Abstract
We have studied on the ability of living organisms to survive under extraterrestrial condition. Several species of terrestrial microorganism, i.e., virus, bacteria, yeast and fungi have been tested in our work. The subject is not restricted to an academic curiosity, but concerns problems to prevent the contamination of outer planets with terrestrial microorganisms carried by spaceprobes. The interplanetary environment in solar system was simulated with a wide range of temperature (100K-500K), high vacuum (1xl0-8 torr) by using a cryostat, and proton irradiation from a Van de Graaff accelerator in Tokyo Institute of Technology. After the exposure to a simulated extraterrestrial circumstance, some species of the microorganisms were examined. Tobacco mosaic virus, some species of coccus and spores of Bacillus subtilis, Aspergillus niger and Clostridium mangenoti showed considerably high survival rates even after proton irradiation.
