September 2, 1957


An experimental device designed by the Los Alamos Scientific laboratory was detonated atop a 500-foot tower in the Yucca Flat firing area at 5:40 a.m. today. It was the 16th full scale nuclear detonation in the summer 1957 series. and was known as Galileo.

There were 26 experiments on the sequence timer. Thirteen aircraft of the U.S. Air Force participated in support flights. Various biomedical experiments were conducted in continuation of a civil effects program.

Approximately 100 paratroopers participated in a "Human Research" study that had been originally scheduled for the Smoky shot but was postponed when the trenches could not be used because of fallout levels predicted. They were stationed in the open 4,800 yards from ground zero.

The cloud top rose to above 37,000 feet and, because of near calm winds at most altitudes it appeared to hover motionless for considerable periods. It also appeared that the mushroom top separated rather cleanly from the stem with less dirt and debris being sucked up through the radioactive top that is usual with tower shots.

One result was that the orange color of the cloud top caused by nitrous and iron oxide, remained clearly visible as the cloud spread slowly in the general direction of the control Point.

Cloud tracking aircraft reported 40 minutes after the detonationn that the total cloud was being divided by the winds into two major sections. The section above 17,000 feet was moving quite slowly toward the southwest, while the section below 17,000 feet was moving even more slowly toward the northwest. Both sections were being dispersed by the action of winds blowing from widely varying directions. If forecast conditions hold, it is probable that both sections will follow clockwise curving paths, and that any significant fallout will be on the Test Site and adjacent portions of the controlled bombing range.

The Blast wave approached 17 milibars of pressure at the Control Point and observer areas. It was felt as a strong shock, and heard as a very sharp crack, followed by the most prolonged rumbling and hill echoes of the series. It was heard as ozonosphere-reflected rumbles and bangs in Inyokern and Bishop, and rumbles at Tonopah, Lund and St. George. There was no report from Sarcobatus.

Because of its yield and tower positioning, Galileo was one of the more sensitive shots on the Plumbbob schedule. Extended postponement might have been anticipated. As it worked out, Galileo was fired only one day later than its September 1 date announced last April. Prior to the firing of Smoky Saturday morning, it was anticipated that Galileo could not be made ready before September 6. After Smoky was fired, it was set for Tuesday, September 3.

Late Saturday evening, weather organization personnel reported that there was a good possibility for Monday morning of a light wind field associated with a neutral point or "col." Technical personnel said there was an outside possibility they could conclude preparations a day earlier than planned.

Because of the Labor Day weekend and the firing of Smoky Saturday, many individuals of the technical, support, and administrative organizations were on leave. Those who were available began work about midnight Saturday. Most key personnel had been reached by mid-morning Sunday and were on duty. Considerable effort was required by many organizations and individuals to conclude major preparations by the Sunday afternoon evaluation meeting, but the technical group has reported that particular credit was earned by workmen of Reynolds Electrical and Engineering Company, who between 3 and 8 a.m. Sunday replaced 2,000 feet of faulty underground signal cable and spliced it into the old cable at the tower.

[Detonation: Galileo]