期刊
METEORITICS & PLANETARY SCIENCE
卷 45, 期 3, 页码 406-433出版社
WILEY
DOI: 10.1111/j.1945-5100.2010.01031.x
关键词
-
资金
- NASA
- NASA Astrobiology Institute and the Goddard Center for Astrobiology
- W. M. Keck Solid State NMR Facility at the Geophysical Laboratory
- U.S. Department of Energy by the Lawrence Livermore National Laboratory [W-7405-ENG-48]
- Office of Science, Office of Basic Energy Sciences, Materials Sciences Division, of the U.S. Department of Energy [DE-AC03-76F00098]
- Deutsche Forschungsgemeinschaft [STE 576/17-2]
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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