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Analytical Methods for Discriminating Stardust in Aerogel Capture Media.

DE2007917878

Publication Date	2007
Personal Author	Brennan, S.; Ishii, H. A.; Brdaley, J. P.; Luening, K.; Ignatyev, K.
Page Count	11
Abstract	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/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 SiO2, 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.
Keywords	Aerogels Stardust mission Solar system Cosmic dust Comets Dust collectors Contaminants Fluorescence Orbits Mapping Analytical methods Impact tests
Source Agency	Technical Information Center Oak Ridge Tennessee
Corporate Authors	Fermi National Accelerator Lab., Batavia, IL.; Department of Energy, Washington, DC.
Supplemental Notes	Sponsored by Department of Energy, Washington, DC.
Document Type	Technical Report
NTIS Issue Number	200806

Analytical Methods for Discriminating Stardust in Aerogel Capture Media.

Analytical Methods for Discriminating Stardust in Aerogel Capture Media.
DE2007917878

Publication Date	2007
Personal Author	Brennan, S.; Ishii, H. A.; Brdaley, J. P.; Luening, K.; Ignatyev, K.
Page Count	11
Abstract	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/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 SiO2, 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.
Keywords	Aerogels Stardust mission Solar system Cosmic dust Comets Dust collectors Contaminants Fluorescence Orbits Mapping Analytical methods Impact tests
Source Agency	Technical Information Center Oak Ridge Tennessee
Corporate Authors	Fermi National Accelerator Lab., Batavia, IL.; Department of Energy, Washington, DC.
Supplemental Notes	Sponsored by Department of Energy, Washington, DC.
Document Type	Technical Report
NTIS Issue Number	200806