Cosmic ray (CR) research can rightfully be called the prime precursor of space research. Initial interest focused on their composition and origin, their use to generate mesons and “strange particles”, and to study solar flares and interplanetary perturbations. I will tell about our work in the high Andes (1949-52) to measure the absorption of CRs in the atmosphere and its variation with geomagnetic latitude, and describe the logistic, political and financial struggles typical of science in a developing country. After 1955 our interest shifted to the study of high-energy solar flare protons and solar wind modulations, for which we established a chain of four CR observatories along the Andes and in Antarctica for the IGY. In 1960 we started with high-altitude balloon and sounding rocket experiments (the first in Latin America), mainly for the detection of Bremsstrahlung x-rays from trapped electrons precipitating in the South Atlantic Anomaly. During a two-year stint as a Senior National Academy Fellow at GSFC in 1964-66, I developed numerical programs on the interaction with the atmosphere of trapped particles (natural and from high altitude nuclear bursts). After our permanent move to the US in 1967, theoretical radiation belt physics became my main subject of research. I will discuss some less-known aspects of that research, like using the concept of drift shell as a tool for the study of internal geomagnetic field sources in the core and mantle, and their secular variations; mapping Jupiter’s auroral precipitation; and attempts to understand the tiny sub-magnetosphere of Ganymede.
Getting involved in international programs, I organized the International Magnetospheric Study, the Solar-Terrestrial Energy Program and GEM, all of which became a rich source of stories to tell. With T. Malone and H. Friedman of the NAS, I organized the initial phase of ICSU’s International Geosphere-Biosphere Program. I will discuss the fierce battles about initial IGBP planning between space, middle atmosphere, lower atmosphere, biosphere and solid earth scientists.