¹F.J.M. Rietmeijer, ²V. Della Corte, ²M. Ferrari, ^2,3A. Rotundi, ⁴R. Brunetto
¹Department of Earth and Planetary Sciences, MSC03 2040, 1-University of New Mexico, Albuquerque, NM 87131-0001, USA
²Istituto di Astrofisica e Planetologia Spaziali – INAF, Via del Fosso del Cavaliere, 100, 00133, Roma, Italy
³Dipartimento di Scienze Applicate, Università degli Studi di Napoli “Parthenope”, CDN, I C4, 80143, Napoli, Italy
⁴Institut d’Astrophysique Spatiale, CNRS, UMR-8617, Université Paris-Sud, bâtiment 121, F-91405 Orsay Cedex, France

Bolide and fireball fragmentation produce vast amounts of dust that will slowly fall through the stratosphere. DUSTER (Dust in the Upper Stratosphere Tracking Experiment and Retrieval) was designed to intercept the nanometer to micrometer meteoric dust from these events for laboratory analyses while it is still in the upper stratosphere. This effort required extraordinary precautions to avoid particle contamination during collection and in the laboratory. Here we report dust from the upper stratosphere that was collected during two campaigns one in 2008 and another in 2011. We collected and characterized forty five uncontaminated meteoric dust particles. The collected particles are alumina, aluminosilica, plagioclase, fassaite, silica, CaCO3, CaO, extreme F-rich C-O-Ca particles, and oxocarbon particles. These particles are found in friable CI and CM carbonaceous chondrite, and unequilibrated ordinary chondrite meteoroids that are the most common source of bolides and fireballs. The oxocarbons have no meteorite counterparts. Some F-bearing CaCO3 particles changed shape when they interacted with the ambient laboratory atmosphere which might indicate their highly unequilibrated state as a result of fragmentation. Equilibrium considerations constrain the thermal regime experienced by the collected particles between ∼2000°C and ∼1000°C, as high as 3,700°C and as low as ∼650°C after 9 secs, followed by rapid quenching (μs) to below 1,600°C, but equilibrium conditions during these events is most unlikely. So far the observed thermal conditions in these events put the temperatures between ∼4,300°C and ∼430°C for 5 seconds and high cooling rates. Such conditions are present in the immediate wake of meteors and fireballs.

Reference
Rietmeijer FJM, Della Corte V, Ferrari M, Rotundi A, Brunetto R (2015) Laboratory Analyses of Meteoric Debris in the Upper stratosphere from Settling Bolide Dust Clouds. Icarus (in Press)
Link to Article [doi:10.1016/j.icarus.2015.11.003]
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