M. Hilchenbach

The solar origin of corotating interaction regions and their formation in the inner heliosphere, Report of Working Group 1

Corotating Interaction Regions (CIRs) form as a consequence of the compression of the solar wind at the interface between fast speed streams and slow streams. Dynamic interaction of solar wind streams is a general feature of the heliospheric medium; when the sources of the solar wind streams are relatively stable, the interaction regions form a pattern which corotates with the Sun. The regions of origin of the high speed solar wind streams have been clearly identified as the coronal holes with their open magnetic field structures. The origin of the slow speed solar wind is less clear; slow streams may well originate from a range of coronal configurations adjacent to, or above magnetically closed structures. This article addresses the coronal origin of the stable pattern of solar wind streams which leads to the formation of CIRs. In particular, coronal models based on photospheric measurements are reviewed; we also examine the observations of kinematic and compositional solar wind features at 1 AU, their appearance in the stream interfaces (SIs) of CIRs, and their relationship to the structure of the solar surface and the inner corona; finally we summarise the Helios observations in the inner heliosphere of CIRs and their precursors to give a link between the optical observations on their solar origin and the in-situ plasma observations at 1 AU after their formation. The most important question that remains to be answered concerning the solar origin of CIRs is related to the origin and morphology of the slow solar wind.

Impact on a comet: Rosetta Lander simulations

Abstract In the year 2012 the Rosetta Lander will be ejected from the Rosetta orbiter and, after a descent time of up to 3xa0h, touch the surface of comet 46P/Wirtanen. The objective of the simulations of the landing on a comet is the analysis and understanding of the dynamics of the Rosetta Lander on impact on the comet surface. The Lander properties are well known prior to launch. The data on the comet surface are far less familiar and must be described within an envelope covering a range of possible physical surface parameters. The kinetic energy of the Lander is damped on impact in less than 1xa0s and the Lander must be secured on the cometary surface. The 3-D simulations are carried out in the frame of a multibody analysis and the positions, velocities, applied and constrain forces are analysed.

The effect of surface texture on the mineralogical analysis of chondritic meteorites using Raman spectroscopy

Abstract Raman imaging on different types of meteorite surfaces was performed. Three different surface textures on a chondritic meteorite from the Dhofar 005 strewnfield and a fourth surface with a very rough texture on a goethite mineral have been investigated. The Raman measurements were made with and without autofocus. The influence of the surface texture on the quality of the Raman spectra was analyzed. The percentage of the informative Raman spectra obtained from every sampled area were sufficient to assert the local mineral composition. For obtaining a spatial distribution of minerals (in the micrometer range), an autofocus device needed to be employed. It was found that approximately 85% of all Raman spectra taken at λ ext =633 nm show sufficient information to establish a clear assignment to a certain mineral. In the case of the rough goethite surface, measured without an autofocus device approx. 60% of the recorded spectra could be assigned.