The Unfriendly Aeropause

The rocketing boys & girls of the comics and science fiction are very much at home in space. They flit from planet to planet as easily and comfortably as a housewife going to the supermarket. The truth about space is different, and no one knows it better than the high-flying sci entists and engineers. Last week the Air Force School of Aviation Medicine held a symposium at San Antonio on the dan gers that will crowd around explorers of the aeropause.*

The greatest obstacle for space travel ers to overcome is man himself. The human body is fitted to meet conditions on the surface of the earth, where the temperature varies only slightly and the pull of gravitation varies hardly at all. The atmosphere provides a steady supply of oxygen, while its cushioning bulk over head protects man's delicate hide from nearly all meteors and ultraviolet, X and cosmic rays. For man to leave this sheltered environment is as difficult as it was for his fishlike forerunners to slither up on to dry land.

Trial by Heat. Since man cannot change his body quickly, he must carry with him a capsule of his earth-surface environment. This, in effect, is what the fish did; the cells in the bodies of land vertebrates, including man, are bathed in a fluid much like the thin brine of the paleozoic sea. But when man tries to carry his environment with him into the aeropause, he finds problems at each level.

At moderate altitudes (20-30 miles), one of the worst is heat. The atmosphere is fiercely cold, but an airplane or rocket must speed through it so fast that the air that strikes it becomes just as fiercely hot.

At the speed necessary for aeropause flight, the craft will be enclosed in a film of hot air at 1,000DEG C. For flights of mod erate speed and duration, refrigerating units like those used on present-day jet fighters may be enough to counteract such temperatures. For long, fast flights, something more elaborate is required. One proposal for rocket-driven craft is to use the intensely cold liquid oxygen fuel as a heat absorber.

Bottled Air. Another aeropause problem is air. Crewmen must have the kind of air they are accustomed to, and such air is hard to find in the aeropause. To compress the thin outside air to breathable density and dissipate the heat of compression would take heavy machinery, and the air so gathered might not be fit to breathe. At 100,000 ft. it contains enough ozone, formed out of oxygen by the sun's ultraviolet light, to poison crewmen. Probably the air they breathe will have to be "bottled."

As empty space approaches, the travelers will face a new difficulty, never before experienced by human beings. The earth's gravitational field still pulls at a space ship, but as soon as the craft is no longer supported by the air, its occupants feel no gravitation. They become weightless. In the comics they float around merrily, enjoying their new freedom, but in sober fact they will probably behave like stumbling idiots. The human body's sense-organs that control balance and muscular action need gravity to guide them. The crewmen of space ships will need a lot of training before they can make their bewildered bodies behave.

Danger from Rays. Outside the sheltering atmosphere, many kinds of violence strike at the space ship. Ultraviolet light and X rays from the sun are among the major hazards. Probably still more dangerous are the cosmic rays that come from mysterious sources deep in space. Many of them are heavy particles (entire atoms) with enormous energy. These violent particles never reach the earth's surface, but they would riddle a space ship, passing right through its crewmen. No one knows what damage they may do, for man has had none of them to experiment with. One authority, Nobelman H. J. Muller of Indiana University, believes that they may cause cancer.

The space-planners are not dismayed, however, by the dragons that await them above the blue sky. The Air Force men seemed to take it for granted that manned rockets, even manned satellites and space ships, are being designed already as serious, practical projects.

*Variously defined, but meaning in general the region above the present ceilings of "inhabited aircraft," i.e., above 75,000 feet.

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