The Mysterious Cloud

The dust gatherer is a bother to the housewife, but it is a boon to the scientist. By sending rockets into space to trap meteoric dust, scientists hope to learn some of the secrets of the great void beyond the earth's atmosphere. Last week they were evaluating the catch of the best dust gatherer yet developed: an Aerobee-Hi sounding rocket, which unfolds its nose toward the top of its climb and spreads out eight graceful petals into space like a great mechanical flower.

The dust-catching Aerobee-Hi, launched last month from White. Sands, N. Mex., climbed for 102 miles before blossoming, folded its petals only after it dropped within 65 miles of the earth's surface. When it finally landed, Physicist Robert K. Soberman of the Air Force Cambridge Research Laboratory hoped to find a few micrometeor punctures in the three-layer sandwich of thin Mylar film and Plexiglas that lined the Aerobee's dust catchers. What he actually found was something quite different: during each second of exposure, some ten meteorites had hit each square centimeter. Most of the holes were microscopic, but a few could be spotted with the naked eye. The larger particles had punctured both layers of film, made craters in the Plexiglas as well.

No dust layer of such density has ever before been observed in space, and Dr. Soberman cannot yet explain his rocket's rich catch. One possible theory is that micrometeorites may have electric charges of the same sign--either positive or negative--when they arrive from space. The charge may accumulate near the top of the atmosphere, slow down later-arriving particles by electrostatic repulsion and make them linger there too.

A second dust-catching rocket launched from Eglin Air Force Base, Fla., carried instruments that reported micrometeorite impacts and sent the information to earth by radio. The tapes of this test will not be fully interpreted for some time, but they have already roughly confirmed the existence of the dust layer. When the analysis is finished, Dr. Soberman hopes to have a better explanation of the mysterious micrometeorite belt that hangs like a faint cloud at the outer fringe of the atmosphere.

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