Carbon Monoxide as a Basis for Primitive Life on Other Planets

Abstract

IN considering the possibility of life on other planets, we are naturally prejudiced towards some variant of the terrestrial photosynthetic mechanism, for CO₂ fixation. Such a prejudice is reasonable: photosynthesis is efficient and we know that it works. But there are reasons why such a cycle may not be likely on a planet such as Mars. The chemical machinery required for photosynthesis is exceedingly complex and is unlikely to be available to the most elementary organisms. Furthermore, on many planets, such as Mars, there is a considerable flux of high energy ultraviolet radiation which reaches the planetary surface¹ and which will tend to rupture bonds in organic molecules. Because photosynthetic organisms must be exposed to light, it seems unlikely that they could survive for long in the face of this radiation. It is, of course, conceivable that an organism could develop protective or self-repairing capabilities, but this would be particularly difficult for primitive life: in these conditions, life would be easiest in the shade. This would disfavour, but not exclude, an energy cycle based on photosynthesis.