Stardust interstellar preliminary examination - First results

A. J. Westphal (1) , C. Allen (2) , S. Bajt (3) , Renaud Bastien (2) , H. A. Bechtel (4) , J. Borg (5) , F. Brenker (6) , G. Bridges (7) , D. E. Brownlee (8) , A. L. Butterworth (1) , M. Burchell (9) , Manfred Burghammer (10) , B. Clark (11) , G. Cody (12) , C. Floss (13) , G. Flynn (14) , D. Frank (1) , Z. Gainsforth (1) , E. Grün (15) , P. Hoppe (16) , A. Kearsley (17) , N. Kelley (1) , H. Leroux (18) , L. R. Nittler (12) , R. Lettieri (1) , B. Mendez (1) , W. Marchant (1) , S. A. Sandford (19) , Alexandre Simionovici (20) , F. Stadermann (13) , Z. Sternovsky (21) , R. M. Stroud (22) , S. Sutton (23) , P. Tsou (24) , A. Tsuchiyama (25) , T. Tyliczszak (4) , B. Vekemans (26) , L. Vincze (26) , J. Warren (2) , M. E. Zolensky (2)

1 SSL - Space Sciences Laboratory [Berkeley]
2 JSC - NASA Johnson Space Center
3 DESY - Deutsches Elektronen-Synchrotron [Zeuthen]
4 ALS - Advanced Light Source [LBNL Berkeley]
5 IAS - Institut d'astrophysique spatiale
6 Goethe-Universität Frankfurt am Main
7 University of Leicester
8 University of Washington [Seattle]
9 University of Kent [Canterbury]
10 ESRF - European Synchrotron Radiation Facility
11 Lockheed Martin Corporation
12 Carnegie Institution for Science
13 WUSTL - Washington University in Saint Louis
14 SUNY Plattsburgh - State University of New York at Plattsburgh
15 MPIK - Max-Planck-Institut für Kernphysik
16 MPIC - Max-Planck-Institut für Chemie
17 NHM - The Natural History Museum [London]
18 Université de Lille, Sciences et Technologies
19 ARC - NASA Ames Research Center
20 LGIT - Laboratoire de Géophysique Interne et Tectonophysique
21 University of Colorado [Boulder]
22 NRL - Naval Research Laboratory
23 APS - Advanced Photon Source [ANL]
24 JPL - Jet Propulsion Laboratory
25 Graduate School of Science, Department of Earth and Space Science
26 UGENT - Universiteit Gent = Ghent University

The Stardust spacecraft exposed an aerogel and aluminum foil collector to the interstellar dust stream for a total of 195 days before its encounter with Comet P81/Wild2. We report the first results of the Stardust Interstellar Preliminary Examination. This is a formidable task because of the large collecting area (~1000 cm 2), the small expected statistics (a few dozen particles), the diminutive size of the captured particles (<1μm), the challenging nature of the collecting media, and the requirement that only minimally destructive techniques be used. We have close coupling between state of the art techniques and these challenging samples. The first analyses have been performed using aerogel keystones and picokeystones [1] extracted directly from the Stardust Interstellar Collector in order to preserve trajectory information. In the first analyses we have focused on contamination and beam damage assessment, and on the composition of high-angle tracks that we considered to be likely secondary ejecta from impacts of meteoroids on the spacecraft. These tracks were discovered by a consortium of >23,000 “citizen scientists” worldwide using the Stardust@home virtual microscope tools. We have confirmed this identification of secondary ejecta by the identification of Ce and Zn in these particles, but also detected evidence for extraterrestrial material from the original impactors in the form of Fe, Ni and Mg. FTIR and STXM analyses give quantitative upper limits on extraterrestrial organics, and have allowed for the quantitative evaluation of beam damage and carbon deposition during analyses. We have also identified alumina as a contaminant in the aerogel. No measurements have yet been made on the Al foil collectors.

Domaines: Astrophysique stellaire et solaire [astro-ph.SR]

A. J. Westphal, C. Allen, S. Bajt, Renaud Bastien, H. A. Bechtel, et al.. Stardust interstellar preliminary examination - First results. Meteoritics and Planetary Science, 2008, 43 (7), pp.A169. ⟨insu-00372486⟩