New ‘CRASH Clock’ Warns of 2.8 Day Window Before Potential Orbital Collision
Last week, a Chinese spacecraft passed within just 655 meters (200 feet) of a Starlink satellite, narrowly avoiding a collision. According to new research, such near misses now occur all the time in low Earth orbit, and the risk of catastrophe is alarmingly high.
The findings, which have yet to be peer-reviewed, paint a disturbing picture. Based on the number of objects in LEO last June, a sudden loss of collision avoidance power could lead to a catastrophic crash in just 2.8 days.
Such a collision may trigger a large debris-generating event that can cause further collisions and possibly trigger the first phase of Kessler syndrome. In this theoretical scenario, LEO is so crowded with orbiters and debris that collisions between objects cause a chain reaction, creating more debris. This would weaken the satellite networks we rely on and make some orbits useless for new satellites and missions.
Kessler syndrome can take decades to fully develop, but we certainly don’t want to start the process if we can’t avoid it. Some experts believe it is already too late.
Counting down to crash
Before you hyperfixate on this extreme situation and stare blankly into space, let’s talk about the immediate dangers. That’s what the authors of this study aimed to measure with their new metric: the Crash Detection and Critical Damage (CRASH) Clock.
The CRASH Clock measures stress on orbit by calculating how long it would take for a catastrophic collision to occur if satellite operators lose the ability to perform evasive maneuvers or lose situational awareness.
The researchers’ calculations show that the CRASH clock is currently at 2.8 days, a dramatic difference from 2018, when it was at 121 days. But that was the era before the megaconstellation. The number of objects in LEO has increased in recent years, jumping from about 13,700 in 2019 to about 24,200 in 2025.
According to this study, satellites in all low-Earth-orbit constellations now pass within 0.6 km of each other approximately every 22 seconds, giving them ample opportunity to collide.
Starlink on the edge
Starlink is the largest megaconstellation in LEO. Its 9,300 active satellites make up the majority of all satellites in Earth orbit, according to Harvard University astronomer Jonathan McDowell, who tracks the number of spacecraft in LEO. That number will only grow as SpaceX continues to launch thousands of Starlinks each year.
The study found that Starlinks passes within 0.6 miles (1 km) of another object every 11 minutes in the densest part of the galaxy. Starlinks currently averages 41 collision avoidance maneuvers per satellite per year—that’s one maneuver every 1.8 minutes across the entire megaconstellation.
Historically, the number of collision avoidance procedures performed by Starlink has doubled every six months, the researchers noted.
Suddenly losing the ability to do these tricks can be devastating. It’s too bad. Although unlikely, the researchers posit two scenarios that could disrupt this ability: a major solar storm and a catastrophic software failure.
It is important that we take these risks seriously, not just when it comes to Starlink, but the entire population of manned spacecraft in LEO. The researchers hope that the CRASH watch and the calculated “massive collision risks” encourage decision makers to change the current approach to satellite deployment and operation “immediately.”
