NEVADA TEST SITE

La Place, the 18th full scale nuclear test of the Summer 1957 series, was fired at 6 a.m. PDT today from a balloon 750 feet above Yucca Flat. The device was designed by Los Alamos Scientific Laboratory. Its designed yield was well below nominal.

The fireball of the hour-glass shape typical of balloon shots quickly turned into a misshapen mushroom cloud which separated from its stem and rose to 19,500 feet.

The cloud was elongated by low speed winds blowing in different directions at different levels. Pilots of cloud tracking planes reported the top of the cloud was being blown slightly west of south, and the lower levels east of south. Under forecast conditions, the cloud was expected to be split into segments moving in various directions, predominantly east and west. Little or no recordable offsite fallout is expected.

There were 14 experiments on the sequence timer. The Department of Defence conducted three experiments involving radiation measurement, photography and radar cloud tracking, and there was one civil effects radiation measurement project. Fifteen U.S. Air Force aircraft participated in support missions. The blast was heard as a sharp crack followed by prolonged rumblings at the Control Point and observer areas. It was heard as bangs and rumbles at Inyokern.