14. August 2014
International Science Team Analyzed Dust from the Interstellar
Medium
“Successful Search for Interstellar Dust Particles / Ghent University Part of the
Science Team“
In our imagination the interstellar region is an empty space. In reality it
does contain several percentages of the whole available mass of the
galaxy. This so-called interstellar matter is extremely important as new
stars and planetary systems are generated from it. It contains the basic
ingredients of all known space objects including our own planet Earth.
The overwhelming part of this matter consists of hydrogen and helium.
Only approximately 1% is dust, containing all of the heavy elements,
representing the building blocks of terrestrial planets and therefore being
regarded as a prerequisite for the formation of life. Samples of such
unique extra-terrestrial matter, even extra-solar, were brought to Earth
by NASA’s Stardust space mission allowing direct non-destructive
studies of this mysterious matter by the best suitable laboratories around
the world.
Horsehead nebula in infrared showing a
dust rich region of the interstellar
medium in which new stars and solar
system are born. Image credit: NASA,
ESA, and the Hubble Heritage Team
(STScI/AURA)
NASA’s Stardust mission is best known for its spectacular flight
through the coma of comet Wild 2. International scientifically specialized research teams were selected and
invited by NASA to study these nanoscopic materials. The research group of Professor Vincze had already
joined one specialized task force team, partnering the ESRF (Grenoble, France) and the Goethe University
Frankfurt (Germany), and was therefore already involved in this study as well.
In addition to the cometary grains the space craft thus also collected dust particles originating from the
interstellar space over months. The tiny, incredible fast flying grains were collected within trays filled with
aerogel, a solid silicon oxide glass foam.
With Prof. Frank Brenker and his colleagues from the Goethe University Frankfurt the Belgian scientists
studied several impact tracks from the sampling tray of the Stardust mission at the ESRF in Grenoble.
Together with Dr. Manfred Burghammer of the ESRF, these tiny particles were studied in-situ, still within
the aerogel, applying nano Synchrotron X-ray fluorescence and X-ray diffraction techniques at the nanofocussing beamline ID13.
The results obtained by the different international science teams led by Dr. Andrew Westphal (University of
Berkeley, California) were published in the latest issue of SCIENCE (Westphal et al. Science, 15 August,
2014: Vol. 345 no. 6198 pp. 786-791).
Until now, only a few micrometer sized particles were identified as being of interstellar origin. Two grains,
suitably named Orion und Hylabrook, were captured within the aerogel including complete impact tracks,
while four other particles impacted on the alumiuim foil separating the aerogel blocks.
Against all predictions and simulations the interstellar grains found are partly crystalline, showing a small
carbon content and no link to high temperature condensation. Their chemical composition is close to the
expected mean interstellar medium, although some important elements such as calcium and aluminum are
present respectively in lower and higher quantities.