Kearsley, A.T. and Borg, J. and Graham, G.A. and Burchell, M.J. and Cole, M.J. and Leroux, H. and Bridges, J.C. and Horz, F. and Wozniakiewicz, P.J. and Bland, P.A. and Bradley, J.P. and Dai, Z.R. and Teslich, N. and See, T. and Hoppe, P. and Heck, P.R. and Huth, J. and Stadermann, F.J. and Floss, C. and Marhas, K. and Stephan, T. and Leitner, J. (2008) Dust from comet Wild 2: Interpreting particle size, shape, structure, and composition from impact features on the Stardust aluminum foils. Meteoritics & Planetary Science, 43 (1-2). pp. 41-73. ISSN 1086-9379.
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Aluminum foils of the Stardust cometary dust collector are peppered with impact features of a wide range of sizes and shapes. By comparison to laboratory shots of known particle dimensions and density, using the same velocity and incidence geometry as the Stardust Wild 2 encounter, we can derive size and mass of the cometary dust grains. Using scanning electron microscopy (SEM) of foil samples (both flown on the mission and impacted in the laboratory) we have recognized a range of impact feature shapes from which we interpret particle density and internal structure. We have documented composition of crater residues, including stoichiometric material in 3 of 7 larger craters, by energy dispersive X-ray microanalysis. Wild 2 dust grains include coarse (>10 mu m) mafic silicate grains, some dominated by a single mineral species of density around 3-4 g cm(-3) (such as olivine). Other grains were porous, low-density aggregates from a few nanometers to 100 mu m, with an overall density that may be lower than I g cm-3, containing mixtures of silicates and sulfides and possibly both alkali-rich and mafic glass. The mineral assemblage is very similar to the most common species reported from aerogel tracks. In one large aggregate crater, the combined diverse residue composition is similar to CI chondrites. The foils are a unique collecting substrate, revealing that the most abundant Wild 2 dust grains were of sub-micrometer size and of complex internal structure. Impact residues in Stardust foil craters will be a valuable resource for future analyses of cometary dust.
|Divisions:||Faculties > Science Technology and Medical Studies > School of Physical Sciences > Centre for Astrophysics and Planetary Sciences|
|Depositing User:||Jane Griffiths|
|Date Deposited:||22 Apr 2009 11:08|
|Last Modified:||22 Apr 2009 11:08|
|Resource URI:||http://kar.kent.ac.uk/id/eprint/15736 (The current URI for this page, for reference purposes)|
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