Overview
- Areg Danagoulian of MIT published a peer-reviewed feasibility study in Nature on Wednesday, July 8, 2026, describing an “inspector” satellite that would detect neutrons knocked loose from uranium or plutonium by high-energy protons in the inner Van Allen radiation belt.
- The detection idea relies on proton-induced spallation, a process where trapped belt protons hit heavy nuclei and eject neutrons that a nearby detector could measure to signal the presence of fissile material.
- Danagoulian’s models estimate a strong signal—up to about 40 million neutrons per second for a thermonuclear device in the belt—and predict roughly 99% detection accuracy if an inspector spent about a week within roughly 2.5 miles of a suspect satellite, or much faster readings with multiple closer sensors.
- Major technical challenges remain, including filtering incoming protons, separating neutrons from Earth-origin “albedo” neutrons, building directional neutron sensors, and conducting precise proximity maneuvers without creating safety or legal risks.
- If developed and accepted by states, the system could close a long-standing verification gap in the 1967 Outer Space Treaty, but it would also raise diplomatic, operational, and possible dual-use concerns that will need legal and policy work before any deployment.