File this one under “We all knew it, but still needed an academic to say it out loud”: The incredible volume of satellites entering low Earth orbit (LEO) is likely unsustainable and could lead to a disaster.
On the surface, this claim is nothing new; here at ExtremeTech, we’ve been writing about Kessler Syndrome and its potential solutions for a long time. It’s intuitively true that forever-free-falling projectiles can’t be packed too closely together without a risk, but in recent years, the big brains of modern business have found ways of refuting this truism to justify continued mass launches into LEO.
Now, a team from the US and Canada has published a paper on how to quantify this problem with the tortured acronym CRASH: Collision Realization and Significant Harm. A CRASH Clock is a score reported as an amount of time, which represents how long it would take for a major collision to occur if the assessed system had no collision-avoidance mechanisms—or, crucially, if those mechanisms broke down.
In 2018, they say, the CRASH Clock was set at 121 days; in 2025, they calculate that it is at just 2.8 days.
That’s pretty worrying. After all, the longest solar storms in recorded history have lasted for days, including the famous Carrington event. That happened before satellites existed, though, so we can’t know how long a disruption it might have created in satellite control.
Credit: Victor de Schwanberg/Science Photo Library/Getty Images
There was also the Gannon event of 2024, which disrupted but didn’t fully break communications with Starlink and other satellites. That one required thousands of satellites to maneuver and make course corrections, however, since it compressed Earth’s plasmophere and thus affected the drag experienced by close-orbiting objects.
As this study points out, the Gannon event could have been a disaster, given the fact that the skies were much less crowded in 2024 than they are today. And that’s not even considering the implications of this recent story.
It’s not hard to imagine a one- to two-day period during which many satellites are unreachable, meaning that even if they have attitude control, they could not be induced to use it. That’s worrying, in the context of a world increasingly dependent on satellite coverage.
There’s no new information being added to the record here, but the CRASH Clock provides a means of quantifying the problem and underscores how close we’re to disaster. The current system has measures in place to prevent disasters, but, as this study shows, those measures have progressively less margin for error at a time when we cannot reliably predict—or, more crucially, prevent—disruptions.
