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Elemental analyses of hypervelocity micro-particle impact sites on interplanetary dust experiment sensor surfacesThe Interplanetary Dust Experiment (IDE) had over 450 electrically active ultra-high purity metal-oxide-silicon impact detectors located on the six primary sides of the Long Duration Exposure Facility (LDEF). Hypervelocity micro-particles that struck the active sensors with enough energy to breakdown the 0.4 to 1.0 micron thick SiO2 insulator layer separating the silicon base (the negative electrode), and the 1000 A thick surface layer of aluminum (the positive electrode) caused electrical discharges that were recorded for the first year of orbit. These discharge features, which include 50 micron diameter areas where the aluminum top layer has been vaporized, facilitate the location of the impacts. The high purity Al-SiO2-Si substrates allow detection of trace (ppm) amounts of hypervelocity impactor residues. After sputtering through a layer of surface contamination, secondary ion mass spectrometry (SIMS) is used to create two-dimensional elemental ion intensity maps of micro-particle impact sites on the IDE sensors. The element intensities in the central craters of the impacts are corrected for relative ion yields and instrumental conditions and then normalized to silicon. The results are used to classify the particles' origins as 'manmade', 'natural' or 'indeterminate'. The last classification results from the presence of too little impactor residue (a frequent occurrence on leading edge impacts), analytical interference from high background contamination, the lack of information on silicon residue, the limited usefulness of data on aluminum in the central craters, or a combination of these circumstances. Several analytical 'blank' discharges were induced on flight sensors by pressing down on the sensor surface with a pure silicon shard. Analyses of these blank discharges showed that the discharge energy blasts away the layer of surface contamination. Only Si and Al were detected inside the discharge zones, including the central craters, of these features. A total of 35 impacts on leading edge sensors and 22 impacts on trailing edge sensors were analyzed.
Document ID
19920018012
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Simon, Charles G.
(Florida Univ. Gainesville., United States)
Hunter, J. L.
(North Carolina State Coll. Raleigh., United States)
Griffis, D. P.
(North Carolina State Coll. Raleigh., United States)
Misra, V.
(North Carolina State Coll. Raleigh., United States)
Ricks, D. R.
(North Carolina State Coll. Raleigh., United States)
Wortman, Jim J.
(North Carolina State Univ. Raleigh., United States)
Date Acquired
September 6, 2013
Publication Date
June 1, 1992
Publication Information
Publication: NASA. Langley Research Center, Second LDEF Post-Retrieval Symposium Abstracts
Subject Category
Astrophysics
Accession Number
92N27255
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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