The Soho project and helioseismology

Abstract

The Solar and heliospheric observatory (Soho) space mission being developed by ESA and NASA will carry together with other instruments devoted to the study of the solar atmosphere and solar wind, a set of instruments that will provide a comprehensive set of measurements of solar oscillations. Two investigations in Soho aim primarily at the study of g-modes and low l p-modes and a third one will have the central interest in high degree oscillations while aiming to extend the validity of its measurements to low 1 modes overlapping with the other two investigations. The Soho mission is being designed having into account the needs of the helioseismology experiments and therefore should be able to provide the best possible infrastructure for the production of good quality data. For the data analysis the three experiments will coordinate their operation and the data handling. It is expected that Soho will greatly profit of the experience gained with GONG, as a large fraction of the co-investigators in the Soho helioseismology investigations form part of the GONG project. The investigations in Soho have finished the definition phase of their instruments and the contractor selected by ESA has started on 1 December 1989 the industrial Phase B, or design phase, of the spacecraft and mission for a launch in March 1995.