TEST A: EXPLOSION IN AIR 



surface, it could not envelop scores of other ships, con- 

 suming them and their important cargoes of test ani- 

 mals and instruments. Such danger was heightened, 

 of course, by the abnormally close spacing of the ships. 



What struck the ships first? Undoubtedly it was 

 the thermal radiation and the gamma radiation. These 

 struck the ships within the first thousandth of a second. 

 The thermal radiation lasted only a few seconds, ceas- 

 ing with the extinction of the fireball. The gamma radi- 

 ation was greatly reduced in intensity as soon as the 

 mushroom got underway in its climb to the strato- 

 sphere. The thermal radiation produced serious effects 

 on exposed test animals and on various kinds of ship 

 equipment, but it produced very little serious damage 

 to ships' hulls and superstructures. Gamma radiation 

 likewise had relatively little effect on ship structures. 



The shock wave did the damage. The impulse it 

 delivered, with its extraordinarily high peak pressures 

 and its long-lasting positive pressure phase, was irre- 

 sistible on the nearest ships. It bent masts, depressed 

 decks, crumpled stacks, unseated cranes, dished side 

 plating. It twisted and broke the flight deck of the 

 nearer aircraft carrier and ripped nearly all the super- 

 structure off a surfaced submarine nearby. 



Detailed surveys of damage had to wait until the 

 mammoth re-entry maneuver had been accomplished. 



Drone planes were first to make close approach to 

 the target center. Only eight minutes after Mike Hour 

 a B-17 drone entered the mushroom at 24,000 feet. A 



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