Bacteria under simulated Martian conditions.

The behavior of organisms in simulated Martian conditions is of great importance to exobiology for two reasons: (1) Because of the extreme environment of Mars, the likelihood of contamination of the planet by earth organisms is considered slight by some scientists. To date, there has been little evidence to contradict this supposition. Such evidence is presented. (2) The selection and adaptation of earth bacteria to Martian conditions is potentially significant in understanding Martian life, if it exists, and may be helpful in designing life-detection techniques and devices. Of course, simulation attempts, based on current knowledge of the Mars environment, may be far from the actual conditions, and extrapolations made from such situations of no real significance. However, generalizations can be made and cautious interpretation of the results of those experiments seems well worth reporting. A new technique for simulation of known parameters of the Martian environment is discussed along with possible biological implications. The response of bacteria to such simulation is demonstrated in terms of survival and growth, showing that certain bacteria will not only survive, but grow during simulated Martian freeze-thaw cycling if water is present. Ways are demonstrated in which water can be present on Mars although not detectable with current technology. Plans for future experimentation are discussed.