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J. Blum (Astrophysical Institute, University of Jena), G. Wurm (LASP, University of Colorado, Boulder), S. Kempf (Max Planck Institute for Nuclear Physics)
The Cosmic Dust Aggregation Experiment (CODAG), designed for the experimental simulation of the first stage of planetesimal formation, was sucessfully flown on STS-95 and on MASER 8. Within several minutes, the initially deagglomerated, electrically uncharged, micron-sized dust grains formed chain-like, fractal (Df \approx 1.3) dust aggregates due to thermal motion in a rarefied gas and subsequent mutual collisions. The data indicate that the mean agglomerate mass grows exponentially with time. The observed agglomerate mass spectrum is quasi-monodisperse. The low fractal dimension of the growing dust aggregates suggests that thermal grain rotation plays an important role in the initial growth of preplanetary dust aggregates.
This work was sponsored by the German Space Agency DLR.