupted. “There was an immediate spike in packet losses,” says Kang, where data doesn’t reach its destination.
The study highlights the challenges that constellations like Starlink, as well as emerging constellations like Amazon's Project Kuiper and several projects in China, will face due to solar activity, not only from a communications perspective, but also in terms of avoiding large position changes that could cause collisions with other satellites.
In February 2022, a powerful solar storm hit the Earth. 40 Newly Launched Starlink Satellites back into the atmosphere where they burned up. Earlier this year, another study found that increased solar activity was hastening death some Starlink satellites.
The May 2024 solar storm was about three times weaker than the largest solar storm on record. Carrington Event of 1859. A storm of this record size is likely to hit Earth again at some point, which could cause big problems for megaconstellation operators. “With a very strong storm, it will be much worse,” says Abdu Jyoti. “But we don't know how much worse.”
In the meantime, I hope we have time to prepare. The May 2024 storm occurred during the peak of solar activity, which operates on a 22-year cycle. A powerful storm could theoretically strike at any time, but will become more likely in the 2040s when the star's activity peaks again. By then there will likely be tens of thousands, if not hundreds of thousands, more satellites in orbit, compared to about 13,000 in orbit today. “The more satellites you have, the bigger the problem,” says Scott Shambaughfounder of Leonid Space, an American company that monitors the effects of space weather on satellites.
“When a solar storm hits, we don't yet have good predictive models of how it will affect resistance in the shorter term,” Shambaugh says. “This means that over the next few hours or days, your companions will not be where you think they will be.”
Matthew Owens from the University of Reading, UK, says one particularly poorly understood area is substorms, small changes in our atmosphere caused by heating from solar activity that can disproportionately affect satellites in different orbits. “A geomagnetic storm consists of many substorms,” he says, but “they are incredibly difficult to predict.”
Constellations such as Starlink provide a unique window into this activity, essentially acting as a giant research network of probes in Earth orbit. “These satellites are probably the first data sensors we have about how local changes in atmospheric drag occur,” says Abdu Jyoti.
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