Solar Flares and Magnetospheric Particles: Investigations Based Upon the ONR-602 and ONR-604 Experiments

Abstract : The study of solar flares, and the interaction of solar flare radiations with the geospace environment, is one of the most fundamental investigations in space science. Involved are basic questions about the mechanism for energy generation in the flare region, the conversion of this energy into high energy charged particles, neutrons, x-rays and gamma rays, the interplanetary propagation of the particles to Earth, the access of these particles to the magnetosphere and the changes initiated in our local environment due to the solar flare. In the latter case, the solar particles are superposed upon an existing background of geomagnetically trapped and pseudo- trapped charged particles, which are themselves of fundamental importance in the dynamics of the geospace environment. While these questions are quite compelling scientifically, they also have important practical applications. The influence of solar activity and the consequent geomagnetic disturbances on the availability and quality of long range, short wave radio communication is perhaps the best known of the solar effects. With the advent of the space program and the ever increasing use of the space environment for both civilian and military applications, the consequences of space radiations are becoming a major operational concern since possible effects of such radiations include: the long-term degradation of hardware in the space environment, the abrupt failure of space systems due to a short-term event or even a single, intensely ionizing particle, and limitations imposed by the radiation environment on the human presence in orbit. Our ability to assess the resulting operational limitations depends both on detailed knowledge of the geospace environment and its spatial and temporal variability and on the degree of sophistication of the space systems that are required to operate there.