The Starfish Prime high-altitude nuclear test is conducted by the United States as part of Operation Fishbowl. It involved detonating a 1.4 megaton nuclear warhead at an altitude of 250 miles (400 km) above Johnston Island in the Pacific. The test was designed in part to study the effects of nuclear explosions in the upper atmosphere and space, including the impact of the resulting electromagnetic pulse (EMP). The detonation created a large electromagnetic pulse (EMP) and radiation belts that damaged or destroyed approximately one-third of satellites in low Earth orbit, including AT&T's Telstar satellite. The EMP also caused electrical damage in Hawaii, disrupting streetlights, telephone networks, and burglar alarms. More
