<title>Approaches to resolving the question of life on Mars</title>

Abstract

After 21 years of study, a case was made that the 1976 Viking Labeled Release (LR) experiment detected microbial life in the Martian soil. However, two key factors prevent general acceptance of that conclusion. They are the failure of the Viking Gas Chromatograph Mass Spectrometer (GCMS) to find organic matter in the Martian soil; and the presumed inability of the Martian environment to support liquid water. Further examination of these often cited factors shows they do not prohibit a biological interpretation of the Mars LR results. Newly revealed information on tests made with the Viking GCMS Engineering Breadboard instrument (EBB/GCMS) attests to its inability to detect organic matter in some terrestrial soils. New work also shows that organic matter from moderate populations of micro-organisms in soil would have been undetectable. These qualifications of the Viking GCMS weaken its historical impact against a biological interpretation of the LR Mars data. The no-liquid-water argument is also shown to be flawed. Empirical data demonstrate that water does exist in liquid phase under ambient atmospheric pressures and temperatures existing on the surface of Mars. NASA's June 22 press conference announcement that the Mars Global Surveyor found extensive evidence of current liquid water on Mars adds ground truth validation. The July 10, 2000, report of indigenous micro-organisms fully metabolizing in sub-freezing South Pole snow where little, if any, water is available, demonstrates the possibility for life on Mars. A leap of faith is no longer required concerning the possibility of indigenous micro-organisms on Mars. The present hiatus from Martian exploration provides an excellent opportunity to mine and analyze data relevant to life on Mars, and to conduct meaningful experiments. An available flight type Viking GCMS can be tested to determine its sensitivity to organic matter, including micro-organisms, and provide guidance in designing future Martian organic detection instruments. Experiments could determine whether terrestrial micro-organisms could survive or grow under Martian conditions as they are now known. This could be done in combination with experiments further determining the limiting conditions of liquid water on Mars. A simple metabolic chirality experiment, based on the LR legacy, is advocated for the next Mars lander. The experiment could determine unequivocally whether living microbes exist in the soil of Mars. Suggestions for further research and development of life detection and analysis experiments are made.