Laser Imaging of Stardust Tracks
Nondestructive 3D Confocal laser imaging of stardust tracks in deconvolution techniques.
M. Greenberg1, D. S. Ebel2
1Brandeis University, Waltham, MA 02454, 2Department of Earth and Planetary Sciences, American Museum of Natural History, Central Park West at 79th St., New York, NY 10024.
Introduction: The Stardust mission to comet Wild 2 returned many cometary particles trapped at a relative velocity of 6.1km/sec in aerogel, leaving 'tracks' of melted silica aerogel. Particles of size 40-300μm reached track terminal regions, leaving myriad smaller particulate fragments behind along tracks [1,2]. A small number of < 1 μm interstellar dust particles was collected on separate aerogel collectors . It has been our goal to perform non-destructive 3D textural analysis on both types of tracks. We see this as a necessary, high-value initial step in track analysis, before flattening, cutting, and other destructive methods. We have turned to Laser Scanning Confocal Microscopy (LCSM) as an accessible alternative to synchrotron-based x-ray tomography . Cometary tracks have been isolated, extracted, and distributed in triangular 'keystones' . We have also worked on many analog keystones, from aerogel shot with various particles in labs , and a single Wild 2 track (#82). Here, we demonstrate greatly improved LCSM images of track #82 at 0.07μm/voxel edge and analogous images of aerogel shot with basaltic glass, imaged at 0.023μm/voxel edge. Axial distortion of 3D images is a serious issue in LCSM, resulting from optical effects along the optic axis of the instrument . Here we describe the correction of axial distortion using a 3-dimensional deconvolution method, based on knowledge of the point-spread function (PSF) for aerogel.
For more information on this project, please visit the Lunar and Planetary Institute (LPI) website at www.lpi.usra.edu. Abstract #1800.
Denton Ebel is an Assistant Curator at AMNH in Earth and Plantary Sciences.