Abstract: 1. Apparatus for the interception of an artificial earth orbiting satellite and the detection of thermonuclear material therein comprising, an interceptor vehicle having means for establishing and maintaining a given attitude in space with respect to said satellite, high-energy electron beam generating means carried within said vehicle, said attitude maintaining means being adapted to direct said electron beam toward said satellite and thereby produce bremsstrahlung from the interaction between said beam and the surface of said satellite, and neutron detector means carried within said vehicle and responsive to neutrons radiated from said satellite as a result of the interaction of said bremsstrahlung with thermonuclear material contained within said satellite.