Chemical and structural studies of 'Brownlee' particlesSeveral techniques were applied to the study of small particles (around 10 microns) collected in the upper atmosphere by U-2 aircraft. The major element chemistry of roughly 1/3 of the particles is similar to that of chondritic meteorites, although considerable variation of element ratios is observed from particle to particle, and even within a given particle. All particles of 'chondritic' composition are polycrystalline aggregates. About half have fully re-entrant structures; the remaining ones have more compact structures ranging from platey to spherical morphologies. Micro-crystallites with various internal structures are observed in the size range from less than 100 A to several microns. Although tracks are clearly observed in transmission electron microscope examination of terrestrial analog crystals, no tracks of solar flare origin have yet been identified in the U-2 particles. Induced fission track analysis of one aggregate shows that the U concentration is less than 15 ppbm, lending support to the extraterrestrial origin hypothesis.
Document ID
19790055149
Acquisition Source
Legacy CDMS
Document Type
Conference Proceedings
Authors
Flynn, G. J. (Washington Univ. Saint Louis, MO, United States)
Fraundorf, P. (Washington Univ. Saint Louis, MO, United States)
Shirck, J. (Washington Univ. Saint Louis, MO, United States)
Walker, R. M. (Washington University St. Louis, Mo., United States)