Researchers have developed a metric showing that the growing number of satellites in Earth's orbit could lead to collisions within just 2.8 days if they all lost the ability to maneuver. This highlights the increasing congestion in space, driven largely by constellations like SpaceX's Starlink. The finding underscores vulnerabilities to events such as solar storms.
The rapid proliferation of satellites has transformed Earth's orbit into a crowded environment, raising concerns about potential disasters. In the past seven years, the satellite count has surged from about 4,000 to nearly 14,000, with SpaceX's Starlink constellation accounting for over 9,000 in low Earth orbit at altitudes between 340 and 550 kilometers.
To address this, Sarah Thiele at Princeton University and colleagues created the Collision Realization And Significant Harm (CRASH) Clock, a tool that quantifies collision risks using public positional data. Their analysis reveals that if all satellites suddenly became unable to perform avoidance maneuvers—perhaps due to a major outage—a collision would occur in just 2.8 days. For comparison, in 2018 before Starlink's launches, the timeline was 121 days.
"We were shocked it was that short," Thiele remarked. SpaceX's operations illustrate the scale: between December 1, 2024, and May 31, 2025, the company executed 144,404 collision avoidance maneuvers, averaging one every 1.8 minutes.
Historically, only one satellite collision has happened, in 2009 when an Iridium Communications satellite struck a defunct Russian Kosmos craft, producing hundreds of debris pieces still in orbit. Solar storms pose a key threat; a May 2024 event caused Starlink satellites to undulate, and a Carrington Event-scale storm from 1859 could disrupt many, though experts like Wineed Vattapally at SES Satellites doubt it would disable everything simultaneously. "It’s unlikely to knock them all out at the same time," he said.
Hugh Lewis at the University of Birmingham noted the CRASH Clock's value in spotlighting orbital crowding. "Can we keep adding to that house of cards?" he asked. With plans for tens of thousands more satellites from SpaceX, Amazon, and Chinese firms, risks are set to escalate.
