Studies have found solar storms can take out satellites’ navigational and communications systems, which enable them to manoeuvre away from each other and prevent collisions.
Even a single collision between satellites may develop into a cascade that could threaten orbits for decades, according to previous research.
As the number of satellites in orbit rapidly increases in this era of mega-constellations such as SpaceX Starlink probes, the chances of satellites colliding grow dramatically.
However, there hasn’t been a proven way to measure exactly how stressed the Earth’s orbital environment has become, said researchers, including those from Princeton University.
This measure estimates how long it may take for a pile-up to happen in low Earth orbit
Now, scientists have developed a “Crash Clock” to quantify the fragility of satellites in low Earth orbit.
This measure estimates how long it may take for a pile-up to happen in low Earth orbit if satellites suddenly stopped avoiding each other, which would be likely in the event of a devastating solar storm.
“It is a measure, in part, of the degree to which the orbital environment is a house of cards,” researchers write in the yet-to-be peer-reviewed study.
Before companies and governments began launching satellite swarms, a collision cascade may have taken about four months to develop after an event like a solar storm.
But the enormous increase in the number of satellites in orbit since 2018 has brought down the number of days for a collision to under three days, the new study warns.
This represents a 30pc probability of one or more satellite collisions happening during 24-hour period of the probes remaining non-manoeuvrable, scientists explain.
Researchers said this probability is within the “caution region”.
Further increase in orbital traffic could raise collision risk into the “danger region”, implying a 50pc chance of at least one collision within 24 hours, they said.
The research takes into consideration the number of collision avoidance manoeuvres performed by satellites each year.
Citing a SpaceX report, scientists noted Starlink satellites make about 40 such manoeuvres per satellite per year “or one collision avoidance manoeuvre every 1.8 minutes across the whole mega-constellation”.