Studies of the Distant Heliosphere Beyond Jupiter

Abstract

There are three motivations for making energetic particle measurements in the outer heliosphere. (1) to understand how solar activity modulates the galactic cosmic ray intensity reaching the Earth; (2) to understand the acceleration mechanisms for the anomalous cosmic rays (discussed in Chap. 8); and (3) to study the outer boundary of the heliopause as we enter for the first time the interstellar medium. The results of these studies establish the radial and latitudinal gradients for the particles, the intensity and energy spectra of the galactic cosmic rays within the constraints of the instrumentation, and if we are lucky time variations may also be revealed. It is interesting to note that the latter part of the twentieth century gave us a unique opportunity to achieve these objectives.