“The Sun is the boss, and we have to work around that.” The line, offered by NASA mission operations engineer Russell DeHart, carries extra weight now that low Earth orbit is filling with machines that depend on constant control, constant tracking, and constant coordination to avoid becoming shrapnel.
A new, not-yet-peer-reviewed study proposes a stark way to visualize how little slack remains in Earth’s busiest orbital lanes: the Collision Realization And Significant Harm (CRASH) Clock. Instead of asking whether satellites might collide, it asks how quickly the first collision could occur after a worst-case loss of control across the population. Using a modeled distribution of spacecraft in low Earth orbit (LEO), the researchers estimate that by the end of 2025 the CRASH Clock sits at about 2.8 days, with a 30% chance of a collision within 24 hours of a broad “everyone goes offline” emergency.
Seven years earlier, the same framework yields a very different picture roughly 128 days before the first collision in a comparable scenario. The speedup is a simple reflection of scale: as of May 2025, there were at least 11,700 active satellites around Earth, concentrated largely in LEO (up to 2,000 kilometers). One driver of that density is the rise of megaconstellations, including Starlink, which had 9,357 satellites in orbit as of Dec. 19, 2025 tracked by astronomer Jonathan McDowell.
In normal operations, the satellite industry’s safety story is built on avoidance: conjunction alerts, last-minute burns, and careful scheduling. European Space Agency experience illustrates the workload: a typical LEO spacecraft can receive hundreds of alerts each week, with analysts escalating the small fraction that look truly dangerous; ESA notes a maneuver is often planned if collision probability rises above about 1 in 10,000. Those defenses, however, assume control links, propulsion, and reliable predictions.
The CRASH Clock is explicitly about what happens when those assumptions fail.
One plausible trigger discussed by the study team is a sizable solar storm, the kind that can scramble systems with radiation and expand Earth’s upper atmosphere. During the May 2024 geomagnetic storm, NASA teams saw orbit drops ranging from dozens to hundreds of meters, including changes as large as 400 to 600 meters for some missions, alongside safe-mode events driven by “bit flips” and other anomalies. In a crowded shell, sudden drag-driven shifts and temporary loss of attitude control do not merely threaten one spacecraft’s data stream; they distort the predictability needed to keep thousands of objects separated.
If satellites stayed inoperable longer than the CRASH Clock value, initial impacts could generate debris clouds capable of striking other spacecraft pushing conditions toward the threshold associated with the Kessler Syndrome, where collisions breed more collisions. That cascading risk is why the clock is framed as an “environmental indicator,” not a countdown to a single event: it measures how little room there is for error when the number of active spacecraft keeps climbing.
The engineering response taking shape across agencies and operators points toward automation and clearer traffic rules. ESA has described machine-learning tools that could assess collision likelihood and accelerate maneuver decisions, reflecting a broader shift toward treating orbital lanes less like open ocean and more like controlled airspace. The CRASH Clock, in that context, functions as a blunt metric for a subtle reality: LEO safety increasingly depends on resilient systems that can keep flying and coordinating when space becomes unpredictable.
