Highest altitude nuclear explosion

A 1.7 kiloton nuclear weapon was detonated 749 km. (466 miles) above the Earth's surface on September 6, 1958, as part of the United States' secret Operation Argus test series. The 98.9 kg (218 pound) W-25 warhead was launched by a modified three-stage Lockheed X-17A missile from the warship USS Norton Sound, located in the South Atlantic 1,770 km. (1,100 miles) southwest of Cape Town, South Africa. Operation Argus was a secret program of atmospheric nuclear explosions motivated by a theory of Lawrence Radiation Laboratory physicist Nicholas Christofilos. He believed that nuclear explosions in space would create belts of trapped radiation equivalent to artificial Van Allen belts. These belts would have a military use because they would destroy enemy satellites and disrupt communication systems. There were three Argus detonations, at altitudes of 160 km. (100 miles) and 292 km. (182 miles) as well as the record-breaking shot to 749 km. (466 miles). The experiment worked as planned and may have inadvertantly hastened the demise of several early satellites.