Assessment and control of organic and other contaminants associated with the Stardust sample return from comet 81P/Wild 2 |
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| Authors: | Scott A SANDFORD Saša BAJT Simon J CLEMETT George D CODY George COOPER Bradley T DEGREGORIO Vanessa
De VERA Jason P DWORKIN Jamie E ELSILA George J FLYNN Daniel P GLAVIN Antonio LANZIROTTI Thomas LIMERO Mildred P MARTIN Christopher J SNEAD Maegan K SPENCER Thomas STEPHAN Andrew WESTPHAL Sue WIRICK Richard N ZARE Michael E ZOLENSKY |
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| Institution: | 1. NASA‐Ames Research Center, Astrophysics Branch, Mail Stop 245‐6, Moffett Field, California 94035–1000, USA;2. Institute of Geophysics and Planetary Physics, Lawrence Livermore National Laboratory, Livermore, California 94550, USA #Present address: DESY Deutsches Elektronen‐Synchrotron, Notkestra?e 85, 22607 Hamburg, Germany;3. ERC, Inc./NASA‐Johnson Space Center, Houston, Texas 77058, USA;4. Geophysical Laboratory, Carnegie Institution of Washington, Washington, D.C. 20015, USA;5. NASA‐Ames Research Center, Astrobiology Branch, Mail Stop 239‐4, Moffett Field, California 94035–1000, USA;6. Naval Research Lab., Code 6366, 4555 Overlook Ave. SW, Washington, D.C. 20375–5320, USA;7. Wyle Integrated Science and Engineering, Houston, Texas 77058, USA;8. Goddard Center for Astrobiology, NASA‐Goddard Space Flight Center, Greenbelt, Maryland 20771, USA;9. Physics Department, SUNY Plattsburgh, 101 Broad Street, Plattsburgh, New York 12901, USA;10. CARS, University of Chicago, Chicago, Illinois 60637, USA;11. The Catholic University of America, Washington, D.C. 20064, USA;12. Department of Earth and Space Sciences, UCLA, California 90095–1567, USA;13. Department of Chemistry, Stanford University, Stanford, California 94305–5080, USA Present address: Sawtooth Labs, Inc., Redwood City, California 94063, USA;14. Department of the Geophysical Sciences, The University of Chicago, 5734 South Ellis Avenue, Chicago, Illinois 60637, USA;15. Space Sciences Laboratory, University of California at Berkeley, Berkeley, California 94720, USA;16. Physics and Astronomy Department, SUNY at Stony Brook, Stony Brook, New York 11794–3800, USA;17. Department of Chemistry, Stanford University, Stanford, California 94305–5080, USA;18. 1KT, NASA‐Johnson Space Center, Houston, Texas 77058, USA |
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| Abstract: | Abstract– Numerous potential sources of organic contaminants could have greatly complicated the interpretation of the organic portions of the samples returned from comet 81P/Wild 2 by the Stardust spacecraft. Measures were taken to control and assess potential organic (and other) contaminants during the design, construction, and flight of the spacecraft, and during and after recovery of the sample return capsule. Studies of controls and the returned samples suggest that many of these potential sources did not contribute any significant material to the collectors. In particular, contamination from soils at the recovery site and materials associated with the ablation of the heatshield do not appear to be significant problems. The largest source of concern is associated with the C present in the original aerogel. The relative abundance of this carbon can vary between aerogel tiles and even within individual tiles. This C was fortunately not distributed among a complex mixture of organics, but was instead largely present in a few simple forms (mostly as Si‐CH3 groups). In most cases, the signature of returned cometary organics can be readily distinguished from contaminants through their different compositions, nonterrestrial isotopic ratios, and/or association with other cometary materials. However, some conversion of the carbon indigenous to the flight aerogel appears to have happened during particle impact, and some open issues remain regarding how this C may be processed into new forms during the hypervelocity impact collection of the comet dust. |
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