The firing mechanism was set into operation in the blockhouse. One after another signals indicated that the various experiments and observations were set to work. Finally a red light went off and a green light appeared on the panel. This meant that the bomb had been detonated.
The men on shipboard watched the enormous fireball through darkened glasses. The firing crew, sealed off in the blockhouse, saw nothing. A couple of long seconds and Graves’ voice announced over their radio: “It was a good shot.” A quick estimate indicated 15 megatons.
Some more slow seconds and the expected ground shock arrived. It was like a big earthquake. A bad moment passed. The blockhouse rocked but held.
Another minute or so and the air shock passed over. One could hear the hinges groan—but this was no longer frightening.
Would the water wave pour over the blockhouse? Everything was watertight. After fifteen minutes a porthole was opened—no water came in. The men in the blockhouse emerged to look at the drifting atomic cloud.
While they watched, Jack Clark’s radiation instrument began to show a reading. The firing crew was called back into the blockhouse. There, in the lowest corner shielded by a considerable amount of sand, they were safe. Outside, the evaporated and condensing coral came down in pellets carrying more and more radioactivity.
In the meantime there was fallout on the ships too. The wind had definitely veered after shot time. Quickly the activity was washed down. No one got a dangerous exposure. But it was wiser to sail away. A message was sent to the blockhouse: “We will come back for you in the evening.”
After a little more than an hour the activity around the blockhouse started slowly to decrease. The firing crew waited patiently inside without communication, without light for the rest of the day.
Finally the ships came back. At sundown a helicopter went out to the island using the last of daylight and allowing as much time as possible for the activity to decay. Clark and his friends rushed out of the blockhouse wrapped in sheets to stop the beta rays and keep off the radioactive dust. They moved as fast as possible to avoid unnecessary exposure.
It was a hard experience but they got no more than two roentgens—no more reason to worry than if they had had a medical X-ray. Toward the east, however, some people were in real trouble.