At this early stage in our understanding of how life originated, the search for evidence that life might have evolved on Mars is necessarily guided by our knowledge of the range of environmental niches that can be successfully occupied by terrestrial life forms. Every year we are surprised to find some new example of micro-organisms that have adapted to thrive under circumstances that would once have seemed out of the question -- in niches that range from boiling hot mid ocean "smokers" to permanently ice-covered lakes to the insides of rocks to lightless subterranean caverns.
Considering the cold, dry characteristics of the martian surface, what kind of micro-organism could survive and develop on Mars? The table below provides some information about the range of hardiness for terrestrial organisms.
Organism Oxygen High resistance High resistance Growth Niches
needs to UV to dessiccation Rate
Green algae Yes No No Fast (h) Soil (surface
and subsurface)
Lychen Yes Yes Yes Very slow Rock surface,
(years) trees
Moss Yes No No Slow (weeks) Wet surface
Blue algae No No Yes Fast (h) Soil (surface
and subsurface)
Typical martian No Yes Yes Very fast Soil (surface
Organism (mn) and subsurface) Water
Return to the Landing Site Catalog