A wealth of unique observations are available for studying explosive processes from the sun in the form of in-situ measurements of plasma properties such as the magnetic field, temperatures, elemental abundances, ion charge state distributions and energy spectra of solar energetic particles. In this talk I will outline some of the outstanding questions concerning coronal mass ejections (CMEs) in two distinct areas; the eruption mechanism of the event itself and the acceleration of solar energetic particles (SEPs). I will then show how in-situ measurements have begun to address these questions. In particular, ion charge state distributions from the CME ejecta reflect the origin of the ejected material as well as the heating that occurred during the launch of the CME. Relative elemental abundances and the energy spectra of different ions of the solar energetic particles can reveal the conditions under which SEP acceleration is efficient at the shocks triggered by a CME.
Received December 6, 2007