Regensburg 2007 – wissenschaftliches Programm
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EP: Fachverband Extraterrestrische Physik
EP 13: Cassini bei Saturn
EP 13.2: Vortrag
Donnerstag, 29. März 2007, 14:00–14:15, H46
Signatures of Enceladus in the elemental composition of E-ring particles — •Frank Postberg1, Sascha Kempf1,2, John Hillier3, Ralf Srama1, Uwe Beckmann1, Simon Green3, Neil McBride3, and Eberhard Gruen1 — 1MPI für Kernphysik, Heidelberg — 2Institut für Geophysik und extraterrestrische Physik, Universität Braunschweig — 3Planetary and Space Sciences Research Institute, The Open University, Milton Keynes, UK
The population of Saturn’s outermost tenuous E-ring, is known to be
dominated by tiny water ice particles. Active volcanism on the moon
Enceladus, embedded in the E-ring, has been known since late 2005 to
be a major source of particles replenishing the ring. Therefore
particles in the vicinity of Enceladus may provide crucial
information about dynamical and chemical processes occuring below
its icy surface.
We present a statistical evaluation of more than 2000 impact
ionisation mass spectra of Saturn’s E-ring particles, with sizes
predominantly below 1 µm, detected by the Cosmic Dust Analyser
onboard the Cassini spacecraft. We focus on the identification of
non-water features in spectra dominated by water ice signatures. We
specify the categorisation of two different spectrum types, which
probably represent two particle populations. Silicate minerals
and/or organic compounds are identified as the most abundant
impurities within the icy particles. This finding hints at dynamic
interaction of Enceladus’ rocky core with liquid water.