Life under Conditions of Ionizing Radiation

Abstract

Life on Earth, throughout its almost 4 billion years history, has been shaped by inter- actions of the organisms with their environment. It has developed with an ever present radiation background. As a powerful mutagen it has contributed to biological evolu- tion, however, it is potentially destructive for individual cells and organisms [1]. Radiation response differs extremely for different organisms and there is not necessarily a correlation between species radiation resistance and levels of exposure in the natural environment [2]. In our solar system Earth is not the only planet, which had the capacity to provide the prerequisites for sustaining life. Mars and the Jupiter moon Europa are suggested to have had the capacity to support life, at least for a certain era. The detection of meteorites on Earth that originate from Mars supports the theory of interplanetary transfer of life (see Chapter 4, Horneck et al.). Life on other planets or while it is transported through space environment encounters radiation conditions different from those on Earth. In order to understand the likelihood of the development and the chance of persis- tence of life on Earth or other planets, following questions have to be asked: 1. What is the "normal" radiation environment under which life flourishes on Earth? 2. What is the "worst case" radiation environment that life will encounter in space? 3. How does radiation interact with living matter and how does life actively modulate radiation effects?