Using optical and radio data first from the SMM spacecraft and then ground stations it was possible to identify periods when CME material passed the spacecraft. Because of limitations in telemetry, the observations were incomplete, but there were sufficient data to identify differences between material from CMEs and the average solar wind. Results of CME composition observations are listed in Table 2. Sector boundary crossings are open field structures associated with reversals in magnetic polarity on the surface of the sun. Some preliminary results are listed in Table 2.
Coronal holes are another type of structure on the solar surface.
Because of the size of the polar coronal holes the high speed solar wind often carries away most of the mass flux and is therefore of great importance. The results relied on the fact that high speed solar wind compresses the magnetosphere so that the spacecraft which was normally inside the magnetopause was temporarily in the magnetosheath, where the abundances of multiply charged ions should not differ appreciably from those in the solar wind. Only a small number of samples met this criterion, and the results are included in Table 2. In Table 2 we compare the composition of solar wind from open and closed magnetic field structures, with the average solar wind, and the photosphere from Table 1. Also included are composition data derived from the Skylab spectroscopic observations that are also associated with well defined magnetic field topologies.