RESUMO
A chamber was constructed to create simulated Martian dust storms and thereby study the survival of airborne micro-organisms while exposed to the rigors of the Martian environment, including ultraviolet irradiation. Representative types of sporeforming and non-sporeforming bacteria present in spacecraft assembly areas and indigenous to humans were studied. It was found that daily ultraviolet irradiation of 2 to 9 X 10(7) erg cm-2 was not sufficient to sterilize the dust clouds. The soil particles protected the organisms from ultraviolet irradiation since the numbers of survivors from irradiated environments were similar to those from unirradiated environments. Pending further data of the Martian environment, the contamination and dissemination of Mars with terrestrial micro-organisms is still a distinct possibility.
Assuntos
Microbiologia do Ar , Meio Ambiente Extraterreno , Marte , Tolerância a Radiação , Raios Ultravioleta , Bacillus cereus/efeitos da radiação , Bacillus subtilis/efeitos da radiação , Contenção de Riscos Biológicos , Escherichia coli/efeitos da radiação , Exobiologia , Serratia marcescens/efeitos da radiação , Solo , Esporos Bacterianos/efeitos da radiação , Staphylococcus aureus/efeitos da radiação , EsterilizaçãoRESUMO
Scanning electron microscopy was used for viewing Bacillus cereus and Staphylococcus aureus in three different soils. Both organisms were detected in the test soils at an approximate concentration of 10(7) cells per gram of soil; theoretically, the minimal number of microorganisms required for detection with the scanning electron microscope technique was between 10(7) and 10(10) cells per gram of soil. Because the concentration of cells was critical, the use of scanning electron microscopy as an extraterrestrial life detection instrument would be limited with soils containing more than 10(7) bacteria per gram of soil.