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EP: Extraterrestrische Physik
EP 5: Mars, Staub
EP 5.6: Fachvortrag
Mittwoch, 10. März 2004, 17:25–17:45, C
Measurements of Interstellar Dust in the Heliosphere at 1 AU — •Nicolas Altobelli1, Sascha Kempf1, Ralf Srama1, Harald Krueger1, and Eberhard Gruen1,2 — 1Max Planck Institut fuer Kernphysik, Postfach 103980, 69029 Heidelberg Germany — 2Hawaii Inst. of Geophysics and Planetology, Univ. of Hawaii, Honolulu, USA
In-situ dust measurements with the Ulysses and Galileo spacecraft outside 3 AU heliocentric distance revealed a collimated stream of interstellar dust particles sweeping through our solar system. Here we report the successful in-situ detection of interstellar particles in the inner solar system at about 1AU. Interstellar dust particles have been successfully measured in the inner solar system with the dust instruments on the Cassini and Galileo spacecrafts. Both instruments employ the impact ionisation mechanism: dust particles hitting a solid metal target vaporize due to the impact and generate a plasma cloud. The measured charge signals generated upon impact provide indications about particles mass, impact speed, and rough elemental composition (the latter only in the case of Cassini). Analysis of the data from both instruments together with kinematic and geometric considerations allowed a separation of interstellar particles from interplanetary dust. The values of the interstellar dust flux derived from the Galileo and Cassini data at about 1 AU are in good agreement together. A detailed analysis of the Galileo interstellar dust data provided new evidences for the radiation pressure filtering, previously identified by Ulysses. Furthermore, the presented data also show evidences of a gravitative focusing effect on interstellar dust.