Here’s what you’ll learn when you read this story:
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With more and more Internet satellites being launched each year, scientists are increasingly concerned about the increasing risk of collisions.
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The CRASH Clock is a new predictor of the time it will be before a collision if a solar storm knocks out power and makes satellites unmanageable.
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Currently, the maximum time we have for satellites to be operational again before an almost inevitable crash is only 5.5 days, and will likely decrease in the future.
More than a thousand miles above the earth, low Earth orbit is growing increasingly crowded as constellations of Internet satellites swarm the sky. What started as an effort to provide large regions of the world with affordable internet has turned into an infestation of metal bots that seem to keep multiplying.
SpaceX recently announced plans to launch a constellation of 7,500 second-generation Starlink satellites in 2031, even as it simultaneously plans to lower the orbits of the current 4,400 satellites before they crash into each other and become space junk. Starlink already still has to double its accident prevention maneuvers every six months, currently conducting about 41 of them each year. Several Chinese companies recently submitted applications to launch up to 200,000 internet satellites by the early 2030s (shortly after the government criticized Elon Musk for his Starlink operations). Every 22 seconds, two satellites pass within 1 kilometer, and this happens once every 11 minutes for Starlink satellites.
Research spacecraft are greatly outnumbered. More light pollution than ever is affecting astronomers. And the risk of collision has increased astronomically since the pre-constellation scene, potentially presaging an imminent satellite apocalypse.
Astrophysicist Sarah Thiele was particularly concerned about the rapid overcrowding of low Earth orbit, especially in the event of a solar storm that would make it impossible to maneuver satellites out of each other’s path on Earth. These craft are likely to shut down whenever there is a solar flare or coronal mass ejection. Streams of hot, charged particles cause the air to expand, burdening satellites with more atmospheric drag, which causes them to burn more fuel to prevent them from drifting out of orbit and running into other objects. And in addition to what satellites do in space, satellite navigation and communications systems can also be disabled by solar storms, cutting them off from Earth.
To address these growing concerns, Thiele and her colleagues developed what they now call the Crash and Significant Injury Achievement Clock (CRASH).
“The CRASH watch [gauges] stress on the time frame for a possible catastrophic collision to occur if there are no satellite maneuvers or there is a severe loss of situational awareness,” the team wrote in a recent study uploaded to the preprint server. arXiv. “Our calculations show that the CRASH clock is currently 5.5 days, suggesting that there is limited time to recover from a widespread disruptive event such as a solar storm.”
Before there were Starlink-style satellite swarms, craft would have had 164 days to recover before designing to hit something seriously damaging. But that was in 2018. Not even a decade later, that grace period has dwindled to less than a week. The CRASH clock took into account all the objects in low Earth orbit – even dead satellites, spent rocket stages and debris floating around – and according to the team, stopping due to a solar storm would mean the craft would only have five and a half days before an almost inevitable crash.
And this is not a distant concern, SF. The possibility of such a phenomenon is disturbingly real, as demonstrated by the Gannon storm of 2024. For three days—dangerously close to the current CRASH limit—almost half of the satellites in low Earth orbit required maneuvers to survive the intense drag they were suddenly subjected to. And while this was a significant eruption, it hardly matches the Carrington Event of 1859, which lasted several days and saw one storm follow another (at least no spacecraft were orbiting the planet back then).
While maneuvers (when we can effectively communicate with the satellites to execute them) may seem like solid solutions to this collective collision problem, they carry risks of their own. First, they create uncertainty in satellite positions, and often inaccuracies are noticed immediately after a maneuver has been performed. On the other hand, increased maneuvers mean there could be deficiencies in capabilities that are supposed to prevent collisions—anything from inaccurate tracking of a satellite’s location (which could cause it to stray from its designated orbit) to miscommunications during maneuvers that could end in disaster. Problems like this are already happening. In 2019, for example, SpaceX’s warning system malfunctioned in a way that prevented operators from seeing a higher chance of a collision, and an ESA satellite was forced to move away to allow a Starlink satellite to pass.
This problem is of such concern that the United Nations has declared that low Earth orbit is a finite resource. Every satellite launched into the limited space around our planet automatically consumes resources, and space junk does so without any additional benefit. In addition, satellites shed bits of scrap metal into the upper atmosphere and are a frustrating source of light pollution for astronomers trying to distinguish extremely faint and distant objects.
“The CRASH clock is, in part, a measure of the consumption of Earth’s orbital space and the extent to which operations there are carried out sustainably,” she said. “Increasing either the orbital density or the collision cross section decreases the collision time on orbit and reduces the margin of error for safe operations.”
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