Researchers have found that a 1‑megatonne nuclear explosion at 500 km over the South Atlantic can form an artificial radiation belt. The burst releases radio‑active debris that releases electrons, which become trapped by Earth’s magnetic field. These electrons keep the belt active for days, repeatedly exposing satellites to high doses of radiation.

In their coupled simulation of prompt X‑ray damage, electron trapping, and belt evolution, the authors mapped satellite failures, collisions, and atmospheric drag for a fleet of 13,306 spacecraft. They discovered that within one week, about 98 % of satellites would be disabled at a 40 krad(Si) tolerance level, and about 97 % remain disabled after two weeks even if tolerance is tripled. Mission‐critical maneuverability is lost, raising collision risk—roughly 20 collisions are projected within two years. Drag can remove many disabled spacecraft from lower altitudes, but replacement satellites might remain trapped in the belt for years.

Under specific conditions—20° S, 35° W, 500 km altitude, and 2 mm aluminium shielding—Table S2 shows that with a 40 krad(Si) failure threshold and a central electron‑source model, 97.8 % of the fleet is disabled by day 7, 99.4 % by day 15, and 99.8 % by day 30. Using a higher 120 krad(Si) threshold results in roughly 90 % fleet loss by day 30, as shown in Table S2. These results demonstrate that even in optimistic circumstances, a single nuclear detonation would cause near‑total loss of the low‑Earth‑orbit satellite fleet over a few weeks.