The increasing number of satellites orbiting Earth, particularly massive constellations like SpaceX’s Starlink, are facing a growing threat: solar storms. While the potential disruptions to communication networks are obvious, a recent study reveals a more complex situation—solar activity significantly affects satellite positions, potentially increasing collision risks and impacting overall satellite lifespan.
The Rising Number of Satellites and Solar Activity
SpaceX’s Starlink, a mega-constellation designed to provide global internet access, currently comprises over 10,000 satellites deployed in orbit. Although around 1,000 satellites re-enter the atmosphere regularly, the sheer scale of the constellation means it covers nearly the entire globe. This widespread presence makes Starlink – and other large constellations – highly susceptible to the effects of solar storms.
A solar storm triggers a geomagnetic storm, where fluctuations in Earth’s magnetic field are created in response to charged particles and magnetic fields from the sun. The study, conducted by Eunju Kang and her colleagues at the University of California, Irvine, investigated the impact of a solar storm in May 2024 by analyzing publicly available satellite-tracking data.
Unexpected Orbital Changes
The researchers found that during the peak of the storm, Starlink satellites facing the sun experienced a noticeable drop in altitude – as much as half a kilometer. This reduction is caused by the atmosphere expanding due to solar radiation, creating increased drag on the satellites. The effect wasn’s limited to those satellites; those near Earth’s poles and over the South Atlantic Anomaly, where the magnetic field is weaker, were also significantly impacted.
What’s more, the study revealed an unusual cascading effect: The satellites, which rely on line-of-sight laser communication to maintain the Starlink network, automatically compensate for altitude changes in neighboring satellites using on-board thrusters. This creates a wave-like effect as satellites adjust to maintain connection, which makes predicting their movements even more complex.
Increased Collision Risks and Communication Disruptions
This unexpected behavior presents a significant challenge, as unpredictable satellite trajectories increase the risk of collisions. Beyond collision risks, the May 2024 solar storm also caused reported network outages for Starlink customers, with users experiencing a spike in “packet loss” – data failing to reach its intended destination.
A Growing Problem
The situation is expected to worsen as the number of satellites in orbit continues to grow. Amazon’s Project Kuiper and several Chinese efforts are also developing large constellations. In 2022, a powerful solar storm knocked around 40 recently launched Starlink satellites out of orbit, and ongoing research indicates increased solar activity is accelerating the demise of some existing satellites.
The Looming Threat of Major Solar Events
The May 2024 storm was only three times weaker than the Carrington Event, the largest recorded solar storm in 1859. Scientists warn that a storm of that magnitude – or even larger – is likely to occur again. Predicting the precise impact of such an event is difficult, as understanding of “substorms,” smaller variations in Earth’s atmosphere, remains limited.
Currently, predictive models for short-term atmospheric drag caused by solar activity are inadequate, according to Scott Shambaugh of Leonid Space. With the expected increase in satellite numbers, the need for better prediction tools becomes more crucial than ever.
Constellations like Starlink are inadvertently providing valuable data, effectively acting as a vast network of research probes, giving us a unique understanding of how local atmospheric drag variations occur. — Sangeetha Abdu Jyothi, University of California, Irvine
In conclusion, the growing reliance on satellite constellations brings new challenges regarding their vulnerability to solar activity. Improving our predictive capabilities and developing mitigation strategies will be essential for ensuring the long-term sustainability and safety of space-based infrastructure.
