National Geographic : 1933 Mar
BALLOONING IN THE STRATOSPHERE Two Balloon Ascents to Ten-Mile Altitudes Presage New Mode of Aerial Travel BY AUGUSTE PICCARD With Illustrationsfrom Photographsby the Author Y OU will probably want to know what the earth looks like from ten miles up. The sky is beautiful up there-almost black. It is a bluish purple-a deep violet shade-ten times darker than on earth, but it still is not quite dark enough to see the stars. The sun, however, seems brighter than when seen from sea level. Forests, rivers, and fields are visible, sometimes through a light mist without any contrast, but on other days with mar velous beauty in striking relief. The towering summits of the Alps from ten miles up assume the aspect of miniature reproductions. Calculation shows that, if there were no mist, a circle of earth hav ing a diameter of 560 miles would be vis ible. That is equal to a surface of 250,000 square miles. We went to that height to study cosmic rays. To what height should we ascend to make interesting studies? A calculation showed me we probably would learn some thing new by rising so high that nine tenths of the atmospheric mass would be below us and only one-tenth above us. At sea level the atmosphere has a pres sure equal to that of a column of mer cury of approximately 30 inches. If nine-tenths of the atmosphere is under neath an observer, the barometric pres sure must be 3 inches. So it was to that height we had to ascend (see diagram, page 355). From the standpoint of cosmic rays, the exact altitude is unimportant, but it is in teresting to know to what height we had to go to find that pressure of one-tenth of the atmosphere. From the aeronautic standpoint, we faced the problem of constructing a craft in which a pilot and his assistant and many instruments could be lifted ten miles into the sky and be permitted to work there. This height surpassed by a great deal any that had been attained previously.* So a new craft had to be constructed to over come many difficulties, of which none, despite their numerical importance, im pressed me as insurmountable. Our problem, then, was to find condi tions that would permit two men to live up there in more or less normal working order, and a means of getting them to the desired height. Men can survive at certain altitudes, varying according to persons; these altitudes are usually between 3 and 4/2 miles. In order to go higher, it is necessary to carry oxygen. Even if the aeronaut breathes in an oxygen mask, he cannot go beyond a certain height without suffering from the reduced pressure. THE PROBLEMS OF AN AERIAL LABORATORY You may have seen what happens when a bottle of beer or champagne is rapidly opened. The gases dissolved in the liquid are suddenly set free, forming a quantity of little gas bubbles, so that the liquid is transformed into foam. Well, if the ex ternal pressure is reduced too quickly, human blood acts the same as champagne, and the gases liberated obstruct the blood vessels that supply and nourish the brain and heart. It is evident that the victim does not continue to observe cosmic rays. To avoid this danger, there was only one thing to do: to transport from below the portion of our atmosphere surrounding the aeronauts and to maintain this atmos phere in its original state, preventing its dilation during the ascent. That could only be accomplished by constructing an air-tight cabin in which the aeronauts would be inclosed during the entire explo ration of the high altitudes (see illustra tions, pages 356, 360). The second part of the problem con sisted in getting this cabin and all its contents into the upper atmosphere. * See "Exploring the Earth's Stratosphere," by Lieut. John A. Macready, in the NATIONAL GEOGRAPHIC MAGAZINE for December, 1926.