Survivability and protection of bacterial spores in space - the BIOPAN experiment

For the study of the responses of organisms to the space environment the survivability of bacterial spores of Bacillus subtilis exposed to different subsets of the extreme environmental parameters in space (vacuum, extraterrestrial solar UV, shielding by protecting materials like clay, red sandstone, Martian "soil" analogue or meteorite powder) was investigated in the BIOPAN facility of the European Space Agency onboard of Russian Earth-orbiting Foton satellites (BIOPAN 1-3 missions). After about 2 weeks in space, unprotected spores were completely or nearly completely inactivated. In contrast, the survival rate was about 1 to 7×10^-3, if spores in dry layer were directly mixed with powder of clay, rock or meteorites. These data confirm the deleterious effects of extraterrestrial solar UV radiation and show the extraordinary resistance of spores against vacuum. It can be concluded that for planetary protection requirements of a lander mission a careful sterilization of all parts of a spacecraft which are not directly exposed to the solar UV radiation is absolutely necessary.