In the year 1948 the “Skyhook” balloons were an official secret. These giant plastic bags, shaped something like a teardrop, a hundred feet and more in diameter, were part of a classified research project sponsored by the United States Navy, and few except the researchers and technicians involved knew of their existence. Carrying cases of heavy instruments, the balloons were launched from various Air Force bases to collect information about the atmosphere high above the earth, the winds in the stratosphere, and the incidence of cosmic rays. Soaring upward, they traveled in courses determined by the winds and changed in direction and speed as they shifted from one wind stream to another. Even at heights of 60,000 feet these objects with their highly reflecting surfaces could be seen from the ground (see Figure 4). Such balloons were especially noticeable against dark-blue skies, which are much more common in the western United States than in the eastern areas. They could reach heights of 100,000 feet, higher than our planes could go. Once considered as a means for collecting information for Military Intelligence, a task later assumed by the U-2 jets, they could travel across the entire continent and even across the oceans. If the plastic skin developed a leak, the resulting loss of gas altered both the appearance and the behavior of the balloon; if the leak became great enough the balloon shriveled and eventually fell to the earth. At high altitudes where the cold was extreme, the skin might become brittle and the balloon would burst into fragments to be dispersed by the winds and vanish. [Illustration: _Figure 4._ Shapes of various balloons. A, Skyhook at launching; B, Skyhook at high altitude; C, radiosonde or pibal; D, balloon cluster; E, blimp or sausage-shaped balloon.] Although these balloons were sometimes visible at distances of fifty or sixty miles and were very conspicuous, officially they did not exist until 1950 when Dr. Urner Liddel of the Office of Naval Research released the facts behind the Skyhook balloon program. He pointed out then that the balloons had given rise to many reports of flying saucers. If the Skyhook project had been public knowledge in 1948 and if information about their launching and movements had not been a matter of security, a courageous pilot might still be alive today and the infant flying-saucer myth would have died long ago. There can be little question that Captain Mantell crashed in trying to intercept a Skyhook balloon, an object he had never heard of. _The Mantell Tragedy_