Antarctica as a Martian model

Previous investigators have reported that the microbiological population of the glacier free valleys of southern Victorialand, Antarctica, is sparse, and that from about 10% of the soil samples examined no micro-organisms could be cultivated. Since these areas are assumed to be more favorable to the growth of terrestrial organisms than any Martian environment, the previous authors concluded that the probability of terrestrial organisms growing on Mars would therefore be so small that sterilization standards could be relaxed by many orders of magnitude. The unsuitability of the Antarctic environment to the multiplication of terrestrial micro-organisms was ascribed by them to limiting amounts of water. We have carried out a survey of a variety of environments in the dry valleys, ranging from mountain crests to valley floors. The main purpose of our investigation was the determination of active microbial multiplication in the soil. A series of techniques was employed which permitted the detection of bacterial growth in situ. All evidence points to an active growth of micro-organisms in the Antarctic soil in all locations which we examined. The measurements were supported by electron micrographs of soil films which showed colonial growth covering soil particles. These findings suggest that Antarctica does not serve as a useful model for the Martian environment in evaluating quarantine standards.