williatw wrote:So it looks like that unless your talking about an insanely powerful nuke 294 miles up you are likely right in your points about EMP.
Gee...maybe I should walk back what I just said?!:
Starfish Prime was a July 9, 1962 high-altitude nuclear test conducted by the United States, a joint effort of the Atomic Energy Commission (AEC) and the Defense Atomic Support Agency. It was the largest nuclear test conducted in outer space and one of five conducted by the US in space.
On July 9, 1962, at 09:00:09 Coordinated Universal Time (July 8, Honolulu time, at nine seconds after 11 p.m.), the Starfish Prime test was detonated at an altitude of 400 kilometres (250 mi). The coordinates of the detonation were
16°28′N 169°38′WCoordinates: 16°28′N 169°38′W. The actual weapon yield came very close to the design yield, which various sources have set at different values in the range of 1.4 to 1.45 megatons (6.0 PJ). The nuclear warhead detonated 13 minutes and 41 seconds after liftoff of the Thor missile from Johnston Island.
Starfish Prime caused an electromagnetic pulse (EMP), which was far larger than expected, so much larger that it drove much of the instrumentation off scale, causing great difficulty in getting accurate measurements. The Starfish Prime electromagnetic pulse also made those effects known to the public by causing electrical damage in Hawaii, about 1,445 kilometres (898 mi) away from the detonation point, knocking out about 300 streetlights, setting off numerous burglar alarms and damaging a telephone company microwave link. The EMP damage to the microwave link shut down telephone calls from Kauai to the other Hawaiian islands