Abstract
In initial analyses of meteoroids, it is crucial to obtain basic information by non-destructive methods as farther detailed analyses usually involve destructive processes. We conducted synchrotron microtomography for intact captured samples in a space exposed aerogel module onboard the European Retrievable Carrier (EuReCa) spacecraft in the low earth orbit during 1992-93. The X-ray microtomography measurements were performed at BL47XU in SPring-8, Japan. Using synchrotron radiation as an X-ray source, we can obtain CT images with the effective spatial resolution of about 1 mm and quantitative values of X-ray linear absorption coefficients by high flux density and monochromatic X-rays. Subtraction method, with which the aerogel specimens were imaged at X-ray energies just above and below the K-absorption edge of Fe, showed no Fe in the samples, suggested their impactors might be artificial orbital debris. We also obtained three-dimensional structures of sub-mm sized impact tracks and the distributions of sample fragments and condensed aerogel particles along the interior of the tracks. This research shows the effectiveness of impact tracks and samples captured in aerogel with synchrotron microtomography in sub-mm scale; it can be applied to the Stardust samples that will return in January 2006.
