Multi-Spacecraft Observations of Energetic Particles Associated With Interplanetary Shocks in the Inner Heliosphere

The Helios 1 and 2 spacecraft made unique observations of the inner heliosphere (0.3 1 AU) during 1974 1986 (Helios 1) and 1976 1980 (Helios 2). In conjunction with observations from near-Earth spacecraft, the properties of energetic particles associated with interplanetary shocks can be investigated at multiple locations. We summarize observations made by the Goddard and University of Kiel instruments on Helios 1 and 2, and Goddard instruments on IMP 8 and ISEE 3 at 1 AU, in the vicinity of a number of interplanetary shocks. These observations include particle intensities, spectra, anisotropies, limited composition information, and the relationship to interplanetary structures. Finally, we discuss the contribution that the combination of Inner Heliospheric Sentinels at 0.25 AU and near-Earth spacecraft might make to understanding interplanetary shock acceleration.