Tantalizingnew evidencehas suggested that there may bea salty lakebelow a glacier on Mars.
But what sort of life form could it be?
We are unlikely to find bigger animals in the lake though.
Mars, however, lacks the food webs needed to sustain higher organisms.
By contrast, many microorganisms are capable of inhabiting hostile environments even when no other organisms are present.
We know from research on Earth that many microbes can survive in brine.
Orange-coloured halophilic algae Dunaliella salina within sea salt.
Some are capable of cellular breathing in the absence of oxygen.
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It is therefore beyond doubt that some microbial systems could be preserved (and probably survive) on Mars.
Indeed, we know that microbes can survive long periodsin a dormant condition even without liquid water.
Microbes have also been recovered from fluids inside ancient salt crystals.
Salt helps determine whether microbial activity can take place in the water.
This parameter can dictate whether life is plausible at a specific location and time.
The types of salt and nutrients dissolved in water affect water activity.
If it is, it may be bad news for microbes.
The exact mechanism underlying this, however, remains unclear.
Such salts, which are known as chaotropic, canenable growth of microbesat much lower temperatures than usual.
The Red Planet welcomes ExoMars south pole visible.
Preservation chamber?
But being preserved is not exactly the same as being alive and kicking.
The known limits for growth on Earth lie in the range -15oC to -20oC for the most-resilient microbial species.
The limits for cellular metabolism lie somewhere in the range -20oC to -40oC.
This article was originally published onThe ConversationbyJohn E. Hallsworth, Lecturer of Environmental Microbiology,Queens University Belfast.
