For two decades, spacefaring nations have operated under a simple rule: any satellite sent into orbit must have a less than one in 10,000 chance of injuring someone on the ground. The rule was written when a few dozen objects reentered the atmosphere each year. By early 2026, with more than 9,000 Starlink satellites in orbit and filings for constellations totaling over 70,000 spacecraft, that arithmetic no longer holds.

Researchers have now done the math that regulators have not. A study published in the journal Acta Astronautica calculated the collective probability that debris from eleven major megaconstellations will hit someone. The result was 40 percent. The figure represents a fundamental gap between how safety is assessed and how risk actually accumulates when tens of thousands of objects come down.

[The original] rules evaluate satellites individually. A constellation of 30,000 satellites, each with a one in 10,000 casualty risk, yields a collective probability of approximately 95 percent that some satellite will cause a casualty. No regulator currently computes or limits that cumulative probability.