"Giant Skyhook" Ready For Launching -- straining at its anchor, the largest known unmanned balloon is set for launching early today. The balloon was to bear cosmic ray directing instruments some 23 miles up, but holes developed in the fragile plastic and the instrument load was taken off. It was decided to releases the balloons anyway for launching experience. The big was constructed for the office of Naval Research to better study cosmic rays. Shown is the upper 100 feet of the balloon, which was 287 feet long. The tiny one at the right is wind-detecting balloon. September 03, 1952. (Photo by AP Wirephoto).