The Atom: Instant Crater

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Some 650 ft. below the hard clay surface of Nevada's Frenchman Flat, technicians carefully installed the device in a 6-ft.-high and 75-ft.-long chamber lined with plywood and floored with fine gravel. For a while a contrary wind sweeping across the area threatened to postpone the shot. Then the wind faded and the device was detonated. Standing on a mountain-top 57 miles away, observers could not hear the explosion. But they saw its effect perfectly: a great mass composed of thousands of tons of granite boulders, sand, clay, yucca trees, sagebrush, tumbleweed, and even stray kangaroo rats, rabbits and rattlesnakes was hurled 7,000 ft. into the sky. It seemed to hesitate, then crashed to the earth in a cloud of dust.

The explosion was the first thermonuclear (H-bomb) device known to have been exploded in North America (all other U.S. H-shots have been in the western Pacific). Generating a force of 100,000 tons of TNT, it was also the most powerful blast ever to be touched off in the U.S. (the atomic bomb that decimated Hiroshima had a force of 20,000 tons of TNT). The Atomic Energy Commission announced that 95% of the blast's radioactivity was either trapped in the ground or returned to earth by the falling debris. Purpose of the explosion: to test the feasibility of using thermonuclear devices to speed up massive civil-engineering projects, such as the digging of harbors, tunnels and canals. In the desert floor, the blast gouged out a crater 300 ft. deep and one-third of a mile wide. And at week's end, the U.S. fired off a low-yield nuclear device a few feet above the desert floor for the first atmospheric test in the U.S. since 1958.