HR: 08:22h
AN: SH21D-02 INVITED     [Abstracts]
TI: Preparing for STEREO - Revisit Helios!
AU: * Schwenn, R
EM: schwenn@linmpi.mpg.de
AF: Max-Planck-Institut fuer Sonnensystemforschung, Max-Planck-Str.2, Katlenburg-Lindau, 37191 Germany
AB: Exactly 30 years ago, the first Helios solar probe was launched into an elliptical heliocentric orbit, with a perihelion of 0.3 AU. It had a set of then modern particle and field instruments on board, but no imagers. One year later, an almost identical probe was put into a very similar orbit, approaching the Sun even a bit closer. For most of their common lifetime of 4 years, the two probes were separated in longitude by no more than about 30 degrees. Further, due to their special orbits, they spent many months above the Sun's limb (as seen from Earth). In conjunction with the Earth-orbiting IMP 7&8 satellites and the Voyager 1&2, and the Pioneer 10&11 space probes, real multipoint studies covering large parts of the heliosphere could be performed successfully for the first time. The Helios mission resembled the upcoming STEREO mission in several respects and was indeed of good use for defining the STEREO science goals. For example, Helios could reveal details about the longitudinal and latitudinal solar wind stream structure, it allowed unique associations between limb CMEs and their radial propagation towards an in-situ observer, and the propagation of solar energetic particles could be studied. However, since then our understanding of the heliosphere has improved considerably, thanks to recent space missions (Ulysses, Yohkoh, SOHO, Wind, ACE) and to more and more refined theoretical models. In view of these new results, it appears worthwhile to revisit the huge Helios data sets since they certainly keep hiding some answers that future observations from STEREO might benefit from.
DE: 7513 Coronal mass ejections
DE: 7851 Shock waves
DE: 2102 Corotating streams
DE: 2164 Solar wind plasma
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2004 AGU Fall Meeting