Journal cover Journal topic
Annales Geophysicae An open-access journal of the European Geosciences Union
Ann. Geophys., 32, 1441-1453, 2014
https://doi.org/10.5194/angeo-32-1441-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.
Regular paper
28 Nov 2014
A comparison between VEGA 1, 2 and Giotto flybys of comet 1P/Halley: implications for Rosetta
M. Volwerk1, K.-H. Glassmeier2, M. Delva1, D. Schmid1, C. Koenders2, I. Richter2, and K. Szegö3 1Space Research Institute, Austrian Academy of Sciences, 8042 Graz, Austria
2Institute for Geophysics and Extraterrestrial Physics, TU Braunschweig, Germany
3Wigner Research Centre for Physics, Institute for Particle and Nuclear Physics, Hungarian Academy of Sciences, Budapest, Hungary
Abstract. Three flybys of comet 1P/Halley, by VEGA 1, 2 and Giotto, are investigated with respect to the occurrence of mirror mode waves in the cometosheath and field line draping in the magnetic pile-up region around the nucleus. The time interval covered by these flybys is approximately 8 days, which is also the approximate length of an orbit or flyby of Rosetta around comet 67P/Churyumov–Gerasimenko. Thus any significant changes observed around Halley are changes that might occur for Rosetta during one pass of 67P/CG. It is found that the occurrence of mirror mode waves in the cometosheath is strongly influenced by the dynamical pressure of the solar wind and the outgassing rate of the comet. Field line draping happens in the magnetic pile-up region. Changes in nested draping regions (i.e. regions with different Bx directions) can occur within a few days, possibly influenced by changes in the outgassing rate of the comet and thereby the conductivity of the cometary ionosphere.

Citation: Volwerk, M., Glassmeier, K.-H., Delva, M., Schmid, D., Koenders, C., Richter, I., and Szegö, K.: A comparison between VEGA 1, 2 and Giotto flybys of comet 1P/Halley: implications for Rosetta, Ann. Geophys., 32, 1441-1453, https://doi.org/10.5194/angeo-32-1441-2014, 2014.
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Short summary
We discuss three flybys (within an 8-day time span) of comet 1P/Halley by VEGA 1, 2 and Giotto. Looking at two different plasma phenomena: mirror mode waves and field line draping; we study the differences in SW--comet interaction between these three flybys. We find that on this time scale (comparable to Rosetta's orbits) there is a significant difference, both caused by changing outgassing rate of the comet and changes in the solar wind. We discuss implications for Rosetta RPC observations.
We discuss three flybys (within an 8-day time span) of comet 1P/Halley by VEGA 1, 2 and Giotto....
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