Nature 362, 428 - 430 (01 April 1993); doi:10.1038/362428a0

Discovery of Jovian dust streams and interstellar grains by the Ulysses spacecraft

E. Grün, H. A. Zook^*, M. Baguhl, A. Balogh^†, S. J. Bame^‡, H. Fechtig, R. Forsyth^†, M. S. Manner^§, M. Horanyi^∥, J. Kissel, B.-A. Lindblad^¶, D. Linkert, G. Linkert, I. Mann^£, J. A. M. McDonnell^**, G. E. Morfill^††, J. L. Phillips^‡, C. Polanskey^§, G. Schwehm^‡‡, N. Siddique, P. Staubach, J. Svestka^§§ & A. Taylor^**

Max-Planck-lnstitut für Kernphysik, 6900 Heidelberg, Germany
^* NASA Johnson Space Center, Houston, Texas 77058, USA
^† The Blackett Laboratory, Imperial College, London SW7 2BZ, UK
^‡ Los Alamos National Laboratory, University of California, Los Alamos, New Mexico 87545, USA
^§ Jet Propulsion Laboratory, Pasadena, California 91109, USA
^∥ Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado 80309, USA
^¶ Lund Observatory, 221 Lund, Sweden
^£ Max-Planck-lnstitut fur Aeronomie, 3411 Katlenburg-Lindau, Germany
^** University of Kent, Canterbury, CT2 7NR, UK
^†† Max-Planck-lnstitut fur Extraterrestrische Physik, 8046 Garching, Germany
^‡‡ European Space Research and Technology Centre, 2200 AG Noordwijk, The Netherlands
^§§ Prague Observatory, 11846 Prague 1, Czech Republic

ON 8 February 1992, the Ulysses spacecraft flew by Jupiter at a distance of 5.4 AU from the Sun. During the encounter, the spacecraft was deflected into a new orbit, inclined at about 80^° to the ecliptic plane, which will ultimately lead Ulysses over the polar regions of the Sun¹. Within 1 AU from Jupiter, the onboard dust detector² recorded periodic bursts of submicrometre dust particles, with durations ranging from several hours to two days, and occurring at approximately monthly intervals (28 ± 3 days). These particles arrived at Ulysses in collimated streams radiating from close to the line-of-sight direction to Jupiter, suggesting a jovian origin for the periodic bursts. Ulysses also detected a flux of micrometre-sized dust particles moving in high-velocity ( =26 km s^-1) retrograde orbits (opposite to the motion of the planets); we identify these grains as being of interstellar origin.

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