Sun-Seeker

Scientists have long known that the sun sends out powerful ultraviolet waves that never reach the earth's surface. One sign: the layers of ionized air high in the atmosphere which are formed by electrical disturbances kicked up by the sun's ultraviolet. But no one has been able to photograph these inaccessible waves.

The U.S. Air Force Cambridge (Mass.) Research Center now tells of a gadget specially designed to do the job from a high-flying rocket. Developed at the University of Colorado, the "sun-seeker" has 21 photoelectric cells that peek from doors opened in the nose of the rocket as it climbs toward the top of the atmosphere. Sunlight falling on the cells tells them just where the sun is. They take note of this information and keep a spectrographic camera pointing straight at the sun, even though the rocket may be rolling.

The first three Aerobee rockets sent up with this apparatus were failures (which surprised no one in the tricky rocket business). The fourth trial succeeded. The sun-seeker found the sun and held the camera steady on it for long enough to get a 28-second exposure. The film, recovered undamaged from the rocket's wreckage, showed a sharp spectrogram of the sunlight taken at 50 miles altitude, above nearly all of the atmosphere. The bulk of the ultraviolet was at just the place on the sun's spectrum where the scientists thought it would be: at 1,216 angstroms.*

Exact knowledge of the ultraviolet will be of great use to meteorologists. Ultraviolet energy heats the top of the atmosphere, causing air movements that affect the weather all over the world. The information will also be useful in the study of the ionized air layers, which reflect many kinds of radio signals.

The sun-seeker itself will probably move into the guided-missile field. It can be made to measure the light that is emitted from lower levels of the atmosphere. By keeping headed toward this light, it can steer a high-flying missile on a steady horizontal course.

The newly photographed ultraviolet waves will be a major hazard for future space pilots in flights above the atmosphere. Human tissue, developed beneath the sheltering air blanket, will probably be injured by ultraviolet unless well protected. "I'd hate to be up there for an hour," said Dr. Howard Edwards, who worked on the project. "In fact, I'd hate to be up there at all."

"Up there" is an unfriendly place for other reasons. Even at 70,000 ft., an altitude already reached by man-carrying planes, cosmic-ray particles still have much of their tremendous original energy. The heavier ones, as yet ungentled by^ the atmosphere, says German Biophysicist Hermann J. Schaeffer, can plow with destructive force straight through a plane's fuselage and on through the human body. An hour's exposure might permanently damage bone marrow and reproductive organs.

* In measuring wave lengths, one angstrom -- 100-millionth of a centimeter. Visible light ranges between 3,900 A. (violet) and 7,900 A. (red).

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