How a High-Altitude Nuclear Explosion Would Impact Satellites
A nuclear detonation approximately 500 kilometers above Earth could incapacitate 99.4% of satellites operating in low Earth orbit (LEO) within just 15 days. This conclusion comes from simulations performed by researchers at the University of Wisconsin-Madison and Princeton University. Their study modeled the effects of a 1-megaton nuclear warhead detonated over the southern Atlantic Ocean, specifically targeting the South Atlantic Anomaly—a region where Earth's magnetic field is notably weaker.
Consequences and Risks Following the Explosion
The simulations reveal that 25% of satellites could fail within the first 24 hours after the blast. By day three, that number rises to 78%, reaching 98% within a week, and nearly total failure (99.4%) by the two-week mark. Even with enhanced radiation shielding, 99.3% of satellites are projected to be disabled within 30 days. The study also indicates that a smaller 100-kiloton blast would render 99% of satellites inoperative over approximately one year.
Post-explosion, a significant number of satellites would lose their ability to maneuver, drastically increasing the risk of collisions in orbit. Within two years, around 20 satellite collisions could occur, and over a decade, these incidents might generate roughly 3,900 new pieces of space debris. Such collision cascades could continue for centuries, leading to an uncontrollable accumulation of orbital debris.
Restoring satellite networks after such a catastrophe would be hindered by persistent radiation hazards and elevated collision risks. Historical precedent exists: the 1962 Starfish Prime test, a 1.4-megaton nuclear explosion detonated near 400 km altitude over the Pacific Ocean, demonstrated that nuclear detonations in space can severely damage satellites. As of November 12, 2026, there are about 13,300 satellites in low Earth orbit, underscoring the critical importance of these findings for current space infrastructure.
These insights are vital for understanding the potential fallout from nuclear explosions in space, particularly regarding the global satellite systems that underpin modern communications, navigation, and Earth observation. Given escalating geopolitical tensions, these results highlight urgent challenges for international security and space policy, emphasizing the need to rethink strategies for safeguarding space assets.