Analytical Methods for Discriminating Stardust in Aerogel Capture Media

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Comet 81P/Wild 2's serendipitous orbit change to the inner solar system in 1974 offered researchers a rare opportunity to sample cometary material from the Kuiper belt, a repository of material left over from solar system formation {approx}4.6 Gyr ago. NASA's Stardust mission intercepted the comet in January 2004 and returned with material collected from its tail in January 2006. The cometary material, consisting of particles ranging from 10 microns down to <2 nm, was collected in aerogel, a very low density ({approx}3 mg/cm cm3) silica foam, to minimize the effects of deceleration from 6.1 km/s. The entire deceleration track is ... continued below

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Brennan, S; Ishii, H A; Bradley, J P; Luening, K; Ignatyev, K & Pianetta, P September 4, 2007.

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Comet 81P/Wild 2's serendipitous orbit change to the inner solar system in 1974 offered researchers a rare opportunity to sample cometary material from the Kuiper belt, a repository of material left over from solar system formation {approx}4.6 Gyr ago. NASA's Stardust mission intercepted the comet in January 2004 and returned with material collected from its tail in January 2006. The cometary material, consisting of particles ranging from 10 microns down to <2 nm, was collected in aerogel, a very low density ({approx}3 mg/cm cm3) silica foam, to minimize the effects of deceleration from 6.1 km/s. The entire deceleration track is extracted from the aerogel block as a pyramidal shape known as a keystone which can be mapped using x-ray fluorescence prior to extraction of terminal or intermediate particles for other analyses. One goal of the track mapping is to determine the bulk composition of the cometary material returned. Unfortunately, although the aerogel is predominantly SiO{sub 2}, there are sufficient quantities of trace elements similar to those expected in the cometary material to require sophisticated discrimination techniques in order to decide whether a fluorescence map pixel contains only aerogel or both aerogel and cometary material. We have developed a dual threshold analysis approach for better distinguishing cometary material from aerogel contaminants and have applied it to five Stardust impact tracks and terminal particles. Here, we present aspects of the dual threshold approach and demonstrate its impact on track composition for one track.

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PDF-file: 11 pages; size: 0.4 Mbytes

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  • Presented at: 2007 Denver X-ray Conference, Colorado Springs, CO, United States, Jul 30 - Aug 03, 2007

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  • Report No.: UCRL-PROC-234456
  • Grant Number: W-7405-ENG-48
  • Office of Scientific & Technical Information Report Number: 917878
  • Archival Resource Key: ark:/67531/metadc879170

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Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

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  • September 4, 2007

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  • Sept. 22, 2016, 2:13 a.m.

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  • Dec. 8, 2016, 2:19 p.m.

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Brennan, S; Ishii, H A; Bradley, J P; Luening, K; Ignatyev, K & Pianetta, P. Analytical Methods for Discriminating Stardust in Aerogel Capture Media, article, September 4, 2007; Livermore, California. (digital.library.unt.edu/ark:/67531/metadc879170/: accessed December 13, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.