NANO-XRF STUDY OF COMETARY MATTER RETURNED BY NASA'S
STARDUST MISSION: A QUANTITATIVE AND QUALITATIVE
APPROACH
SCHOONJANS, Tom1, BRENKER, Frank E.2, SCHMITZ, Sylvia2, SILVERSMIT, Geert1, DE
SAMBER, Björn1, VEKEMANS, Bart1, BURGHAMMER, Manfred3, RIEKEL, Christian3, VINCZE,
Laszlo1
1 X-Ray
Microspectroscopy and Imaging Research Group, Department of Analytical Chemistry,
Ghent University, Krijgslaan 281, B-9000 Gent, Belgium. Tom.Schoonjans@UGent.be
2 Institut für Geowissenschaften, Facheinheit Mineralogie - Abt. NanoGeoscience,
Altenhöferallee 1, D-60438 Frankfurt am Main, Germany.
3 European Synchrotron Radiation Facility (ESRF), BP 220, F-38043, Cedex, France.
Stardust is an interplanetary spacecraft launched on February 7, 1999, by NASA, whose primary
purpose was to investigate the make up of comet Wild2 and its coma. The spacecraft was
equipped with aerogel (highly porous silica foam with an extremely low density) collectors, in order
to facilitate the capture of cometary dust particles. After the return of Stardust to Earth on January
15, 2006, the acquired samples were distributed among more than 150 researchers worldwide,
including the X-Ray Microspectroscopy and Imaging group of Ghent University.
Each presented sample contains an elongated cavity (called track) produced by the impact and
deceleration of a single comet coma particle. We performed multiple experiments on such tracks
and their terminal particle at the ESRF (beamline ID13) using several non-destructive X-ray based
methods such as conventional 2D scanning nano X-ray fluorescence (XRF) and confocal nano
XRF. The nanobeam of X-rays was produced by a linear Bragg-Fresnel lens assembly which
reduced the dimensions of the beam to the 100-200 nm level.
Although the interpretation of the acquired data is still an ongoing process, some preliminary
results have already come forth. The data have been analyzed both in a quantitative and
qualitative manner, using software developed at our research group. The presented quantitative
results have been obtained by the fundamental parameter XRF quantification method, resulting in
area concentration (conventional XRF) distributions and volume concentration (confocal XRF)
distributions for the most prevalent elements within this unique cometary matter.