Habitability Assessment
Life is understood to require liquid water, but it is not the only essential requirement for life. These requirements include water, an energy source, and materials necessary for cellular growth, while all under appropriate environmental conditions. The confirmation that liquid water once flowed on Mars, the existence of nutrients, and the previous discovery of a past magnetic field that protected the planet from cosmic and solar radiation, together strongly suggest that Mars could have had the environmental factors to support life. To be clear, the find of past habitability is not evidence that Martian life has ever actually existed.
When there is a magnetic field, the atmosphere is protected from erosion by solar wind, and ensures the maintenance of a dense atmosphere, necessary for liquid water to exist on the surface of Mars. The two current ecological approaches for predicting the potential habitability of the Martian surface use 19 or 20 environmental factors, with emphasis on water availability, temperature, presence of nutrients, an energy source, and protection from solar ultraviolet and galactic cosmic radiation. In particular, the damaging effect of ionising radiation on cellular structure is one of the prime limiting factors on the survival of life in potential astrobiological habitats. Even at a depth of 2 meters beneath the surface, any microbes would likely be dormant, cryopreserved by the current freezing conditions, and so metabolically inactive and unable to repair cellular degradation as it occurs.
Therefore, the best potential locations for discovering life on Mars may be at subsurface environments that have not been studied yet. The extensive volcanism in the past, possibly created subsurface cracks and caves within different strata, and liquid water could have been stored in these subterraneous places, forming large aquifers with deposits of saline liquid water, minerals, organic molecules, and geothermal heat – potentially providing a current habitable environment away from the harsh surface conditions.
Read more about this topic: Water On Mars
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