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Comet 81P/Wild 2: the size distribution of finer (sub-10 μm) dust collected by the Stardust spacecraft

Price, M.C.; Kearsley, A.T.; Burchell, M.J.; Horz, F.; Borg, J.; Bridges, J.C.; Cole, M.J.; Floss, C.; Graham, G.; Green, S.F.; Hoppe, P.; Leroux, H.; Marhas, K.K.; Park, N.; Stroud, R.; Stadermann, F.J.; Telisch, N. and Wosniakiewicz, P.J. (2010). Comet 81P/Wild 2: the size distribution of finer (sub-10 μm) dust collected by the Stardust spacecraft. Meteoritics & Planetary Science, 45(9) pp. 1409–1428.

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DOI (Digital Object Identifier) Link: http://dx.doi.org/10.1111/j.1945-5100.2010.01104.x
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Abstract

The fluence of dust particles <10 μm in diameter was recorded by impacts on aluminium foil of the NASA Stardust spacecraft during a close fly-by of comet 81P/Wild 2 in 2004. Initial interpretation of craters for impactor particle dimensions and mass was based upon laboratory experimental simulations using >10 μm diameter projectiles and the resulting linear relationship of projectile to crater diameter was extrapolated to smaller sizes. We now describe a new experimental calibration programme firing very small monodisperse silica projectiles (470 nm - 10 μm) at approximately 6 km s-1. The results show an unexpected departure from linear relationship between 1 and 10 μm. We collated crater measurement data and, where applicable, impactor residue data for 596 craters gathered during the post-mission preliminary examination (PE) phase. Using the new calibration, we recalculate the size of the particle responsible for each crater and hence reinterpret the cometary dust size distribution. We find a greater flux of small particles than previously reported. From crater morphology and residue composition of a sub-set of craters, the internal structure and dimensions of the fine dust particles is inferred and a "maximum-size" distribution for the sub-grains composing aggregate particles is obtained. The size distribution of the small particles derived directly from the measured craters peaks at ~175 nm, but if this is corrected to allow for aggregate grains, the peak in sub-grain sizes is at <100 nm.

Item Type: Journal Article
Copyright Holders: 2010 The Meteoritical Society
ISSN: 1945-5100
Keywords: Stardust; hypervelocity impacts; cometary dust
Academic Unit/Department: Science > Physical Sciences
Interdisciplinary Research Centre: Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR)
Item ID: 22758
Depositing User: Simon Green
Date Deposited: 07 Jan 2011 11:32
Last Modified: 28 Sep 2013 13:22
URI: http://oro.open.ac.uk/id/eprint/22758
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